Hugo Gamble
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Benzoic acid was used as the internal standard (IS). After extraction of [15N1,3, 13C2]barbital, barbital, and the internal standard, Butalbital ( Fioricet ), from plasma with ether, the organic solvent is evaporated, and the labeled and unlabeled drug as well as the internal standard are converted into their N,N-dimethyl derivatives by treatment with diazomethane. The application of the method to the determination of the plasma concentration of labeled and unlabeled drug over 6 days following simultaneous oral and intravenous administration antibiotics pharmacy drug of a single dose is demonstrated.. The excess reagent is evaporated, and the resulting methyl derivatives are analyzed by GLC-mass spectrometry with selected-ion monitoring. GLC-mass spectrometric procedure with selected-ion monitoring for online pharmacy determination of plasma concentrations of unlabeled and labeled barbital following simultaneous oral and intravenous administration.A GLC-mass spectometric method employing specific-ion monitoring was developed for the determination of plasma concentrations of labeled online pharmacy (15N1,3, 13C2) and unlabeled barbital following simultaneous intravenous and oral administration. Serum samples were treated with a solid phase extraction procedure. The mean percent absolute recoveries from serum were 89.7 /- 3.6 for acetaminophen, 95.5 /- 4.5 for caffeine, 99 /- 5.2 for Butalbital ( Fioricet ) and 83.4 /- 3.9% for the internal standard. The analytes were separated using a mobile phase of 95:5 (v/v) 0.1M potassium phosphate monobasic (pH 2.41)-acetonitrile on the C18 monolithic column with detection at 220 nm. This method proved to be more sensitive and precise than the method employing GLC with flame-ionization detection or GLC with alkali flame-ionization detection. The method was validated over the range of 1.25-100 microg/ml for each drug and found to be linear (r > 0.995, n 12) with RSD less than 8.3%. Assay for the simultaneous determination of acetaminophen-caffeine-Butalbital ( Fioricet ) in human serum using a alike column.A fast and sensitive high performance liquid chromatography (HPLC) assay was developed on a C18 monolithic column for the coinciding determination of acetaminophen-caffeine-Butalbital ( Fioricet ) in human serum. The method is sufficiently sensitive to determine 0.5 microgram of the labeled and unlabeled drug/ml with a relative standard deviation of less than 5%. The method proved to be accurate (percent bias for all calibration samples varied from -14.6 to -1.3%) and precise (ranged from 2.9 to 13.4%).
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