Calibration in quantitative analysis Part 1. General considerations

Mathematical procedures for calibration require assumptions to be made, e.g. the homogeneity of variances and the mathematical relationship between the analyte content x and the signal y. Little is known about the magnitude of errors arising from incorrect assumptions. The variation of the standard deviation of the analytical procedure with the content of the analyte, the selection of the type of mathematical relationship between x and y, and the types of errors made in testing hypotheses are discussed. In certain practical situations, the standard deviation (s.d.) is nearly independent ofx if x 50p. If the s.d. is constant, calibration relations of the typey = a + bx are frequently to be preferred; with a constant r.s.d.. relations of the type log y = a + b logx have advantages

Calibration in quantitative analysis Part 1. General considerations

Mathematical procedures for calibration require assumptions to be made, e.g. the homogeneity of variances and the mathematical relationship between the analyte content x and the signal y. Little is known about the magnitude of errors arising from incorrect assumptions. The variation of the standard deviation of the analytical procedure with the content of the analyte, the selection of the type of mathematical relationship between x and y, and the types of errors made in testing hypotheses are discussed. In certain practical situations, the standard deviation (s.d.) is nearly independent ofx if x 50p. If the s.d. is constant, calibration relations of the typey = a + bx are frequently to be preferred; with a constant r.s.d.. relations of the type log y = a + b logx have advantages

Determination of and differentiation between cassimerite and silicate-bound tin in silicate rocks containing traces of tin

A simple, sensitive and reproducible method is described for the determination of tin in silicate rocks at the ppm level. By applying a selective decomposition it seems possible to differentiate between tin present in the silicate lattice, in readily-accessible cassiterite (SnO2) and in cassiterite enclosed in the silicate. The final determination is made by extraction and photometry with phenylfluorone. Results for total tin agree well with those obtained by X-ray fluorescence