Test strips for detecting electrolytes in urine contain a dye coupler or colour indicator and a buffer in volume-defined detection zones of the test strip. Detection zones for Mg ions are pref. impregnated with xylidyl blue and Good buffer (pH 11-12); those for Ca ions are impregnated with o-cresolphthalein and Good buffer (pH 10-11); those for phosphate are impregnated with ammonium molybdate and buffer (pH 1-3); those for Fe<2+> are impregnated with "Ferro Zine" and Good buffer (pH 4-6); those for K ions are impregnated with Kryptofix 222 and Good buffer (pH 8-10); and those for Na and Cl ions are impregnated with Mg uranyl acetate and buffer (pH 5-7).
