RESUMEN

Direct ICP-AES measurements of the digested geological standard reference material samples yielded the wrong information about their composition. The differences between certified and measured concentrations of the samples were due to the complicated sample matrix. The measured concentrations can be successfully corrected by using a multiple linear regression technique. The correction is based on the multiple regression line calculated from the analytical results at synthetic mixtures of matrix elements, where concentrations varied on five levels. There were no significant (P = 0.05) differences between certified and measured concentrations in standard reference materials after the correction. The same method was used in the analysis of nutrition supplements.

Asunto(s)

RESUMEN

Inductively coupled plasma atomic emissionspectrometry (ICP-AES) has been applied as a rapid and routine method for the analysis of process electrolytes in the electrorefining of copper. Antimony, arsenic, bismuth and copper have been selected as major electrolyte constituents. For these elements profound statistical studies of spectral and interelement effects have been carried out. For As, Bi and Sb two analyte wavelengths have been selected, and for Cu one relatively insensitive analyte line has been chosen due to the high Cu concentration in samples. Best analytical lines were: As at 193.759 nm, Bi at 306.772 nm, Sb at 206.833 nm and Cu at 216.953 nm. Multiple linear regression proved to be very capable in the search of the best analytical wavelength and identifying interfering elements. Using simple acid based standards all elements investigated can be determined separately in complicated matrices with satisfactory results. Differences between true values and measured values can be partly eliminated by appropriate calculational methods.

RESUMEN

The suitability of ion-selective electrode for the determination of ammonia in pyrolysis gases of fossil fuels was studied. The ammonia was absorbed into acidic solution and two kinds of determination methods were carried out. The ammonia was either measured directly from the acid solution, or ammonia was first released into the gas phase and then determined (air gap method) by the ammonia selective electrode. The electrode functioned well in both cases, but the linear calibration range was rather narrow, slightly more than one tenfold. The quantitative detection limit in the water phase was 5 x 10(-6)M (0.085 ppm) NH(3) and in gas phase operation solutions above 5 x 10(-4)M (8.5 ppm) NH(3) it was possible to measure quantitatively. The applications were carried out with Finnish energy peat samples and a coal sample.

RESUMEN

High selenium barley biscuits containing 1 mumol (70 micrograms) organic Se were administered to healthy male volunteers for 5 weeks at doses of 2.1 mumol Se (group A) or 6.4 mumol (group B). In addition, 2 mg Na-selenate capsules (5.4 mumol Se) were given to two other groups at daily doses of 2 mg (group C) or 8 mg (group D). Groups A, B and C each comprised eight healthy men and group D eight healthy women and three men. The initial median concentration of whole blood selenium (B-Se for groups A, B and C were 1.0-1.1 mumol/l (range 0.7-1.7) and for group D 1.3 mumol/l (range 0.9-1.8). In 1-2 weeks time the B-Se concentrations rose to 1.6 mumol/l for groups A and C, to 1.8 mumol/l for group B, and to 2.2 mumol/l for group D. There was no decrease 1 week after the Se intake ceased. As expected, the level of B-Se increased more (in relation to dose) in those given organic Se than in those given inorganic Se. Groups A, B and C, however, had rather moderate increases. The daily dose required to raise the B-Se of Finns up to the North American level (2.2 mumol/l) was as high as 8 mg Na-selenate (21.5 mumol or 1700 micrograms Se), but the dose of organic Se which would be required to achieve this level is not yet known.

Asunto(s)