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Hirano A, Nagatoishi S, Wada M, Tsumoto K, Maluf KN, Arakawa T. Technical Capabilities and Limitations of Optical Spectroscopy and Calorimetry Using Water-Miscible Solvents: The Case of Dimethyl Sulfoxide, Acetonitrile, and 1,4-Dioxane. J Pharm Sci 2019; 109:524-531. [PMID: 31682831 DOI: 10.1016/j.xphs.2019.10.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/22/2019] [Accepted: 10/29/2019] [Indexed: 01/09/2023]
Abstract
In drug development, water-miscible solvents are commonly used to dissolve drug substances. Typical routine procedures in drug development include dilution of the stock drug solution into an aqueous solution containing target macromolecules for drug binding assays. However, water-miscible solvents impose some technical limitations on the assays on account of their light absorption and heat capacity. Here, we examined the effects of the dilution of 3 water-miscible solvents, that is, dimethyl sulfoxide, acetonitrile, and 1,4-dioxane, on the baseline stability and signal/noise ratio in circular dichroism spectroscopy, isothermal titration calorimetry, and differential scanning calorimetry. Dimethyl sulfoxide and 1,4-dioxane affect the signal/noise ratio of circular dichroism spectra at typically used concentrations due to their light absorbance. The water-miscible solvents generate interfering signals in the isothermal titration calorimetry due to their mixing heat. They show negative or positive slope in the differential scanning calorimetry. Such interfering effects of the solvents are reduced by appropriate dilution according to the analytical techniques. Because the water-miscible solvents have solubilization capacity for alkyl chain moieties and aromatic moieties of chemicals, drug substances containing these moieties can be dissolved into the solvents and then subjected to the analyses to examine their interactions with target proteins after appropriate dilution of the drug solutions.
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Affiliation(s)
- Atsushi Hirano
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan.
| | - Satoru Nagatoishi
- The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Momoyo Wada
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
| | - Kouhei Tsumoto
- The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan; School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Karl N Maluf
- Alliance Protein Laboratories, Division of KBI Biopharma, San Diego, California 92121
| | - Tsutomu Arakawa
- Alliance Protein Laboratories, Division of KBI Biopharma, San Diego, California 92121
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2
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Arakawa T. Acetonitrile as solvent for protein interaction analysis. Int J Biol Macromol 2018; 114:728-732. [DOI: 10.1016/j.ijbiomac.2018.03.174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 02/23/2018] [Accepted: 03/28/2018] [Indexed: 10/17/2022]
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3
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Review: The Application of Liquid Chromatography Electrochemical Detection for the Determination of Drugs of Abuse. SEPARATIONS 2016. [DOI: 10.3390/separations3040028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Teixeira H, Verstraete A, Proença P, Corte-Real F, Monsanto P, Vieira DN. Validated method for the simultaneous determination of Δ9-THC and Δ9-THC-COOH in oral fluid, urine and whole blood using solid-phase extraction and liquid chromatography–mass spectrometry with electrospray ionization. Forensic Sci Int 2007; 170:148-55. [PMID: 17614225 DOI: 10.1016/j.forsciint.2007.03.026] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 03/23/2007] [Accepted: 03/23/2007] [Indexed: 11/18/2022]
Abstract
A fully validated, sensitive and specific method for the extraction and quantification of Delta(9)-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Delta(9)-THC (THC-COOH) and for the detection of 11-hydroxy-Delta(9)-THC (11-OH THC) in oral fluid, urine and whole blood is presented. Solid-phase extraction and liquid chromatography-mass spectrometry (LC-MS) technique were used, with electrospray ionization. Three ions were monitored for THC and THC-COOH and two for 11-OH THC. The compounds were quantified by selected ion recording of m/z 315.31, 329.18 and 343.16 for THC, 11-OH THC and THC-COOH, respectively, and m/z 318.27 and 346.26 for the deuterated internal standards, THC-d(3) and THC-COOH-d(3), respectively. The method proved to be precise for THC and THC-COOH both in terms of intra-day and inter-day analysis, with intra-day coefficients of variation (CV) less than 6.3, 6.6 and 6.5% for THC in saliva, urine and blood, respectively, and 6.8 and 7.7% for THC-COOH in urine and blood, respectively. Day-to-day CVs were less than 3.5, 4.9 and 11.3% for THC in saliva, urine and blood, respectively, and 6.2 and 6.4% for THC-COOH in urine and blood, respectively. Limits of detection (LOD) were 2 ng/mL for THC in oral fluid and 0.5 ng/mL for THC and THC-COOH and 20 ng/mL for 11-OH THC, in urine and blood. Calibration curves showed a linear relationship for THC and THC-COOH in all samples (r(2)>0.999) within the range investigated. The procedure presented here has high specificity, selectivity and sensitivity. It can be regarded as an alternative method to GC-MS for the confirmation of positive immunoassay test results, and can be used as a suitable analytical tool for the quantification of THC and THC-COOH in oral fluid, urine and/or blood samples.
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Affiliation(s)
- Helena Teixeira
- Delegation of Coimbra, National Institute of Legal Medicine, Coimbra, Portugal.
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Abbara C, Galy R, Benyamina A, Reynaud M, Bonhomme-Faivre L. Development and validation of a method for the quantitation of Δ9 tetrahydrocannabinol in human plasma by high performance liquid chromatography after solid-phase extraction. J Pharm Biomed Anal 2006; 41:1011-6. [PMID: 16500063 DOI: 10.1016/j.jpba.2006.01.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 12/27/2005] [Accepted: 01/07/2006] [Indexed: 11/17/2022]
Abstract
A high performance liquid chromatography (HPLC) procedure for the determination of Delta9 tetrahydrocannabinol (THC) in human plasma is described. A two-step solid-phase extraction on CN cartridges was coupled with a reversed phase HPLC system. THC was eluted using a mobile phase composed of methanol, acetonitrile and tetrabutylammonium perchlorate solution (0.005 M, pH 3.2), through a C18 Nucleosil column and detected at a wavelength of 215 nm. Calibration curve was linear over the range 5-100 ng/ml with a lower limit of quantification validated at 5 ng/ml. Extraction recovery using the developed extraction procedure was higher than 85%. This method is presently used for the quantification of THC in plasma samples from regular cannabis smokers.
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Affiliation(s)
- Chadi Abbara
- Laboratoire de Pharmacologie, Service de Pharmacie, Hôpital Paul BROUSSE (AP-HP), 12, Avenue Paul Vaillant Couturier, 94800 Villejuif, France.
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Wojtasik E, Anyzewska M, Arent I. THE OPTIMIZATION OF THE SEPARATION CONDITIONS FOR CANNABINOIDS FROM CANNABIS SATIVA L. VAR INDICA AND APPLICATION OF THE METHOD TO DETERMINE THE CONTENT OF Δ 9-TETRAHYDROCANNABINOL IN PLANT MATERIAL. J LIQ CHROMATOGR R T 2002. [DOI: 10.1081/jlc-120003272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- E. Wojtasik
- a Department of Plant Materials and Herbal Medicine , Drug Institute , 30/34 Chelmska, Str., Warsaw, 00725, Poland
| | - M. Anyzewska
- a Department of Plant Materials and Herbal Medicine , Drug Institute , 30/34 Chelmska, Str., Warsaw, 00725, Poland
| | - I. Arent
- a Department of Plant Materials and Herbal Medicine , Drug Institute , 30/34 Chelmska, Str., Warsaw, 00725, Poland
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Backofen U, Matysik FM, Lunte CE. Determination of cannabinoids in hair using high-pH* non-aqueous electrolytes and electrochemical detection. Some aspects of sensitivity and selectivity. J Chromatogr A 2002; 942:259-69. [PMID: 11822390 DOI: 10.1016/s0021-9673(01)01348-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Non-aqueous capillary electrophoresis with electrochemical detection (NACE-ED) was applied to the determination of cannabinoids in hair. The effect of different electrolyte compositions on the selectivity of the separation of tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD) and tetrahydrocannabinol carboxylic acid (THCA) was studied. Complete electrophoretic resolution was obtained using a strongly basic background electrolyte consisting of 5 mM sodium hydroxide dissolved in acetonitrile-methanol (1:1). Electrochemical detection yielded well defined signals in the oxidation mode. In order to obtain low limits of detection experimental parameters, which determine the sensitivity and the noise level, were optimized. A crucial parameter for sensitive measurements using a wall-tube flow cell as end-column detector is the distance between the capillary outlet and the working electrode. The highest signal-to-noise ratio using a 50 microm I.D. capillary was obtained at a distance of 25 microm. When the capillary outlet was moved away from the working electrode, thus reducing the strength of the separation field present at the working electrode, a large low frequency noise developed. This rise was attributed to disturbances of the hydrodynamic pattern in the flow cell. Analytical aspects such as sensitivity, reproducibility and selectivity were addressed in this work. The precision of NACE-ED regarding migration time and peak height for a sample containing 1 microg/ml THC was 0.4% and 1.1% (RSD), respectively (n=5). The calibration curve was linear for concentrations ranging between 0.1 and 10 microg/ml (r=0.998). The limit of detection for THC was 37 ng/ml, which is almost two orders of magnitude lower when compared with on-column UV detection. The method was evaluated using hair samples containing cannabinoids as sample material.
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Affiliation(s)
- Ulli Backofen
- University of Kansas, Department of Chemistry, Lawrence 66045, USA
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Backofen U, Hoffmann W, Matysik FM. Determination of cannabinoids by capillary liquid chromatography with electrochemical detection. Biomed Chromatogr 2000; 14:49-52. [PMID: 10664565 DOI: 10.1002/(sici)1099-0801(200002)14:1<49::aid-bmc967>3.0.co;2-d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- U Backofen
- Forschungszentrum Karlsruhe, Institut für Instrumentelle Analytik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Krämer E, Kovar KA. On-line coupling of automated solid-phase extraction with high-performance liquid chromatography and electrochemical detection. Quantitation of oxidizable drugs of abuse and their metabolites in plasma and urine. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 731:167-77. [PMID: 10510769 DOI: 10.1016/s0378-4347(99)00212-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The concentration effect of automated on-line solid-phase extraction (SPE) in combination with HPLC and very sensitive electrochemical detection was employed for the determination of N-ethyl-4-hydroxy-3-methoxy-amphetamine (HMEA, the main metabolite of the ecstasy analogue MDE), delta 9-tetrahydrocannabinol (THC) and 11-nor-delta 9-tetrahydrocannabinol-carboxylic acid (THC-COOH) in plasma and urine in comparison to a previously published psilocin assay. For the SPE either CBA (functional group: carboxypropyl)- or CH (functional group: cyclohexyl)-sorbent was used. The following separation was carried out on a reversed-phase column (LiChroCart, Superspher 60 RP select B from Merck). Depending on the hydrodynamic voltammogram of the analyzed substance the oxidation potential varied from 920 mV up to 1.2 V. In spite of using high potentials, precision and accuracy were always within the accepted statistical requirements. The limits of quantitation were between 5 ng/ml (THC, THC-COOH in plasma) and 20 ng/ml (HMEA in plasma). Advantages of on-line SPE in comparison with off-line methods were less manual effort, evidently smaller volumes (< or = 400 microliters) of plasma or urine and almost always higher recovery rates (> 93%). The assays have been successfully proven with real biological samples and found suitable for use in routine analysis.
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Affiliation(s)
- E Krämer
- Pharmaceutical Institute, University of Tübingen, Germany
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Abstract
A method for cannabis testing in human whole blood is presented. The procedure involves extraction of a 2 mL specimen acidified with 0.2 mL of 10% acetic acid in a silanized vial in presence of deuterated internal standards into hexane:ethyl acetate. After evaporation to dryness the drug and its metabolite were derivatized by methylation with iodomethane in tetrabutylammonium hydroxide-dimethyl sulphoxide (DMSO). The derivatives were extracted into isoocatane for analysis by gas chromatography-mass spectrometry (GC-MS). The limit of quantification was 1.0 and 0.5 ng/mL for delta 9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THC-COOH), respectively.
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Affiliation(s)
- P Kintz
- Institut de Médecine Légale, Strasbourg, France
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Simpson D, Braithwaite RA, Jarvie DR, Stewart MJ, Walker S, Watson IW, Widdop B. Screening for drugs of abuse (II): Cannabinoids, lysergic acid diethylamide, buprenorphine, methadone, barbiturates, benzodiazepines and other drugs. Ann Clin Biochem 1997; 34 ( Pt 5):460-510. [PMID: 9293303 DOI: 10.1177/000456329703400502] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Requirements for the provision of an efficient and reliable service for drugs of abuse screening in urine have been summarized in Part I of this review. The requirements included rapid turn-around times, good communications between requesting clinicians and the laboratory, and participation in quality assessment schemes. In addition, the need for checking/confirmation of positive results obtained for preliminary screening methods was stressed. This aspect of the service has assumed even greater importance with widespread use of dip-stick technology and the increasing number of reasons for which drug screening is performed. Many of these additional uses of drug screening have possible serious legal implications, for example, screening school pupils, professional footballers, parents involved in child custody cases, persons applying for renewal of a driving licence after disqualification for a drug-related offence, doctors seeking re-registration after removal for drug abuse, and checking for compliance with terms of probation orders; as well as pre-employment screening and work-place testing. In many cases these requests will be received from a general practitioner or drug clinic with no indication of the reason for which testing has been requested. This also raises the serious problems of a chain of custody, provision of two samples, stability of samples, and secure and lengthy storage of samples in the laboratory-samples may be requested by legal authorities several months after the initial testing. The need for confirmation of positive results is now widely accepted but it may be equally important to confirm unexpected negative results. Failure to detect the presence of maintenance drugs may lead to the patient being discharged from a drug treatment clinic and, if attendance at the clinic is one of the terms of continued employment, to dismissal. It seems likely that increasing abuse of drugs and the efforts of regulatory authorities to control this, will lead to the manufacture of more designer drugs. Production of substituted phenethylamines was facilitated by the drug makers' cook book, 'PIHKAL' (Phenethylamines I Have Known And Loved) by Dr Alexander Shulgin and Ann Shulgin, and production of substituted tryptamines is promised in their next book, TIHKAL. Looking to the future, laboratories will need to ensure that they can detect and quantitate an ever-increasing number of drugs and related substances. The question of confidence in results of drugs of abuse testing raised in 1993 by Watson has assumed even greater importance as a result of attention focused on the OJ Simpson trial in Los Angeles. Toxicological investigations are likely to be challenged more frequently in the future. Even if analyses have been performed by GC-MS, there is a need to establish the level of match between the spectrum of the unknown substance and a library spectrum which is considered acceptable for legal purposes. It will also be essential to ensure that computer libraries contain spectra for all substances likely to be encountered in drugs of abuse screening.
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Affiliation(s)
- D Simpson
- Department of Clinical Biochemistry, Royal Infirmary, Edinburgh, UK
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12
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Fisher DH, Broudy MI, Fisher LM. Quantification of 9-carboxy-11-nor-delta 9-tetrahydrocannabinol in urine using brominated 9-carboxy-11-nor-delta 9-tetrahydrocannabinol as the internal standard and high-performance liquid chromatography with electrochemical detection. Biomed Chromatogr 1996; 10:161-6. [PMID: 8831959 DOI: 10.1002/(sici)1099-0801(199607)10:4<161::aid-bmc579>3.0.co;2-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A method was developed for quantitating 9-carboxy-11-nor-delta 9-tetrahydrocannabinol in human urine as part of the process for validating an automated enzyme immunoassay for marijuana metabolites. Sample cleanup was accomplished using a mixed-mode solid-phase extraction. 9-Carboxy-11-nor-delta 9-tetrahydrocannabinol and the internal standard, brominated 9-carboxy-11-nor-delta 9-tetrahydrocannabinol, were quantified using high-performance liquid chromatography with electrochemical detection (+ 0.85 V). The linear range for this method is 0.012-0.20 microgram/mL. No interference was seen for 22 drugs and metabolites. The pooled relative standard deviation is 4.1% (n = 27) for the quality control samples. This method was compared to gas chromatography with mass spectrometry by linear regression analysis. The slope of the line is 1.00 +/- 0.05 (standard error), the intercept is approximately zero, the coefficient of determination is 0.994, and the standard error of the estimate is 0.006 microgram/mL.
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Affiliation(s)
- D H Fisher
- Department of Medical Laboratory Science, Northeastern University, Boston, MA 02115, USA
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Nyoni EC, Sitaram BR, Taylor DA. Determination of delta 9-tetrahydrocannabinol levels in brain tissue using high-performance liquid chromatography with electrochemical detection. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 679:79-84. [PMID: 8998573 DOI: 10.1016/0378-4347(96)00027-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
delta 9-Tetrahydrocannabinol (delta 9-THC) is the major psychoactive component of cannabis. To assist in investigating the mechanism(s) of action of delta 9-THC, a convenient method for determining its levels in brain tissue is required. We now describe a method for determining nanogram quantities of delta 9-THC in rat brain tissue. The method employs solvent extraction with methanol-hexane-ethyl acetate, followed by analysis using liquid chromatography with electrochemical detection. Overall recoveries were greater than 80%. The relationship between the peak-height ratio for processed standards extracted in the presence of tissue (delta 9-THC/internal standard) and the amount of delta 9-THC added was shown to be linear within the range of concentrations examined. Quantitative measurements of delta 9-THC in different brain regions following the intravenous administration of delta 9-THC are presented as examples of the applications of this method.
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Affiliation(s)
- E C Nyoni
- Department of Pharmaceutics, Monash University, Parkville, Victoria, Australia
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Bianchi V, Donzelli G. Rapid reversed-phase high-performance liquid chromatographic method for the assay of urinary 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid and confirmation of use of cannabis derivatives. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 675:162-7. [PMID: 8634759 DOI: 10.1016/0378-4347(95)00330-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The main active cannabis (marijuana and hashish) derivative delta 9-tetrahydrocannabinol is, in vivo, transformed and excreted mainly as 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and its glucuronide. The method presented here allows the confirmation of the presence of THC-COOH by means of a basic hydrolysis, solid-phase extraction clean-up on reversed-phase (RP) disposable cartridges followed by analysis on a C8 RP column and UV detection; the mobile phase used was a 55% acetonitrile solution in acid phosphate buffer. Over 600 samples both from drug addicts in therapeutic communities and subjects who were not on any drugs therapy were analysed. This method was precise with a linearity range from 10 to more than 500 ng/ml [the lower limit proposed by the National Institute on Drug Abuse (NIDA) for cannabinoid confirmation method is 15 ng/ml]. The sample preparation is simple and fast, allowing the analysis of large numbers of samples. Perfect correlation was observed between data from the HPLC method and a fluorescence polarization immunoassay screening method. The THC-COOH metabolite was found to constitute 30% of all the cannabinoids excreted in urine of abusers.
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Affiliation(s)
- V Bianchi
- Vincenza Bianchi Laboratory of Clinical Pathology, City Hospital, Alessandria, Italy
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Incidence of Psychoactive Cannabinoids in Drivers Killed in Motor Vehicle Accidents. J Forensic Sci 1993. [DOI: 10.1520/jfs13451j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Simultaneous Quantitation of Delta-9-tetrahydrocannabinol (THC) and 11-Nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) in Serum by GC/MS Using Deuterated Internal Standards and Its Application to a Smoking Study and Forensic Cases. J Forensic Sci 1992. [DOI: 10.1520/jfs13282j] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Clatworthy AJ, Oon MC, Smith RN, Whitehouse MJ. Gas chromatographic-mass spectrometric confirmation of radioimmunoassay results for cannabinoids in blood and urine. Forensic Sci Int 1990; 46:219-30. [PMID: 2376363 DOI: 10.1016/0379-0738(90)90308-l] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A simple gas chromatographic-mass spectrometric (GC-MS) method is described for the detection of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (delta 9-THC-COOH) in blood and urine samples found to be positive by two in-house cannabinoid radioimmunoassays (RIAs). The delta 9-THC-COOH in the samples, which is partly present as its glucuronide conjugate, is isolated by solvent extraction after hydrolysis of the glucuronide. It is converted to its trimethylsilyl derivative and analysed by capillary GC-MS in the electron impact mode with selected ion recording. All samples that were positive by both RIAs were also positive by GC-MS apart from four blood and two urine samples in which the GC-MS results were inconclusive owing to the presence of coextractives. No sample that was positive by both RIAs was found to be negative by GC-MS.
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Affiliation(s)
- A J Clatworthy
- Metropolitan Police Forensic Science Laboratory, London, U.K
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