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.
Milk and blood ketone bodies, blood isopropanol and plasma glucose in dairy cows; methodological studies and diurnal variations.
Summary 
 
Eight hyperketonaemic cows were used to investigate the diurnal variations of ketone bodies in blood and milk. The effect of sampling time was significant for blood isopropanol, plasma glucose, plasma β-hydroxybutyrate and milk β-hydroxybutyrate. High coefficients of correlation between acetone plus acetoacetate in milk and ketone bodies in blood and the absence of significant diurnal variations make this parameter suitable to measure at routine sampling. The concentration of acetone plus acetoacetate in preserved milk was stable at room temperature for seven days, which is sufficient for sample handling under field conditions. 
 
 
 
Zusammenfassung 
 
Milch- und Blutketonkorper, Blut-Isopropanol und Plasmaglukose bei Milchkuhen: Methodische Untersuchungen und Tagesschwankungen 
 
 
 
Bei 8 hyperketonamischen Kuhen wurden die Tagesschwankungen der Ketonkorper im Blut und in der Milch untersucht. Der Zeitpunkt der Probenentnahme hatte einen signifikanten Einflus auf Blut-Isopropanol, Plasmaglukose, Plasma-β-hydroxybutyrat und Milch-β-hydroxybutyrat. Aufgrund der hohen Korrelationskoeffizienten zwischen Aceton plus Acetoacetat in der Milch und den Ketonkorpern im Blut und des Fehlens von signifikanten Tagesschwankungen sind diese Parameter geeignet fur Routineuntersuchungen. Die Konzentrationen von Aceton plus Acetoacetat blieben bei Zimmertemperatur wahrend 7 Tagen stabil, was fur die Probenentnahmen unter Feldbedingungen ausreichend ist. 
 
 
 
Resume 
 
Corps cetoniques du lait et du sang, isopropanol sanguin et glucose du plasma chez des vaches laitieres: recherches methodiques et variations journalieres 
 
 
 
Les variations journalieres des corps cetoniques dans le sang et le lait ont ete examinees chez 8 vaches hypercetonhemiques. Le mouvement du prelevement a eu une influence significative sur l'isopropanol du sang, le glucose du plasma, β-hydroyxybutyrate du plasma et du lait. Ces parametres se pretent a des recherches de routine sur la base des coefficients eleves de correlation entre acetone + acetoacetate dans le lait et les corps cetoniques dans le sang et l'absence de variations journalieres significatives. Les concentrations d'acetone + acetoacetate sont restees stables durant 7 jours a la temperature ambiante, ce qui est suffisant pour des prelevements dans des conditions du terrain. 
 
 
 
Resumen 
 
Cuerpos cetonicos en leche y sangre, isopropanol en sangre y glocosa en plasma sanguineo de vacas lecheras: Estudios metodologicos y variaciones diurnias 
 
 
 
En 8 vacas hipercetonemicas se estudiaron las oscilaciones diurnias de los cuerpos cetonicos en sangre y leche. El momento de la toma de la muestra ejercia un influjo significativo sobre isopropanol en sangre, glucosa plasmatica, β-hidroxibutirato plasmatico y β-hidroxibutirato lacteo. A la vista de los coeficientes elevados de correlacion entre acetona mas acetoacetato en la leche y los cuerpos cetonicos en la sangre y la ausencia de variaciones diurnias significantes, estos parametros resultan ser apropiados para analisis de rutina. Las concentraciones de acetona mas acetoacetato permanecieron estables a temperatura de habitacion durante 7 dias, lo cual es suficiente para la toma de muestras bajo condiciones campales.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.