| 摘要 |
The test strips used in chemical and medical practice for rapid analysis are based on a colorimetric principle, and their objective evaluation requires a special colorimeter. The finished products described here are based on the reversed titrimetric principle: glass tubes (or paper strips) contain, on a hydrophilic carrier, a sparingly soluble titrant which undergoes a colour change on reaction. On immersion, the rising solution uses up some of the titrant, resulting in a differently coloured zone whose sharp boundary directly indicates the concentration of the required substance. Reading off can be carried out immediately after the impregnation, which requires a few minutes; even during the subsequent hour. Because no chemical equipment is required, the method is suitable, in particular, for terrain analyses. The basic formulae are derived for the method and the designation "titrigraphy" is proposed. Examples which are described are tubes for determining: a) chlorides (in water or urine), containing silver chromate on a silica gel/polyamide carrier, b) iron(II), containing tris(laurylammonium) ferricyanide on polyamide, and c) zinc or cadmium, containing molybdenyl ferrocyanide on cellulose.
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