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The conversion of ephedrine to methamphetamine and methamphetamine-like compounds during and prior to gas chromatographic/mass spectrometric analysis of CB and HFB derivatives (1992)

Wu, Alan H. B. ; Wong, Shan S. ; Johnson, Kent G. ; [et al.]

Chichester : Wiley-Blackwell

Biological Mass Spectrometry 21 (1992), S. 278-284

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ISSN: 1052-9306

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Ephedrine and methamphetamine standards were separately derivatized with heptafluorobutyric anhydride (HFBA) and carbethoxyhexafluorobutyryl chloride (CB) and analyzed by full-scan gas chromatography/ion trap mass spectrometry with electron ionization (EI) and chemical ionization (CI). Using EI, a high-concentration ephedrine standard produced a total ion gas chromatogram containing several minor HFB derivatives in addition to ephedrine. One of these had the same retention time as the derivative of methamphetamine, while another eluted 3 s later. Both contained the same major mass fragmentation ions that could be erroneously used in targeted selected ion monitoring gas chromatographic/mass spectrometric analysis for methamphetamine. The full-scan EI and CI spectra showed that these derivatives were not methamphetamine. CI mass spectrometric studies of ephedrine scanning up to m/z 700 demonstrated that reaction with HFBA caused acylation of both the hydroxyl and secondary amino groups. The HFBA used in this study was contaminated with pentafluoropropionic anhydride and tri-fluoroacetic anhydride and produced mixtures of derivatives, some with retention times near or identical to that of methamphetamine. In contrast, CB derivatization of ephedrine produces a single methamphetamine-like compound that has the same retention time and mass spectra as methamphetamine, and is produced only when high gas chromatograph injector temperatures are used ( 〉 260°C). Collision-induced decomposition tandem mass spectrometric studies for the CB derivative verified that methamphetamine is produced from ephedrine at elevated GC injection port temperatures. In view of these findings, substance abuse testing for methamphetamine in urine must proceed with caution when ephedrine and other sympathomimetic amines are present. Definitive analyses can be accomplished by full-scan CI gas chromatographic/mass spectrometric analysis with HFB derivatives, or by lowering gas chromatograph injector temperatures with CB derivatives.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/bms.1200210603

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Biosynthesis of prostaglandins by human spermatozoa in vitro and their role in acrosome reaction and fertilization (1992)

Roy, Ashim C. ; Ratnam, Shan S.

New York, NY [u.a.] : Wiley-Blackwell

Molecular Reproduction and Development 33 (1992), S. 303-306

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ISSN: 1040-452X

Keywords: Arachidonic acid ; Calcium ionophores ; Cyclooxygenase ; Cyclooxygenase inhibitors ; Lipoxygenase products ; Phospholipase A2 ; Thromboxanes ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: Five homogenates of human sperm cells were separately incubated with [14C]arachidonic acid in the presence of reduced glutathione, L-tryptophan, and haematin as cofactors. The cyclooxygenase products of archidonic acid metabolism were extracted, separated, and measuréd for their radioactivity. The rate of formation of prostaglandin (PG)D2, PGE2, PGF2α, 6-keto PGF1α, and thromboxane (TX)B2 were 18.0 ± 1.11, 10.9 ± 0.68, 5.8 ± 0.21, 3.9 ± 0.13 and 6.6 ± 0.52 pmol/106 cells/min, respectively. These results are discussed in relation to the hypothesis that cyclooxygenase metabolites of certain polyunsaturated fatty acids play an important part in the sperm acrosome reaction and fertilization. © 1992 Wiley-Liss, Inc.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/mrd.1080330311

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A new technique for detecting oxytocinase activity in electrophoresis gels (1992)

Roy, Ashim C. ; Saha, Nilmani ; Tan, Suan M. ; [et al.]

Weinheim : Wiley-Blackwell

Electrophoresis 13 (1992), S. 396-397

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ISSN: 0173-0835

Keywords: Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Chemistry and Pharmacology

Notes: A sensitive staining method for the detection of oxytocinase (EC 3.4.11.3) activity in electrophoresis gels has been described. The method is based on the enzymatic release of p-nitroaniline (PNA) from two specific synthetic oxytocinase sub-strates, S-benzyl-L-cysteine-p-nitroanilide (BCN) and L-leucine-p-nitroanilide (LN), respectively. The PNA is then diazotized with sodium nitrite and subsequently coupled to a chromogen, N-(1-naphtyl)-ethylenediamine dihydrochloride (NED) to produce a deep pink/magenta colored azo-dye at the site of oxytocinase activity.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/elps.1150130181

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Source Characteristics of the 2012 Haida Gwaii Earthquake Sequence (2015)

Kao, H. ; Shan, S.-J. ; Farahbod, A. M.

Seismological Society of America

In: Bulletin of the Seismological Society of America. 2015; 105(2B): 1206-1218. Published 2015 Apr 07. doi: 10.1785/0120140165.

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Publication Date: 2015-04-07

Description: All the significant (ML≥4) events in the 2012 Haida Gwaii earthquake sequence are systematically relocated, and their moment tensor solutions are determined from waveform inversion. The focal mechanism of the mainshock shows low‐angle thrust faulting along a shallowly dipping plane with a strike parallel to the Queen Charlotte fault (QCF), consistent with the inference of Pacific plate underthrusting beneath the overriding North American plate. The epicenter of the mainshock is located ∼5 km landward (northeast) of the surface trace of the QCF, suggesting the nucleation of the rupture was near the bottom of the seismogenic (locked) interface. Significant aftershocks appear to cluster on the periphery of the main rupture zone with most events located immediately seaward of the deformation front. The majority of these events show normal‐faulting mechanisms that are probably associated with the bending stress within the Pacific plate near the deformation front. Several normal and strike‐slip events at greater depths within the subducted Pacific slab show a consistent pattern of T‐axis in the down‐dip direction, implying the subducted plate is under a stress regime of down‐dip extension. Only a few strike‐slip events were observed along or near the QCF. The limited size and distribution of these events suggest that most of the elastic strain accumulated along the QCF was not released during the 2012 Haida Gwaii sequence. Major strike‐slip earthquakes are likely to occur along the southernmost part of the QCF system in the future.

Print ISSN: 0037-1106

Electronic ISSN: 1943-3573

Topics: Geosciences , Physics