Determination of Atenolol in Pharmaceutical Preparations by Gas Chromatography with Flame Ionization and Mass Spectrometric Detection

The present work describes the methodology and validation of gas chromatography with flame ionization (FID) and mass spectrometric (MS) detection after derivatization with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) for determination of atenolol with an internal standard (metoprolol) in pharmaceutical preparations. The linearity was established over the concentration range of 0.5–20 μg/mL for GC/FID and 12.5–500 ng/mL for GC/MS method. The intra- and inter-day relative standard deviation was less than 4.72 and 5.80%, respectively. Limit of quantification was determined as 500 ng/mL and 12.5 ng/mL for GC/FID and GC/MS, respectively. No interference was found from tablet excipients at the selected assay conditions. Developed GC/FID and GC/MS methods in this study are accurate, sensitive, and precise and can be easily applied to Tensinor tablet as pharmaceutical preparation.     

Comparison of different mass spectrometry techniques in the measurement of L‐[ring‐13C6]phenylalanine incorporation into mixed muscle proteins

Precise measurement of low enrichment of stable isotope labeled amino‐acid tracers in tissue samples is a prerequisite in measuring tissue protein synthesis rates. The challenge of this analysis is augmented when small sample size is a critical factor. Muscle samples from human participants following an 8 h intravenous infusion of L‐[ring‐¹³C₆]phenylalanine and a bolus dose of L‐[ring‐¹³C₆]phenylalanine in a mouse were utilized. Liquid chromatography tandem mass spectrometry (LC/MS/MS), gas chromatography (GC) MS/MS and GC/MS were compared to the GC‐combustion‐isotope ratio MS (GC/C/IRMS), to measure mixed muscle protein enrichment of [ring‐¹³C₆]phenylalanine enrichment. The sample isotope enrichment ranged from 0.0091 to 0.1312 molar percent excess. As compared with GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS showed coefficients of determination of R² = 0.9962 and R² = 0.9942, and 0.9217 respectively. However, the precision of measurements (coefficients of variation) for intra‐assay are 13.0%, 1.7%, 6.3% and 13.5% and for inter‐assay are 9.2%, 3.2%, 10.2% and 25% for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. The muscle sample sizes required to obtain these results were 8 µg, 0.8 µg, 3 µg and 3 µg for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. We conclude that LC/MS/MS is optimally suited for precise measurements of L‐[ring‐¹³C₆]phenylalanine tracer enrichment in low abundance and in small quantity samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Monitoring of Polychlorinated Biphenyls in Surface Water Using Liquid Extraction,GC/MS,and GC/ECD

Abstract

A rapid and reliable analytical method, at trace level concentration was developed and validated for monitoring polychlorinated biphenyls (PCBs) in Jordanian surface water. The method combines the advantage of liquid extraction together with gas chromatography‐mass spectrometry (GC/MS) and gas chromatography‐electron capture detector (GC/ECD). The performance of the method was evaluated by analyzing certified reference material (CRM) of the analytes and applied on real water samples collected from different sites in Jordan. A mixture of 60∶40 dichloromethan‐petroleum ether was chosen as a convenient binary solvent for liquid–liquid extraction. The GC conditions for GC/MS were optimized using He as a carrier gas, temperature programming, and chlorpropham as an internal standard (IS).

The conditions for GC/ECD were performed using N₂ gas and a temperature program from 160 to 280°C with different increasing rates. The method of GC/MS in the selective ion mode (SIM) gave linear relationships for all PCBs tested between 0.60–6.0 µg/l with R ²=0.9934 (n=7×18). Recoveries from spiked water samples ranged between 87.6 and 91.4%. The mean accuracy and precision obtained were 4.9% and 2.16%, respectively. The mean of detection limit was 0.14±0.04 µg/l. In GC/ECD, linear relationships for all PCBs examined over the range of 0.3–2.4 µg/l was verified as characterized by a linear regression equation and correlation coefficient, R ²=0.9915 (n=12). The average precision and accuracy were 4.86% and 5.21%, respectively. Analyses results clarified that none of the examined Jordanian water samples contained any of the searched for PCBs within the detection limit achieved.     

Analysis of coal tar and petroleum pitches by computerized pattern recognition

Pyrolysis gas chromatography (P/GC) has been successful in differentiating coal tar pitches which are used in the manufacture of high temperature graphite materials [1,2]. In the present study, coal tar and petroleum pitches received from five suppliers were readily differentiated using three distinct methods of polymer analysis: dynamic headspace and pyrolysis gas chromatography mass spectrometry (DH/GC/MS and P/GC/MS, [3]), and pyrolysis mass spectrometry (P/MS, [4,5]). All of these methods are appropriate for the analysis and pattern recognition study of coal and petroleum products; however, methods which incorporate GC usually necessitate long analysis times and are subject to problems associated with gas chromatographic reproducibility (e.g. active sites [6], and nonconstant retention times). As a fingerprint analysis method, P/MS is rapid and ideally suited to computerized pattern recognition study of pitches due to the simple format of P/MS data (computer tabulation of normalized intensities versus masses); whereas, in the present study, the normalized peak area versus retention time date from DH/GC/MS and P/GC/MS analyses were not suitable for direct input to a computerized pattern recognition analysis program, (due to non-constant retention times and improper data format). One limitation is that P/MS does not provide positive identification of thermally evolved products (as can DH/GC/MS and P/GC/MS) due to the complexity of the spectra of a mixture of compounds produced by P/MS. Within the limits of the commercial instrumentation and computer programs used in this study, a combination of all three techniques provided the greatest capability for the differentiation of the five coal tar and petroleum based pitches studied.     

Comparative Analysis of Medroxyprogesterone Acetate Residue in Animal Tissues by ELISA and GC‐MS

Abstract

Medroxyprogesterone acetate is a xenobiotic growth promoter of meat‐producing animals. In this study, the liver, kidney, and muscle of rabbits were obtained after the medroxyprogesterone acetate was administrated successively for 5 days at 0.8 mg/kg and withdrawn for 7 days before slaughter. The medroxyprogesterone acetate residues were determined by ELISA method. The average residue in muscle, liver, and kidney, as 7, 6, and 23 µg/kg, respectively. Residues were confirmed by GC/MS by monitoring four ions, 373, 283, 265, and 145 m/z. A good correlation was observed between the GC/MS and ELISA methods.     

Determination of N-Nitrosonornicotine in Tobacco by Gas Chromatography/Mass Spectroscopy

Abstract

N-Nitrosonornicotine has been determined in tobacco products. Quantitation was accomplished by GC/MS operated in the chemical ionization mode with selected-ion recording of N-nitrosonornicotine and the deuterated internal standard, N-nitrosonornicotine-d₄. Levels ranging from 0.7 to 26 mcg/gm were found.     

Detection of Anabolic Steroids By Gc/Sim/Ms With Trifluoroacetylation in Equine Plasma and Urine

ABSTRACT

A method to detect three anabolic steroids (boldenone, nandrolone and mesterolone) is presented. The anabolic steroids are isolated from equine plasma and urine by extraction with diethyl ether and C₁₈ Sep-Pak cartridge adsorption, respectively. The extracts obtained were derivatized with trifluoroacetyl anhydride and analyzed by GC/SIM/MS. The selected ion monitoring (SIM) mode was applied to increase the sensitivity and, when possible, the higher m/z ions were selected to improve identification. Stability of derivatives was good and compounds having hydroxy and conjugated ketone groups produced trifluoroacetyl ester derivatives that were also stable. Repeatability of the chromatographic analysis was evaluated on the basis of area repeatability, and the coefficient of variation obtained was lower than 4.4. The detection limit was 1 and 5 ng/ml for all the anabolic steroids studied in equine plasma and urine, respectively.     

Rapid and Sensitive Analysis of Diclofenac in Human Plasma by GC/SIM/MS

ABSTRACT

An analytical method for the determination of diclofenac with tolfenamic acid as the internal standard was developed and validated in human plasma by capillary gas chromatography-mass spectrometry (GC/MS). After the addition of the internal standard, the compounds were extracted from plasma at acidic pH into diethylether, which was then evaporated to dryness. The compounds were derivatized with pentafluoropropionic anhydride (PFPA) and a mixture (1000:2:3, v/w/w) of N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), ammonium iodide (NH₄I), and dithioerythritol (DTE). They were determined by GC/MS at m/z 349 (a molecular ion) for diclofenac and m/z 270 (a base ion) for tolfenamic acid. The recovery of this procedure was 97.8%, and the linearity for calibration was 0.9907 as the coefficient factor. The detection and quantitation limits were 0.1 and 0.5 ng/mL, respectively.     

Rapid determination of parabens in personal care products by stable isotope GC‐MS/MS with dynamic selected reaction monitoring

In this study, a rapid and sensitive analytical method for the determination of methyl‐, ethyl‐, propyl‐, and butyl esters of para‐hydroxy benzoic acid (parabens) in personal care products was developed and fully validated. Test portions were extracted with methanol followed by vortexing, sonication, centrifugation, and filtration without derivatization. The four parabens were quantified by GC‐MS/MS in the electron ionization mode. Four corresponding isotopically labeled parabens were selected as internal standards, which were added at the beginning of the sample preparation and used to correct for recovery and matrix effects. Sensitivity, extraction efficiency, and recovery of the respective analytes were evaluated. The coefficients of determination (r²) were all greater than 0.995 for the four parabens investigated. The recoveries ranged from 97 to 107% at three spiked levels and a one‐time (single) extraction efficiency greater than 97% was obtained. This method has been applied to screen 26 personal care products. This is the first time that a unique GC‐MS/MS method with dynamic selected reaction monitoring and confirmation of analytes has been used to determine these parabens in cosmetic personal care products.     

Analysis of cholesterol oxidation products by Fast gas chromatography/mass spectrometry

The aim of the present study was to set‐up a Fast gas chromatography/mass spectrometry method for the analysis of cholesterol oxidation products (COPs). A silylated mixture of seven oxysterol standards was injected into a Fast GC/MS system. A capillary GC column (10 m×0.1 mm internal diameter×0.1 μm film thickness) coated with 95% dimethyl‐ and 5% diphenyl‐polysiloxane, was used. The method gave a fast (total analysis time=3.5 min) and satisfactory resolution (R>1.2) of the COPs standards, with a good repeatability and sensitivity, similar to those of conventional GC/MS; recoveries were tested on mice liver. Fast GC/MS method suitability for COPs analysis in food was also tested on an oxidized sardine fillet, which had been previously saponified and purified by NH₂ solid‐phase extraction (SPE); a good repeatability and sensitivity was also obtained. The analytical performance of the Fast GC/MS method for the determination of COPs, together with the consequent significant reduction of the analysis time and consumables, demonstrates that Fast GC/MS represents a valid alternative to conventional GC/MS and evinces the great potential of such an analytical technique, which could be applied for both food and biological samples.     

Multilevel profiling and identification of Dalbergia odorifera and Dalbergia stevensonii by FTIR,NMR and GC/MS

Chemical differences of the extractives revealed by FTIR methods can be further confirmed by ¹H NMR and ¹³C NMR. Meanwhile, the volatile compounds in the extractives can be identified by GC/MS     

GC/MS characterization of urinary metabolites of doxylamine succinate: Identification of the aglycones formed from intestinal microflora metabolism of the polar glucuronide metabolites

This study describes the use of high performance liquid chromatography (HPLC) and capillary gas chromatography/mass spectrometry (GC/MS) in the characterization of polar glucuronide conjugates of doxylamine and their subsequent aglycones following deconjugation. Rat urinary extracts which contained doxylamine and both nonconjugated and conjugated doxylamine metabolites, were examined by HPLC before and after incubation with rat intestinal microflora. The subsequent deconjugated urinary metabolites and the nonconjugated products remaining in the urinary extracts were then isolated, acetylated, and assayed by GC/MS. Incubation with the intestinal microflora indicated that anaerobic bacteria were capable of effecting hydrolytic cleavage of these polar O-glucuronide metabolites of doxylamine and its demethylated products to their subsequent aglycones. GC/MS analysis was performed using a fused silica DB-5 GC column and was utilized for the identification of these deconjugated metabolites.     

Gas Chromatography - Mass Spectroscopy (GC/MS) of Single and Double Spin Adducts of PBN and the Hydroxylamines of Corresponding Structure

Abstract

The GC/MS spectra of the methyl adduct of PBN as the aminoxyl and as the corresponding hydroxylamine are reported. Similar results are obtained with higher alkyl analogues. With excess alkyl Grignard the O-alkyl hydroxylamine ether (PBN double adduct) is obtained if the solution is exposed to O₂ in the presence of the alkyl spin adduct of PBN. A mechanism involving radical trapping by the alkyl spin adduct is proposed.     

毛细管色谱-质谱法测定环境大气中挥发性有机污染物

毛细管色谱-质谱法测定了环境大气中挥发性污染物。用液氧冷冻法和常温吸附法(TenaxGC)分别采集大气样品,然后用两种系统进行浓缩,并进入毛细管色谱-质谱体系,完成了有机污染物的定性定量分析。解决了一些色谱-质谱联用中的问题。并且还讨论了无分流进样问题,比较了两种采样方法。用此方法测定了某炼油厂环境大气中的污染物。     

Description of a Method for Automated Determination of Organic Pollutants in Water

Abstract

A method for automated determination of 73 organic pollutants in water is described. The compounds, which are key representatives for different types of pollutants are determined in two chromatographic runs. 11 halogenated aliphatic hydrocarbons are determined using capillary GC equipped with electron capture detector. The remaining pollutants, representing both basic/neutral and acidic compounds are determined by using GC/MS combined with an automated search computer program. The majority of the compounds have a limit of quantitation at 1 ig/1 or lower. The precision of the GC method is in the range of 1.8% to 4.3%, with an average of 3.2%. The precision for compounds determined by GC/MS is in the range of 1% to 38%, with an average of 14%.

So far 30 water samples representing both polluted fjord areas as well as effluents from municipal treatment plants, refineries, petrochemical industries and metallurgic industries have been analysed. The method has been found to be an interesting alternative to traditional methods for monitoring water quality, and has demonstrated its potential both as a screening method for detecting “hot spots” as well as for routine monitoring of specific hazardous compounds.     

Selective Determination of Se4+ and Se6+ Using SPME and GC/MS

A method for the selective determination of Se⁴⁺ and Se⁶⁺ using solid phase microextraction (SPME) and GC/MS analysis is presented. Se⁴⁺ is selectively derivatized by reaction with 4,5-dichloro-1,2-phenylenediamine to form the corresponding piazselenolo complex, extracted by the SPME fiber, and determined by GC/MS. The RSD at a 5 μg/L concentration was 9.88% and the theoretical detection limit 6 ng/L. The method was employed to test real matrices; tap and river water were analyzed before and after spiking giving a recovery rate of 102% in river water and 97% in tap water.     

The Observation of Metastable Transitions in a High Resolution Double Focussing Mass Spectrometer

Three metastable transitions are observed with 3₁ 5-t-butyldimethylsiloxy-dehydrosterone (BDMS-DHEA) by detecting their daughter ion at m/z 269 in a double focussing mass spectrometer. Because of their specificity, the transitions of molecular ion could be served as quantitation routes for the determination of the steroid in human blood plasma using direct insertion probe with ionization chamber temperature ≥230°C. Thus, as is in MS/MS it would significantly reduce sample work-up time and possibly eliminate the need for a GC separation in detecting the level of this steroid in human blood.     

The Chemical Characterization of Potential Organic Interferences in Two Commercially Available Polymeric Adsorbents

Abstract

Current use of synthetic adsorbents for the collection of trace organics in environmental samples is quite extensive. It has been suggested that high levels of organic contaminants in these resins may interfere with subsequent analyses, however, the identity of these suspected contaminants has not been reported.

This paper reports a qualitative and quantitative characterization of the residual organics in two polymeric adsorbents.

Both resins are commercially available polymers of styrene divinyl-benzene. The structures of the contaminants were verified by combined gas chromatography/mass spectrometry (GC/MS). High artifact levels are typical for both of the Amberite® resins studied. The majority of these materials, as verified by capillary GC/MS, were alkyl derivatives of benzene, styrene, naphthalene and biphenyl.     

Analysis of Semi-Volatile Aromatic Chlorinated Acids in Drinking Water by Liquid-Solid Extraction GC/MS

Abstract

An analytical procedure utilizing solid phase extraction with octadecylsilane bonded to silica (C₁₈) cartridges combined with gas chromatography/mass spectrometry (GC/MS) was developed to analyze semi-volatile chlorinated acids found in drinking water. A system has been designed which will enable the analysis of this class of compounds with minimum sample manipulation and detection limits in the low ng/L range. The overall accuracy and precision were comparable to other methods used for compliance purposes. Among the advantages of the developed methodology are its applicability for field sampling and at the same time, provides a simple and inexpensive mean for sample preservation.     

GC/MS and ESI/MS identification of the new generation plasticizers - cis and trans isomers of some 1,2-cyclohexane dicarboxylic acid di(n- and isononyl) esters

1,2-Cyclohexane dicarboxylic acid diisononyl ester is also known as diisononyl cyclohexane-1,2-dicarboxylate (DINCH) is a complex mixture of the hydrogenation products of diisononyl benzene-1,2-dicarboxylate (DINP). They are the new generation plasticizers used instead of the dialkyl benzene-1,2-dicarboxylate in order to improve the flexibility of polymers (mainly PVC) and strongly reduce the toxic effects on human health during their release from polymers to the environment. The identification of these compounds was done by syntheses of some DINCH constituents, i.e. cis and trans isomers of three di(n- and isononyl) cyclohexane-1,2-dicarboxylates, such as di(3,5,5-trimethylhexyl) cyclohexane-1,2-dicarboxylates, di(2-methyloctyl) cyclohexane-1,2-dicarboxylates and dinonyl cyclohexane-1,2-dicarboxylates by catalytic hydrogenation of appropriate DINP and their analyses by gas chromatography – mass spectrometry (GC/MS) and electrospray - mass spectrometry (ESI/MS) methods. Both GC data (values of the retention times t_R and arithmetic retention indices I_A) and mass spectra obtained for these isomers allowed to determine their chemical structures. ESI/MS mode of analysis of these compounds gives the knowledge about their mass fragmentation without the differentiation between individual cis and trans isomers.