Gas chromatographic-mass spectrometric determination of british anti-lewisite in plasma

British anti-Lewisite (BAL) (2,3-dimercapto-1-propanol) is a potential therapeutic compound when used against the effects of cutaneous sulfur mustard, and a method for its determination in plasma has been developed. BAL and the internal standard (IS) ethane dithiol were isolated from plasma samples through solid-phase extraction and then reacted with 1-pentafluoropropionylimidazole, forming stable pentafluoropropionyl derivates that are sensitive to gas chromatographic-mass spectrometric analysis. Examination of concentration versus peak-area ratios of the BAL and IS derivatives demonstrated the method to be linear over a concentration range of 0.48 to 124 ng/mL in plasma when fit to a weighted (1/y2) least-squares regression. Correlation coefficients were 0.9943 to 0.9995 for six runs, and coefficients of variation (CV) were 2.5 to 8.7% over the eight concentrations tested. The intra- and interday accuracy and precision of this method was measured by examining six groups of eight unknown test samples (n = 6). Intraday accuracy, as expressed by percent error, was found to range from -15.4 to 0.21%, whereas the precision, expressed as %CV, was less than 9.8% over all sample concentrations. Interday test unknown sample results were similar in that the accuracy was shown to be -7.1 to 0.4%, and precision was 4.7 to 9.5%. BAL levels in frozen plasma (-70 degrees C) remained constant for more than 14 days with a CV of less than 10% for the eight concentrations tested. The data indicate that the method will provide accurate and precise determination of BAL at concentrations down to approximately 1 ng/mL in plasma. This procedure has been applied to determine preliminary time-concentration profile studies of BAL in the hairless guinea pig.

Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense

An army medical field laboratory presently has the capability of performing standard protocols developed at the US Army Medical Research Institute of Chemical Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chemical warfare agents using gas chromatography/mass spectrometry. Additionally, chemical warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biological half-lives and can be used as diagnostic biomarkers of chemical agent exposure. An analytical technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examined for its potential to analyze these biomarkers. The technique is capable of detecting large biomolecules and modifications made to them. Its fast analysis time makes MALDI-TOF/MS technology suitable for screening casualties from chemical or biological attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

Serial capillary gas chromatography/Fourier transform infrared spectrometry/mass spectrometry (GC/IR/MS): qualitative and quantitative analysis of amphetamine, methamphetamine, and related analogues in human urine

A method using serial capillary gas chromatography/Fourier transform infrared spectroscopy/mass spectrometry (GC/IR/MS) for the analysis of derivatized amphetamine, methamphetamine, and related analogues was developed. The GC/IR/MS was configured and optimized with a Hewlett-Packard (HP) 5890A gas chromatograph with a 12-m x 0.32-mm i.d. HP-5 capillary column serially interfaced through an HP 5965A infrared detector to an HP 5970 mass selective detector with a fused-silica 1.2-m x 0.10-mm i.d. column. Urine samples are extracted and derivatized as heptafluorobutyryl (HFBA) derivatives. For quantitation GC/MS in the selected ion monitoring (SIM) mode was used, with D,L-amphetamine-D5 as the internal standard. Gas chromatography/Fourier transform infrared spectrometry (GC/FT-IR) quantitation uses a selected wavelength chromatogram, spectral subtraction, double internal standard method using both D,L-amphetamine-D5 and 4-phenyl butylamine. Sensitivity for the combined GC/MS and GC/FT-IR system for amphetamine and methamphetamine shows limits of linearity of 100 to 5000 ng/mL, a limit of detection of 25 ng/mL, and a limit of quantitation of 98 ng/mL. The overall recovery for amphetamine and related analogues was greater than 85%. Precision studies for concentrations over the range of 200 to 1500 ng/mL showed coefficients of variations ranging from 2.8 to 13.0%. Correlation studies for quantitative GC/MS SIM and GC/FT-IR are greater than 0.98 for amphetamine, methamphetamine, and related analogues. Each analysis includes GC/MS SIM and GC/FT-IR quantitation, qualitative nonselective full spectra GC/FT-IR, and GC/MS scans of HFBA derivatives cross-referenced with an internal drug library, which provides high confidence and a means for the surveillance of amphetamine-like chemical analogues.

Solid phase extraction of phencyclidine from urine followed by capillary gas chromatography/mass spectrometry

This communication describes a method for the solid phase extraction of phencyclidine (PCP) from urine, followed by GC/MS analysis. The method is linear over the range 5-1000 ng/mL and consistently produces cleaner chromatograms than can be obtained by liquid-liquid extraction. The limits of detection and quantitation are 0.47 and 1.38 ng/mL, respectively. Extraction efficiency, or recovery, was found to be 100.8 +/- 6.5%, and the between-run precision was 3.5% (25 ng/mL, n = 51). This solid phase method for extraction of PCP from urine has several advantages over liquid-liquid extraction for laboratories of any size.

Solid Phase Extraction of Abused Drugs

The current standard for acceptable practice in forensic urine drug testing, as reflected in both National Institute for Drug Abuse (NIDA) and military guidelines, requires an initial immunoassay followed by gas chromatography/mass spectrometry (GC/MS) confirmation. The GC/MS confirmatory procedures mandate extraction of the drug from the urine matrix, followed in most cases by chemical derivatization, prior to injection into the gas chromatograph. Classically, the extraction step has been accomplished using liquid-liquid techniques, but in recent years, the use of solid phase chromatographic techniques has become increasingly popular. Numerous companies now market solid phase columns that are designed specifically for extraction of drugs, some of them containing as many as three different components for extracting acidic, basic, and neutral drugs. A survey of NIDA laboratories, conducted specifically for this review article, revealed that 40 to 50% of the extraction procedures currently performed involved the use of solid phase cartridges. This article reviews chromatographic separation techniques in general, specific products that are currently available on the market, the performance of those products, and examines the results of the survey of NIDA-certified laboratories.

Accuracy and precision of methods for theophylline measurement in physicians' offices

We tested the accuracy and precision of five theophylline methods intended for use in physicians' offices. The Syntex AccuLevel, Ames Seralyzer, and 3M Diagnostics TheoFAST methods were less reproducible (CVs 6.3% to 9.2%) than the Abbott Vision and Kodak DT-60 (CVs 2.2% to 3.3%). Caffeine interfered with the Vision, Seralyzer, and AccuLevel methods, and theobromine interfered with the Vision, Seralyzer, and TheoFAST methods. Only the DT-60 method was free from interference from any of the 24 compounds tested. Results by all methods correlated well with those by the HPLC comparison method (Clin Chem 1981;27:1931-3) and by the Abbott TDx method for assay of 100 serum (or, when appropriate, paired whole-blood) samples. The frequency of sample results differing from the comparison method by greater than 2.0 mg/L was as follows: TDx, 11%; Vision (serum), 12%; Vision (whole blood), 18%; DT-60, 14%; AccuLevel, 18%; Seralyzer, 25%; and TheoFAST, 31%. The Kodak DT-60 method was the most nearly accurate and precise among these physician's office methods. Some physician's office methods for theophylline analysis are not adequate to guide dosage adjustments.

Accuracy and precision of methods for theophylline measurement in physicians' offices

We tested the accuracy and precision of five theophylline methods intended for use in physicians' offices. The Syntex AccuLevel, Ames Seralyzer, and 3M Diagnostics TheoFAST methods were less reproducible (CVs 6.3% to 9.2%) than the Abbott Vision and Kodak DT-60 (CVs 2.2% to 3.3%). Caffeine interfered with the Vision, Seralyzer, and AccuLevel methods, and theobromine interfered with the Vision, Seralyzer, and TheoFAST methods. Only the DT-60 method was free from interference from any of the 24 compounds tested. Results by all methods correlated well with those by the HPLC comparison method (Clin Chem 1981;27:1931-3) and by the Abbott TDx method for assay of 100 serum (or, when appropriate, paired whole-blood) samples. The frequency of sample results differing from the comparison method by greater than 2.0 mg/L was as follows: TDx, 11%; Vision (serum), 12%; Vision (whole blood), 18%; DT-60, 14%; AccuLevel, 18%; Seralyzer, 25%; and TheoFAST, 31%. The Kodak DT-60 method was the most nearly accurate and precise among these physician's office methods. Some physician's office methods for theophylline analysis are not adequate to guide dosage adjustments.

Commercial radioimmunoassay for beta subunit of human chorionic gonadotropin: falsely positive determinations due to elevated serum luteinizing hormone

Among 17 men who had received seemingly curative treatment for unilateral non-seminomatous germ cell tumors for the testis and who had consistently normal serum human chorionic gonadotropin (HCG) levels at a reference laboratory, 7 (41%) had at least one falsely positive commercial serum HCG determination. To investigate the cause of these falsely positive determinations the authors measured the cross reactivity of luteinizing hormone (LH) and follicle stimulating hormone (FSH) standards in the commercial HCG assay, and studied the relationship between commercial HCG levels and serum LH levels, serum FSH levels and gonadal status in men with and without normal gonadal function. The falsely positive HCG determinations appeared to be due to elevated serum LH levels and cross reactivity of LH in the commercial HCG assay because: 1) there was substantial cross reactivity of the LH standards in the commercial assay, 2) the serum LH was elevated in four of six men with solitary testes, 3) there was a striking correlation between elevated serum LH levels and falsely elevated commercial HCG levels in ten men with solitary or absent testes, and 4) there were no falsely positive HCG determinations in 13 normal men but there were falsely positive HCG determinations in seven of ten anorchid men.