State v. Sercey (825 So. 2d 959, 2002)

BARFIELD, J.

In this prosecution for DUI manslaughter and other related offenses, the State of Florida appeals the trial court’s order which excludes all evidence of marijuana in the defendant’s blood. Applying the principles enunciated in Frye v. United States, 293 F. 1013 (D.C.Cir.1923), and its Florida progeny, we reverse the order in part.

About noon on April 19, 1998, Rachel Sercey was driving a van carrying disabled persons on State Road 121 in Ala-chua County. The vehicle was traveling at a high rate of speed when the right rear tire began to come apart. According to witnesses, Sercey failed to brake and eventually lost control of the vehicle, which overturned. Three of the ejected disabled passengers died of their injuries. The injured Sercey was taken to a hospital, where it was noted that she smelled of alcohol and she admitted, “I had a couple beers before work” and “I smoke a little weed.”

A medical specimen of Sercey’s blood, drawn about one hour after the accident and tested in the hospital lab, indicated that her blood alcohol concentration (BAC) was “below detectable limits” (i.e., less than .02 grams/deciliter). A legal specimen of Serce/s blood, drawn almost three hours after the accident at the request of the Florida Highway Patrol (FHP) and tested by the Florida Department of Law Enforcement (FDLE) crime laboratory, indicated a BAC of .068 grams/deciliter.

The legal blood specimen was sent to the Chemical Toxicology Institute in Foster City, California, a private clinical and forensic toxicology lab directed by Dr. Randall Baselt, Ph.D. The lab received the blood specimen, and an accompanying letter from the FHP requesting analysis for marijuana, by express mail on May 27, 1998. The blood specimen was analyzed for marijuana on June 11 and 12, 1998. It was initially subjected to a preliminary radioimmunoassay (RIA) which indicated the presence of cannabinoids (chemical compounds found in marijuana) including tetrahydrocannabinol (THC), the psychoactive component of marijuana. The blood specimen was then subjected to GC/MS analysis to confirm and quantify the amount of THC and its more stable primary inactive metabolite, carboxytetrahy-drocannabinol (referred to variously as cTHC, earboxy-THC, THCCOOH, or THC acid). Briefly stated, GC/MS analysis involves solvent extraction of the cannabi-noids from the blood matrix, evaporation of the solvent and chemical reaction of the residue with a derivatizing agent to obtain a compound that can be directly injected into the GC/MS instrument, and separation of the individual cannabinoids by gas chromatography (GC), using a connecting mass spectrometer (MS) as the detector. This confirmation test indicated that the blood specimen contained 5.5 ng/ml THC and 91 ng/ml cTHC.

Sercey was charged with three counts of DUI manslaughter, three counts of vehicular homicide, and two counts of DUI with serious bodily injury. Her coworker, Ev-ertice Cole, was charged with seven counts of abuse or- neglect of disabled persons, and pled no contest to seven counts of culpable negligence. Cole was expected to testify at Sercey’s trial that she was with Sercey the entire day of the accident, but did not see Sercey consume marijuana, and that Sercey did not appear to be impaired. The state apparently, does not have an eyewitness willing to testify that Sercey consumed marijuana prior to the accident.

Sercey filed motions in limine seeking to exclude opinion testimony by the state’s toxicology experts, Dr. Baselt and Dr. Bruce Goldberger, regarding the results of the RIA screen and GC/MS analysis, as well as their opinions regarding the recen-cy of her use of marijuana prior to the blood specimen being drawn, the method of ingestion (i.e., that she had smoked marijuana as opposed to ingesting it by other means), and whether she was impaired by alcohol and marijuana at the time of the accident. She asserted that Dr. Baselt’s testing procedures “are not reliable and not generally accepted in the relevant scientific field,” that the general principle or theory underlying the expert opinions “is not sufficiently established to have gained general acceptance in the relevant scientific fields,” and that “application of the scientific principles to the facts of this case and the conclusions drawn by the State’s experts are not reliable and not generally accepted by the scientific community.” She argued that no conclusions regarding impairment could be drawn from the THC/cTHC test results because there was only one blood specimen and because there is “no consensus in the scientific community as to any specific level of THC in blood that correlates with impairment.” She asserted that impairment is an element'of the state’s proof of DUI manslaughter, an ultimate issue which is for the jury to decide by applying a legal standard to the facts, and that any opinion regarding impairment by the state’s experts “is speculative and is not based on scientific principles” because the scientific tests upon which the state’s experts rely “only show whether a driver consumed alcohol or drugs” and “do not measure impairment,” and because there is “no consensus in the scientific community that the use of marijuana necessarily impairs a person’s ability to drive” and “no consensus in the scientific community as to any specific level of THC or THC metabolites in the blood that correlates with impairment.”

Sercey argued that “opinions as to the time of usage of marijuana” based on mathematical models developed in studies conducted by Dr. Huestis and others (the Huestis models) are not sufficiently established to have gained general acceptance in the relevant scientific community for several reasons. She asserted that the Hues-tis models were developed using “naive users of marijuana,” that they were based on smoking marijuana (as opposed to other routes of ingestion), that they were based on “analysis of plasma concentrations of THC, as opposed to analysis of whole blood” (asserting that conversion between plasma and whole blood test results is more complex for THC than for alcohol), and that they “have not yet been widely peer reviewed for use in a forensic, legal setting.” She argued that application of the Huestis models to the facts of this case is improper and unreliable because Dr. Baselt’s calculations erroneously assumed that the partition coefficient for cTHC was the same as for THC, because there was evidence that she was a chronic marijuana user, but no evidence that she smoked marijuana on the date of the accident, and because the ranges of possible times of use based on the Huestis models “are too broad, and there is too much uncertainty as to the accuracy of those ranges in this case.”

The state contended that because there was no serious controversy with regard to the relevance of the challenged testimony or the qualifications of the experts, the only issue was whether the expert testimony was based on a scientific principle or discovery that is “sufficiently established to have gained general acceptance in the particular field in which it belongs.” It conceded that “the burden is on the proponent of the evidence to prove the general acceptance of both the underlying scientific principle and the testing procedures used to apply that principle to the facts at hand,” but pointed out that a Frye hearing “is not necessary for areas of science well established over the years.” The state did not dispute “that the scientific basis and methodology underlying the determination that an identifiable quantity of either alcohol or marijuana was in the defendant’s blood is arguably subject to a Frye determination,” but it challenged the suggestion by defense counsel “that once the ability of an expert to testify as to the presence of alcohol or marijuana in blood is established and meets the Frye test, an additional Frye determination must be made as to the opinion that flows from the data concerning the presence of alcohol or marijuana in the blood.” It asserted that “the mere fact that the defense will produce testimony challenging the conclusions and methodologies employed by the State’s experts does not require suppression when the Court nonetheless finds those conclusions to be generally accepted in the scientific community,” citing Coppolino v. State, 223 So.2d 68 (Fla. 2d DCA 1968), appeal dismissed, 234 So.2d 120 (Fla.1969), cert. denied, Coppolino v. Florida, 399 U.S. 927, 90 S.Ct. 2242, 26 L.Ed.2d 794 (1970).

Citing Florida Power & Light Co. v. Tursi, 729 So.2d 995 (Fla. 4th DCA 1999), the state asserted that “there is nothing new or novel about an expert who possesses the requisite background to do so rendering an opinion as to impairment based on the presence of intoxicants such as alcohol and marijuana,” and that “under Section 90.704, the facts or data relied upon by an expert to support an opinion need not be admissible so long as those facts or opinions are of a type reasonably relied upon by experts in that field.” Citing State v. McClain, 525 So.2d 420 (Fla.1988), and other cases, it contended that “evidence of the presence of intoxicants is relevant and admissible in a prosecution of the sort involved in this case even if no quantitative analysis is possible because even a small amount of drugs can explain impaired conduct.” It asserted that the expert opinions on impairment were scientific, not legal, and challenged the argument that the opinions “would invade the ultimate province of the jury,” citing Gutierrez v. State, 739 So.2d 1175 (Fla. 3d DCA 1999). It stated that it would establish “by the required burden of preponderance that the methodology employed by the State’s experts in this case is generally accepted in the relevant scientific community, that the results obtained thereby are thus admissible, and that the State’s expert witnesses should be allowed to render opinions interpreting such for the assistance of the jury.”

THE FRYE HEARING

At the hearing on the motions in limine, the court qualified two experts for the state and three experts for the defense. The experts agreed on the pharmacokinet-ics of marijuana in the human body, explaining that marijuana is “a very lipophilic” chemical which is rapidly absorbed into the bloodstream when smoked, then is transferred into the fat tissues of the body, including the brain. The level of THC in the blood declines rapidly over the first few hours, then “levels out” and is dissipated over a period of days. The potency of the marijuana does not affect the absorption and dissipation calculations. A chronic user would have a residual or baseline level of THC in the blood as high as 2 ng/ml, and a baseline level of cTHC in the range of 10-20 ng/ml. All of the experts opined that Sercey’s reported blood levels of THC and cTHC were significantly higher than the expected residual levels of chronic users.

The experts agreed that the generally accepted method of analyzing for THC and cTHC in blood or plasma employs an RIA screen to determine which drugs are present, then confirmation and quantification by GC/MS after isolation of the target compound from the matrix. The experts who were queried regarding the issue agreed that a single blood specimen is common in law enforcement, and that use of a single blood specimen does not affect the accuracy of the GC/MS analysis. None of the experts found fault with the techniques Dr. Baselt’s lab used for preparing the calibration standards and internal standard solutions used in the analysis, nor with the liquid-liquid extraction technique used to isolate the THC/cTHC from the blood specimen and the standards, nor with the techniques for evaporating the solvent and chemically reacting the residues with the derivatizing agent, nor with the injection of the prepared specimen and standards into the GC/MS instrument, nor with the calibration and functioning of the GC/MS instrument.

The experts agreed that certain “quality control” procedures are necessary to insure the accuracy and precision of analytical test results. Analytical laboratories are accredited by various organizations and, as part of the accreditation, are regularly inspected and participate in “proficiency studies,” in which identical portions of the same sample are analyzed by many labs at the same time in order to check the accuracy of each procedure as it is performed in the individual participating labs. Dr. Baselt’s lab is accredited by the California Department of Health and the U.S. Department of Health and Human Services. The lab participates in proficiency testing for cTHC, but not THC because, as Dr. Baselt explained: “I don’t think anybody has found a stable medium for THC that could be sent out to many different laboratories across the country and analyzed at different times.” Dr. Baselt testified that his 1983 study of comparative testing of THC and cTHC in whole blood and in serum/plasma demonstrated that THC is not stable in blood, and the other experts agreed with this conclusion.

Another quality control requirement upon which the experts agreed is that a new analytical procedure must be validated before it is routinely used, usually by exhaustive and rigorous studies. The experts agreed that the GC/MS procedure has been properly validated and is considered the most accurate method of identifying and quantifying drugs and their constituent components, including THC and cTHC.

The experts also agreed that in order to quantify the GC/MS results, it is important to analyze, simultaneously with the “unknown sample” (in this case, Sercey’s legal blood specimen), one or more of several types of “known samples.” However, the testimony in this case is complicated by the various names and descriptions the experts used with regard to these “known samples,” of which we have been able to delineate three categories.

The first category of known samples discussed by the experts is a set of “calibrators” or “standards,” samples prepared in a matrix of blood, ethanol, or some other solvent, each of which contains a known amount of the target compound. A set of calibration standards includes a sample that contains none of the target compound (a “negative” standard), a sample that contains a known amount of the target compound which is more than the amount expected to be in the “unknown sample,” and several samples that contain various known amounts of the target compound within the foregoing range. Dr. Baselt’s lab extracted and analyzed, simultaneously with Sercey’s blood sample, a set of six calibration standards prepared in a blood matrix, including a “negative” standard and five “positive” standards, each of' which was “spiked” with a different measured amount of THC/cTHC. The concentrations of the standard samples ranged from no THC to 25 ng/ml THC, and from no cTHC to 250 ng/ml cTHC. The concentrations of THC and cTHC in Sercey’s blood specimen fell within the range of concentrations of this “standard curve.”

The second category of known samples, frequently used in GC analysis, is an “internal standard,” a measured amount of a compound which is chemically similar to the target compound and is added to every sample, both known and unknown. Because the response time for the internal standard is slightly different from the response time for the target compound, the responses can be separately read and compared. The use of internal standards to compensate various types of potential problems in the analysis, including loss of minute amounts of sample during the extraction and injection procedures, fluctuating response, and signal suppression by the matrix, is the recommended method of assuring the highest precision for quantitative gas chromatography. Dr. Baselt explained:

[I]nternal standards are drugs that are supposed to resemble the substance that you are testing for, as closely as possible, but be differentiatable [sic] through your instrumental procedures. And the purpose of adding this is that you would put it into the sample very early in the analysis. And that this would [serve] as an internal marker of the carefulness with which you conducted your test. And, for instance, if you were to add this internal marker at the beginning of the test, at the end of the test and you did not find the internal marker, this would be an occasion that [indicates] that the test had failed. If you were to do the test, and you did find the internal marker at about the level that you expected, this would be an indication that the test had succeeded. That’s, basically, the purpose of it.

Because the internal standard should have chemical properties similar to the target compound, a deuterated form of the target compound is often used as the internal standard. Dr. Baselt’s lab used deuterat-ed forms of THC and carboxy THC for the internal standards in this analysis. The mass spectrometer selectively monitors ions from THC and deuterated THC, the responses for which are near each other; there is a similar correspondence in responses from cTHC and deuterated cTHC. The quantitation calculation uses the “ion ratios,” with an acceptable variation from the equivalent standard ranging from ± 20% to ± 30%, depending upon the authority consulted. None of the experts found fault with the deuterated internal standards used by Dr. Baselt’s lab, but they disagreed on the issue of whether Dr. Baselt’s ion ratio calculations were acceptable.

The third category of known samples is an “external control,” which is used to check the reproducibility of results of an analysis over time. An external control is a sample which is prepared in the same type of matrix as the unknown sample, but which has a known concentration of the target compound that is near (± 20%) the expected concentration of the “unknown sample,” and which is stable over a significant period of time, at a minimum several months. Samples from proficiency studies, if they are sufficiently stable, are often used as external controls. The experts differed on the issue of whether Dr. Ba-selt’s decision not to use external controls for THC and cTHC would invalidate the GC/MS analysis.

The experts also discussed their opinions regarding whether Sercey ate or smoked the marijuana, the likely time of her ingestion of marijuana (based on the experts’ experience and based on the Huestis models), the conversion of the whole blood THC/cTHC values to serum or plasma THC/cTHC values (relevant to comparison with the Huestis models), Sercey’s likely blood THC/cTHC levels at the time of the accident, and the eorrelation of degree of impairment -with blood THC/cTHC levels and with blood alcohol/THC/cTHC levels.

TRIAL COURT ORDER

The order granting the motions in li-mine stated: “In Florida, an expert’s opinion which is based upon a scientific principle is admissible only where the underlying principle, theory or methodology is generally accepted in the field to which it belongs, and the procedures followed to apply the technique are also generally accepted in the relevant scientific community. The burden of proof is on the proponent by a preponderance of the evidence.” The trial judge found that “there is no generally accepted per se limit for impairment of THC and cTHC in blood” and that establishing a link between impairment and specific amounts of THC in blood is complicated by the fact that “chronic users of marijuana would likely have a baseline level of THC in their blood at all times,” but that there was “no agreement as to how much THC would remain in the blood of chronic users as a baseline” and the “learned articles” supplied by both parties indicated that “the research to date has been conducted in laboratories involving volunteers rather than with chronic everyday users living in the community.” He concluded that “there is no reliably established baseline level of THC in the blood of chronic marijuana users,” and that chronic users “would require higher quantities than non-chronic users in order to become impaired.” He found that the experts agreed “that the GC/MS is an appropriate scientific instrument for qualitatively identifying and quantifying THC and cTHC in liquids,” and also “that THC and cTHC are not stable in whole blood, but degrade rapidly and at an unknown rate.” He found that the experts did not agree, and the state had not established by a preponderance of the evidence, “that scientists using the GC/MS can reliably quantify the amount of THC and cTHC in whole blood at the earlier time of the blood draw, much less at some other hypothetical time in the past such as the time of the crash in this case.”

The judge found that the state had failed to establish “that Dr. Baselt’s testing procedures utilizing the GC/MS are reliable and generally accepted in the relevant scientific community.” He specifically found that Dr. Baselt “failed to follow quality controls generally accepted in the relevant scientific community” and that the experts agreed that “quality control is critical to the integrity of GC/MS testing.” He found that Dr. Baselt “tests no controls contemporaneous with testing for the unknown,” and that “good scientific practices” require running both a “positive” and a “negative” control “at the same time and in the same run with the unknown.” He stated that “[b]y comparing the GC/MS analytical results of the controls, the analyst can determine the accuracy of the analytical results of the unknown,” and found that this is “particularly important with THC and cTHC because the scientists are working with low levels (nanograms per milliliter) of the controlled substance.” He found that Dr. Baselt’s testimony regarding the impossibility of obtaining or making reliable THC and cTHC controls in whole blood was “contradicted by the other experts” who testified that controls can be made by “spiking” whole blood that is free of controlled substances with known quantities of THC and cTHC, and that these controls are reliable “for a period of days (or weeks according to some testimony).” He found that these “spiked” samples “are stable enough for the purpose of running positive controls for a given analysis.” He rejected Dr. Baselt’s testimony “that his failure to run controls should be excused because he is periodically ‘proficiency tested’ ” and because “his laboratory from ‘time to time’ compares results with other laboratories, by analyzing samples that other laboratories have analyzed.” He stated that “Dr. Baselt’s failure to follow quality controls generally accepted in the relevant scientific community undermines this Court’s confidence in the results of his tests and the conclusions drawn therefrom.” He found that these results “are further called into question” because, according to Dr. Bateh, “there is no consistency in the ion ratio range that he used to identify and quantify the THC.”

The judge concluded that “the testing procedures utilized by Dr. Baselt in the case at bar do not pass the Frye test” and that the expert opinions of Dr. Baselt and Dr. Goldberger “that rely upon those tests will not be allowed.” Applying section 90.403, Florida Statutes, he further found that “the probative value of admitting evidence of the presence of THC and cTHC in the Defendant’s blood at the time of Dr. Baselt’s June 11, 1998, analysis is substantially outweighed by the danger of unfair prejudice, confusion of the issues, and misleading the jury,” and that “testimony and evidence of the presence of THC and cTHC in the Defendant’s blood will not be allowed.”

ARGUMENTS

The state contends that Frye “does not apply in this situation,” because GC/MS analysis is well established and has been generally accepted in the relevant scientific community, citing Parker v. State, 777 So.2d 937 (Ala.Crim.App.2000), and Jones v. State, 716 S.W.2d 142 (Tex.App.-Austin 1986). Alternatively, it asserts that courts have repeatedly found that GC/MS is generally accepted and satisfies the Frye standard, citing Jones and U.S. v. Distler, 671 F.2d 954 (6th Cir.), cert. denied, 454 U.S. 827, 102 S.Ct. 118, 70 L.Ed.2d 102 (1981), and that federal courts have found GC/MS satisfies Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993), citing U.S. v. Bynum, 3 F.3d 769 (4th Cir.1993), cert. denied, 510 U.S. 1132, 114 S.Ct. 1105, 127 L.Ed.2d 416 (1994), and U.S. v. Vitek Supply Corp., 144 F.3d 476 (7th Cir.1998), cert. denied, 525 U.S. 1138, 119 S.Ct. 1026, 143 L.Ed.2d 37 (1999). It argues that whether the correct quality control procedures were followed “are foundational considerations governed by ordinary evidentiary standards” which go to the weight of evidence, not its admissibility, unless “the testing procedures are so fundamentally flawed that the test results are rendered unreliable.” The state asserts there is no dispute about the basic reliability of the test results, noting that the RIA screened Sercey’s blood positive for THC prior to the GC/MS analysis, that “an external proficiency test was performed just prior to the test at issue,” and that positive and negative standards prepared in whole blood “were run at the same time and in the same run as- appellee’s blood.” It argues that a GC/MS analysis which uses internal standards but not external controls is admissible under the Frye standard, and that the perceived “confusion” in Dr. Baselt’s testimony results from the fact that the trial judge does not understand the difference between internal standards and external controls. The state asserts that what Dr. Bateh was recommending was really a second set of standards from another source, not a “true control,” which is a solution kept for an extended period of time and used to compare to all samples sent to the lab, while standards are prepared “every couple of weeks.” It cites Vitek and State v. St. Pierre, 693 So.2d 102 (Fla. 5th DCA 1997), as examples of-cases in which the courts found- GC/MS test results accurate and reliable even where not every possible quality control protocol was followed.

The state challenges the trial court’s statement during the hearing that the federal and Florida administrative rules governing lab procedure constitute evidence of the requirements imposed by both governments on this particular analysis. It asserts that these 'rules do not clearly require both “controls” and “standards,” but appear to treat them as interchangeable, that the rules do not on their face apply to drug testing of blood) and that in any case, use of standards rather than controls substantially complies with the rules. It contends that failure to follow administrative rules, manufacturer protocols, or protocols established by scientific groups does not render test results inadmissible under Frye, but only goes to the weight of the evidence and is for the jury to consider, citing Williams v. State, 710 So.2d 24 (Fla. 3d DCA), rev. denied, 725 So.2d 1111 (Fla.1998), State v. Tankersley, 191 Ariz. 359, 956 P.2d 486 (1998), and State v. Brown, 949 S.W.2d 639 (Mo.App. E.D.1997). The state asserts that the experts’ opinions that Sercey’s blood THC level was higher at the time of the accident than when tested were based not upon GC/MS, but upon the fact that blood THC degrades rapidly. It argues that the levels of THC and cTHC in Sercey’s blood are highly relevant to the proof of her impairment, notwithstanding that a statutory “per se limit for impairment of THC and cTHC” has not been established, noting that the prosecution may prove impairment even when the defendant’s BAC is less than the .08 statutory level. It asserts .that if chemical analyses performed by “one of the few labs that does this type of testing due to its complexity” are excluded from evidence based on the failure to use “controls” when no controls are available and when “blood standards” put through the same extraction process were used as the nearest possible equivalent, “there will be no prosecutions for drug impaired drivers because the State will never be able to perform drug testing that satisfy [sic] the trial court’s requirements.”

Sercey contends that the notice of appeal should be treated as a petition for certiorari review because the evidence was not “suppressed.” She argues that under the certiorari standard, this court must accept the trial court’s findings of fact because they are supported by competent substantial evidence, and can look only at whether the trial court applied the correct law, not for “legal error.” She asserts that the state’s argument that Frye does not apply was not preserved below, that its suggestion that Daubert applies is contrary to Florida supreme court decisions, and that the cases the state cites are distinguishable. Finally, Sercey argues that even if the de novo appeal standard were applicable, the trial court applied the correct law and drew the correct legal conclusions that the procedure employed in this case was not generally accepted in the scientific community, and the court was not shown to have abused its discretion in ruling that the evidence would not be admitted because its probative value is outweighed by the danger of unfair prejudice, confusion of the issues, and misleading the jury.

The state replies that its appeal is authorized by Florida Rule of Appellate Procedure 9.140(c)(1)(B), because Sercey’s blood THC/cTHC results are “evidence obtained by search and seizure,” and that it may appeal this order because, unlike a defendant who may appeal a conviction, the state would have no remedy if the defendant were acquitted because it was not allowed to present evidence. It concedes that the argument that no Frye hearing was required was not presented to the trial court, but argues that Frye challenges are unique in that de novo appellate review is not limited to the record below, and that this court can take judicial notice for the first time on appeal that a scientific procedure is not novel, citing Florida Power & Light Co. v. Tursi and Hayes v. State, 660 So.2d 257 (Fla.1995). It argues that the appellate court determines de novo the legal issues and decides whether competent substantial evidence supports the trial court’s factual findings. It contends that the trial judge “simply did not understand the testimony regarding negative and positive standards,” that he “improperly went beyond addressing the threshold question of admissibility of expert testimony under Frye by engaging in an analysis of the weight to be assigned to the expert testimony,” and that he “improperly turned a Frye issue into a 403 balancing issue.” The state asserts that it is not relying on Daubert, but that the two “gate-keeping” tests in Frye and Daubert (both “designed to remove junk science from the courtroom”) are sufficiently similar that Dau-bert-based cases specifically involving gas chromatography are persuasive.

JURISDICTION

We review this case as a direct appeal of a nonfinal order under rule 9.140(c)(1)(B), which authorizes the state to appeal an order “suppressing before trial confessions, admissions, or evidence obtained by search and seizure,” because the legal blood specimen upon which the expert opinion testimony sought to be excluded is based was “obtained by search and seizure.”

RULES OF EVIDENCE

To determine whether the challenged evidence is admissible, we must apply to the facts the pertinent rules of evidence. Section 90.401, Florida Statutes, provides: “Relevant evidence is evidence tending to prove or disprove a material fact.” Section 90.402 provides: “All relevant evidence is admissible, except as provided by law.” Because there is no dispute that the testimony of the state’s experts is relevant to some of the issues involved in this prosecution, the expert witness testimony is admissible unless otherwise excluded by law.

Section 90.702 provides: “If scientific, technical, or other specialized knowledge will assist the trier of fact in understanding the evidence or in determining a fact in issue, a witness qualified as a expert by knowledge, skill, experience, training, or education may testify about it in the form of an opinion; however, opinion is admissible only if it can be applied to the evidence at trial.” There were no objections to the qualification of the state’s witnesses as experts in the field of toxicology, nor was there any dispute that their scientific knowledge would assist the jury in understanding the evidence presented in this trial. Section 90.703 provides: “Testimony in the form of an opinion or inference otherwise admissible is not objectionable because it includes an ultimate issue to be decided by the trier of fact.” The fact that some of the state’s experts’ opinions involved issues which the jury was called upon to determine (i.e., whether, at the time of the accident, Sercey’s faculties were impaired by alcoholic beverages, or by marijuana, or by a combination of alcohol and marijuana) does not make their testimony inadmissible. Section 90.704 provides: “The facts or data upon which an expert bases an opinion or inference may be those perceived by, or made known to, the expert at or before the trial. If the facts or data are of a type reasonably relied upon by experts in the subject to support the opinion expressed, the facts or data need not be admissible in evidence.” There is no dispute that RIA and GC/MS test results are the type of data reasonably relied upon by toxicologists to support their opinions about the presence and quantification of marijuana in a subject’s blood, nor is there a dispute that textbooks and peer-reviewed published scientific studies in toxicology and pharmacokinetics are the type of data upon which toxicologists reasonably rely for opinions relating the presence and quantification of alcohol and marijuana in the subject’s blood to other issues, including when the substances were ingested, the manner of ingestion, and whether it is probable that the subject was impaired at times related to the time the blood specimen was drawn.

Section 90.403 provides: “Relevant evidence is inadmissible if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of issues, misleading the jury, or needless presentation of cumulative evidence.” In excluding the expert witness testimony, -the trial court found that “the testing procedures utilized by Dr. Baselt in the case at bar do not pass the Frye test” and that “the probative value of admitting evidence of the presence of THC and cTHC in the Defendant’s blood at the time of Dr. Baselt’s June 11, 1998, analysis is substantially outweighed by the danger of unfair prejudice, confusion of the issues, and misleading the jury.” To determine whether this ruling is legally valid, we must examine the Frye reliability standard.

THE FRYE RELIABILITY STANDARD

In Frye, which involved the admissibility of evidence involving a precursor to the “lie detector,” the court noted the “novel question” involved, and stated:

... Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

We think the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made.

293 F. at 1014. In Stokes v. State, 548 So.2d 188, 193 (Fla.1989), the supreme court reaffirmed the applicability of the Frye test in Florida, notwithstanding adoption of the Florida Evidence Code:

The underlying theory for this rule is that a courtroom is not a laboratory, and as such it is not the place to conduct scientific experiments. If the scientific community considers a procedure or process unreliable for its own purposes, then the procedure must be considered less reliable for courtroom use.

In Flanagan v. State, 625 So.2d 827, 828 (Fla.1993), the supreme court reiterated “the basic principle that novel scientific evidence is not admissible in Florida unless it meets the test established in [Frye],” under which, “in order to introduce expert testimony deduced from a scientific principle or discovery, the principle or discovery ‘must be sufficiently established to have gained general acceptance in the particular field in which it belongs.’ ” It noted that “pure opinion testimony” need not meet the Frye test “because this type of testimony is based on the expert’s personal experience and training,” but it found that the sex offender profile testimony challenged in that case “by its nature necessarily relies on some scientific principle or test, which implies an infallibility not found in pure opinion testimony,” and therefore “must meet the Frye test, designed to ensure that the jury will not be misled by experimental scientific methods which may ultimately prove to be unsound.” Id.

Notwithstanding the U.S. Supreme Court’s ruling in Daubert that the Federal Evidence Code had superceded the Frye test in federal court proceedings, Florida has continued to adhere to Frye. In Ramirez v. State, 651 So.2d 1164 (Fla.1995), the supreme court stated:

The admission into evidence of expert opinion testimony concerning a new or novel scientific principle is a four-step process. First, the trial judge must determine whether such expert testimony will assist the jury in understanding the evidence or in determining a fact in issue. Second, the trial judge must decide whether the expert’s testimony is based on a scientific principle or discovery that is “sufficiently established to have gained general acceptance in the particular field in which it belongs.” ... The third step in the process is for the trial judge to determine whether a particular witness is qualified as an expert to present opinion testimony on the subject in issue. Fourth, the judge may then allow the expert to render an opinion on the subject of his or her expertise, and it is then up to the jury to determine the credibility of the expert’s opinion, which it may either accept or reject.

Id. at 1166-67 (citations omitted). The court noted that the second step of this process embodies the Frye test, and observed that “[t]he principle inquiry under the Frye test is whether the scientific theory or discovery from which an expert derives an opinion is reliable.” Id. at 1167. It stated that in utilizing the test, “the burden is on the proponent of the evidence to prove the general acceptance of both the underlying scientific principle and the testing procedures used to apply that principle to the facts of the case at hand,” that the trial judge “has the sole responsibility to determine this question,” and that “general acceptance under the Frye test must be established by a preponderance of the evidence.” Id. at 1168.

In Hadden v. State, 690 So.2d 573, 578 (Fla.1997), the supreme court reaffirmed its “intent to use the Frye test as the proper standard for admitting novel scientific evidence in Florida, even though the Frye test is not set forth in the evidence code,” observing that “Reliability is fundamental to issues involved in the admissibility of evidence” and that, like hearsay evidence, “[n]ovel scientific evidence must also be shown to be reliable on some basis other than simply that it is the opinion of the witness who seeks to offer the opinion.” It noted that the appropriate standard of review is de novo, that an appellate court “should consider the issue of general acceptance at the time of the appeal rather than at the time of trial,” and that the appellate court “may examine expert testimony, scientific and legal writings, and judicial opinions in making its determination.” Id. at 579. It observed that “the Frye standard for admissibility of scientific evidence is not applicable to an expert’s pure opinion testimony which is based solely on the expert’s training and experience.” Id. at 579-80.

In Berry v. CSX Transp., Inc., 709 So.2d 552 (Fla. 1st DCA), rev. denied, 718 So.2d 167 (Fla.1998), this court addressed the Frye test in the context of toxic tort litigation. It noted that the challenged expert testimony “was grounded upon numerous peer-reviewed and published epidemiological studies demonstrating an association between exposure to organic solvents and toxic encephalopathy,” but found that “the trial court went beyond addressing the threshold question of admissibility of expert testimony under Frye, which was the issue before it, and in effect engaged in an analysis of the weight to be assigned to the expert testimony or the sufficiency of the evidence.” Id. at 554. Declining to interpret language in Hadden “as meaning that in all cases expert opinion testimony, not otherwise developed through clinical experience, must be Frye tested,” the court held that “under Frye and its Florida progeny, when the expert’s opinion is well-founded and based upon generally accepted scientific principles and methodology, it is not necessary that the expert’s opinion be generally accepted as well.” Id. at 566-67. It found that the claims of bias, lack of plausibility, and other alleged defects in the studies upon which the expert relies “go to the weight, rather than the admissibility, of the studies,” which is to be considered by the fact finder. Id. at 571. It held: “The fact that the experts have all derived their opinions from the same generally-accepted methodology, the epidemiological studies contained in the record, but simply disagree upon how to interpret the scientifically (and legally) reliable data, is not a valid reason for excluding the plaintiffs’ experts’ opinions altogether.” Id.

In U.S. Sugar Corp. v. Henson, 787 So.2d 3, 5 (Fla. 1st DCA 2000), approved, 823 So.2d 104 (Fla.2002), this court held that the Frye standard applies in workers’ compensation cases, and affirmed the lower tribunal’s reliance on the claimant’s experts, finding that “there is general acceptance in the relevant scientific community both (i) for claimant’s general causation theory that certain pesticides to which he was repeatedly exposed over a long period of time can cause peripheral neuropathy, and (ii) for the differential diagnosis methodology employed by claimant’s physicians, which they used to exclude the other factors that might cause his condition and to determine that his pesticide exposure specifically caused his injury.” It stated:

We share Judge Altenbernd’s concerns with an appellate court undertaking a de novo review not only based upon the scientific literature considered by the lower court or submitted by the parties on appeal, but also based upon literature outside of the record. See Brim, 779 So.2d at 435 (“Both due process and the limited technical competence of the judiciary require that this review take place with certain safeguards that we have not yet provided.”). Nevertheless, we read the Florida Supreme Courts’s opinion in Brim v. State, 695 So.2d 268, 274 (Fla.1997), as requiring such an undertaking for this court to reach a de novo determination of whether there is general acceptance within the relevant scientific community of the novel science before us. Further, the issue of general acceptance is to be made as of the time of appeal, rather than the trial. See Hadden, 690 So.2d at 579; E.I. DuPont, 748 So.2d at 1115.

787 So.2d at 15. The court noted that the expert’s role “is to apply the generally accepted principles to the facts relating to the claimant’s condition” and emphasized that “the weight to be given to stated scientific theories, and the resolution of legitimate but competing scientific views, are matters appropriately entrusted to the trier of fact.” Id. at 20.

ANALYSIS

It is clear from the case law that the Frye reliability standard applies only to expert opinions which are based on new. or novel scientific principles or procedures. It is clear from this record that neither the RIA screen for THC/cTHC, nor the GC/MS analysis for THC/cTHC can be considered “new or novel,” and that both tests are generally accepted in the scientific community. Under Ramirez, once the judge found that the scientific principles and procedures underlying the experts’ opinions regarding the presence of THC and cTHC in Sercey’s blood (i.e., the RIA and GC/MS analyses, and the numerous chemical, biochemical, and physical principles upon which those procedures are based) are generally accepted in the relevant scientific community (i.e., chemistry/toxicology), the threshold determination of admissibility of those opinions was met, and the judge was required to allow the experts to render opinions on the presence of THC and cTHC in Sercey’s blood, leaving for the jury to determine the credibility of those expert opinions. The issue of whether the particular analysis of Ser-cey’s blood by Dr. Baselt’s lab was performed in the proper manner, including whether sufficient quality control procedures were used to ensure the accuracy of the test results, was a question of credibility and probative value for the jury to determine, after hearing the testimony of all the experts.

Sercey sought to exclude both the results of the RIA and GC/MS analyses and the experts’ opinions deduced from those results with regard to how the marijuana was ingested, how recently it was ingested prior to the blood draw, and whether Ser-cey was impaired at the time of the accident. To the extent these opinions are based solely upon the experts’ knowledge and experience, they constitute “pure opinion” and are not subject to Frye analysis. To the. extent they are based on generally accepted scientific principles, they are not subject to Frye analysis. To the extent they are based upon new or novel scientific theories or studies, they would be subject to Frye scrutiny.

The expert opinion testimony that Sercey smoked marijuana (as opposed to orally ingesting it) appears to be based on the experts’ knowledge and experience, and on the pharmacokinetics of THC and cTHC, about which there is no dispute. The expert opinion testimony regarding the recency of Sercey’s use of marijuana prior to the blood specimen being drawn appears to be based upon the experts’ knowledge and experience, independent of the Huestis mathematical models, and is therefore not subject to Frye analysis. But any opinions as to recency of use of marijuana which were based upon the Huestis models would be subject to Frye scrutiny, to determine whether the Huestis models are generally accepted in the toxicology community.

The results of the initial study on which the Huestis models are based, and the other articles referring to the Huestis models, have been peer-reviewed and published in respected scientific journals, an indication that they may be generally accepted among toxicologists, within the announced limits of their application. However, both Dr. Goldberg and Dr. Baselt testified that the models do not apply to “excessive” levels of THC/cTHC like those involved in this case, that they are of limited usefulness with chronic users, and that the time of marijuana usage predicted by Model I in this case (1-1.5 hours prior to the blood draw, which was three hours after the accident) would not be possible. On this record, we find that the trial court could reasonably find that the probative value of application of the Huestis models to the particular facts in this case is substantially outweighed by the danger of misleading the jury, and that opinions based on the Huestis models should be excluded under section 90.403, Florida Statutes.

The experts’ opinions that Sercey was impaired by alcohol and marijuana at the time of the accident appear to be based on the experts’ knowledge and experience, as well as peer-reviewed and published studies indicating that the combined use of moderate amounts of alcohol and marijuana results in significant impairment. Sercey did not challenge these scientific findings, but instead focused on the fact that there is no consensus among toxicologists on a minimum per se level of THC upon which courts could base a presumption of impairment, as there is with alcohol. In Florida, the state may prove impairment by alcohol even when the BAC is less than the .08 “legal” limit, using evidence of the presence of alcohol in the defendant’s blood and other evidence of impairment, including erratic driving and the fact that an accident occurred. In the same way, the state may also prove impairment by a controlled substance, or impairment by a combination of alcohol and a controlled substance. Evidence of the presence of THC/cTHC in Sercey’s blood is therefore admissible even if it cannot be quantitatively related to impairment, unless it is excluded under section 90.403, Florida Statutes.

The trial court’s ruling that “the probative value of admitting evidence of the presence of THC and cTHC in the Defendant’s blood at the time of Dr. Baselt’s June 11, 1998, analysis is substantially outweighed by the danger of unfair; prejudice, confusion of the issues, and misleading the jury” seems inextricably tied to his findings that the expert witness testimony did not meet the Frye reliability standard, in particular that “the testing procedures utilized by Dr. Baselt in the case at bar do not pass the Frye test.” In light of the fact that Sercey did not challenge GC/MS analysis and the scientific principles underlying GC/MS, which has been considered for many years the “gold standard” for drug analysis, and considering that a challenge to the way in which a particular test was administered pertains to the weight and credibility of the evidence rather than to its admissibility, this ruling under section 90.403 must be reversed.

The trial court’s determination that Ser-cey’s particular test results were not reliable because Dr. Baselt’s lab did not use “controls” appears to be the result of semantic confusion. What Dr. Bateh refers to as the required negative and positive THC/cTHC “controls” (made by spiking “clean” blood samples with known amounts of THC/cTHC and running the spiked samples through the same extraction procedure and GC/MS analysis as the “unknown” sample of Sercey’s blood) are precisely what Dr. Baselt refers to as the negative and positive THC/cTHC “standards” his lab actually used in this analysis. All the experts agree that, because of the instability of THC in blood, what Dr. Baselt correctly refers to as a THC/cTHC “external control” (a blood sample with known THC/cTHC concentrations that can be run with each analysis over an extended period of time, for the purpose of determining whether the analytical procedure gives the same result over time) is not feasible.

Our extensive research of the scientific principles underlying the issues, required in order to fulfill our obligation to review this case de novo, highlights two areas of inquiry that in our opinion were not adequately explored by the attorneys at the pre-trial hearing, and might be helpful to the jury in understanding the accuracy of the particular GC/MS results in this case. These are the explanation of the “deuterated internal standards” which were added to all the blood samples, including the calibration standards, and the question of whether Dr. Baselt’s preparation and use of calibration standards in a blood matrix, combined with the aforementioned internal standards, proficiency studies, and duplicate analyses of samples by another lab, ensured the accuracy of the analysis in this case. It is our opinion that Dr. Baselt’s lab followed the protocols necessary to ensure the accuracy of the test results, given the unstable nature of THC in a blood matrix. However, this determination is for the jury to make, after considering fully the quality control aspects of the GC/MS analysis.

The trial court’s exclusion of any expert witness opinion testimony regarding the recency of Sercey’s use of marijuana which is based upon the Huestis models is AFFIRMED. The remainder of the order is REVERSED and the case is REMANDED for further proceedings consistent with this opinion.

WOLF and LEWIS, JJ., CONCUR.

. The McGraw-Hill Encyclopedia of Science and Technology describes gas chromatography as "a method for the separation and analysis of complex mixtures of volatile organic and inorganic compounds” which is "based on the fact that different compounds move at different rates through a column containing a solvent liquid or solid.” It notes that "[a]fter separation of the mixture with gas chromatography, each component can be analyzed further with a mass spectrometer, which determines molecular structure based on the fragmentation of ions formed when the molecules are ionized.” GC/MS is also briefly described in U.S. v. Distler, 671 F.2d 954 (6th Cir.), cert. denied, 454 U.S. 827, 102 S.Ct. 118, 70 L.Ed.2d 102 (1981), and in Andrews v. Webb, 685 F.Supp. 579 (E.D.Va.1988).

The scientific principles underlying solvent extraction, gas chromatography, and mass spectrometry were discovered and developed in the early 1900s, and the particular combined method of analysis referred to as GC/MS has been in use for over forty years in a wide variety of applications, including drug testing. The experts agreed that GC/MS analysis is generally accepted in the scientific community as the best method for determining the presence and quantity of THC and cTHC in blood. The principal reasons for preferring GC/MS analysis for drug analysis are "its sensitivity in detecting minute amounts of a given substance and its selectivity in distinguishing various compounds,” Jones v. State, 716 S.W.2d 142, 149 (Tex.App.Austin 1986). GC/MS has been described as the "gold standard” for drug confirmation testing. See Goebel v. Warner Transp., 612 N.W.2d 18, 22 (S.D.2000). See also Andrews v. Webb (RIA and GC/MS analysis for THC in urine); Williams v. Secretary of Navy, 787 F.2d 552 (Fed.Cir.1986)(RIA, GC, and GC/MS analysis for THC in urine); Parker v. State, 777 So.2d 937 (Ala.Crim.App.2000) (GC/MS analysis of cocaine); U.S. v. Bynum, 3 F.3d 769 (4th Cir.1993), cert. denied, 510 U.S. 1132, 114 S.Ct. 1105, 127 L.Ed.2d 416 (1994) (GC analysis of cocaine impurities). And see State v. Price, 731 S.W.2d 287 (Mo.App. W.D. 1987) ("The reported decisions and authorities confirm that the mass spectrometry and gas chromatography technique is an extremely reliable specific test for the measurement, separation and identification of particular organic compounds-drugs among them”).

. Dr. Bruce Goldberger, Ph.D., Director of Toxicology at the University of Florida College of Medicine and a federal inspector of laboratories, has been qualified about 30 times in the last three years in federal, state, and military courts as an expert in the field of forensic toxicology. He regularly gives opinions regarding impairment from drugs or alcohol.

Dr. Randall Baselt, Ph.D., has a B.S. in chemistry and a Ph.D. in pharmacology, and has worked as a toxicologist since 1965, including two years of toxicology research for the City of San Francisco, a ten-year professorship of toxicology, and positions as director of four toxicology labs, including director of his current lab since 1984. He has been qualified as an expert in toxicology more than 2200 times in 25 states (including Florida), the federal courts, and three foreign countries. In each of the Florida cases, he testified regarding recent usage of marijuana and impairment based on THC in blood. In 1983, he authored a study of comparative testing for THC/cTHC in whole blood and in serum/plasma.

Dr. Ricky Bateh, Ph.D., is an attorney, chemist, former clinical lab director, consultant, and adjunct professor at Florida Community College in Jacksonville, where he teaches GC/MS, toxicology, and environmental clinical chemistry. He has testified 75-80 times in state, federal, and military courts as an expert in forensic chemistry and toxicology. He has done some research, but he has not published anything on blood THC.

Dr. Edward Willey, M.D., a former hospital pathologist, testified that he does not consider himself a toxicologist because he is not a chemist, but he considers himself qualified to testify regarding the results of toxicological tests. He admitted that he had been hired to interpret the blood alcohol data and give a possible explanation for the two different test results, and that he did not challenge the GC/MS results or the RIA results.

Thomas Burr has a B.S. in chemistry and biology with 32 years experience in areas relating to forensic testing and forensic science, including 21 years in a Minnesota crime lab and "quite a few” years running GC/MS analyses. He has testified as an expert on alcohol and drugs in 22 states, in federal court, and in Canada, and he has testified as an expert in Florida cases "on numerous occasions.” He has written a number of review articles in the area of alcohol testing and has given a dozen or more seminars on the effects of alcohol and drugs on human performance and the forensic aspects of alcohol and drug testing. He has not published any articles on THC, has done no research, and has done no THC analysis in blood, only in urine specimens.

. Dr. Baselt opined that the levels of THC and cTHC his lab found in Sercey's blood

... are in our experience very significant concentrations. They each exceed the typical numbers that we see in forensic situations involving marijuana. And together, they would indicate recent usage of marijuana by the individual. And they would also be consistent with the person being under the influence of marijuana at the time of the blood collection.

Dr. Goldberger testified that Sercey’s cTHC level was "actually in the [higher] range that you'd find in urine.” Dr. Bateh testified that there have been studies in which baseline THC levels for chronic users have been as high as 4 ng/ml, but he admitted that a cTHC level of 91 ng/ml is "excessive.” Dr. Willey testified that 5.5 ng/ml at the terminal phase is "a reasonably high level.” Burr testified that he would not expect 5.5 ng/ml to be a residual level of THC, and that he did not see anything in the scientific literature to suggest that baselines for chronic users "could be that high.”

. Dr. Goldberger testified that Dr. Baselt "is highly regarded in the field of forensic toxicology," and observed that "in California the rules about a forensic laboratory are very strict, probably more strict than they are in the State of Florida.” Dr. Bateh testified that Dr. Baselt is well-respected in the field of toxicology, but that he is not certified by any forensic organization.

. The most recent cTHC proficiency test prior to the June 11, 1998, analysis of Sercey's blood specimen was performed on April 14, 1998. Dr. Baselt testified that in that proficiency test, his lab obtained a 94 ng/ml reading for a sample with a target value of 101 ng/ml, which "tells us that we are doing reasonably well.”

. A deuterated compound is one in which one or more hydrogen atoms have been replaced by deuterium atoms. Deuterium is an isotope of hydrogen, which contains an extra neutron, and therefore has double the atomic weight of hydrogen.

. Dr. Baselt explained:

The ion ratio is simply the ratio between the abundance of two different ions within the same chemical, or two ions representing different chemicals, such as THC in a person's bloodstream, and the internal standard deuterated form of THC. So these can be used either qualitatively or quantitatively; meaning, you would either employ them in identifying the substance, or in measuring the amount of the substance.

. Dr. Baselt testified that t