Cynthia Coulter

South China University of Technology, Shengcheng, Guangdong, China

Are you Cynthia Coulter?

Claim your profile

Publications (30)62.63 Total impact

  • Cynthia Coulter, Margaux Garnier, Christine Moore
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the determination of tetrahydrocannabinol (THC) and its metabolite, 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in oral fluid using solid-phase extraction and liquid chromatography with tandem mass spectral detection (LC-MS-MS) and its application to proficiency specimens. The method employs collection of oral fluid with the Quantisal™ device, base hydrolysis, solid-phase extraction and LC-MS-MS in positive ion electrospray mode. Because the concentration of the metabolite in oral fluid is quite low, extremely sensitive analytical methods are necessary. The requisite sensitivity was achieved by a simple, rapid derivatization of the compound after extraction. The derivatization conditions did not affect parent THC. The method was fully validated using standard parameters including linearity, sensitivity, accuracy, intra-day and inter-day imprecision, drug recovery from the collection pad, limit of quantitation, limit of detection and matrix effects. The procedure was applied to oral fluid proficiency specimens previously analyzed to assess the stability of THC-COOH.
    Journal of analytical toxicology 04/2012; 36(6):413-7. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The determination of carisoprodol and its metabolite meprobamate in oral fluid using solid-phase extraction and liquid chromatography with tandem mass spectral detection (LC-MS-MS) and its application to authentic specimens is described. The method employs collection of oral fluid with the Quantisal device, extraction using cation exchange/hydrophobic solid-phase columns, and LC-MS-MS in positive ion electrospray mode. The method was fully validated using various parameters, including selectivity, linearity, accuracy, intra-day and inter-day imprecision, drug recovery from the collection pad, limit of quantitation and matrix effects. The method was applied to both routine research specimens and an authentic specimen taken from an individual prescribed a daily dose of 350 mg carisoprodol following surgery.
    Journal of analytical toxicology 04/2012; 36(3):217-20. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The use of prescription pain relievers, specifically opioids, has been increasing over the last few years. Oral fluid is easier to collect than urine, is difficult to adulterate, and is a reflection of free drug in the body, so its analysis is becoming more widespread in the monitoring of opioids. The demethylated metabolites of oxycodone, hydrocodone, and codeine are present at higher concentrations in oral fluid than oxymorphone, hydromorphone, and morphine, respectively; therefore, their detection in saliva indicates ingestion of the medication rather than diversion, and should be included in the analysis of opioids in this matrix. Since the compounds have the same nominal molecular weights, the same M + H(+) precursor ions in positive electrospray mode, and potentially identical collisionally activated fragmentation patterns, the importance of chromatography to separate the various opioids as well as the selection of mass spectral transitions is critical for correct identification. A procedure for the simultaneous determination of 12 opioid related compounds in oral fluid using liquid chromatography with tandem mass spectrometry (LC-MS/MS) is presented. The recovery of opioids from the collection device was over 80% at 20 ng/ml; intra-day imprecision was less than 6.8%; inter-day imprecision less than 6.2%. In authentic specimens, the predominant metabolite of oxycodone was noroxycodone; for specimens containing codeine, no morphine was detected; and for hydrocodone positives, norhydrocodone was detected at significantly higher levels than hydromorphone. The importance of monitoring specific mass spectral transitions and chromatographic separation is demonstrated.
    Drug Testing and Analysis 02/2012; 4(6):395-401. · 3.17 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The concentration of tetrahydrocannabinol (THC) and its main metabolite 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) as well as cannabinol (CBN), and cannabidiol (CBD) were measured in oral fluid following realistic exposure to marijuana in a Dutch coffee-shop. Ten healthy subjects, who were not marijuana smokers, volunteered to spend 3h in two different coffee shops in Groningen, The Netherlands. Subjects gave two oral fluid specimens at each time point: before entering the store, after 20 min, 40 min, 1h, 2h, and 3h of exposure. The specimens were collected outside the shop. Volunteers left the shop completely after 3h and also provided specimens approximately 12-22 h after beginning the exposure. The oral fluid specimens were subjected to immunoassay screening; confirmation for THC, cannabinol and cannabidiol using GC/MS; and THC-COOH using two-dimensional GC-GC/MS. THC was detectable in all oral fluid specimens taken 3h after exposure to smoke from recreationally used marijuana. In 50% of the volunteers, the concentration at the 3h time-point exceeded 4 ng/mL of THC, which is the current recommended cut-off concentration for immunoassay screening; the concentration of THC in 70% of the oral fluid specimens exceeded 2 ng/mL, currently proposed as the confirmatory cut-off concentration. THC-COOH was not detected in any specimens from passively exposed individuals. Therefore it is recommended that in order to avoid false positive oral fluid results assigned to marijuana use, by analyzing for only THC, the metabolite THC-COOH should also be monitored.
    Forensic science international 07/2011; 212(1-3):227-30. · 2.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Fentanyl is an extremely potent synthetic opioid that is widely used for chronic pain treatment; it is highly addictive and prone to abuse. The objective is to develop a high throughput homogeneous enzyme immunoassay (HEIA) for the rapid detection of fentanyl in human urine. The HEIA is based on an immunoassay format in which both the antibody and enzyme-drug conjugate are in ready-to-use solution. In the absence of the target analyte in the specimen, enzyme-labeled drug conjugate binds to the antibody and results in a decrease of the enzyme (G6PDH) activity; hence there is lower absorbance at 340 nm. If the target analyte is present in the specimen, it competes with the enzyme-labeled drug to bind to limited amount of specific antibody that result in more enzyme activity and yields an increased absorbance at 340 nm. A polyclonal "in-house" antibody was selected that is capable of measuring fentanyl at low concentrations thus the assay detection limit was determined to be 1 ng/mL. The assay was validated with clinical urine specimens that previously confirmed positively or negatively for fentanyl/norfentanyl by LC-MS/MS. The intra-day (n = 20) and inter-day (n = 100) precision of the assay was less than 1% CV. No interferences from structurally unrelated and commonly ingested drugs were observed at a concentration of 10,000 ng/mL. A total of 209 LC-MS/MS confirmed urine specimens (149 positive and 57 negative samples) were analyzed by HEIA. The sensitivity, specificity, and accuracy values were 99%, 95%, and 98% respectively. This paper describes the development of a highly sensitive homogenous enzyme immunoassay for detecting fentanyl in urine at a cut-off concentration of 2 ng/mL.
    Forensic science international 03/2011; 206(1-3):127-31. · 2.10 Impact Factor
  • Source
    Cynthia Coulter, Margaux Garnier, Christine Moore
    [Show abstract] [Hide abstract]
    ABSTRACT: At the end of 2010, the U.S. Drug Enforcement Administration (DEA) used its emergency scheduling authority to temporarily control five chemicals, JWH-018, JWH-073, JWH-200, CP-47497, and cannabicyclohexanol (CP-47497 C8), often referred to as "Spice", K2, or "synthetic cannabinoids" because of their reported cannabis-like effects. JWH-250 is commonly encountered, and HU-210 was already controlled, so these were also included in the research. We report the first analytical procedure for the simultaneous determination of these compounds in oral fluid specimens collected with the Quantisal™ device using solid-phase extraction and liquid chromatography with tandem mass spectrometry. The method was validated and applied to specimens taken from two individuals who had purchased the synthetic compounds while still legally available in the U.S. After a single session of smoking "Blueberry Posh", the peak concentration of JWH-018 detected was 35 μg/L 20 min after smoking; JWH-018 was still detectable 12 h after a single intake. After a single session of smoking "Black Mamba", JWH-018 was detected with a peak concentration of 5 μg/L after 20 min. In this subject, the compound was not detectable after 12 h.
    Journal of analytical toxicology 01/2011; 35(7):424-30. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this project was to validate a new high-throughput homogeneous enzyme immunoassay (HEIA) for the rapid detection of carisoprodol in human urine. Carisoprodol (Soma(®)) and meprobamate are widely prescribed as musculoskeletal pain relief drugs and are listed as one of the 10 most frequently identified drugs associated with DUI cases. Carisoprodol has a short elimination half-life of 1-3 h; however, its major active metabolite, meprobamate, has a longer elimination half-life of 6-17 h. As a result, it is important for an immunoassay to cross-react with both compounds. The advantage of this new assay is that cutoff concentrations can be adjusted between 100 and 500 ng/mL. The reportable range was 25 to 1000 ng/mL for carisoprodol and 50 to 10,000 ng/mL for meprobamate. The intraday coefficient of variation (% CV) for the semi-quantitative assay was less than 1%. The homogeneous assay was validated with a total of 86 urine samples previously analyzed by liquid chromatography-tandem mass spectrometry with carisoprodol concentrations ranging from 50 to 10,000 ng/mL. The accuracy was found to be 100% when immunoassay cutoff concentrations of carisoprodol and meprobamate were set at 100 and 1000 ng/mL, respectively.
    Journal of analytical toxicology 01/2011; 35(2):108-12. · 2.11 Impact Factor
  • Source
    Margaux Garnier, Cynthia Coulter, Christine Moore
    [Show abstract] [Hide abstract]
    ABSTRACT: A retrospective analysis of data from oral fluid specimens was conducted in order to identify a relevant cutoff concentration for opiates and/or synthetic opiates in oral fluid. Previously proposed regulations from the Substance Abuse and Mental Health Services Administration (SAMHSA) have recommended 40 μg/L as a cutoff concentration. In this study, data from oral fluid specimens collected using the Quantisal™ device and screened with enzyme linked immunosorbent assays (ELISA) for both opiates and oxycodone were retrospectively assessed for screen positives > 20 μg/L and those between negative and 20 μg/L. Specimens identified at these concentrations were then analyzed using liquid chromatography with tandem mass spectral detection using a fully validated procedure. Overall, 156 positive specimens were identified using 40 μg/L; 191 specimens using 20 μg/L; and 241 specimens between negative and 20 μg/L. Specifically, the number of 6-acetylmorphine (6-AM) positives increased from 10 to 16; morphine 4 to 9; codeine from 11 to 19; oxycodone from 56 to 74; hydrocodone from 73 to 119; and hydromorphone from 2 to 4 when specimens with enzyme inhibition between negative and 20 μg/L were analyzed. For workplace testing where only codeine, morphine, and 6-AM are considered, the use of a lowered cutoff concentration produced significant increases in the positive rate.
    Journal of analytical toxicology 01/2011; 35(6):369-74. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A semi-quantitative analytical screening procedure for the determination of cocaine, amphetamines, opiates, and delta-9-tetrahydrocannabinol in hair has been developed. The procedure employs an aqueous extraction buffer, uses only 10mg of hair, requires 2h of incubation for the extraction to occur, and multiple drug classes can be screened using enzyme linked immunosorbent assays. Hair calibration standards were prepared around the recommended cut-off concentrations of the Society of Hair Testing. All drug classes showed excellent linearity over the concentration range tested, indicating that immunochemical screening can be used in a semi-quantitative mode for hair analysis using an aqueous buffer, rapid extraction and a small amount of hair.
    Forensic science international 03/2010; 196(1-3):70-3. · 2.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An analytical procedure for the determination of the new pain medication tapentadol and its main metabolite N-desmethyltapentadol (DMT), in urine and oral fluid has been developed and validated using liquid chromatography with tandem mass spectral detection (LC-MS-MS). Oral fluid was collected using Quantisal™ devices, and drugs present were quantified using solid-phase extraction followed by LC-MS-MS. For confirmation, two transitions were monitored and one ratio determined which had to be within 20% of that of the known calibration standard. For tapentadol, 222.1 > 107 was used as the quantifying transition; 222.1 > 121 for the qualifier. For DMT, 208.1 > 107 was used for quantification; 208.1 > 121 as the qualifier. For saliva, the linear range was 10-100 ng/mL; the lower limit of quantitation (LLOQ) was 10 ng/mL; the intraday precision was 3.6% (n = 6) and interday precision was 13.6% (n = 24). The recovery of tapentadol and DMT from the oral fluid collection pad was > 99%. For urine, the specimens were diluted and injected directly into the LC-MS-MS. The LLOQ was 50 ng/mL; the intraday and interday precisions were 2.1% and 4.4%, respectively, for tapentadol and 2.9% and 5.7%, respectively, for DMT. This is the first analytical procedure for tapentadol and DMT in urine and oral fluid.
    Journal of analytical toxicology 01/2010; 34(8):458-63. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An analytical procedure for the determination of widely prescribed drugs for the treatment of depression and anxiety disorders, including amitriptyline, cyclobenzaprine, imipramine, dothiepin, doxepin, fluoxetine, sertraline, trimipramine, protriptyline, chlorpromazine, clomipramine, and some of their metabolites (nortriptyline, desmethyldoxepin, desipramine, desmethyltrimipramine, norclomipramine) in oral fluid has been developed and validated using liquid chromatography with tandem mass spectral detection. The oral fluid samples were collected using the Quantisal device and screened with enzyme-linked immunosorbent assay. Any drugs present were quantified using mixed-mode solid-phase extraction followed by mass spectrometric detection in positive electrospray ionization mode. For confirmation, two transitions were monitored, and the ratio between the two was required to be within 20% of the known calibration standard. Because of the worldwide shortage of acetonitrile, which was first reported in October 2008, the mobile phase was optimized to use methanol as the organic component. For all compounds, the lower limit of quantitation was 5 ng/mL; the intraday precision ranged from 2.9 to 8.2% (n = 6); interday precision from 1.5 to 6.2% (n = 30) at a concentration of 40 ng/mL. The percentage recovery of antidepressants from the oral fluid collection pad was calculated at a concentration of 40 ng/mL and ranged from 51.4 to 84.1% (n = 6). The aim of the study was to develop a confirmatory procedure for drugs in oral fluid that had been identified as presumptively positive for antidepressants and related compounds. The methods were applied to research oral fluid specimens received into our facility for testing.
    Journal of analytical toxicology 01/2010; 34(2):64-72. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sleep disorders are common conditions that affect about 40 million people in the U.S every year, the most common of which is insomnia, which is characterized by difficulty falling or staying asleep. Zolpidem (Ambien) is a non-benzodiazepine prescription drug that is used to treat insomnia and is often preferred over the commonly used benzodiazepines due to a lesser side effect profile. This is because the non-benzodiazepine binding is more selective to GABA-A receptors versus the non-selective binding of benzodiazepines. With the increasing popularity of non-benzodiazepines, drug abuse and driving-while-impaired cases involving sleep-inducing drugs have risen. Therefore, a highly sensitive and rapid homogeneous immunoassay (EMIT-type assay) has been developed for the detection of zolpidem in urine. The zolpidem antibody is highly specific and does not cross-react with other newer sleep aids such as zopiclone and zaleplon. This assay has a detection limit of 5 ng/mL for zolpidem in urine. Further evaluation of this assay using liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis of authentic urine samples demonstrated that the accuracy of the assay is greater than 90%. Because this assay is designed to measure the non-conjugated drug in urine, it resulted in simplification for gas chromatography-MS or LC-MS-MS confirmation methods that do not require urine hydrolysis before solid-phase extraction or liquid-liquid extraction.
    Journal of analytical toxicology 10/2009; 33(8):486-90. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ractopamine belongs to a group of beta-agonist compounds. It is a forbidden food additive in most countries because of the many reported collective intoxication outbreaks in humans. Because the drug can be rapidly metabolized and eliminated from animal body, the objective of this study was to develop an efficient and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) analytical method for the detection of ractopamine with cutoff below 1 ng/mL to extend the detection window after withdrawal of the drug and at the same time to meet the requirements of zero-tolerance policy set by most countries. After solid-phase cleanup of the non-hydrolyzed and hydrolyzed urine samples, the residues were dissolved in methanol and analyzed directly by LC-MS-MS. Two transitions were monitored and one ratio determined. Samples reported as positive were required to have the ratio of the transitions within 20% of that determined from known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion has the potential of limiting the sensitivity of the assay. The limits of detection and quantitation of the assay were 0.1 and 0.25 ng/mL, respectively. The intraday precisions at 0.25 and 35 ng/mL were 4.88% and 0.95%, respectively. Interday precisions were 5.64% and 0.9% at the same concentrations. The percentage recoveries at 0.25 and 0.5 ng/mL were 117.8% and 108.4%, respectively.
    Journal of analytical toxicology 08/2009; 33(6):289-93. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A quantitative analytical procedure for the determination of Delta(9)-tetrahydrocannabinol (THC) in hair has been developed and validated using liquid chromatography with tandem mass spectral detection (LC-MS/MS). Specimens that were determined as containing cannabinoids following immunoassay testing were quantified using solid-phase extraction followed by liquid chromatographic separation and tandem mass spectral detection in positive electrospray ionization mode. For confirmation, two transitions were monitored and one ratio determined. Samples being reported as positive were required to have both transitions present, the ratio of quantifying transition to qualifying transition being within 20% of that determined from known calibration standards. The limit of quantitation and the limit of detection was 10 pg/mg. The percentage recovery of the THC from hair at 20 pg/mg was 56% and a matrix effect of the hair showed an ion suppression percentage of -51%. The immunochemical screening method was performed following a rapid aqueous extraction, requiring only 10 mg of hair; the confirmatory procedure required 20 mg of hair. The methods were applied to proficiency specimens from the Society of Hair Testing, which had been received in August 2008.
    Drug Testing and Analysis 05/2009; 1(5):234-9. · 3.17 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An analytical procedure for the determination of Delta9-tetrahydrocannabinol (THC), 11-nor-9-carboxy-Delta9-tetrahydrocannabinol (THCA), and 11-hydroxy-Delta9-tetrahydrocannabinol (11-OH-THC) in whole blood has been developed and validated using liquid chromatography with tandem mass spectral detection (MS). Cannabinoids present in the blood samples were quantified using solid-phase extraction followed by MS detection in positive electrospray ionization mode. For confirmation, two transitions were monitored and one ratio determined. Samples being reported as positive were required to have both transitions present, the ratio of quantifying transition to qualifying transition being within 20% of that determined from known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion has the potential of limiting the sensitivity of the assay, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. The limit of quantitation was 0.5 ng/mL for THC, 5 ng/mL for THCA, and 2 ng/mL for 11-OH-THC. The limit of detection was 0.5 ng/mL for THC, 4 ng/mL for THCA, and 1 ng/mL for 11-OH-THC. The percentage recovery of the cannabinoids from whole blood at a concentration of 5 ng/mL was 71.5% for THC, 64.5% for 11-OH-THC, and 61.2% for THCA (n = 3).
    Journal of analytical toxicology 11/2008; 32(8):653-8. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An analytical procedure for the determination of phencyclidine in oral fluid has been developed and validated using liquid chromatography with tandem mass spectral detection, following initial screening with enzyme linked immunosorbent assay. The oral fluid samples were collected using the Quantisal device, and any drugs present were quantified using mixed mode solid-phase extraction followed by mass spectrometric detection in positive atmospheric pressure chemical ionization mode. For confirmation, two transitions were monitored and one ratio determined, which had to be within 20% of that of the known calibration standard. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion has the potential of limiting the sensitivity of the assay, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. The limit of quantitation was 5ng/mL; the intra-day precision of the assay (n=5) was 3.04%; inter-day precision 3.35% (n=5) at a concentration of 10ng/mL. The accuracy was determined at four concentrations (5, 10, 20 and 40ng/mL) within the linear range of the assay. The percentage recovery of phencyclidine from the oral fluid collection pad was 81.7% (n=6). The methods were applied to both proficiency specimens and to samples obtained during research studies in the USA.
    Journal of Chromatography B 03/2008; 863(1):123-8. · 2.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A quantitative analytical procedure for the determination of cocaine, benzoylecgonine and cocaethylene and norcocaine in hair has been developed and validated. The hair samples were washed, incubated, and any drugs present were quantified using mixed mode solid-phase extraction and liquid chromatography with tandem mass spectrometric detection in positive atmospheric pressure chemical ionization mode. For confirmation, two transitions were monitored and one ion ratio was determined, which was within 20% of that of the known calibration standards. The monitoring of the qualifying transition and requirement for its presence within a specific ratio to the primary ion limited the sensitivity of the assay, particularly for benzoylecgonine, however, the additional confidence in the final result as well as forensic defensibility were considered to be of greater importance. Even with simultaneous monitoring, the concentrations proposed by the United States Federal guidelines for hair analysis were achieved. The limits of quantitation were 50 pg/mg; the limit of detection was 25 pg/mg. The intra-day precision of the assays at 100 pg/mg (n=5) was 1.3%, 8.1%, 0.8% and 0.4%; inter-day precision 4.8%, 9.2%, 15.7% and 12.6% (n=10) for cocaine, benzoylecgonine, cocaethylene and norcocaine, respectively. The methods were applied to both proficiency specimens and to samples obtained during research studies in the USA.
    Journal of Chromatography B 12/2007; 859(2):208-12. · 2.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This article details the rapid extraction of amphetamines from oral fluid using low specimen volume, low sorbent bed mass, and fast gas chromatography with mass selective detection. The collection of a known amount of sample volume coupled with high percentage recovery of drug from the collection pad has allowed oral fluid to be increasingly employed as the specimen of choice for the detection of drug use in various applications. Additionally, low specimen volume for confirmation is required, so that adequate test volume remains for second analysis in case of batch failure or for testing at a different laboratory facility. The extracts were prepared using low bed mass sorbent, so less conditioning, washing, and elution solvent further reduced the overall cost of sample preparation. The limits of quantitation for the assay were 25 ng/mL; the intraday precision of the assays (n = 5) ranged from 0.3 to 3.99%; interday precision ranged from 0.72 to 4.6% for the amphetamine class. The percentage recovery of the drugs from the collection pads ranged from 85.4 to 89.1% (n = 6). The process lends itself to widely available automated processing instrumentation and significantly increases the efficiency of laboratories providing high-volume oral fluid analysis for drugs of abuse.
    Journal of analytical toxicology 11/2007; 31(8):442-6. · 2.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Buprenorphine is now increasingly prescribed as an alternative to methadone for the treatment of heroin addiction. Because of its potency (dosage usages from 0.2 mg to 8 mg), the drug concentrations in body fluids are normally very low. Here, we report the first recombinant glucose-6-phosphate dehydrogenase (G6PDH)-based homogeneous immunoassay (EMIT-type assay) for free buprenorphine and free norbuprenorphine in urine. The antibody used in this assay cross-reacts nearly identically with buprenorphine and norbuprenorphine and, at the same time, has less than 1% cross-reactivity with a wide range of commonly prescribed opiates, particularly those structurally related compounds such as morphine, codeine, and dihydrocodeine. More importantly, this assay has a low detection limit of 1 ng/mL for buprenorphine or norbuprenorphine. Further evaluation of this technique using gas chromatography-mass spectrometry (GC-MS) of authentic urine samples demonstrated that the accuracy of the assay is greater than 95%. Because this assay is designed to measure the free drugs in urine, it resulted in simplification for GC-MS or liquid chromatography-MS confirmation methods that did not require urine hydrolysis before solid-phase or liquid-liquid extraction.
    Journal of analytical toxicology 10/2007; 31(7):377-82. · 2.11 Impact Factor
  • Christine Moore, Sumandeep Rana, Cynthia Coulter
    [Show abstract] [Hide abstract]
    ABSTRACT: Tetrahydrocannabinol (THC) is an important psychoactive ingredient in marijuana, which is the most widely used illegal recreational drug in the USA. Since it is generally smoked, the constituents of the plant material, as well as THC may be present in oral fluid specimens collected for the purposes of drug testing. We present an analytical procedure for the simultaneous determination of the pyrolytic precursor Delta(9)-tetrahydrocannabinolic acid A, tetrahydrocannabinol, cannabinol and cannabidiol in human oral fluid specimens using gas chromatography mass spectrometry (GC/MS). Solid phase extraction and GC/MS/EI with selected ion monitoring were used, and the linearity of the method ranged from 0-16 ng/mL of neat oral fluid. The recovery of the cannabinoids from the collection pad into the transportation buffer was greater than 70% for all cannabinoids tested at 4 ng/mL, and the intra- and inter-day precision was less than 10.3 and 15.2% for all analytes. The stability of the drugs in oral fluid and of the extracted derivatives was investigated. The procedure was applied to oral fluid specimens taken from habitual marijuana smokers. We have previously reported the presence of the metabolite 11-nor-Delta(9)-tetra-hydrocannabinol-9-carboxylic acid in oral fluid, but this is the first report of the plant constituent 2-carboxy-THC being detected in saliva.
    Journal of Chromatography B 07/2007; 852(1-2):459-64. · 2.49 Impact Factor