In acidic solution, a stable purple complex of strontium was formed with a new photometric reagent, 2-(4'-chloro-2'-phosphonazo)-7-(2',6'-dibromo-4'-chlorophenylazo)-1,8-di hydroxy-3,6-naphthalenedisulfonic acid (DBC-CPA). This complex exhibits absorption max. at 630 nm with apparent molar absorptivity of 6.3 ?104 L mol-1 cm-1. The Sr/DBC-CPA ratio of this complex is 1:2. In the presence of acetone, Na2SO4, and EDTA and with the absorbance determine by the dual-wavelength, there is no interference by the presence of large amts. of barium, calcium, iron, magnesium, and a no. of other ions. A method has been developed for the determination of strontium in seawater, magnesium oxide, and silicon-iron alloy with satisfactory results.

Key words: SPECTROPHOTOMETRY, ORGANO BROMINE COMPOUNDS, STRONTIUM, SEA WATER, COLOR REACTION, ORGANO CHLORIDE COMPOUNDS, MAGNESIUM OXIDE, CHLOROPHOSPHONAZO, SILICON CONTAINING ALLOYS, IRON ALLOYS