Catabolism of 6-keto prostaglandin E1 by rat kidney homogenates

1984 ◽  
Vol 62 (8) ◽  
pp. 709-714 ◽  
Author(s):  
C. R. Pace-Asciak ◽  
S. Micallef
Keyword(s):  
Mass Spectrometry ◽  
Chemical Ionization ◽  
Rat Kidney ◽  
Trimethylsilyl Ether ◽  
Negative Ion ◽  
Electron Capture Detection ◽  
Prostaglandin E ◽  
Rat Stomach ◽  
Negative Ion Chemical Ionization ◽  
Stomach Fundus

6-Keto prostaglandin E1 (PGE1) was catabolized into two major products by homogenates of rat kidney in the presence of NAD. Rat brain was mostly deficient in this catabolic activity. A total profile of products from these experiments could be obtained using the pentafluorobenzyl esters, O-methyloxime, and trimethylsilyl ether derivatives and analysis by capillary gas chromatography with electron capture detection. The same samples could be effectively analyzed by mass spectrometry using negative ion chemical ionization (NICI) detection. While 6-keto PGE1 showed spasmogenic activity on the rat stomach fundus as well as inhibition of the ADP-induced platelet aggregation, its catabolites lacked such activity. Analysis of rat whole blood by mass spectrometry using the NICI technique showed the presence of small amounts of 6-keto PGE1 and its 15-keto and 15-keto 13, 14-dihydro catabolites in two of eight blood samples.

Four-Laboratory Validation Study of the Determination of Chloramphenicol in Veal Calf Urine

1995 ◽  
Vol 78 (2) ◽  
pp. 483-490
Author(s):  
Kathleen P Holland ◽  
A Carolyn Henry ◽  
T Roger Wilson ◽  
S John Dreas ◽  
B Raymond Ashworth
Keyword(s):  
Validation Study ◽  
Chemical Ionization ◽  
Trimethylsilyl Ether ◽  
Negative Ion ◽  
Electron Capture Detection ◽  
Selected Ion Monitoring ◽  
Coefficients Of Variation ◽  
Veal Calf ◽  
Negative Ion Chemical Ionization

Abstract A four-laboratory validation study of a method for the quantitation and confirmation of low part-perbillion levels of chloramphenicol extracted from veal calf urine was done. With this method, chloramphenicol, derivatized to the bis(trimethylsilyl) ether, was quantitated by gas chromatography with electron capture detection (GC–ECD) and confirmed by selected-ion monitoring in a negative ion chemical ionization gas chromatograph-mass spectrometer (GC–NICI–MS). Four analysts from 4 laboratories participated in the portion of the study devoted to chloramphenicol quantitation. Every analyst analyzed 5 sets, one set per day, on 5 different days. Each set included 6 samples consisting of a blank, 2 fortified samples, 2 incurred urine samples, and one duplicate. Thus, each analyst worked on a total of 30 samples. Chloramphenicol concentrations ranged from 0 to 9.7 ppb. All data were reported to 0.1 ppb. Coefficients of variation for distribution, CVd, ranged from 8.82 to 14.14% and for precision, CVr, ranged from 9.15 to 14.80%. Three analysts from 3 laboratories also participated in the confirmatory portion of the study, which was carried out to test whether the NICI–MS method developed earlier for higher concentrations of chloramphenicol and for an extract of muscle tissue could be applied to lower levels of chloramphenicol and to an extract prepared from urine. The extracts of 10 of the 30 samples were designated for confirmation only, but were obtained by the same procedure as extracts used for the quantitation part of the study. The confirmation part of the study failed to determine whether NICI–MS is still valid for these levels and this matrix because source temperature lower than that recommended by the originating laboratory as used by all collaborating laboratories. The spectra generated by collaborators were different from those expected.

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