– Detection of subclinical mastitis in five different breeds of cows were done on the territory of a municipality Ključ, through all four year seasons by using the California mastitis test, at the level of the udder’s quarter with a certificate of bacteriological findings in order to justify their application in the diagnosis of mastitis. In total, 2150 cows of different breed composition: Simmental 1090, red Holstein 322, Holstein-Friesian 340, montafon 108 and various crossbreeds of 290 in total. After 1978 tested cows, 56.02% of cases had positive reactions to the California mastitis test. The most common positive reaction we found in the milk was in one or two quarters with the intensity of the reaction of one and two plus. The most common causes of mastitis were staphylococci, streptococci and mixed infections. Continuing use of these methods it is possible to timely detect the presence of subclinical mastitis and get satisfactory results in the prevention and treatment of mastitis as well as increasing the quantity and improving the quality of milk.

A procedure for the determination of trace levels of Cd, Co, Cr, Fe, Mn, Ni, and Pb by flame atomic absorption spectrometry using a column preconcentration system is described in which the metals were adsorbed on pulverized banana peel, an economically and environmentally acceptable sorbent. In the optimization procedure, five variables (sample pH, mass of biosorbent, type of eluent, sample flow rate, and volume) were optimized and the capacity of the biosorbent was established. Under the optimized conditions, the detection limits of the method were 2.4, 27.0, 49.4, 31.1, 6.7, 29.6, and 46.2 µg L−1 for Cd, Co, Cr, Fe, Mn, Ni, and Pb, respectively. The precision, expressed as relative standard deviation, was less than 4% based on twelve measurements. The recoveries were 81.1% (Cd), 91.4% (Co), 87.2% (Cr), 90.1% (Fe), 88.0% (Mn), 94.1% (Ni), and 93.2% (Pb) under the optimum conditions (pH; 9, sample flow rate; 3 mL min−1, mass of biosorbent; 200 mg; eluent; 1 mol L−1 nitric acid, preconcentration factor; 10). The sorption capacity of pulverized banana peel was 15.12, 28.85, 32.70, 30.44, 30.94, 28.97, and 8.21 µmol per gram of adsorbent for Cd, Co, Cr, Fe, Mn, Ni, and Pb, respectively.