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.
Clinical evaluation of ketone bodies in body fluids of cows in late pregancy and their fetuses
Ketone body concentrations were determined in six body fluids of cows in late pregnancy and their fetuses (blood plasma and urine of cows, amniotic and allantoic fetal fluids, and fetal blood serum and urine) using the head-space gas chromatographic method. Physiological ratios 0/T% of oxidized (acetone and acetoacetic acid) to total (acetone, isopropanol, acetoacetic and 3-hydroxybutyric acids) ketone bodies were below 10% in cow blood plasma and urine, fetal serum and urine, and allantoic fluid, and below 20% in amniotic fluid. A scheme for the evaluation of the degree and duration of ketosis based on the 0/T% ratio is proposed. The existence of a renal regulatory mechanism for excretion of ketone bodies is suggested by analogy with the renal acidobasic regulation.
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.