โ Scribed by A.B. Calder
No coin nor oath required. For personal study only.
log intensity ratio) are plotted on a linear scale against log concentration. This is the usual "autocalibration" method. The "Selecta" no. 373+ A3, semi-logarithmic paper was used in both cases. A background correction was applied for the zinc and titanium determinations using a special slide rule based on Gaussian logarithms [2].
The different analytical lines used, are listed in Table 1. The quoted concentration ranges refer to the use of two weakening filters (G, and G,) where only about 6 per cent of the incident light reached the spectrograph.
The log intensity ratios are corrected for the amount of "third" element in the sample.
The working curves are based on the following spectrographic or chemical standards: JM AA, AB and AC series. BCS no. 151/l and 216, BAM 200,206 and 305. The coefficient of variation varies from 2 to 10 per cent, .and the relative error by three determinations is *lO per cent. The effect from the "third" element on the working curves has been found to be negligible in this method.
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The necessity for using appropriate evaluation methods in environmental chemical analysis is demonstrated in examples from the River Sajo ยดand the urban air of Miskolc. River Sajo ยดis a natural ecosystem, whereas the city of Miskolc is an artificial environment. Chemical analysis was performed on Ri
## Abstract This paper treats the importance of calibrating procedures and methods of chemical analysis against known reference materials, and gives examples of how even accredited laboratories return erroneous results, with particular reference to the determination of chloride and sodium in harden