A capillary column gas-chromatographic method for the identification of drugs of abuse in urine samples

Determining plasma morphine levels using GC-MS after solid phase extraction to monitor drug levels in the postoperative period

OBJECTIVE

To implement a selective and sensitive analytical method to quantify morphine in small volumes of plasma by gas-liquid chromatography-mass spectrometry (GC-MS), aimed at post-operatively monitoring the drug.

METHOD

A gas-liquid chromatographic method with mass detection has been developed to determine morphine concentration in plasma after solid phase extraction. Morphine-d3 was used as an internal standard. Only 0.5 mL of plasma is required for the drug solid-phase extraction in the Bond Elut-Certify, followed by the quantification of morphine derivative by GC-MS using a linear temperature program, a capillary fused silica column, and helium as the carrier and make-up gas. The method was applied to determine morphine content in plasma samples of four patients during the postoperative period of cardiac surgery. Patient-controlled analgesia with morphine was performed by a venous catheter, and a series of venous blood samples were collected. After the oro-After the orotracheal extubation, morphine plasma levels were monitored for up to 36 hours.

RESULTS

The run time was 16 minutes because morphine and the internal standard were eluted after 8.8 minutes. The GC-MS method had 0.5 -1000 ng/mL linearity range (r(2)=0.9995), 0.1 ng/mL limit of detection, intraday and interday precision equivalent to 1.9% and 6.8%, and 0.1% and 0.8% systematic error (intraday and interday, respectively). The analytical method showed optimal absolute (98%) and relative (100.7%) recoveries. Morphine dose requirements and plasma levels are discussed.

CONCLUSION

The analytical gas-liquid chromatography-mass spectrometry method is selective and adequate for morphine measurements in plasma for applications in clinical studies.

Urine toxicology screening among chronic pain patients on opioid therapy: frequency and predictability of abnormal findings

OBJECTIVE

To examine the incidence of abnormal urine toxicology screening among chronic pain patients prescribed opioids for their pain and to relate these results to patient descriptors and type, number, and dose of prescribed opioids.

METHODS

A retrospective analysis of data from 470 patients who had urine screening at a pain management program in an urban teaching hospital was performed. Urine samples were analyzed using gas chromatography-mass spectrometry. Patients were categorized as having urine screens that were "normal" (expected findings based on their prescribed drugs) or abnormal. Abnormal findings were those of (1) absence of a prescribed opioid, (2) presence of an additional nonprescribed controlled substance, (3) detection of an illicit substance, and (4) an adulterated urine sample.

RESULTS

Forty-five percent of the patients were found to have abnormal urine screens. Twenty percent were categorized as having an illicit substance in their urine. Illicit substances and additional drugs were found more frequently in younger patients than in older patients (P<0.001). No other variables were found to predict abnormal urine screen results.

DISCUSSION

These results confirm past findings that random urine toxicology screens among patients prescribed opioids for pain reveal a high incidence of abnormal findings. Common patient descriptors, and number, type, and dose of prescribed opioids were found to be poor predictors of abnormal results.

Screening for and validated quantification of phenethylamine-type designer drugs and mescaline in human blood plasma by gas chromatography/mass spectrometry

In recent years, several newer designer drugs of the so-called 2C series such as 2C-D, 2C-E, 2C-P, 2C-B, 2C-I, 2C-T-2, and 2C-T-7 have entered the illicit drug market as recreational drugs. Some fatal intoxications involving 2C-T-7 have been reported. Only scarce data have been published about analyses of these substances in human blood and/or plasma. This paper describes a method for screening and simultaneous quantification of the above-mentioned compounds and their analog mescaline in human blood plasma. The analytes were analyzed by gas chromatography/mass spectrometry in the selected-ion monitoring mode, after mixed-mode solid-phase extraction (HCX) and derivatization with heptafluorobutyric anhydride. The method was fully validated according to international guidelines. Validation data for 2C-T-2 and 2C-T-7 were unacceptable. For all other analytes, the method was linear from 5 to 500 microg/L and the data for accuracy (bias) and precision (coefficient of variation) were within the acceptance limits of +/-15% and <15%, respectively (within +/-20% and <20% near the limit of quantification of 5 microg/L).

Routine analysis of amphetamine class drugs as their naphthaquinone derivatives in human urine by high-performance liquid chromatography

We describe a simple HPLC method which is suitable for the routine confirmation of immunoassay positive amphetamine urine samples. The precolumn derivisation method employing sodium naphthaquinone-4-sulphonate was found to have adequate sensitivity, selectivity and precision for the measurement of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethylamphetamine (MDEA) at 500 microg/l cutoff level for confirmatory analysis of amphetamines in urine. The specificity of the method is enhanced by detecting the peaks at two different wavelengths. The ratios of the peak heights measured at the two wavelengths were different for each of the 5 amphetamines analysed. There was no interference from other phenylethylamine analogues that are commonly found in "over the counter" preparations. The HPLC method is compared to a commercial TLC system for detecting amphetamines in urine of drug abusers attending drug rehabilitation programmes. The HPLC confirmatory method described is a viable alternative to GC or to the more complex and costly GC-MS techniques for confirming amphetamine, methamphetamine, MDMA, MDA and MDEA in urine of drug abusers especially when used in a clinical care setting.

Detection of drug misuse--an addictive challenge

It is now accepted that drug misuse is a large and growing problem in the United Kingdom, some estimates of the number of regular illicit drug users being as high as three million. The aim of this paper is to provide insight into the methods used to detect drug misuse. The strategy adopted by one laboratory is described and methods of screening for, and identification of, a wide range of compounds are provided. No claim is made that this is the best approach or that the list of drugs detected is comprehensive; the range of drugs encountered is always increasing and the lists are constantly updated. It is hoped that users of toxicology laboratory services will gain an appreciation of the capabilities and limitations of the techniques available; and that those who may wish to provide such a service will find the necessary information in a readily accessible format.

A method for the rapid detection of the zopiclone degradation product 2-amino-5-chloropyridine

Zopiclone (Zimovane) is a cyclopyrrolone compound which exhibits hypnotic and sedative effects while also exhibiting anticonvulsant and muscle relaxant activities. The detection and quantification of zopiclone is difficult. It has a high molecular weight compared to most other commonly used drugs, therapeutic levels are not high, and it is unstable in nucleophilic solvents. A degradation product of zopiclone, 2-amino-5-chloropyridine (ACP) together with a method for its detection using high-performance liquid chromatography with diode array detection has been described previously. An account is presented of a simple method for the detection of ACP using gas chromatography with mass selective detection (GC/MS) which will facilitate detection of zopiclone use as part of a routine screen.

Detection and identification of morphine in urine extracts using thin-layer chromatography and tandem mass spectrometry

The application of tandem mass spectrometry to the analysis and identification of morphine following thin-layer chromatography is described. FAB-mass spectrometry and mass spectrometry-mass spectrometry were performed following chromatography on silica gel high-performance thin-layer chromatography plates. The successful application of this simple methodology to a urine extract suggests that this approach has practical utility for confirming the identity of abused drugs detected by thin-layer chromatography.

Screening for drugs of abuse (II): Cannabinoids, lysergic acid diethylamide, buprenorphine, methadone, barbiturates, benzodiazepines and other drugs

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.

Analysis of the antiepileptic phenyltriazine compound lamotrigine using gas chromatography with nitrogen phosphorus detection

A method is described for the determination of lamotrigine in serum or plasma, based on gas chromatography with nitrogen-phosphorus detection. The method requires minimal sample preparation. The drug is extracted from 1.0 ml of serum at pH 11 into butylacetate containing prazepam as internal standard. An aliquot of the organic phase is then injected onto an HP-5 fused silica capillary column and analyzed with temperature programming from 90 degrees to 250 degrees C. Lamotrigine is characterized by a relative retention time of 0.832 (+/-0.03) compared with prazepam. The method is competitive with the reported high-performance liquid chromatography procedures in terms of precision and sensitivity. Coefficients of variation, calculated from the results of between-run reproducibility tests, were 6.7%, 4.6%, 4.8%, and 6.2% for samples spiked with 0.20, 1.21, 2.42 and 10.84 micrograms/ml lamotrigine, respectively. The lower limit of quantitation of the method is 0.15 microgram/ml. The proposed procedure can be integrated easily in a comprehensive toxicology screening.

Highly sensitive gas chromatographic-mass spectrometric method for morphine determination in plasma that is suitable for pharmacokinetic studies

A sensitive method was devised to determine morphine plasma concentrations by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) with nalorphine as the internal standard. This method was rugged, reliable, selective and sensitive and was used to determine the morphine content of over 2000 samples. Sample preparation involved extraction of basified sample using n-butyl chloride-chloroform (5:1) and evaporation of the extract to dryness. The residue was derivatised with pentafluoropropionic anhydride, evaporated to dryness, reconstituted in 40 microl toluene and injected onto the GC-MS. For a sample size of 1 ml, the limit of quantitation was 0.75 ng/ml (S/N ratio 10:1) and the estimated limit of detection was calculated to be 0.2 ng/ml (S/N ratio 3:1), expressed as morphine base. Precision (n=5) was 4.9% at 0.75 ng/ml, 6.8% at 1.5 ng/ml, 3.0% at 37.5 ng/ml and 2.3% at 150 ng/ml. Standard curves for the range of 0-750 ng/ml morphine in plasma were linear with all r2 values greater than 0.99. No interfering peaks were seen for either morphine or internal standard in the blank samples. The method is suitable for pharmacokinetic studies after subclinical doses of morphine where it has been used to study morphine plasma concentrations for 6 h after a dose of only 2 mg.

Stimulants, narcotics and beta-blockers: 25 years of development in analytical techniques for doping control

More than 25 years of developing doping control methods have led to comprehensive screening and confirmation procedures for stimulants, narcotics and beta-blockers. Much of this work has been initiated and/or improved by the late Prof. Dr. Manfred Donike. The methodological approach covered in this overview was applied to doping control procedures during the XXV Summer Olympics in Barcelona, Spain, in 1992 and the XVII Winter Olympics in Lillehammer, Norway, in 1994. Urine samples are screened through a combination of two analytical methods that are complementary: (a) gas chromatographic analysis of the parent compound and unconjugated metabolites, following single-step sample extraction and detection by a nitrogen-specific detector based on a retention index identification system and (b) gas chromatographic analysis including also conjugated drugs and metabolites after hydrolysis, solid-phase extraction, derivatisation and mass spectrometric detection. Confirmation and identification is always performed by gas chromatographic separation and full scan mass spectrometric detection. These methods facilitate the rapid screening and confirmation of more than 100 stimulants, narcotic analgesics and beta-blockers in urine for at least 24 h after the intake of a pharmaceutical dose. Application of the methods ensures high quality standards for the unequivocal identification of doping agents as well as a rapid turnaround time for sample analyses.

Determination of some non-steroid anti-inflammatory drugs by capillary isotachophoresis

The isotachophoretic (ITP) behaviour and separation of the anti-inflammatory drugs kebuzone (KB), tribuzone (TB) and phenylbutazone (PB) was studied in the operational system of HCl/His (leading electrolyte, LE) and 4-nitrophenol (terminating electrolyte, TE). The effective mobilities were 19.4 x 10(-9) m2 V-1 s-1 for KB, 18.1 x 10(-9) m2 V-1 s-1 for TB and 18.9 x 10(-9) m2 V-1 s-1 for PB when using an optimised system with 10 mM HCl + 40 mM His (pH 6.63) as LE and 10 mM 4-nitrophenol as TE. The calibration graphs were rectilinear (r = 0.9982-0.9996) in the range 20 to 600 mumol 1-1 of KB, TB or PB. The ITP method was used for determining the content of KB, TB or PB in mass-produced pharmaceuticals as tablets, coated tablets, injections, and ointments. The results of the ITP determination were in good agreement with those of standard pharmacopoeial methods.

Screening for drugs of abuse. I: Opiates, amphetamines and cocaine

(1) In order to provide an efficient and reliable service for drugs of abuse screening in urine, the laboratory should analyse 20-30 samples per week, and the staff should include a scientist with special expertise in the subject. (2) Turnaround times should be between 2-3 days of sample collection. To achieve this aim it may be necessary to make special arrangements for the delivery of samples to the laboratory. Results should preferably be transmitted by electronic mail or facsimile with the necessary precautions for security and confidentiality: hardcopy reports may also be required. (3) Good communications between the requesting clinician and the laboratory are essential. An advisory service should be provided by the laboratory and clinicians should be encouraged to discuss requests and results with laboratory staff. It is important that the laboratory inform doctors of the range of substances detected and the sensitivity and specificity of laboratory assays. (4) Assays should be performed according to the manufacturer's protocols, or by modified methods that have been rigorously validated. Quality control samples should be included in each analytical run and participation in an external quality assessment scheme, e.g. UKNEQAS, is essential to provide independent confirmation and confidence that results compare with those from other laboratories. Other requirements include adequate training and supervision of staff, and careful recording of samples and results. (5) Drugs to be tested will depend on the drug 'scene' in the area but should include those drugs regularly prescribed for maintenance therapy (e.g. methadone, dihydrocodeine, benzodiazepines), and drugs frequently misused (e.g. heroin, buprenorphine, amphetamines, cocaine). (6) Positive results obtained by preliminary screening methods e.g. EMIT, should be confirmed by another analytical technique, e.g. TLC, GC or GC-MS. If there are potentially serious or legal implications, and in employment and preemployment testing, confirmation of positive results is mandatory. In some cases, e.g. checking for methadone or benzodiazepine compliance, it may be considered unnecessary to confirm positive results although possible spiking of samples cannot be excluded without checking for the presence of metabolites by a chromatographic procedure.

Drugs of abuse screening in the West Midlands: a 6 year retrospective survey of results

We describe the results of urinary drugs of abuse screening performed by the West Midlands Regional Laboratory for Toxicology, Birmingham, UK, on more than 27,800 urine specimens received between January 1988 and December 1993. The number of specimens positive for amphetamine declined from 1988 to 1990, but this was followed by a doubling of specimens testing positive from 5.7% in 1990 to 12.0% in 1993. There is very little evidence of methamphetamine or Ecstasy abuse in the West Midlands. Morphine (assumed to be from heroin abuse) is the most common opiate detected, with 11.7% of all specimens received proving to be positive in 1993. The incidence of cocaine abuse is low, less than 5% when requests are based on clinical judgement, and less than 3% in the overall population monitored.

Gas chromatographic-mass spectrometric method for the determination of flurazepam and its major metabolites in mouse and rat plasma

A capillary gas chromatographic-negative chemical ionization (NCI) mass spectrometric method for the determination of flurazepam and its metabolites N-1-hydroxyethyl-flurazepam and N-1-desalkyl-flurazepam in mouse and rat plasma was described. Derivatization of the metabolites of flurazepam with BSTFA allowed a highly stable, accurate, and sensitive GC-MS analysis. The use of a single internal standard (halazepam) for the quantification of all compounds saved cost and time. The detection limits were 0.1 ng/ml for N-hydroxyethyl-flurazepam-TMS (M(r) = 404), 0.5 ng/ml for desalkyl-flurazepam-TMS (M(r) = 360), and 0.5 ng/ml for flurazepam (M(r) = 387) with an injection volume of 1 microliter at a signal-to-noise ratio greater than 5. The quantitation limit was set to 10 ng/ml for all compounds.

Gas chromatographic-mass spectrometric procedures used for the identification and determination of morphine, codeine and 6-monoacetylmorphine

An overview of the analysis of opiates by gas chromatography-mass spectrometry (GC-MS) is presented. The review is focused on the hydrolysis, extraction and derivatization procedures most widely used for the identification and determination by GC-MS of legal and illegal opiates in various biological fluids.

A broad spectrum immunoassay using fluorescence polarization for the detection of amphetamines in urine

Rapid immunoassays are widely used to screen for amphetamine abuse. Broad spectrum immunoassays are the most useful for this purpose followed by physicochemical techniques for verification and identification of particular drugs. We describe the production of an antiserum with a broad specificity for the amphetamine group of drugs. The antiserum was produced in a sheep using an immunogen linking amphetamine to keyhole limpet haemocyanin via an N-aminobutyl bridge. This antiserum was used to develop a fluorescence polarization immunoassay for application to urine samples. A limited investigation into the use of saliva as an alternative sample was also performed. The effects of chemical modifications to the basic amphetamine structure on antibody binding are discussed.

Rapid measurement of basic drugs in blood applied to clinical and forensic toxicology

A gas chromatographic method is presented to measure blood, serum or plasma concentrations of more than 40 basic drugs. The sensitivity is 0.05 mg/L or less, which represents medium-high therapeutic and overdose concentrations, and in many instances the major active metabolites are also quantified. The paper describes a single step extraction from basic solution into n-butyl acetate containing maprotiline internal standard. Disposable glass tubes are used, with direct chromatography of the upper organic layer. GLC analysis is conducted for 10 min isothermally on a packed column (3% SP2250) with nitrogen-phosphorus detection. The coefficient of variation (CV) of the assay is between 2% and 5%, and data on the reproducibility of retention times are presented.