专利名称：Stabilized solutions of metal-specific
indicator dyes
发明人：WILDENHAYN REGINALD申请号：US11221461申请日：19610524公开号：US3159586A公开日：19641201
摘要：Stable solutions of metal specific indicator dyes are prepared by dissolving ametal specific indicator dye of the o-o1-diaryldiazo type in a polyhydric alcohol, or amixture of several polyhydric alcohols, with or without water. The polyhydric alcohol ispreferably a polyglycol, e.g. polyethylene or polypropylene glycol, and to avoid the useof a buffer a water soluble amino alcohol or a mixture of several of such alcohols isadded to the stabilized solution of the indicator dye in an amount which is 1-40% byvolume of the final solution. By adding this amount of amino alcohol, the pH of thesolution is maintained at 9-10,5. Amino alcohols mentioned are
tris(hydroxymethylamino)-methane; diisopropanolamine and triethanolamine. A smallamount of the magnesium or zinc complex salt of ethylenediamine tetraacetic acid(EDTA) may be added as well as an indifferent water-soluble yellow dye, e.g. methylorange, may be added to ensure a sharp colour change at the end point of titration. Inthe examples, stabilized indicator dye solutions are prepared in which the dye is
Eriochrome-black-T. The stabilized indicator dye solutions may be used to determine thealkaline earth metal content of a sample and the residual hardness in soft water.
申请人：GEBRUDER HEYL CHEMISCHE FABRIK K. G.
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