Pentafluoropropionic Acid Anhydride Research Articles

High-sensitivity quantification of serum androstenedione, testosterone, dihydrotestosterone, estrone and estradiol by gas chromatography–tandem mass spectrometry with sex- and puberty-specific reference intervals

BackgroundAndrogen and estrogen determinations serve as important diagnostic markers in a variety of clinical conditions. However, one challenge is to enhance assay sensitivity for determination in the lowest range, such as in prepubertal children.We here present a recently developed gas chromatography–tandem mass spectrometry (GC–MS/MS) method for determination of androstenedione (A4), dihydrotestosterone (DHT), testosterone (T), estrone (E1), and estradiol (E2) in children, which we have compared with the sensitive radioimmunoassays; E2 extraction-RIA and T-RIA. MethodsSteroids were extracted in ethyl acetate n-hexane solution from serum spiked with isotopically labeled internal standard and derivatized sequentially with pentafluorobenzyl bromide, pentafluorobenzyl hydroxylamine and pentafluoropropionic acid anhydride and analyzed by GC–MS/MS using a triple quadrupole mass spectrometer operated in negative chemical ionization mode. Leftover routine samples (n = 414) were used to evaluate the concordance between GC–MS/MS and RIAs and the validity of GC–MS/MS for pediatrics; of these samples, 101 were from seemingly healthy children. Pubertal stage was recorded for reference interval evaluation. ResultsLower limit of detection for A4, T, DHT, E1, and E2 were 0.1 nmol/L, 0.1 nmol/L, 27 pmol/L, 9 pmol/L, and 2 pmol/L, respectively. Good agreement was found between GC–MS/MS and T-RIA (r = 0.98) as well as between GC–MS/MS and E2 extraction-RIA (r = 0.98, for E2 concentrations above 14 pmol/L). In boys, T and DHT increased significantly from prepuberty throughout pubertal development, and in girls the same increase was observed for E1 and E2. The greatest increase in A4 for both genders, as well as E1 and E2 in boys and T and DHT in girls, occurred in mid to late puberty. ConclusionsWe report the development of a GC–MS/MS method sensitive enough to accurately determine serum levels of androgens and estrogens in children.

Determination of ethyl glucuronide in hair: a rapid sample pretreatment involving simultaneous milling and extraction

A combination of simultaneous milling and extraction known as micropulverized extraction was developed for the quantification of the alcohol marker ethyl glucuronide (EtG) in hair samples using a homogeneous reference material and a mixer mill. Best extraction results from 50mg of hair were obtained with 2-mL plastic tubes containing two steel balls (∅ = 5mm), 0.5mL of water and with an oscillating frequency of 30s(-1) over a period of 30min. EtG was quantified employing a validated GC-MS procedure involving derivatization with pentafluoropropionic acid anhydride. This micropulverization procedure was compared with dry milling followed by separate aqueous extraction and with aqueous extraction after manual cutting to millimeter-size snippets. Micropulverization yielded 28.0 ± 1.70pg/mg and was seen to be superior to manually cutting (23.0 ± 0.83pg/mg) and equivalent to dry grinding (27.7 ± 1.71pg/mg) with regard to completeness of EtG extraction. The option to process up to 20 samples simultaneously makes micropulverization especially valuable for the high throughput of urgent samples.

Determination of N-methyl-1,3-propanediamine in bovine muscle by liquid chromatography with triple quadrupole and ion trap tandem mass spectrometry detection

Morantel, pyrantel and their drug-related metabolites in food of animal-origin are regulated as sum of residues which may be hydrolysed to N-methyl-1,3-propanediamine (NMPA). In this study, an isotope dilution liquid chromatography tandem mass spectrometry (LC–MS/MS) method with pentafluoropropionic acid anhydride (PFPA) derivatization was developed for the determination of NMPA in bovine muscle. A stable isotope labeled internal standard N-methyl-d3-3,3′-d2-propane-1,3-diamine (NMPA-d5) was synthesized as internal standard. NMPA was derivatized with PFPA to form an N,N′-bis (pentafluoroacyl) derivative (NMPA-PFPA) and analyzed by liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) and liquid chromatography ion trap mass spectrometry (LC-IT-MS/MS) using negative ion electrospray ionization (ESI). Chromatographic behavior of several perfluorocarboxylic acid anhydride derivatives of NMPA and other structurally related diamines on C-18 and perfluorophenyl (PFP) columns was studied. Conversion of the parent drugs to NMPA under various hydrolysis conditions was evaluated. In addition, comparison of the matrix effect and linearity with isotopically labeled internal standard (I.S.) and analogous I.S. were performed and investigated. The method was validated using fortified bovine muscle samples. The apparent recovery (obtained after correction with an isotopically labeled I.S.) was between 89% and 97% and repeatability was less than 10%. The lowest LOD and LOQ (0.42 and 1.39μg/kg, respectively) were obtained with LC-QqQ-MS/MS.

Microdialysis of melatonin in the confluens sinuum of the rat following quantification by gas chromatography-mass spectrometry in the negative chemical ion mode.

In this study, an original surgical implantation technique in the confluens sinuum via the superior sagittal vein was developed to quantify melatonin secretion by the pineal gland. Melatonin (CAS 73-31-4) was determined using gas chromatography couples to negative ion chemical ionisation mass spectrometry following liquid extraction and derivatisation by penta-fluoropropionic acid anhydride (PFPA). The minimum detectable amount was 40 fg per injection, corresponding to 1 pg.ml-1 in dialysate. The assay was linear in the range 20-1000 pg.ml-1. This method was suitable for routine melatonin determination in dialysats of peripheral and central circulation with coefficients of variation of 11.2 and 24.6%, respectively for within and between analyses. Profiles of melatonin concentration were obtained (n = 3 rats) over a 2-day experimentation with a slowly diminution of the filtration capacity of the probe during the second day. The nocturnal concentrations of melatonin in the confluens sinuum dialysat ranged from 1003.9 to 2345 pg.ml-1 in the dialysat, indicating wide interindividual variations in the melatonin levels.

Analysis of 4-Aminobiphenyl Hemoglobin Adducts in Smokers and Nonsmokers by Pseudo Capillary On-Column Gas Chromatography-Tandem Mass Spectrometry*

We describe here a hemoglobin adduct assay applied to an analysis of samples from smokers and nonsmokers. The assay includes a sensitive method for quantification of orthotoluidine 2-aminonaphthylene, and 3- and 4-aminobiphenyl hemoglobin adducts in human blood using capillary gas chromatography-tandem mass spectrometry. Basic hydrolysis and derivatization with pentafluoropropionic acid anhydride are followed by programmable temperature vaporization and pseudo on-column capillary gas chromatography with positive electron ionization tandem mass spectrometry analysis. Standard deviation of calibration curves (n = 6) shows that the limits of detection for o-toluidine, 2-aminonaphthylene, and 3- and 4-aminobiphenyl were 0.23, 0.39, 0.30, and 0.24 pg total on-column, respectively. The effective working limit of detection is estimated at approximately 5.22 pg/g Hb and 18.73 pg/g Hb for 4-aminobiphenyl and 2-aminonaphthylene, respectively. In a group that was predominately male and African-American, the level of 4-aminobiphenyl Hb adducts was significantly different between smokers and nonsmokers. Among 93 nonsmokers with serum cotinine concentrations less than 10 ng/mL, the geometric mean (95% CI) concentration of 4-aminobiphenyl was 29.9 pg/g hemoglobin (Hb; 29.4 to 30.4). Conversely, in 100 smokers the 4-aminobiphenyl adducts geometric mean concentration was significantly greater at 73.0 pg/g Hb (72.6 to 73.4). 4-Aminobiphenyl hemoglobin adduct and serum cotinine concentrations were correlated (r = 0.496; p < 0.0001; n = 193). In 15% of smokers, 3-aminobiphenyl was detected at low concentration. Adduct levels of 2-aminonaphthylene and ortho-toluidine were not significantly different between the smoker and nonsmoker participants. Our study shows that 4-aminobiphenyl Hb adducts remain the preferred biomarker for identifying people exposed to aromatic amines from tobacco smoke.

Use of the dried blood spot sampling process coupled with fast gas chromatography and negative-ion chemical ionization tandem mass spectrometry: application to fluoxetine, norfluoxetine, reboxetine, and paroxetine analysis

The objective of this work was to combine the advantages of the dried blood spot (DBS) sampling process with the highly sensitive and selective negative-ion chemical ionization tandem mass spectrometry (NICI-MS-MS) to analyze for recent antidepressants including fluoxetine, norfluoxetine, reboxetine, and paroxetine from micro whole blood samples (i.e., 10 microL). Before analysis, DBS samples were punched out, and antidepressants were simultaneously extracted and derivatized in a single step by use of pentafluoropropionic acid anhydride and 0.02% triethylamine in butyl chloride for 30 min at 60 degrees C under ultrasonication. Derivatives were then separated on a gas chromatograph coupled with a triple-quadrupole mass spectrometer operating in negative selected reaction monitoring mode for a total run time of 5 min. To establish the validity of the method, trueness, precision, and selectivity were determined on the basis of the guidelines of the "Société Française des Sciences et des Techniques Pharmaceutiques" (SFSTP). The assay was found to be linear in the concentration ranges 1 to 500 ng mL(-1) for fluoxetine and norfluoxetine and 20 to 500 ng mL(-1) for reboxetine and paroxetine. Despite the small sampling volume, the limit of detection was estimated at 20 pg mL(-1) for all the analytes. The stability of DBS was also evaluated at -20 degrees C, 4 degrees C, 25 degrees C, and 40 degrees C for up to 30 days. Furthermore, the method was successfully applied to a pharmacokinetic investigation performed on a healthy volunteer after oral administration of a single 40-mg dose of fluoxetine. Thus, this validated DBS method combines an extractive-derivative single step with a fast and sensitive GC-NICI-MS-MS technique. Using microliter blood samples, this procedure offers a patient-friendly tool in many biomedical fields such as checking treatment adherence, therapeutic drug monitoring, toxicological analyses, or pharmacokinetic studies.

Simultaneous determination of bisphenol A, triclosan, and tetrabromobisphenol A in human serum using solid-phase extraction and gas chromatography-electron capture negative-ionization mass spectrometry

This study aimed at optimizing and validating a sensitive method for simultaneous determination of bisphenol A (BPA), triclosan (TCS), and tetrabromobisphenol A (TBBPA) in human serum using solid-phase extraction (SPE) and gas chromatography coupled to electron-capture negative-ionization mass spectrometry (GC-ECNI/MS). Sample preparation involved denaturation of serum proteins with formic acid followed by SPE on an Oasis HLB cartridge. Fractionation was performed on Florisil from which the phenolic compounds were eluted with methanol-dichloromethane (DCM) (5:1, v/v). The phenolic fraction was further derivatized with pentafluoropropionic acid anhydride (30 min at 70 degrees C). Further liquid-liquid partitioning using hexane-DCM (4:1, v/v) and K(2)CO(3) 3% aqueous solution was used to eliminate excess reagent and acidic by-products formed during derivatization. The cleaned extract was injected into a GC-ECNI/MS system operated in selected ion monitoring mode. For thorough method validation, each step of the procedure was rigorously optimized. The method limits of quantitation for BPA, TCS, and TBBPA were 0.28 ng mL(-1), 0.09 ng mL(-1) and 0.05 ng mL(-1), respectively. Furthermore, the method was applied to 21 Belgian human serum samples. The median concentrations obtained for BPA (0.71 ng mL(-1)) and TCS (0.52 ng mL(-1)) in Belgian human serum samples were similar to previously reported data for human fluids. Slightly higher levels of TBBPA (0.08 ng mL(-1)) were found in Belgium samples compared to Norwegian serum.

Comparison of methamphetamine concentrations in oral fluid, urine and hair of twelve drug abusers using solid-phase extraction and GC-MS

Introduction : Methamphetamine (MA) is the most abused drug in Korea. In order to investigate the correlation of MA disposition in oral fluid, urine and hair specimens, quantitative analysis for MA and its main metabolite amphetamine (AM) was performed. Methods : Twelve drug abuser's oral fluid, urine and hair samples, submitted by the Police for drug testing, were used. As the preliminary test, MA was screened in urine and oral fluid by fluorescence polarization immunoassay. Extraction for MA was performed using solid-phase extraction after dilution with phosphate buffer. Hair samples were finely cut and incubated for 20 h in 1 mL methanol. Samples were derivatized with pentafluoropropionic acid anhydride for oral fluids and urines and trifluoroacetic acid anhydride for hairs. Quantitation of MA and AM was performed by GC-MS using SIM mode for oral fluids and hairs and full scan mode for urines. Results and conclusion : Concentrations of MA and AM in twelve urine samples ranged 120.4–73 216.0 and 67.6–4238.4 ng/mL, respectively. For oral fluids, just one sample gave negative result, and concentrations of MA and AM in eleven samples ranged 104.2–4603.3 and 32.4–268.6 ng/mL, respectively. For hairs, the concentrations of MA and AM were 3.40–98.25 and 0.21–4.35 ng/mg, respectively in twelve samples. The average ratios of AM/MA in urine, oral fluid and hair for eleven samples were 0.12, 0.11 and 0.06, respectively. Two-way ANOVA showed a significant difference of AM/MA ratios between three specimens. Multiple comparison by Tukey method, AM/MA ratio of hair was significantly lower than urine and oral fluid.

Extractable organic compounds in polyurethane foam with special reference to aromatic amines and derivatives thereof

Methods for determination of aromatic amines and related compounds in flexible toluene diisocyanate (TDI)-based polyurethane (PUR) foam were investigated. The foam was extracted using 0.1% (w/v) aqueous acetic acid (HAc). Extraction solutions were analysed and aromatic amines were determined as ethyl chloroformate (Et) and pentafluoropropionic acid anhydride (PFPA) derivatives. The determinations were performed using liquid chromatography (LC) and mass spectrometry (MS) detection with electrospray ionisation (ESI) or gas chromatography (GC)–MS with chemical ionisation monitoring negative ions (NCI). The Et derivatives were determined using LC–ESI +-MS with detection limit of 2 pg of toluenediamine (TDA). The PFPA derivatives were determined using LC–ESI −-MS or GC–NCI-MS with detection limits of 0.1 and 0.02 pg of TDA, respectively. Using trideuterium labelled TDA as internal standard, linear calibration curves were obtained in the range of 0.01–0.50 μg ml −1 ( n=7), with correlation coefficients >0.999. When plotting calibration curves for TDA–PFPA derivatives determined using LC–MS against TDA–PFPA using GC–MS and TDA–Et using LC–MS, linear curves were obtained. The relative standard deviation (R.S.D.) for determination of TDA in foam extraction solutions were 13%. LC–MS determination of PFPA derivatives was more selective, as compared to LC–MS of Et derivatives. In foam extraction solutions, 2,4- and 2,6-TDA, several isomers of methylenedianiline (MDA) and dimers of TDA/TDI were observed. 2,4-TDA and 4,4′-MDA are possible human carcinogens. Hydrolysis of the extraction solution revealed a large pool of TDA/TDI compounds and oligomers. The concentration of TDA in foam was affected by the extraction media, temperature and duration. The choice of derivatisation procedure also affected the determination of TDA. In extraction solutions from six different commercially available flexible foam qualities 2,4- and 2,6-TDA were found in the range of 0–7 and 0–6 μg g −1 foam, respectively. When flexible foam was heated, considerable higher concentrations of TDA were observed.

Determination of 3,3'-Dichlorobenzidine in Industrial Wastewaters

Abstract A solid-phase extraction, chemical derivatization, and gas chromatography/mass spectrometry (GC/MS) method has been developed for the determination of trace 3,3'-dichlorobenzidine (DCB) in industrial wastewater samples. Instead of an octadecylsilane (ODS) cartridge, a Porapak RDX cartridge was used since the latter could be optimized for the extraction of DCB. After the pre-concentration, interfering coextractives in the sample were selectively removed from the cartridge by elution with a 1:1 mixture of acetonitrile and water. DCB was then eluted with acetonitrile and derivatized with pentafluoropropionic acid anhydride. The product was subsequently analyzed by GC/MS in either the electron impact or negative ion chemical ionization mode. Recoveries of DCB and the surrogate, DCB-d6, were better than 90% at spiking levels of 10, 1, and 0.1 µg/L. Based on a concentration factor of 100, the detection limits for DCB in wastewater samples were determined to be 0.1 µg/L by electron impact GC/MS detection, and 0.01 µg/L by negative ion chemical ionization GC/MS detection, respectively. This method has been successfully applied to wastewater samples collected in the Toronto area.

Determination of amines as pentafluoropropionic acid anhydride derivatives in biological samples using liquid chromatography and tandem mass spectrometry.

Determination of amines in biological samples as markers of exposure to the amines or the corresponding isocyanates is an important tool for industrial exposure assessment. In this study, a liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for determination of amines in biological samples as perfluorofatty amides derivatives is presented. The method enables determination of diamines such as methylene diamine (MDA), toluene diamine (TDA), naphthalene diamine (NDA), hexamethylene diamine (HDA), isophorone diamine (IPDA), methylenedi(cyclohexylamine)(HMDA) and 4,4'-methylene-(2-chloroaniline)(MOCA) in human urine and plasma. The work-up procedure included hydrolysis of the biological samples with 3 M H(2)SO(4) at 100 degrees C for 16 h and extraction of the amines into toluene, where derivatisation of the amines with perfluorofatty acid anhydride was performed. Following removal of excess reagent and the acid formed and an exchange of solvent, the derivatives were analysed using gradient elution with an acetonitrile/water mobile phase composition and electrospray ionisation (ESI) with multiple reaction monitoring (MRM) of [M - H](-)-->[M - H - 120](-) or [119](-). Several perfluorofatty acid anhydrides were evaluated as derivatisation reagents, but the LC chromatographic properties of the pentafluoropropionic acid anhydride (PFPA) derivatives were favourable. Quantification of amine-PFPA derivatives was performed using deuterium labelled amine-PFPA derivatives as internals standards with good precision and linearity in the investigated range of 0-20 ng ml(-1) urine. The instrumental detection limits for the amine-PFPA derivatives were 0.2-3 fmol for MRM of [M - H](-)-->[119](-) and 0.3-8 fmol for [M - H](-)-->[M - H - 120](-). In 10 urine and 6 plasma samples from workers exposed to isocyanates, determination of TDA and MDA as PFPA derivatives was performed using LC-MS/MS and a reference GC-MS method. No significant difference between the two methods was observed.

Development, validation and characterization of an analytical method for the quantification of hydrolysable urinary metabolites and plasma protein adducts of 2,4- and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate and 4,4'-methylenediphenyl diisocyanate

Occupational exposure to diisocyanates within the plastic industry causes irritation and disorders in the airway. The aim of this study was to develop, validate and characterize a method for the determination of 2,4-toluenediamine (2,4-TDA), 2,6-toluenediamine (2,6-TDA), 1,5-diaminonaphthalene (1,5-NDA) and 4,4′-methylenedianiline (4,4′-MDA) in hydrolysed urine and plasma, and to study the correlation between the plasma and urinary levels of these potential biomarkers of 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 1,5-naphthalene diisocyanate (1,5-NDI) and 4,4′-methylenediphenyl diisocyanate (4,4′-MDI), respectively. Samples were hydrolysed with 0.3 M NaOH at 100°C for 24 h. The diamines were extracted, derivatized with pentafluoropropionic acid anhydride, and quantified by selected ion monitoring on gas chromatography-mass spectrometry. The repeatability and reproducibility of the method were 7-18% and 7-19%, respectively. Dialysis experiments showed that the metabolites of 2,4-TDI, 2,6-TDI, 1,5-NDI and 4,4′-MDI in plasma were exclusively protein adducts. No free diamines were found in urine, indicating that all diisocyanate-related metabolites were in a conjugated form. For each diisocyanate-related biomarker, there were strongly significant correlations (p<0.001) between individual levels of metabolites in plasma and urine, with Spearman's rank correlation coefficient (rs) values of 0.74-0.90. The methods presented here will be valuable for the development of biological monitoring methods for diisocyanates.

Screening of sulphonamides in egg using gas chromatography–mass-selective detection and liquid chromatography–mass spectrometry

A rapid extraction and clean-up procedure for sulphonamide antibiotics in eggs suitable for both GC–MSD and LC–MS end determinations has been developed. The drugs were extracted using acetonitrile, acidified using acetic acid and cleaned-up using cation- and anion-exchange. For determination by GC–MSD, extracts were derivatised with diazomethane followed by pentafluoropropionic acid anhydride. For LC–MS extracts were taken up in water and used directly. The methodology developed was validated at the 100 and 25 μg kg −1 levels, equivalent to the MRL and one quarter of the MRL. Results for the GC–MS procedure were quantitated against deuterated sulphadiazine with relative recoveries ranging from 54% for sulphachloropyridazine to 135.5% for sulphamethazine. Recoveries for the LC–MS procedure ranged from 33% for sulphaguanidine to 92% for sulphamethazine and sulphadimethoxine.

Determination of 17β-Estradiol and Its Metabolites in Sewage Effluent by Solid-Phase Extraction and Gas Chromatography/ Mass Spectrometry

The paper describes a simple and quantitative method for monitoring non-conjugated 17 beta-estradiol (E2) and its metabolites estrone (E1) and estriol (E3) as environmental contaminants in municipal sewage effluents. Estrogens were preconcentrated and cleaned up by solid-phase extraction using a reversed-phase C18 cartridge. They were derivatized with pentafluoropropionic acid anhydride, and the products were analyzed by gas chromatography/mass spectrometry. Recoveries from spiked distilled water and sewage were better than 87% at fortification levels of 100 and 20 ng/L. For a 1 L sewage sample and a concentration factor of 5000, detection limits were 5 ng/L for E1 and E2 and 10 ng/L for E3. In a brief survey of Canadian wastewater, these estrogens were detected in many raw sewage and effluent samples at concentrations ranging from 6 to 109 ng/L for E1, from < 5 to 15 ng/L for E2, and from < 10 to 250 ng/L for E3.

Simultaneous quantification of insecticides including carbaryl in drinking water by gas chromatography using dual electron-capture and nitrogen–phosphorus detection

A rapid and simple gas chromatographic method for the simultaneous determination of malathion, parathion, fenitrothion, diazinon and carbaryl in drinking water is presented. A fused-silica SE-54 column was used for the separation of the insecticides and was split into two specific detectors; electron-capture and nitrogen–phosphorus detectors by using column switching. A water sample was extracted with methylene chloride. The organic phase was evaporated and the residue was derivatized with pentafluoropropionic acid anhydride. The detection limit was below 0.1 ng/ml and the calibration curves showed good linearity with r=0.998∼1.000. The method was sensitive, reproducible and simple enough to permit the reliable routine analysis of the pesticides in drinking water.

The analysis of PAHs nitrogen derivatives in the sewage sludges of upper Silesia, Poland

The dimethylformamide extracts from sewage sludges from a chosen sewage — treatment plant in highly industrialized region of Poland were investigated. Using the column chromatography with Al2O3 and silicic acid as the stationary phases, the fraction of azaarenes has been separated. GC-MS analysis of azaarenes fraction made it possible to identify 10 azaarenes and several of their alkyl derivatives, which dominate in the organic matter extracted from sewage sludges. The silicic acid column chromatography in connection with the reduction of nitroarenes and derivatization with pentafluoropropionic acid anhydride yielded an enriched nitrofraction. Nitroarenes present in this fraction as amide derivatives were also analysed by GGMS method. There was found presence of 3 nitroarenes and their methyl derivatives.

4,4'-Methylenedianiline in hydrolysed serum and urine from a worker exposed to thermal degradation products of methylene diphenyl diisocyanate elastomers.

A 45-year-old mechanic employed in blowing hot air (350 degrees-600 degrees C) onto the surface of a polyurethane methylene diphenyl diisocyanate (MDI) conveyer belt developed dyspnoea, rhinoconjunctivitis and fever. The illness was suggestive of an MDI-associated illness, compatible with both immediate hypersensitivity and a complement-mediated immune-complex reaction. In his serum there were specific IgG and IgE antibodies against MDI and other isocyanates, and high values of circulating immune complexes. The patient's blood and urine samples were analysed for the presence of 4,4'-methylenedianiline (MDA) in hydrolysed urine and plasma. MDA was derivatized to amides using pentafluoropropionic acid anhydride (PFPA). Gas chromatography-mass spectrometry determinations were made monitoring the (M-20; M = molecular mass) fragments from the MDA-PFPA and the [2H2]MDA-PFPA derivative. The first urine sample was obtained 22 h and the last sample 114 h after start of exposure. The urine concentrations of MDA were corrected for creatinine. The half-time of MDA was 70-80 h. The first serum sample was obtained 19 h and the last sample 1967 days after the start of exposure. The half-time was 21 days, which suggests the presence of MDI/MDA plasma protein adducts in the exposed worker.

Comparison of quantitative results of drugs in human hair by [formula omitted

Until the first determination of opiates in human hair by GC MS in 1985, radioimmunological results of hair examinations met with opposition. Since then, further GC MS methods have been developed that have led not only to considerably increased sensitivity, but can also be used in hair analysis for screening purposes and can detect substances for which RIA kits are not available. In the present study different extraction methods were used along with two GC MS processes which back-up each other. These methods include the enzymatic dissolution of the hair, incubation with a buffer solution followed by a solid-phase extraction and incubation with methanol without a further extraction. The GC MS examination for heroin, cocaine, hashish and selected pharmaceuticals was carried out after derivatization with pentafluoropropionic acid anhydride or pentafluoro-1-propanol. Because of the higher sensitivity and versatility of GC MS , two GC MS processes were used to confirm each other instead of backing-up radioimmunological measurements with GC MS .

Determination of Diethylstilbestrol Glucuronide in Beef by Gas Chromatography.

A gas-liquid chromatographic (GLC) method was developed for the determination of diethylstilbestrol glucuronide (DESG), a metabolite of diethylstilbestrol, in beef. DESG was extracted from beef with 90% acetonitrile. The extract was cleaned up without hydrolysis of DESG by Sep-pak NH2 cartridge and C18 cartridge. The purified extract was evaporated to dryness and reacted with pentafluoropropionic acid anhydride (PFPA) for 50 min at 50°C. PFPA derivatives of DESG were measured by GLC, using a 2% OV-17 column and electron capture detector. Recoveries of DESG obtained from beef spiked at 0.005-0.02 μg/g (as is DES) levels were 86.8-89.2%. The detection limit of DESG was 0.001 μg/g.

Morphine: Its quantitative determination in nanogram amounts in small samples of whole blood by electron-capture gas chromatography

A method for the determination of nanogram quantities of morphine in hemolyzed whole blood taken post mortem, or other blood samples of poor quality, has been developed. Morphine was extracted into ethyl acetate from blood at pH 8.7–9.0, and purified by absorption onto a column of acid aluminium oxide and elution with methanol. Nalorphine was added as an internal standard, the compounds derivatized with pentafluoropropionic acid anhydride, and the derivatives formed quantified by electron-capture gas chromatography. The recovery of morphine added to whole blood was 83%, the coefficient of variation 6.7%. The method is capable of measuring morphine concentrations of 1 ng/g in 0.1–0.2 g of post-mortem blood.