Search

We developed an assay for antipyrine in serum using micellar electrokinetic capillary chromatography. A capillary electrophoresis system with a 70-cm fused-silica capillary and pH 8.2 borate-sodium dodecyl sulfate buffer was used. Standard curves ranging from 0.5 microgram/ml to 25 micrograms/ml were analyzed. The resulting electropherograms showed no interfering endogenous peaks and the assay was linear in the range of concentrations analyzed. The intra-day and inter-day relative standard deviations ranged from 0.7 to 5.2% and 1.7 to 8.1%, respectively. Analytical recovery of antipyrine ranged from 78.2 to 105.0%. The theoretical plate number for antipyrine was calculated to be 561,000 +/- 79,000 plates/m.

Evaluation of fetal protein metabolism requires measurement of a number of variables including umbilical blood flow, CO2 radioactivity, as well as plasma specific activities, whole blood concentration, and radioactivity of leucine and alpha-ketoisocaproate. This report details methods of analysis for whole blood concentration and radioactivity of leucine and alpha-ketoisocaproate using high-performance liquid chromatography that can be done on minimal blood volumes and are sufficiently accurate to detect the small arteriovenous differences important in measurements of fetal metabolism. Using these methods, the important components of fetal protein metabolism such as protein synthesis can be calculated with sufficient accuracy to detect differences as small as 10% provided appropriate experimental designs are used.

A rapid and simple high-performance liquid chromatographic assay for the determination of propyphenazone in plasma is described. Phenylbutazone was used as the internal standard. Plasma proteins were precipitated with acetonitrile before injection onto a 3-microns Supelcosil LC-18 column. The mobile phase, ethanol containing 0.2% (v/v) heptylamine-0.005 M potassium dihydrogenphosphate (30:70, v/v), was used at a flow-rate of 1.3 ml/min. The quantitation was performed by ultraviolet detection at a wavelength of 270 nm. The chromatographic time was 7 min. The within- and between-day coefficients of variation were less than 6% and the recoveries close to 100% for concentrations between 0.4 and 22 mumol/l. The limit of quantitation was 0.4 mumol/l (ca. 100 ng/ml).

A novel analytical methodology was developed for simultaneous high-performance liquid chromatographic quantitation of antipyrine and lorazepam in biological fluids using phenacetin and flunitrazepam as internal standards, respectively. A gradient solvent system was used to achieve specificity and sensitivity for each of the compounds in biological fluids. The between-run coefficients of variation for replicate analysis of antipyrine and lorazepam in identical plasma samples were 9.4 and 6.4% at 60 micrograms/ml and 5.5 micrograms/ml, respectively, for antipyrine, and 9.1 and 9.9% at 110 ng/ml and 10.5 ng/ml, respectively, for lorazepam. Accuracy ranged from 99.7 to 101.4% at concentrations of 8, 45 and 105 micrograms/ml for antipyrine and from 94.8 to 95.8% at concentrations of 12, 55 and 125 ng/ml for lorazepam. This method requires only one organic extraction procedure for all four compounds, allows quantitation of these two drugs in samples also containing indocyanine green, and sample throughput following extraction is totally automated.

A rapid, selective and sensitive method was developed for the determination of antipyrine and its main metabolites in plasma, saliva and urine by an automated high-performance liquid chromatographic system. Using a MOS-Hypersil reversed-phase column with a phosphate buffer--acetonitrile mobile phase, baseline separation of antipyrine, its metabolites 3-hydroxymethylantipyrine, norantipyrine and 4-hydroxyantipyrine, and the internal standard, phenacetin, was achieved within 6 min. Factors regarding the accuracy and precision of the method and the stability of phase I metabolites during sample preparation are discussed, taking into account certain drawbacks of previously published methods. Based on the same chromatographic system a method was developed for the assay of 4,4'-dihydroxyantipyrine in urine. This compound is an important metabolite of antipyrine in the rat, representing 12.6 +/- 1.8% of the administered dose (n = 18).