Simultaneous determination of tetrathiomolybdates and molybdates in spiked blood plasma by differential pulse voltammetry and their speciation.

A selective, sensitive and reliable voltam- metric method for the simultaneous determination of MoS(2-)(4) and MoO(2-)(4) has been developed. The reduction of HgMoS(4) at -0.43 V and the reduction of Mo as complex of MoO(2)-oxine(2) at -0.63 V in acetate buffer at pH 4.9 are utilized for the simultaneous determination by differential pulse cathodic stripping voltametry (DPCSV). Cadmium and lead form complexes with MoS(2-)(4), but do not interfere with the determination. The limit of detection is 0.59 microg/l Mo for MoS(2-)(4) and 1.8 microg/l Mo for MoO(2-)(4). The R.S.D at a concentration level of 20 microg/l is 4.7% for MoO(2-)(4) and 3.6% for MoS(2-)(4). The method is applied to spiked blood plasma samples for the determination of free tetrathiomolybdates and molybdates. Additionally, labile tetrathiomolybdates and molybdates can be determined in spiked blood plasma after treatment of the sample with 0.15 mol/l KCN and ultrafiltration.

Aspects of protein bound copper in sheep plasma and its release in vitro especially after treatment with ammonium tetrathiomolybdate.

The distribution of protein-bound copper in sheep plasma between a globulin and an albumin fraction, as well as copper release in vitro by means of various agents, either from the above-mentioned fractions or from those formed after ammonium tetrathiomolybdate (TTM) treatment, were studied. Copper bound in both plasma globulin and albumin (CuGA) is 95.1% of the total plasma copper (CuT); copper release from the globulin fraction by means of trichloracetic acid (TCA) or cyanides (CN-) is relatively low, 17.1% and 25.8% respectively, while there is not any copper release after TTM treatment; however, the copper release from the albumin fraction by means of TCA and CN- is relatively high, 59.2% and 74.9%, respectively, while the treatment with TTM has the same effect of no copper release as mentioned above for the globulin fraction.

Determination of cobalt in vegetable animal foodstuffs by differential pulse adsorptive voltammetry using alpha-benzil dioxime.

A selective and sensitive voltammetric method for the determination of cobalt in vegetable animal foodstuffs is developed. The method is based on the use of alpha-benzil dioxime (alpha-BD) as a chelating agent for differential pulse adsorptive stripping voltammetry (DPASV) and is free from zinc interferences. The influence of pH, time and alpha-BD concentration on the peak resolution and height are discussed. The method was successfully applied in some typical vegetable animal foodstuffs with R.S.D. < 6%.

Some aspects of chronic copper poisoning in sheep.

The variations in an analytical fraction of plasma copper, as well as those of direct and indirect plasma bilirubin, were studied for a period of twenty-three days in ten native crossbred sheep suffering from chronic copper poisoning. The findings of the experiment, which was begun just before the appearance of any acute symptoms, show that the proportion of the above fraction of plasma copper, characterized as "soluble in trichloroacetic acid" (STAPC), represents approximately 45% as a mean percentage of the total plasma copper (TPC), while in the controls it was 12%; further, the former proportion, despite progressive reduction in the absolute values on the respective concentrations, shows, at least during the course of the experiment, a relatively small decrease, while in the controls it remains constant. Further findings regarding direct and indirect plasma bilirubin are discussed.