scholarly journals Quantitative Identification of Pesticides as Target Compounds and Unknowns by Spectral Deconvolution of Gas Chromatographic/Mass Spectrometric Data

2008 ◽  
Vol 91 (6) ◽  
pp. 1467-1477 ◽  
Author(s):  
Albert Robbat ◽  
Andreas Hoffmann ◽  
Kevin Mac Namara ◽  
Yongli Huang
Keyword(s):  
Mass Spectra ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
False Negatives ◽  
Orange Oil ◽  
Complex Samples ◽  
Spectrometric Data ◽  
Lemon Oil ◽  
Quantitative Identification ◽  
Chromatographic Mass

Abstract The results of gas chromatography/mass spectrometry (MS), with Ion Signature Technology, Inc. (North Smithfield, RI) quantitative deconvolution software, are discussed for pesticides identified both as target compounds by using retention and MS data and as unknowns by using only mass spectra. Target compound analysis of 32 pesticides, surrogates, and an internal standard added to lemon oil over a wide concentration range produced precision and accuracy that are well within the acceptable criteria of 25 and 50 for complex samples. When 112 pesticides were added to orange oil and searched as unknowns, 110 of the 112 compounds were correctly identified, with an average pesticide recovery of 101 19. The injection volume of the orange oil fortified with pesticides was selected so that 4 ng per compound was injected on column. No false negatives were found, because ion signals for the 2 unidentified pesticides were not acquired by the instrument in either the standard mixture or the oil. No false positives were detected, although >750 widely different compounds were included in the library search.

Determination of Polychlorodibenzo-p-dioxins and Related Compounds in Commercial Chlorophenols

1972 ◽  
Vol 55 (1) ◽  
pp. 85-92 ◽  
Author(s):  
David Firestone ◽  
John Ress ◽  
N L Brown ◽  
R P Barron ◽  
J N Damico
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Electron Capture ◽  
Gas Chromatography Mass Spectrometry ◽  
Alumina Column ◽  
Spectrometric Data ◽  
Chromatography Mass Spectrometry ◽  
Related Compounds ◽  
Chromatographic Mass

Abstract Twenty-one commercial chlorophenols were examined for the presence of polychlorodibenzo- p-dioxins (chlorodioxins) and related compounds. The chlorophenols were dissolved in aqueous alkali, extracted with petroleum ether, and fractionated on an alumina column. Alumina fractions were examined by electron capture gas chromatography and combined gas chromatography-mass spectrometry. Chlorodioxin content was estimated by electron capture gas chromatography. The presence of chlorodioxins, polychlorodibenzofurans (chlorofurans), and polychlorodiphenyl ethers (chloroethers) was confirmed by combined gas chromatography-mass spectrometry. The 2,3,-7,8-tetrachlorodioxin was found in 3 of 6 samples of 2,4,5-trichlorophenol but was not detected in any of the 11 samples of tetra- and pentachlorophenol that were examined. Hexachlorodioxin was present at levels ranging from 0.17 to 39 ppm in all 8 pentachlorophenols examined. Hexa-, hepta-, and octachlorodioxins as well as a wide variety of chlorofurans and chloroethers of varying chlorine content were present in most of the tetra- and pentachlorophenols. In addition, the gas chromatographic- mass spectrometric data suggested that some of the chlorophenols contained methoxy- and dimethoxypolychlorofurans and methoxypolychloroethers as well as polychlorohy droxybiphenyl.

Oxybuprocaine and five metabolites simultaneously determined in urine by gas chromatography and gas chromatography-mass spectrometry after extraction with Extrelut.

1987 ◽  
Vol 33 (5) ◽  
pp. 697-700 ◽  
Author(s):  
F Kasuya ◽  
K Igarashi ◽  
M Fukui
Keyword(s):  
Gas Chromatography ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Aminobenzoic Acid ◽  
Acid Metabolite ◽  
Fragment Ions ◽  
Characteristic Fragment ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract We describe a gas-liquid chromatographic (GC) method for determination of oxybuprocaine, and a gas chromatographic-mass spectrometric (GC-MS) method for simultaneous determination of four of its nine metabolites in urine. We used an Extrelut column to simply and rapidly extract oxybuprocaine and its metabolites from urine. For the GC-MS analyses, we monitored the characteristic fragment ions at m/z 353, 395, 369, 411, and 235 for 3-butoxy-4-aminobenzoic acid (metabolite 2, M-2), 3-butoxy-4-acetylaminobenzoic acid (M-3), 3-hydroxy-4-aminobenzoic acid (M-4), 3-hydroxy-4-acetylaminobenzoic acid (M-5), and methaqualone (internal standard), respectively. We quantified the glucuronide of M-2 after enzymic treatment. The assay's selectivity and reproducibility (within-day and between-day CVs less than 8% for all metabolites) make it applicable to determine oxybuprocaine and its metabolites in human urine. Mean 9-h urinary excretion of oxybuprocaine and its five metabolites from four healthy volunteers was 89.2% after a 100-mg oral dose.

scholarly journals Calibration-Curve-Locking Database for Semi-Quantitative Metabolomics by Gas Chromatography/Mass Spectrometry

Metabolites ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 207
Author(s):  
Kosuke Hata ◽  
Yuki Soma ◽  
Toshiyuki Yamashita ◽  
Masatomo Takahashi ◽  
Kuniyo Sugitate ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Calibration Curve ◽  
Mass Spectra ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Time Saving ◽  
Quantitative Metabolomics ◽  
Chromatography Mass Spectrometry ◽  
Calibration Curves

Calibration-Curve-Locking Databases (CCLDs) have been constructed for automatic compound search and semi-quantitative screening by gas chromatography/mass spectrometry (GC/MS) in several fields. CCLD felicitates the semi-quantification of target compounds without calibration curve preparation because it contains the retention time (RT), calibration curves, and electron ionization (EI) mass spectra, which are obtained under stable apparatus conditions. Despite its usefulness, there is no CCLD for metabolomics. Herein, we developed a novel CCLD and semi-quantification framework for GC/MS-based metabolomics. All analytes were subjected to GC/MS after derivatization under stable apparatus conditions using (1) target tuning, (2) RT locking technique, and (3) automatic derivatization and injection by a robotic platform. The RTs and EI mass spectra were obtained from an existing authorized database. A quantifier ion and one or two qualifier ions were selected for each target metabolite. The calibration curves were obtained as plots of the peak area ratio of the target compounds to an internal standard versus the target compound concentration. These data were registered in a database as a novel CCLD. We examined the applicability of CCLD for analyzing human plasma, resulting in time-saving and labor-saving semi-qualitative screening without the need for standard substances.

Serum quinidine concentrations: comparison of fluorescence, gas-chromatographic, and gas-chromatographic/mass-spectrometric methods.

1976 ◽  
Vol 22 (6) ◽  
pp. 810-812 ◽  
Author(s):  
D H Huffman ◽  
C E Hignite
Keyword(s):  
Extraction Method ◽  
Mass Spectra ◽  
Chromatographic Method ◽  
Internal Standard ◽  
Fluorescence Method ◽  
Substantial Correlation ◽  
Gas Chromatographic Method ◽  
Therapeutic Doses ◽  
Serum Quinidine ◽  
Chromatographic Mass

Abstract Serum quinidine concentrations were determined in patients on chronic therapeutic doses. Although results were higher by a protein precipitate-fluorescence method as compared to a specific extraction fluorescence method, there was substantial correlation between results by the two methods (r = 0.945, P less than 0.001). We established the specificity of the extraction method by a methylation gas-chromatographic method in which the base peak in the mass spectra of the methylated products of both quinidine and cinchonidine, the internal standard, was monitored. We conclude that the protein precipitate method should be discarded.

Gas Chromatographic-Mass Spectiometric Determination of Adipate-Based Polymeric Plasticizers in Foods

1988 ◽  
Vol 71 (2) ◽  
pp. 394-396 ◽  
Author(s):  
Laurence Castle ◽  
Angela J Mercer ◽  
John Gilbert
Keyword(s):  
Internal Standard ◽  
Size Exclusion ◽  
Gas Chromatography Mass Spectrometry ◽  
Stable Isotope Dilution ◽  
Relative Standard ◽  
Exclusion Chromatography ◽  
Deuterated Internal Standard ◽  
Polymeric Plasticizer ◽  
Chromatographic Mass

Abstract A method for the quantitative determination of adipate-based polymeric plasticizers in foods is described. The procedure involves extraction from the food and transmethylation of the polymeric plasticizer to form dimethyladipate (DMA). The derivative is cleaned up by size-exclusion chromatography and determined by capillary gas chromatography-mass spectrometry with selected on monitoring. The use of a deuterated internal standard at the extraction stage enables quantitation by stable isotope dilution. A detection limit of 0.1 mg/kg of the polymeric plasticizer in foods and a relative standard deviation of 4% have been achieved routinely. The method has been applied successfully to the analysis of cheese, sandwiches, meat, biscuits, and cake that have been in contact with polymeric plasticized polyvinyl chloride) films.

Characterization of drug interferences caused by coelution of substances in gas chromatography/mass spectrometry confirmation of targeted drugs in full-scan and selected-ion monitoring modes

1994 ◽  
Vol 40 (2) ◽  
pp. 216-220 ◽  
Author(s):  
A H Wu ◽  
D Ostheimer ◽  
M Cremese ◽  
E Forte ◽  
D Hill
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography Mass Spectrometry ◽  
Spectrometric Analysis ◽  
Targeted Drugs ◽  
Selected Ion Monitoring ◽  
Internal Standards ◽  
Target Drug ◽  
Full Scan ◽  
Chromatographic Mass

Abstract Interference by substances coeluting with targeted drugs is a general problem for gas chromatographic/mass spectrometric analysis of urine. To characterize these interferences, we examined human urine samples containing benzoylecgonine and fluconazole, and other drug combinations including deuterated internal standards that coelute (ISd,c) with target drugs, by selected-ion monitoring (SIM) and full-scan mass spectrometry. We show that, by SIM analysis, detecting the presence of an interferent is dependent on the specific IS used for the assay. When an ISd,c is used, the presence of another coeluting substance (interferent) suggests that the intensity of IS ions is substantially diminished, because the interferent affects both the ISd,c and target drug. When a noncoeluting IS (ISnc) is used, the interferent cannot be discerned unless it coincidently contains one or more of the ions monitored for either the target drug or ISnc. Under full-scan analysis, a coeluting interferent is directly discernable by examining the total ion gas chromatogram.

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.

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