Thermospray liquid chromatographic-mass spectrometric method for the analysis of metribuzin and its metabolites

A thermospray liquid chromatographic-mass spectrometric (TSP LC-MS) method has been developed for the analysis of the herbicide metribuzin and its three major metabolites in plant tissue. Metribuzin and its metabolites exhibited widely varying sensitivities in positive-ion TSP, with metribuzin being the most sensitive and deaminated diketo metribuzin being the least sensitive. All four compounds of interest were detected in an extract of a soybean plant which had been treated with metribuzin.     

Gas chromatographic-mass fragmentographic determination of propiverine and its metabolites in plasma and urine

1-Methyl-4-piperidyl diphenylpropoxyacetate hydrochloride has been developed clinically for the therapy of urinary bladder dysfunction. A gas chromatographic-mass fragmentographic method was developed for the determination of this drug and its seven metabolites in plasma and urine. The sample was first treated with a Sep-Pak C18 cartridge, the methanol eluate was evaporated to dryness, and the resulting residue was redissolved in distilled water. This solution was then extracted with chloroform and adjusted to pH 9.0 with 0.1 M sodium borate solution. The acidified aqueous layers were extracted with ethyl acetate. The chloroform layer, which contained non-polar metabolites, was concentrated to dryness, then subjected to trifluoroacetylation, decomposition and methylation. The extract from the plasma sample was trimethylsilylated. The dried residue of the ethyl acetate layer, which contained polar metabolites, was subjected to methylation, trifluoroacetylation and decomposition. Aliquots of each reactant solution were injected into the gas chromatograph-mass spectrometer and analysed by the selected-ion monitoring method using an internal standard. Detection was limited to 1-2 ng/ml of plasma and urine for each metabolite. A precise and sensitive assay for the determination of 1-methyl-4-piperidyl diphenylpropoxyacetate hydrochloride and its metabolites in plasma and urine was thus established, and it should prove useful in basic and clinical pharmacological studies.     

Gas chromatographic-mass spectrometric method for polycyclic aromatic hydrocarbon analysis in plant biota

Using gas chromatography-mass spectrometry, a new method was developed for the identification and the quantification of polycyclic aromatic hydrocarbons (PAHs) in plants. This method was particularly optimised for PAH analyses in marine plants such as the halophytic species, Salicornia fragilis Ball et Tutin. The saponification of samples and their clean up by Florisil solid-phase extraction succeeded in eliminating pigments and natural compounds, which may interfere with GC-MS analysis. Moreover, a good recovery of the PAHs studied was obtained with percentages ranging from 88 to 116%. Application to the determination of PAH in a wide range of coastal halophytic plants is presented and validated the efficiency, the accuracy and the reproducibility of this method.     

Gas chromatographic-mass spectrometric method for trazodone and a deuterated analogue in plasma

A plasma assay method for trazodone and a 2H4 analogue is described which uses gas chromatography--electron-impact selected-ion monitoring mass spectrometry. Etoperidone is used as an internal standard. The analytes are extracted from basic medium into n-butyl chloride, then back extracted into aqueous 0.1 M hydrochloric acid. The aqueous layer is made basic and re-extracted with n-butyl chloride. The solvent is reduced under nitrogen at 35 degrees C and the residue is redissolved in toluene for gas chromatographic--mass spectrometric analysis. The ions monitored are m/z 231, 235, and 225 for trazodone, [2H4] trazodone and etoperidone, respectively. Quantitation is in the range 40-1000 ng/ml with acceptable precision and accuracy. The method is suitable for biopharmaceutical studies.     

Gas chromatographic-mass spectrometric method for the determination of selenium in biological samples.

The determination of selenium by capillary gas chromatography-mass spectrometry (GC-MS), using an enriched stable isotope 76Se as internal standard, is described. Reference values for selenium in human biological fluids (serum, red blood cells and urine) are reported. With the advent of new compact capillary GC-MS (benchtop) instruments, this method will be very simple and accurate for routine analysis.     

Mass spectrometric analysis of cyclofenil and its metabolites in human urine

Using gas chromatography/electron impact-mass spectrometry (GC/EI-MS) and high performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS), the structures of cyclofenil metabolites in human urine have been assigned. The hydroxyl metabolites liberated from the glucuronide conjugates after acid hydrolysis were characterized as the trimethylsilyl (O-TMS) derivatives using GC/MS. The conjugate glucuronide forms were detected without hydrolysis by HPLC/MS. Cyclofenil was not observed in urine. Tentative structures for the two metabolites are proposed.     

Gas chromatographic-mass spectrometric determination of intact C3-hydroxylated benzodiazepine glucoronides in urine.

A method is described for the determination C3-hydroxylated benzodiazepine glucuronides in biological samples. Oxazepam and lorazepam glucuronides are measured as methyl esters and trimethylsilyl derivates by a gas chromatographic procedure. The applicability of the method has been tested on the urine of rats, guinea pigs, rabbits and man, receiving oxazepam orally. Oxazepam glucuronide was not found in rat urine but it was present in the urine of rabbits (5.7% of the administered dose), guinea pigs (9.5%) and man (13.4-26.9%).     

Gas chromatographic-mass spectrometric analysis of volatile constituents in saliva

Present methods for the development of metabolic profiles are limited to the use of headspace techniques and solvent extraction methods. A new method for the development of saliva profiles which provides information complementary to existing analyses has been developed. The results of the developed methodology provide a reliable, reproducible method for metabolic profiling. Gas chromatographic-mass spectrometric analysis of the volatile constituents provided positive identification of 39 compounds. Application of the developed protocol toward the investigation of saliva as a vehicle for the non-invasive detection of certain pathological states, specifically diabetes mellitus and liver disorders, may be possible.     

Capillary gas chromatographic-mass spectrometric method for the identification and quantification of some benzodiazepines and their unconjugated metabolites in plasma

A gas chromatographic-mass spectrometric method for the identification and/or quantification of diazepam, clobazam, flunitrazepam, triazolam, midazolam, oxazepam and lorazepam and some of their desmethylated and hydroxylated metabolites in plasma is described. Benzodiazepines were extracted from plasma with butyl acetate at pH 9; the hydroxylated compounds were then silylated with N,O-bis (trimethylsilyltrifluoroacetamide). Analysis was performed using a compact mass-selective detector operating in the electron-impact mode. Depending on the concentration, identification was performed either by direct comparison of the observed mass spectra with reference spectra or by the relative intensities of the most intense and characteristic ions in the selected-ion monitoring (SIM) mode. Quantification was performed in the SIM mode using the most intense ion. The intra-assay precision and accuracy were better than 5-6%; linearity was satisfactory up to 1-2 micrograms/ml. The detection limit was 1-5 ng/ml for most of the benzodiazepines. This method can be easily used in clinical situations when a safe and rapid response is essential for patient treatment.     

Liquid chromatographic-mass spectrometric analysis of glucuronide-conjugated anabolic steroid metabolites: method validation and interlaboratory comparison

Liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method for simultaneous and direct detection of 12 glucuronide-conjugated anabolic androgenic steroid (AAS) metabolites in human urine is described. The compounds selected were the main metabolites detected in human urine after dosing of the most widely abused AAS in sports, e.g. methandienone, methenolone, methyltestosterone, nandrolone and testosterone, and certain deuterium-labeled analogs of these metabolites. Sample preparation and the LC-ESI-MS/MS method were optimized, validated, and the overall process was implemented and the results between seven laboratories were compared. All the metabolites were extracted simultaneously by solid-phase extraction (SPE) and analyzed by LC-ESI-MS/MS with positive ionization mode and multiple reaction monitoring (MRM). Recovery of the SPE for the AAS glucuronides was 89-100% and ten out of twelve compounds had detection limits in the range of 1-10 ng/ml in urine. The results for inter/intraday repeatability were satisfactory and the interlaboratory comparison with authentic urine samples demonstrated the ease of method transfer from one instrument setup to another. When equivalent triple quadrupole analyzers were employed the overall performance was independent from instrument manufacturer, electrospray ionisation (ESI) or atmospheric pressure chemical ionization (APCI) and liquid chromatohraphic (LC) column, whereas major differences were encountered when changing from one analyzer type to another, especially in the analysis of those AAS glucuronides ionized mainly as adducts.     

Studies on anabolic steroids. I. Integrated methodological approach to the gas chromatographic-mass spectrometric analysis of anabolic steroid metabolites in urine

The analytical and methodological imperatives for large-scale and routine gas chromatographic-mass spectrometric screening of anabolic steroid urinary metabolites are described. Several aspects of their isolation, enzymatic hydrolysis, derivatization and metabolism in humans are discussed. Gas chromatographic-mass spectrometric data illustrating artifacts arising from enzymatic hydrolysis of 3 beta-ol-5-en steroids, and describing new metabolites of boldenone, methanedienone and stanozolol, as well as the conversion of norethisterone into 19-nortestosterone metabolites through de-ethylation at C-17, are presented. The analytical approach developed for gas chromatographic-mass spectrometric screening of anabolic steroids is based on the sequential selection-ion monitoring of specific and discrete ion groups characteristic to the steroids of interest under high-resolution chromatographic conditions. The major analytical and methodological requirements necessary to provide irrefutable evidence, in the case where the presence of a synthetic anabolic steroid or a testosterone to epitestosterone ratio higher than 6:1 is suspected in a given urine specimen, are also discussed.     

Gas chromatographic-mass spectrometric analysis of plasma oxybutynin using a deuterated internal standard

A gas chromatographic-mass spectrometric method is described for the quantitative analysis of plasma oxybutynin. Deuterated oxybutynin served as the internal standard and its synthesis is described. Chromatographic separation on a methylsilicone capillary column avoided the thermal decomposition observed using a packed column. Electron-impact ionization and selected-ion monitoring of the alpha-cleavage fragments of drug and internal standard permitted quantitation of oxybutynin down to 0.25 ng/ml of plasma. At the 2 ng/ml level the accuracy and precision are 4 and 10%, respectively, and improved at higher drug concentrations. Application of the method to the pharmacokinetics of oral oxybutynin in man demonstrated rapid absorption and elimination of the drug.     

Screening procedure for the detection of antiparkinsonian drugs and their metabolites in urine using a computerized gas chromatographic-mass spectrometric technique

Summary A method for the identification of antiparkinsonian drugs and their metabolites in urine after acid hydrolysis is described. The acetylated extract is analysed by computerized gas chromatography-mass spectrometry. An on-line computer allows for the rapid detection using mass chromatography with the masses m/z 86, 98, 136, 150, 165, 196, 197 and 208. The identity of positive signals in the reconstructed mass chromatogram is established by a comparison of the stored entire mass spectra with those of standards. The mass chromatogram, the underlying mass spectra and the gas chromatographic retention indices (OV 101) are documented.

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Screening-Verfahren zum Nachweis von Parkinson-Mitteln und ihren Metaboliten im Urin mit Hilfe einer Computerunterstützten GC-MS-Technik

Zusammenfassung Eine Methode zum Nachweis von Parkinson-Mitteln und ihren Metaboliten im Urin nach saurer Hydrolyse wird beschrieben. Der acetylierte Extrakt wird mit der Kopplung Gas-Chromatographie-Massenspektrometrie-Datenverarbeitung analysiert. Ein on-line-Computer erlaubt eine rasche Auswertung durch die Verwendung der Massenchromatographie mit den Massen m/z 86, 98, 136, 150, 165, 196, 197 und 208. Die Verbindungen, die im rekonstruierten Massenchromatogramm angezeigt werden, können durch Vergleich der zugrunde liegenden Massenspektren mit Referenzspektren identifiziert werden. Das Massenchromatogramm, die zugrunde liegenden Massenspektren und die gaschromatographischen Retentionsindices (OV-101) werden gezeigt.

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Dedicated to Prof. Dr. Dr. h. c. mult. Egon Stahl on the occasion of his 60th birthday     

Gas chromatographic-mass spectrometric profile of organic acids in urine and serum of diabetic ketotic patients

The organic acids in the urine and serum of diabetic patients with ketoacidosis and disturbance of consciousness were studied using acidification, extraction, evaporation, methoxime formation and trimethylsilylation, gas chromatographic separation and mass spectrometric identification procedures. The organic acid profile of 1 ml of serum ultrafiltrate was obtained with good separation using a gas chromatograph equipped with a glass capillary column and a splitless injector. 5-Hydroxyhexanoic acid and 3-hydroxyvaleric acid were identified for the first time in the urine of diabetic patients with ketoacidosis. Urinary excretion and serum concentrations of 2,3-dideoxypentonic acid were increased in diabetic patients.     

Gas chromatographic-mass spectrometric analysis of formaldehyde in ambient air using a sampling tube

A gas chromatographic-mass spectrometric technique for the analysis of trace concentrations of formaldehyde in air is described. Molecular Sieve 13X was found to be an excellent adsorbent. The collected samples were thermally desorbed onto the analytical column (Porapak T) for separation, and quantified by mass fragmentography (m/e 29 and 30). Advantages of the technique include ppb sensitivity, selectivity and quantitative recovery. Experimental results are given for air samples in a rural area.     

Gas chromatographic-mass spectrometric method for the qualitative and quantitative determination of disaccharides and trisaccharides in honey

An improved method has been developed to identify and quantify honey disaccharides and trisaccharides by gas chromatography and mass spectrometry. The procedure, based on mass spectral and retention data ("retention time windows") determined on two capillary columns with different stationary phases allowed the identification and quantitation in honey of 16 disaccharides and 9 trisaccharides, some of which were not previously identified by GC. The reliability of the analytical results was considerably improved by the use of this procedure: several unidentified disaccharides and trisaccharides were detected, and their presence was taken into account in the quantification.     

Atmospheric pressure photoionization liquid chromatographic-mass spectrometric determination of idoxifene and its metabolites in human plasma

This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) interface for the LC–MS determination of idoxifene and its major metabolite, SB245419 (SB19), in human plasma. The results indicate that analyte response in APPI is highly dependent on the solvent composition, especially to water in the mobile phase. Other parameters investigated are the mobile phase flow-rate, the chemical noise, and signal suppression by matrix interferences. APPI appears to be six to eight times more sensitive than APCI for idoxifene and its SB245419 metabolite; the response for the SB245420 metabolite is considerably better than for APCI conditions, but still not sufficient for trace level pharmacokinetic determinations in human plasma. The LOQ for the parent drug and its major metabolite were 10 and 25 ng/ml, respectively, in human plasma. From post-column infusion experiments we conclude that there is little difference in matrix suppression between APCI and APPI. From these studies we suggest APPI may be an additional tool in pharmaceutical LC–MS applications.