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Filename: drivers/Session_files_driver.php
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Filename: Session/Session.php
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Function: require_once
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Filename: controllers/Detail.php
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Function: _error_handler
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Filename: controllers/Detail.php
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File: /var/www/html/application/controllers/Detail.php
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Filename: controllers/Detail.php
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Function: _error_handler
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Filename: controllers/Detail.php
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Function: _error_handler
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Filename: models/Detail_model.php
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Function: strpos
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Function: insertAPISummary
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Filename: helpers/my_audit_helper.php
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Filename: controllers/Detail.php
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Line: 256
Function: _error_handler
File: /var/www/html/index.php
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Message: Trying to access array offset on value of type null
Filename: controllers/Detail.php
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File: /var/www/html/application/controllers/Detail.php
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Function: _error_handler
File: /var/www/html/index.php
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Filename: controllers/Detail.php
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Function: _error_handler
File: /var/www/html/index.php
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Filename: controllers/Detail.php
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Filename: controllers/Detail.php
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Filename: controllers/Detail.php
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Function: _error_handler
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Filename: controllers/Detail.php
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Function: _error_handler
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Filename: controllers/Detail.php
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Filename: controllers/Detail.php
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Filename: controllers/Detail.php
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Filename: controllers/Detail.php
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Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
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Function: require_once
A target analysis method for the sensitive and discriminative determination of the nerve agent hydrolysis products alkyl methylphosphonic acids as their tert-butyldimethylsilyl (TBDMS) derivatives was developed using a combination of selectable one- and two-dimensional (D/D) GC-MS, and applied to the analysis of samples with significant interfering matrices. After sample drying, the alkylmethylphosphonic acids and methylphosphonic acid (MPA) were converted to TBDMS derivatives by addition of N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide with heating, and subjected to D/D GC-MS. The apparatus consisted of an initial low thermal mass DB-5 column and a second DB-17 column together with an electron ionization quadrupole mass spectrometer, offering simple and flexible switching between one- and two-dimensional GC-MS analysis in a single GC-MS system. Using D/D GC-MS, analytes that do not co-elute with matrix components can be separated using D GC mode alone. Only those parts of the chromatogram that are negatively affected by the co-elution of matrix components need to be transferred and separated with D GC. Quantitation can be performed by a combination of both separations and mass spectrometric detection. The TBDMS derivatives of ethyl-, isopropyl-, isobutyl-, pinacolyl-, and cyclohexyl-MPA (cHMPA) and MPA itself were well separated within 3min and determined in D GC-MS mode with detection limits of around 10ng/ml of reaction mixture (except for the cHMPA derivative, whose mass spectrum contained noisy background peaks). In D-GC-MS mode, where each 0.04min elution window from the D GC was subjected to heart-cut (H/C) and transferred to the second column after back-flushing the first column, the peak for the cHMPA TBDMS derivative was isolated and afforded a clean mass spectrum within 6min. The recoveries of all the derivatives on D GC from D GC were estimated to be over 66%, and the detection limits were around 10ng/ml of reaction mixture. In the presence of urine extract, the target compounds were not detected as separated peaks in D GC-MS mode (except for isobutyl-MPA), and quantification based on extracted ion monitoring could not be achieved. However, D GC-MS of the H/C fractions of the target derivatives gave single peaks with well-defined mass spectra, and the recoveries of the derivatives were over 70% except for cHMPA (31% at 1.25μg/ml). Phosphonic acids could be detected at less than 60ng/ml. Sulfuric acid and phosphoric acid also negatively affected the determination of alkyl methylphosphonic acid TBDMS derivatives in D GC-MS, and the MPA-TBDMS-derivative peak was completely obscured by the large sulfuric-acid-derivative peak. However, under D/D GC-MS conditions, baseline separation of the MPA derivative and sulfuric acid derivative was achieved, enabling highly sensitive MPA detection at 20ng/ml.
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http://dx.doi.org/10.1016/j.chroma.2017.04.024 | DOI Listing |
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