A new indicator for calcium, 2-hvdroxy-l-(2-hydroxy-4sulfo-l-naphthylazo)-3-naphthoic acid, has been synthesized which permits an accurate titration of calcium in the presence of magnesium with (ethylenedinitrilo) tetraacetate.The indicator produces a sharp, stable color change from wine red to pure blue. Calcium and magnesium separations are not necessary. Titration procedures for the determination of calcium and magnesium in water, limestone, salt, and boiler scale are described. The usual ammonia-ammonium chloride buffer is replaced by an odorless monoethanolaminehydrochloric acid buffer containing complexed magnesium.Through the synthesis of a new indicator, the authors have made possible a direct titration of calcium in the presence of magnesium. The new indicator produces a sharp color change from wine red to pure blue when calcium is titrated with (ethylenedinitrilo) tetraacetate at pH values between 12 and 14.Accurate determinations of calcium with no interference from magnesium have been made on a variety of samples including water, limestone, salt, blood serum, milk, and urine. Calcium and magnesium separations were not necessary.
for the separation of hydrocarbon mixtures. Samples from 2 to 20 ml. were fractionated. The order of displacement was paraffins, monocycloparaffins, and aromatics. Binary mixtures of paraffins and cycloparaffins were separated, and paraffin and cycloparaffin fractions of purity higher than 99% were recovered from naphtha. There was a definite tendency for the separation of mono-and dicycloparaffins, a fraction containing 76% dicycloparaffins having been obtained from a California naphtha distillate. This technique should prove useful to component analysis, and to the preparation of fractions for spectrometer calibration in hydrocarbon type analysis. LITERATURE CITED
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