A GAS-CHROMATOGRAPHIC HEADS PACE METHOD FOR THE DETERMINATION OF ACETONE IN BOVINE MILK , BLOOD AND URINE
WINTERBACH, HANLIE E. K. & APPS , P . J. , 1991. A gas-chromatographic headspace method for the determination of acetone in bovine milk, blood and urine. Onderstepoort Journal of Veterinary Research, 58,75-79 (1991) An automated headspace gas-chromatographic method has been developed for the determination of acetone in the milk, blood and urine of dairy cows. Five me samples were saturated with 2 g of sodium chloride and equilibrated for 30 min at 90°C in a Hewlett-Packard HP 19395A automatic headspace sampler. The headspace volatiles were transferred without splitting to a 25 m x 0,3 mm x 0,4 11m Carbowax column in a Shirnadzu GC 9A gas chromatograph, operating isothermally at 50 °C. The coefficients of variation for the determination of acetone were 1,5-4,4 % for urine , 10,0-24 ,9 % for milk and 2,0-19,6 % for blood . The detection limits were 0,0055 mg/100 me for milk, 0,0072 mg/100 me for blood and 0,0080 mg/100 me for urine . The analysis time of 5 mm per sample provided an adequate rate of throughput for routine monitoring.
An enzymatic fluorimetric micromethod for the determination of acetoacetate, -hydroxybutyrate, pyruvate and lactate.
Abstract A simple and rapid method was developed for determining acetoacetate, β-hydroxybutyrate, pyruvate and lactate in whole blood in a sample of 0.2 ml. The procedures were based on enzyme-catalyzed reactions involving changes m the concentration of coenzyme (NADH), which was measured by its native fluorescence. Proportionality between concentration and fluorescence emission was established, problems with non-specific NADH reaction were overcome and the blank fluorescence was markedly reduced. This makes the method highly reliable and well-suited for routine use.
Interactions of glucose, acetoacetate and insulin in mammary-gland slices of lactating rats.
1. Utilization of 5mM-glucose by slices of lactating mammary gland was decreased 33% on addition of acetoacetate (2mM) to the incubation medium. This inhibition was accompanied by increases in the intracellular concentrations of citrate and glucose 6-phosphate. 2. In the presence of acetoacetates the accumulation of pyruvate in the medium approximately doubled. 3. Insulin completely reversed the inhibitory effect of acetoacetates on glucose utilization, without altering the amount of acetoacetate removed or pyruvate formed. 4. Similar results were obtained with mammary-gland slices from diabetic rats, except that insulin did not completely reverse the effects of acetoacetates. 5. Acetoacetate inhibited the formation of 14CO2 from [1-14C]pyruvate; this effect was not overcome by insulin. 6. Insulin increased the proportion of [3-14C]acetoacetate that was converted into lipid and decreased that oxidized to CO2.7. The physiological significance of these findings is discussed.