Lipid composition of membranes ofEscherichia coli by liquid chromatography/tandem mass spectrometry using negative electrospray ionization

2007 ◽  
Vol 21 (11) ◽  
pp. 1721-1728 ◽  
Author(s):  
Delphine Oursel ◽  
Corinne Loutelier-Bourhis ◽  
Nicole Orange ◽  
Sylvie Chevalier ◽  
Victor Norris ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Electrospray Ionization ◽  
Lipid Composition ◽  
Ofescherichia Coli ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Negative Electrospray Ionization

scholarly journals Determination of Clenbuterol, Salbutamol, and Cimaterol in Bovine Retina by Electrospray Ionization–Liquid Chromatography–Tandem Mass Spectrometry

2004 ◽  
Vol 87 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Joseph H W Lau ◽  
Cheang S Khoo ◽  
John E Murby
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Electrospray Ionization ◽  
Tandem Mass ◽  
Bovine Retina ◽  
Chromatography Tandem Mass Spectrometry ◽  
Protease Enzyme ◽  
Liquid Chromatography Tandem Mass

Abstract An electrospray ionization–liquid chromatography–tandem mass spectrometry (ESI/LC/MS/MS) method was developed for the simultaneous determination of the β-agonists clenbuterol, salbutamol, and cimaterol in bovine retina. The tissue was homogenized in alkaline buffer and spiked to give 10, 15, and 20 ng/g each of the 3 analytes together with the internal standards d6-salbutamol and d6-clenbuterol. The mixture was incubated with protease enzyme to release any protein-bound analytes and then made alkaline before extraction with isobutanol. The extract was dissolved in water and transferred to a clenbuterol immunoaffinity column. After washing, the analytes were eluted and analyzed by ESI/LC/MS/MS using a C18 column with acetic acid–methanol as mobile phase. No interferences were observed from the spiked retina extract at the various single-reaction monitoring modes. Average recoveries for clenbuterol, salbutamol, and cimaterol were 94, 85, and 87% with coefficients of variation (CVs) of 9.4, 9.9, and 8.6%, respectively. A correlation coefficient of r2 = 0.9999 was obtained for all analytes. The limits of detection for clenbuterol, salbutamol, and cimaterol, determined from 3 times the standard deviation of 7 replicates of the lowest spike, were 2.5, 3.5, and 2.0 ng/g with CVs of 8.9, 11.6, and 7.2%, respectively.

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