Enzymatic digestion, solid-phase extraction, and gas chromatography/mass spectrometry of derivatized intact oxazepam in urine

1991 ◽  
Vol 37 (9) ◽  
pp. 1595-1601 ◽  
Author(s):  
J G Langner ◽  
B K Gan ◽  
R H Liu ◽  
L D Baugh ◽  
P Chand ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Solid Phase ◽  
Internal Standard ◽  
Enzymatic Digestion ◽  
Gas Chromatography Mass Spectrometry ◽  
Extraction Recovery ◽  
Mass Selective Detector ◽  
Operation Conditions ◽  
Ms Analysis ◽  
Gas Chromatography Mass Spectroscopy

Abstract Enzymatic digestion with beta-glucuronidase (EC 3.2.1.31) was used to release intact oxazepam from urine samples containing the d5-analog internal standard. The resulting specimens were extracted with Du Pont PREP Type W cartridge (processed by a PREP Automated Sample Processor), Bond Elut Certify, and J.T. Baker "spe" columns for comparison of the columns' extraction recovery and overall effectiveness. Methyl iodide/tetrahexylammonium hydrogen sulfate and N,O-bis(trimethylsilyl)trifluoroacetamide/trimethylchlorosilane (10 g/L) were used for the methylation and trimethylsilylation studies. We used a Hewlett-Packard HP 5790 mass-selective detector equipped with a 13-m J & W DB-5 column (5% phenyl polysiloxane phase) for gas chromatography/mass spectroscopy (GC/MS) analysis and the Thru-Put Target software package for data processing. After several exploratory experiments, we adopted the Du Pont PREP system methylation procedure because of its effective recovery, the superior stability of the derivatization product, the possibility of incorporating a clean-up step, and the potential for high throughput. The extraction recovery from a set of control samples was 87%. Coefficients of variation obtained for six replicates of GC/MS analysis and for the overall procedure were 1% and 3%, respectively. Excellent linearity was established in the 50-8000 micrograms/L concentration range studied. With the use of 3-mL samples, a 20-microL final reconstitution volume, oxazepam at 50 micrograms/L was easily detected under the adopted operation conditions.

scholarly journals SPME-GC/MS Analysis of Methanol in Biospecimen by Derivatization with Pyran Compound

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 41 ◽  
Author(s):  
Joon-Bae Lee ◽  
Yong Ae Jeong ◽  
Dae Jun Ahn ◽  
Iel Soo Bang
Keyword(s):  
Gas Chromatography ◽  
Solid Phase ◽  
Internal Standard ◽  
Standard Addition ◽  
The Body ◽  
Gas Chromatography Mass Spectrometry ◽  
Reaction Products ◽  
Complex Matrix ◽  
Alternative Analysis ◽  
Ms Analysis

Methanol is metabolized in the body to highly toxic formaldehyde and formate when consumed accidentally. Methanol has been typically analyzed with gas chromatography-flame ionization detector (GC-FID). However, its retention time may overlap with other volatile compounds and lead to confusion. Alternative analysis of methanol using gas chromatography/mass spectrometry (GC/MS) also has limitations due to its similar molecular weight with oxygen and low boiling point. In this study, methanol and internal standard of deuterium-substituted ethanol were derivatized with 3,4-dihydro-2H-pyran under acid catalysis using concentrated hydrochloric acid. The reaction products including 2-methoxytetrahydropyran were extracted with solid-phase microextraction followed by GC/MS analysis. This method was successfully applied to measure the lethal concentration of methanol in the blood of a victim with a standard addition method to overcome the complex matrix effect of the biospecimen. Identification of the metabolite formate by ion chromatography confirmed the death cause to be methanol poisoning. This new method was a much more convenient and reliable process to measure methanol in complex matrix samples by reducing sample pretreatment effort and cost.

scholarly journals Investigations on the Key Odorants Contributing to the Aroma of Children Soy Sauce by Molecular Sensory Science Approaches

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1492
Author(s):  
Jia Huang ◽  
Haitao Chen ◽  
Zhiming Zhang ◽  
Yuping Liu ◽  
Binshan Liu ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Solid Phase ◽  
Internal Standard ◽  
Retention Indices ◽  
Soy Sauce ◽  
Gas Chromatography Mass Spectrometry ◽  
Volatile Components ◽  
Active Compounds ◽  
Standard Curve ◽  
Key Odorants

To investigate the key odor-active compounds in children’s soy sauce (CSS), volatile components were extracted by means of solvent extraction coupled with solvent-assisted flavor evaporation (SE-SAFE) and solid-phase microextraction (SPME). Using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS), we identified a total of 55 odor-active compounds in six CSSs by comparing the odor characteristics, MS data, and retention indices with those of authentic compounds. Applying aroma extract dilution analysis (AEDA), we measured flavor dilution (FD) factors in SE-SAFE isolates, ranging from 1 to 4096, and in SPME isolates, ranging from 1 to 800. Twenty-eight odorants with higher FD factors and GC-MS responses were quantitated using the internal standard curve method. According to their quantitated results and thresholds in water, their odor activity values (OAVs) were calculated. On the basis of the OAV results, 27 odorants with OAVs ≥ 1 were determined as key odorants in six CSSs. These had previously been reported as key odorants in general soy sauce (GSS), so it was concluded that the key odorants in CSS are the same as those in GSS.

scholarly journals Simultaneous Quantification of the New Psychoactive Substances 3-FMC, 3-FPM, 4-CEC, and 4-BMC in Human Blood using GC-MS

2019 ◽  
Vol 17 (1) ◽  
pp. 902-911
Author(s):  
Abdulsallam Bakdash
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Human Blood ◽  
Solid Phase ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
New Psychoactive Substances ◽  
Selected Ion Monitoring ◽  
Simultaneous Quantification ◽  
Chromatography Mass Spectrometry

AbstractA gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of 3-fluoromethcathinone (3-FMC), (±)-3-fluorophenmetrazine (3-FPM), 4-chloroethcathinone (4-CEC) and 4-Bromomethcathinone (4-BMC) in human blood with (±)-methcathinone-D3 as internal standard has been developed and validated. Whole blood samples were treated with 10% trichloroacetic acid for protein precipitation before solid phase extraction. The method was selective, the calibration curves showed linearity for all substances with R2 ranging from 0.991 to 0.998 in the range 5-1.000 ng/mL. Analysis of blank samples showed no-sign of carryover. Precision and accuracy were acceptable with values less than 20% (RSD) and ± 20% (Bias). The limit of quantification (LOQ) for all substances was 5ng/mL. Intra-day and inter-day precision were 2.111.7% and 1.3 -10.2% respectively and accuracy biases were between -10.6-19.6% % (intra-day) and 11-12.1% (inter-day). The extraction efficiencies were 85.4, 82.8, 79.1 and 74.9% for 3-FMC, 3-FPM, 4-CEC and 4-BMC respectively.A robust and reliable simultaneous quantification method using gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS-SIM) is reported.

scholarly journals Determination of Bitertanol Residues in Strawberries by Liquid Chromatography with Fluorescence Detection and Confirmation by Gas Chromatography/Mass Spectrometry

1998 ◽  
Vol 81 (6) ◽  
pp. 1252-1256 ◽  
Author(s):  
Yoshie Yamazaki ◽  
Takahiro Ninomiya
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Fluorescence Detection ◽  
Solid Phase ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Internal Standard Method ◽  
Chromatography Mass Spectrometry

Abstract A simple and rapid method was developed for determining bitertanol residues in strawberries. Bitertanol was extracted from samples with ethyl acetate. Bitertanol acetate was added prior to extraction as a surrogate standard. The ethyl acetate extract was cleaned up by passing through tandem solid-phase extraction columns consisting of anion-exchange (SAX) and aminopropyl (NH2) bonded silica. The eluate was evaporated to dryness and reconstituted with methanol. Bitertanol residues were determined by liquid chromatography with fluorescence detection. Recoveries at 4 fortified levels (0.05,0.25,0.5, and 1.0 (µg/g), calculated by the internal standard method, ranged from 92.1 to 99.1 %, with coefficients of variation ranging from 0.3 to 4.0%. The detection limit was 0.01 µg/g. Of 25 commercial strawberry samples analyzed for bitertanol residues, 5 contained bitertanol residues at concentrations ranging from 0.02 to 0.51 µg/g. Positive samples were confirmed by gas chromatography/mass spectrometry with mass-selective detection (m/z 170 and 168).

Simultaneous Determination of Eight Sympathomimetic Amines in Urine by Gas Chromatography/Mass Spectrometry

2010 ◽  
Vol 93 (1) ◽  
pp. 116-122 ◽  
Author(s):  
Michael Moawad ◽  
Cheang S Khoo ◽  
Samiuela Lee ◽  
James R Hennell
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Extraction Procedure ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Organic Layer ◽  
Sympathomimetic Amines ◽  
Alkaline Urine ◽  
Ms Analysis

Abstract A GC method was developed for the identification and quantitation of eight sympathomimetic amines in urine, i.e., amphetamine, methamphetamine, mephentermine, ephedrine, pseudoephedrine, methylenedioxyamphetamine, methylenedioxymethamphetamine, and methylenedioxyethylamphetamine. Methoxyphenamine was used as the internal standard (IS). The assay is rapid, sensitive, and simple to perform. It involves a liquidliquid extraction procedure with simultaneous in-solution derivatization of the organic layer with pentafluorobenzoyl chloride (PFB-Cl), followed by GC/MS analysis. These derivatives and the IS were extracted from 1 mL alkaline urine into hexane before derivatization with PFB-Cl. The organic layer was then removed and evaporated to dryness before dissolution with hexane for GC/MS analysis. Calibration curves for each analyte showed linearity in the range of 255000 ng/mL (r2 ≥ 0.997). Recoveries ranged from 88 to 99, with the precision of recoveries typically ≤5%. The LOD values ranged from 7 to 28 ng/mL, and the LOQ values ranged from 23 to 94 ng/mL. At least four ions were available for each analyte for confirmation of identity by MS.

scholarly journals A Multiresidue Pesticide Monitoring Procedure Using Gas Chromatography/Mass Spectrometry and Selected Ion Monitoring for the Determination of Pesticides Containing Nitrogen, Sulfur, and/or Oxygen in Fruits and Vegetables

2004 ◽  
Vol 87 (5) ◽  
pp. 1224-1236 ◽  
Author(s):  
Gregory E Mercer ◽  
Jeffrey A Hurlbut
Keyword(s):  
Gas Chromatography ◽  
Fruits And Vegetables ◽  
Impact Ionization ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Fruit And Vegetable ◽  
Selected Ion Monitoring ◽  
Pesticide Monitoring ◽  
Mass Selective Detector ◽  
Monitoring Procedure

Abstract A procedure for the analysis of over 100 pesticides that only contain combinations of carbon, hydrogen, nitrogen, sulfur, and oxygen (i.e., no phosphorous or halogen atoms) has been developed. The procedure employs gas chromatography with a mass selective detector (GC/MSD), electron impact ionization, and selected ion monitoring. This GC/MSD procedure provided lower limits of quantitation and increased confirmational data compared to the traditional element-selective GC procedures that are commonly used for the detection of this “class” of pesticides. These analytical improvements were demonstrated by 26 pesticides that were detected at ng/g levels in a variety of fruit and vegetable matrixes using this procedure; these pesticides were missed by the traditional element-selective GC procedures. Validation of the procedure was performed using acetone extraction with solid-phase extraction cleanup. Twenty representative target pesticides were used to demonstrate repeatability and linearity of the chromatographic response and recovery from fruit and vegetable matrixes.

scholarly journals An Effective and Efficient Sample Preparation Method for 2-Methyl-Isoborneol and Geosmin in Fish and Their Analysis by Gas Chromatography-Mass Spectrometry

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liang-liang Tian ◽  
Feng Han ◽  
Essy Kouadio Fodjo ◽  
Wenlei Zhai ◽  
Xuan-Yun Huang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Sample Preparation ◽  
Large Scale ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry ◽  
Ms Analysis ◽  
Fish Samples

The intensive aquaculture strategy and recirculating aquaculture system often lead to the production of off-flavor compounds such as 2-methyl-isoborneol (2-MIB) and Geosmin (GSM). The regular purge and trap extraction followed by analysis with gas chromatography-mass spectrometry (GC-MS) usually involve a complicated assembly of facilities, more working space, long sample preparation time, and headspace solid-phase microextraction (SPME). In this work, a method with easier sample preparation, fewer and simplified facilities, and without SPME on GC-MS analysis is developed for the determination of 2-MIB and GSM in fish samples. Unlike previous methods, solvent extract from samples, QuEChERS-based cleanup, and solid-phase extraction for concentration are applied. The LOD (S/N > 3) and LOQ (S/N > 10) of this method were validated at 0.6 μg/kg and 1.0 μg/kg for both 2-MIB and GSM, which are under the sensory limit (1 μg/kg). Application of this method for incurred fish samples demonstrated acceptable analytical performance. This method is suitable for large-scale determination of 2-MIB and GSM in fish samples, owing to the use of simple facility and easy-to-operate procedure, rapid sample preparation, and shorter time for GC-MS analysis without SPME.

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