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.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.