The sensitizing effect of polymeric surfactant poly(propylene oxide)-a-stearyldimethylammonium (PPOSA) chloride on the dibromogallein (BG) complex systems Mo(VI)-BG and W(VI)-BG was studied. The complex reaction conditions for these systems were optimized with simplex method. In a strong acidic medium, PPOSA forms ternary complexes with Mo(VI) or W(VI) and BG; the composition of both complex is 1:2:1 (metal:BG:PPOSA). The molar absorptivities of the complexes at the absorption max. 642 nm (Mo) and 618 nm (W) are 1.08 ?105 and 9.8 ?104 dm3 mol-1 cm-1, resp. The use of PPOSA and Triton X-100 increases the molar absorptivity of Mo(VI) complex to 1.25 ?105 dm3 mol-1 dm-1. The properties of the complexes were investigated by electrophoresis and other methods. Procedures for the detns. of Mo and/or W are proposed. For the simultaneous determination of Mo and W with BG and PPOSA, the multiwavelength linear regression method was recommended. Mo and W were determine in steels and alloys with satisfactory results.

Key words: SPECTROPHOTOMETRY, SURFACTANTS, POLYETHYLENE OXIDE, COLOR REACTION, MOLYBDENUM, MOLYBDENUM, BROMIDE, HIGHPOLYMER, TUNGSTEN, TUNGSTEN