The use of the first-derivative curves of absorption spectra in quantitative analysis

The first-derivative curves of u.v.—visible spectra (ΔE/Δλ ) are useful in quantitative analysis. A base-line technique and its algebraic version are reported for (i) the correction of quadratic irrelevant absorption, and (ii) the determination of a substance in the presence of another with overlapping spectra. The method is illustrated by the determination of atropine sulphate in the presence of phenyl-mercury(II) nitrate. The results obtained suggest that the method warrants careful study over a wide field of applications.