Fentanyl-Norfentanyl Concentrations During Transdermal Patch Application: LC-MS-MS Urine Analysis.

Poklis and Backer published a survey of the concentrations of fentanyl and norfentanyl that could be expected in urine from patients using Duragesic®, a transdermal fentanyl patch. That study employed a relatively small number of patient data points and analysis by Gas Chromatography/Mass Spectrometry. This work examines a larger population of patient positives for fentanyl and norfentanyl to determine whether more than a decade later the original report remains accurate in predicting the range and median levels of fentanyl and norfentanyl concentrations physicians can expect to see from their patients. Additionally, these data were transformed to develop a model that results in a near Gaussian distribution of urine drug test results. This retrospective approach was developed to transform and normalize urine drug testing results to provide a historical picture of expected patient values for this important analgesic. The resulting near Gaussian distribution is dose independent and as such should be of value to physicians in quickly assessing whether their patient is consistent with this historical population in the broad terms of this model. While this comparison alone is not definitive for adherence with a treatment regimen, together with patient interviews, prescription history and other clinical criteria, it can add an idea of expected patient values from urine drug testing.

Acetylcodeine, an impurity of illicitly manufactured heroin, elicits convulsions, antinociception, and locomotor stimulation in mice.

Acetylcodeine is one of the major impurities present in illicitly manufactured heroin (diacetylmorphine). Data on its pharmacology and toxicology are limited and its ability to alter the toxic effects of diacetylmorphine is not known. The first objective of the present study was to compare the acute pharmacological and toxicological effects of acetylcodeine to those of codeine and diacetylmorphine in mice by assessing nociception in the tail-flick test, locomotor stimulation, and convulsive behavior. The second goal of this study was to determine whether acetylcodeine would alter the convulsant effects of diacetylmorphine. The antinociceptive potencies of acetylcodeine and codeine were similar, as reflected by their ED50 (95% confidence limits) values of 35 (29-44) and 51 (40-65) micromol/kg, respectively. Acetylcodeine was somewhat less potent than codeine in stimulating locomotor behavior, with ED50 values of 28 (22-37) and 12 (6-24) micromol/kg, respectively. Diacetylmorphine was considerably more potent than the other two drugs, producing antinociception and locomotor stimulation at ED50 values of 2.4 (1.4-4.1) and 0.65 (0.36-1.2) micromol/kg, respectively. On the other hand, the convulsant effects of acetylcodeine (ED50=138 (121-157) micromol/kg) and diacetylmorphine (ED50=115 (81-163) micromol/kg) were similar in potency and both were more potent than codeine (ED50=231 (188-283) micromol/kg). Finally, a subthreshold dose of acetylcodeine (72 micromol/kg) decreased the convulsant ED50 dose of diacetylmorphine to 40 (32-49). These findings suggest that the convulsant effects of acetylcodeine are more potent than predicted by its effects on locomotor activity and antinociception. The observation that acetylcodeine potentiated the convulsant effects of diacetylmorphine suggests a mechanism for some of the heroin-related deaths reported in human addicts.

The pharmacological activity of inhalation exposure to marijuana smoke in mice.

Although the majority of cannabinoid users smoke marijuana, the preponderance of laboratory animal research is based on administration of Delta9-tetrahydrocannabinol (Delta9-THC) or other cannabinoid agents via injection. The aim of the present study was to evaluate the impact of inhaling marijuana, or ethanol-extracted placebo smoke in the mouse model of cannabinoid activity by assessing inhibition of spontaneous activity, antinociception, catalepsy, and body temperature. In order to determine dosimetry, blood levels of Delta9-THC were obtained following either marijuana exposure or intravenous injection of Delta(9)-THC. Inhalation exposure to marijuana produced dose-related increases in antinociception and catalepsy, with estimated ED50 doses of Delta9-THC of 2.4 and 3.8 mg/kg, respectively. However, hypothermia and locomotor depression occurred in both the placebo- and marijuana-exposed mice. The CB1 receptor antagonist, SR 141716A antagonized the antinociceptive effects of marijuana (AD50 = 0.6 mg/kg), but only slightly decreased marijuana-induced catalepsy, and failed to alter either the hypothermic or locomotor depressive effects. In contrast, SR 141716A antagonized the antinociceptive, cataleptic, and hypothermic effects of intravenously administered Delta9-THC in mice that were exposed to air alone, though all subjects exhibited locomotor depression, possibly related to the restraint. In accordance with reports of others, these data suggest that exposure to smoke alone has pharmacological consequences. Our findings also indicate that marijuana-induced antinociception is mediated through a CB1-receptor mechanism of action and are consistent with the notion that Delta9-THC is mainly responsible for this effect.

Performance evaluation of four on-site drug-testing devices for detection of drugs of abuse in urine.

On-site drug tests are becoming increasingly more popular because of their easy test protocols and instantaneous results. This study evaluates the performance of four on-site drug testing devices that use competitive binding immunoassays to qualitatively determine the presence of drugs in urine: Triage Panel for Drugs of Abuse plus TCA, QuickScreen Pro-Multi Drug Screening Tests, Syva Rapid Test d.a.u. 5 and d.a.u. 2, and Rapid Drug Screen. All devices simultaneously determine the presence of the following drugs of abuse: amphetamine (AMP), benzoylecgonine (BE), 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCA), opiates (OPI), and phencyclidine (PCP). Triage and Rapid Drug Screen also simultaneously test for benzodiazepines (BZB) and barbiturates (BRB), whereas QuickScreen and Rapid Test require separate devices for the BZB and BRB analyses. Urine specimens (222) containing drug concentrations around or above cutoff values were screened by ONLINE or EMIT II immunoassays. Of these, 199 yielded positive gas chromatography-mass spectrometry results with at least 17 positive specimens in each drug class. Specimens with the target drugs added at 16.7% above and below the cutoff, 33.3% above and below the cutoff, and 66.7% above the cutoff were also used to evaluate the test devices. Sensitivity and specificity calculations demonstrated that Triage performed most predictably in the donor urine specimens and the drug-added specimens. In addition, it required the least amount of test volume and was the only device in which the appearance of a colored line indicated a positive result. Therefore, of the devices studied, Triage was the most dependable and reproducible on-site drug-screening device.

GC-MS analysis of methamphetamine impurities: reactivity of (+)- or (-)-chloroephedrine and cis- or trans-1,2-dimethyl-3-phenylaziridine.

S-(+)-Methamphetamine is frequently found as the only isomer in urine specimens from methamphetamine abuseres. Enantiomerically pure S-(+)-methamphetamine can be synthesized from ephedrine or pseudoephedrine via chloroephedrine intermediates. These intermediates are unstable and capable of cyclizing to form cis- and trans-1,2-dimethyl-3-phenyl aziridine. Studies were done to determine if these intermediates could be detected when using a common gas chromatographic-mass spectrometric analytical method (derivatization with heptafluorobutyric anhydride, HFBA) for toxicological screening of methamphetamine. Analysis of (+)- or (-)-chloroephedrine after extraction into hexane and derivatization with HFBA indicated that both pseudoephedrine and ephedrine were the major compounds detected. Direct derivatization of a hexane solution of cis-1,2-dimethyl-3-phenyl aziridine yielded only the derivatives of ephedrine and pseudoephedrine, indicating that the aziridine intermediate is responsible for the formation of the ephedrine or pseudoephedrine. These studies indicate that the aziridine intermediates would not be detected in methamphetamine samples following HFBA derivatization.

Rapid gas chromatographic procedure for the determination of topiramate in serum.

A rapid gas chromatographic method for the routine determination in serum of the new anticonvulsant drug topiramate (Topamax) (TOP) is described. The method involves extracting 0.50 mL of sample, previously adjusted to pH 9.5 with saturated borate buffer with ethyl acetate. One-microliter aliquots of the extract were injected into a 10-m x 0.53-mm i.d. x 0.5-microm 100% methyl silicone megabore capillary column connected to a nitrogen-phosphorus detector. The column temperature was initially at 170 degrees C for 0.1 min, then programmed at 10 degrees C/min to 240 degrees C, then 20 degrees C/min to 280 degrees C for 0.5 min. Under these conditions of the assay, the retention times of TOP and mepivicaine, internal standard, were 4.0 and 3.4 min, respectively. Quantitative determinations were performed with peak-height ratios of TOP to the internal standard. Calibration curves were linear from 2.5 to 150 mg/L TOP. The assay had a limit of quantitation of 2.5 mg/L. The overall within-run precision of the method yielded coefficients of variation (CV) of 3.9% at 10 mg/L (n = 10) and 3.1% at 100 mg/L (n = 10). The overall between-run precision calculated by three determinations on a single day for a week yielded CVs of 7.3% at 23 mg/L (n = 12) and 7.8% at 85 mg/L (n = 12). Common anticonvulsant and basic/neutral extractable drugs were found not to interfere with the assay. At present, no correlation has been demonstrated between trough plasma TOP concentrations and clinical efficacy. However, TOP values observed in our laboratory in serums from patients receiving adjunctive treatment for seizure disorders ranged from 2.5 to 35 mg/L.

Pharmacological evaluation of aerosolized cannabinoids in mice.

The reemergence on the debate of the use of marijuana for medicinal purposes has been the impetus for developing an acceptable delivery form of aerosolized cannabinoids. The goals of the present study were to: (1) develop and characterize the physical properties of an aerosolized form of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the major psychoactive constituent present in marijuana; and (2) assess the pharmacological effects of cannabinoid inhalation in mice. A Small Particle Aerosol Generator (SPAG) nebulizer, used to generate the aerosol, had an output of approximately 0.154 mg/l of aerosolized Delta(9)-THC with a 2.0 microm mass median aerodynamic diameter and a 2.2 geometric standard deviation (GSD). Virtually all the particles were less than 5.0 microm in diameter suggesting that they were sufficiently small to penetrate deeply into the lungs. Inhalation exposure to aerosolized Delta(9)-THC in mice elicited antinociceptive effects that were dependent on concentration and exposure time with an estimated Delta(9)-THC dose of 1.8 mg/kg. On the other hand, inhalation exposure to Delta(9)-THC failed to produce two other indices indicative of cannabinoid activity, hypothermia and decreases in spontaneous locomotor activity. The antinociceptive effects occurred within 5 min of exposure and lasted approximately 40 min in duration. The cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl (SR 141716A), but not naloxone, blocked these antinociceptive effects (AD(50)=0.09 mg/kg) indicating a cannabinoid receptor mechanism of action. Similarly, inhalation exposure to a water soluble cannabinoid analog, 3-(5'-cyano-1', 1'dimethylheptyl)-1-(4-N-morpholinobutyrloxy)-Delta(8)-te trahydrocann abinol (O-1057), produced antinociception that was blocked by SR 141716A. These results demonstrate that the development of an aerosolized form of cannabinoids for human medicinal use is feasible.

Recommendations for toxicological investigations of drug-facilitated sexual assaults.

The recent increase in reports of drug-facilitated sexual assaults has caused alarm in the general public and prompted forensic toxicologists from across North America to address the toxicological issues surrounding this matter. The authors have developed recommendations and guidelines to inform law enforcement, medical, and scientific personnel of the requirements for performing successful toxicological examinations in cases of drug-facilitated rape.

The effect of oral dehydroepiandrosterone (DHEA) on the urine testosterone/epitestosterone (T/E) ratio in human male volunteers.

Dehydroepiandrosterone (DHEA) is an endogenous androgenic steroid produced by the ovaries and adrenal glands. Research suggests that DHEA can be converted to testosterone in peripheral tissues. Classified as a nutritional supplement, this compound may be purchased without a prescription. The military and international sports organizations prohibit the use of exogenous androgenic/anabolic steroids. Steroid-screening results are considered "positive" when the urinary ratio of testosterone to epitestosterone (T/E), an inactive synthetic byproduct, exceeds 6:1. Human volunteers ingested the recommended daily dose of 50 mg each morning for 30 days to determine if DHEA causes an adverse effect on this ratio. Urinary samples were collected before ingestion and 2-3 h after ingestion. Urine samples were extracted using solid-phase columns and analyzed using a previously developed gas chromatography-mass spectrometry method. T/E results were compared to an average baseline generated from three urine samples obtained before the study. Mean baseline T/E ratios averaged 0.67 for the seven subjects (range 0.1-1.2). The mean T/E ratio after DHEA ingestion ranged from 0.03 to 2.11. Individual postdose T/E ratios ranged from 0.01 to 3.7. The results from these individuals indicate that the administration of DHEA at this dose, for this period of time, has a minimal effect on urine T/E ratios and would not be expected to result in a positive screen for testosterone abuse. One subject agreed to take a single dose of 250 mg. This acute, high dose caused his T/E ratio to increase by 40% relative to the predose value.

An evaluation of the role of ROC plots in the prediction of heroin use from total codeine and total morphine concentrations in urine.

A diagnostic system to predict the presence of 6-acetylmorphine (6AM) in opiate-positive urines was recently proposed. A twofold criterion based on the total morphine concentration and the total codeine to total morphine concentration ratio was identified. Using relative operating characteristic (ROC) analysis, it was determined that the diagnostic system had a sensitivity of 92%, a specificity of 79%, and an overall accuracy of 73%. We applied similar decision criteria to a study population of 125 opiate-positive urines collected from criminal justice clients of a West Coast reference laboratory. ROC analysis on this population produced very different results: a sensitivity of 91%, a specificity of 49%, and an accuracy of 45%. These data illustrate the importance of choosing a representative study population without any selection biases that may compromise the validity of the accuracy measure. The ROC plot is an important tool for assessing a clinical test's performance, but in order for toxicologists and Medical Review Officers to benefit from the diagnostic test results, they must also know the predictive value (based on test accuracy and the prevalence of heroin use) of the test results. They need to know how well the test predicts the presence of 6AM, and therefore, the illicit use of heroin, in the population of interest whether it be workplace, criminal justice, hospital emergency department clients, or a combination of all populations.

Urinary excretion of d-amphetamine following oral doses in humans: implications for urine drug testing.

Seven healthy male volunteers received a single oral dose of 5 mg, 10 mg, or 20 mg of d-amphetamine. Urine was collected at 2, 4, 8, 12, 18, and 24 h post-dose. Total urine volume was measured, and pH and creatinine were determined. All specimens were analyzed by TDx Amphetamine/Methamphetamine II (TDx), Emit-d.a.u. Monoclonal Amphetamine/Methamphetamine (EM), and Emit II Amphetamine/Methamphetamine (EII) immunoassays at a cutoff value of 1000-ng/mL amphetamine. Quantitation of urinary amphetamine in all specimens was performed by gas chromatography-mass spectrometry. All urine testing results by the three immunoassays, EM, EII, and TDx, were in agreement; there were no discordant findings. Of the 42 total urine specimens collected following a 5-mg dose of amphetamine, only 8 (19%) screened positive by immunoassay. Twenty-four of 36 (67%) urine specimens yielded positive responses following a 10-mg dose, and 37 of 42 (88%) were positive by immunoassay following a 20-mg dose. These data demonstrate the present guideline for regulated forensic urine drug testing (FUDT) for amphetamine with a screening cutoff of 1000 ng/mL is too high to consistently detect the administration of a single 5-mg oral dose of d-amphetamine. There was considerable overlap of amphetamine concentrations in individual specimens following the various doses. Peak urinary amphetamine ranged from 620 to 3160 ng/mL following 5-mg doses. The time to peak concentration also varied widely at each dose, occurring in urines collected 2 to 18 h post-administration. The mean percent of dose excreted as unchanged amphetamine over 24 h at each dose ranged from 35 to 44%. The data demonstrated that amphetamine excretion increases with increasing urine flow and decreasing urine pH. Thus, a positive FUDT result for amphetamine means only that the individual was administered or self-administered amphetamine at some time prior to collection of the specimen.

Disposition of valproic acid in a case of fatal intoxication.

The case history and toxicological findings of a fatal suicidal valproic acid overdose are presented. Valproic acid concentrations were determined in body tissues and fluids by gas-liquid chromatography (GLC) following both direct extraction and the method of standards addition and quantitative fluorescence polarization immunoassay. The quantitative results obtained by the three procedures were in good agreement. Qualitative identification of valproic acid as its methylated derivative was by ion-trap gas chromatography-mass spectrometry. Toxicological analysis by direct extraction GLC yielded the following valproate concentrations (mg/mL or mg/kg): blood, 1050; bile, 713; brain, 510; heart, 670; kidney, 1580; liver, 985; and vitreous, 516. A total of 15.1 g of valproate was recovered in the stomach contents. These findings far exceed those associated with valproate therapy and are similar to the limited valproate disposition data reported in prior fatal overdoses.

The detection of acetylcodeine and 6-acetylmorphine in opiate positive urines.

Acetylcodeine (AC), an impurity of illicit heroin synthesis, was investigated as a urinary biomarker for detection of illicit heroin use. One hundred criminal justice urine specimens that had been confirmed positive by GC/MS for morphine at concentrations > 5000 ng/ml were analyzed for AC, 6-acetylmorphine (6AM), codeine, norcodeine and morphine. The GC/MS analysis was performed by solid phase extraction and derivatization with propionic anhydride. Total codeine and morphine concentrations were determined by acid hydrolysis and liquid/liquid extraction. AC was detected in 37 samples at concentrations ranging from 2 to 290 ng/ml (median, 11 ng/ml). 6AM was also present in these samples at concentrations ranging from 49 to 12 600 ng/ml (median, 740 ng/ml). Of the 63 specimens negative for AC, 36 were positive for 6AM at concentrations ranging from 12 to 4600 ng/ml (median, 124 ng/ml). When detected, the AC concentrations were an average of 2.2% (0.25 to 10.2%) of the 6AM concentrations. There was a positive relationship between AC concentrations and 6AM concentrations (r = 0.878). Due to its very low concentration in urine, AC was found to be a much less reliable biomarker for illicit heroin use than 6AM in workplace or criminal justice urine screening programs. However, AC detection could play an important role in determining if addicts in heroin maintenance programs are supplementing their supervised diacetylmorphine doses with illicit heroin.

Simultaneous determination of acetylcodeine, monoacetylmorphine, and other opiates in urine by GC-MS.

In addition to 6-monoacetylmorphine (6-MAM), acetylcodeine (AC) has been suggested as a marker for the use of illicit heroin. We report a sensitive opiate gas chromatographic-mass spectrometric assay that detects AC, diacetylmorphine, and the propionylated derivatives of codeine, morphine, 6-MAM, and norcodeine. The analytes were extracted by solid phase with recoveries from 62 to 98%. The limits of detection (LOD) and quantitation (LOQ) for AC was 0.5 and 1.0 microgram/L. The LOD of the other analytes was 2.0 micrograms/L and the LOQs ranged from 2 to 10 micrograms/L. The assay was linear for each analyte from the LOQ to 200 micrograms/L or 400 micrograms/L (morphine and codeine) with r > or = 0.996, except for diacetylmorphine which was linear to 100 micrograms/L with r = 0.994. The within-run and between-run precision were below 10% CV for all analytes. There was no significant hydrolysis of AC to codeine in urine (pH 4.7 and 8.0) after 23 weeks of refrigeration or freezing. After storage at room temperature in urine of pH 8.0, AC was completely hydrolyzed after 5 weeks, but at pH 4.7, 58% of the AC remained after 15 weeks of storage at room temperature. The sensitivity of this assay was adequate to detect AC in the urine of heroin abusers. In preliminary studies, AC was detected in 6 of 69 opiate positive urines. Concentrations ranging from 1 to 48 micrograms/L were observed. These concentrations were found to be low when compared with the concentrations of 6-MAM, codeine, and morphine also detected in the urines.

Comparison of an ion-trap and a quadrupole mass spectrometer using diazepam as a model compound.

Recent innovations in mass spectrometry (MS) have led to the development of instruments with increased capabilities, smaller footprints, and relatively low cost. The traditional MS in most toxicology laboratories is a quadrupole system equipped with electron impact ionization. Recently, an ion trap with electron impact, positive chemical ionization, negative chemical ionization, and tandem MS capabilities was introduced by Finnigan MAT. This paper compares the sensitivity and precision of ion-ratio measurements between a Finnigan GCQ ion-trap mass spectrometer (ITMS) and a Hewlett Packard quadrupole mass spectrometer (QMS) using electron impact ionization with diazepam as the model compound. Additionally, the sensitivity and precision of ion ratio measurements are evaluated for the ITMS using positive chemical ionization, negative chemical ionization and tandem MS modes of analysis. In the full scan mode (m/z 50-650, 1 Hz), the ITMS had an average signal-to-noise ratio (S/N) of 1400 for a 2-ng injection of diazepam (10 injections per day for 5 days), within-run ion ratio precision had coefficients of variation from 5 to 11%. Using similar full scan conditions, a 10-ng injection of diazepam on the QMS had an average S/N ratio of 160, and precision of ion ratio measurements varied from 5 to 13%. In the selected ion mode (SIM) of analysis (three ions, 2 Hz), the ITMS had an average S/N of 14,000 for a 2-ng injection and ion-ratio precision ranging from 6 to 15%. Using similar SIM conditions, a 2-ng injection in the QMS had an average S/N of 3000 with ion ratio standard deviations of 0.67 to 2.9%. Overall, the ITMS provided at greater S/N, equivalent precision in full scan, but was 5- to 10-fold less precise in measuring ion ratios in the SIM mode as compared with the QMS.

The stability of ethanol in human whole blood controls: an interlaboratory evaluation.

Sterile whole human blood control materials were commercially prepared in batches containing anticoagulants and preservatives and approximately 90, 150, and 230 mg/dL ethanol with and without 0.3% (w/v) sodium azide. Aliquots in sealed vials were stored by the manufacturer at 2-8 degrees C until shipped monthly to three academic toxicology laboratories that analyzed them in duplicate by gas chromatographic headspace methods at monthly intervals for one year. The resulting data were pooled, and grand mean values were statistically analyzed to determine the respective alcohol stability in these azide-free and azide-containing blood samples. Azide-containing blood samples showed no alcohol losses during the 1-year period. Azide-free blood containing 1.0% (w/v) sodium fluoride and anticoagulants had small alcohol decreases over time, the total losses after one year being less than 5% of the original alcohol concentrations. The initial alcohol concentration of approximately 40 mg/dL also did not change during storage of additional samples of azide-free blood for one month at 4 degrees C. We concluded that addition of sodium azide to performance-test and control blood specimens for alcohol analysis is unnecessary and unwarranted and that alcohol losses in such blood samples can be minimized by simple appropriate treatments and conditions.

Fatal fentanyl intoxication following excessive transdermal application.

The case history and toxicological findings of a fatal fentanyl intoxication due to the application of multiple transdermal patches are presented. An 83 year-old white female with terminal cancer was found dead with three 100 mg/h fentanyl patches on her chest. The autopsy and subsequent histological studies revealed extensive areas of gastric carcinoma, a large atrial tumor, ulceration of esophagus, metastasis of peripancreatic lymph nodes and a recent surgical removal of part of the lower lobe of the left lung. Toxicological analysis by GC/MS yielded fentanyl concentrations of blood, 25 ng/mL; brain, 54 ng/g; heart 94 ng/g; kidney 69 ng/g; and liver 104 ng/g. The cause of death was determined to be fentanyl overdose and the manner of death was ruled undetermined as the investigation was unable to conclusively establish whether this was an accidental overdose, a suicide, an assisted suicide, or possible a homicide. This case demonstrates the need for caution in self-administration of transdermal fentanyl patches, in particular, the dangers inherent in the application of multiple patches which can result in the release of potentially toxic or lethal doses.

A simple, rapid gas-liquid chromatographic procedure for the determination of valproic acid in serum.

A simple, rapid method for the gas-liquid chromatographic (GLC) determination of valproic acid in serum without prior derivatization on a Nukol wide-bore capillary column is presented. The method was determined to have a lower limit of detection (LOD) of 5 mg/L and a lower limit of quantitation (LOQ) of 10 mg/L; the method was linear up to 6000 mg/L. Within-run precision (expressed as percent coefficient of variation [CV]) for control specimens containing 60 mg/L and 120 mg/L was 4.3% CV (n = 10) and 3.0% CV (n = 10), respectively. The between-run precision of control sera analyzed over four week yielded 8% at 25 mg/L, 5% at 60 mg/L, and 3% at 120 mg/L. The absolute, uncorrected, analytical recoveries of valproic acid at 10, 32, and 120 mg/L were 97% (n = 5), 101% (n = 5), and 84% (n = 5), respectively. The absolute recovery of the internal standard was 97% (n = 9). Drugs commonly indicated for therapeutic monitoring and other serum constituents were found not to interfere with the procedure. The results of an intermethod comparison study of serum specimens analyzed by TDx immunoassay versus the presented GLC method demonstrated good correlation. At 95% confidence limits, no statistically significant differences were observed between results (p < 0.05). The method is particularly advantageous to toxicology laboratories because chromatography is performed on a polar GLC column that can be modified readily for the routine clinical analysis of other polar compounds such as ethylene glycol and other glycols.