磷酸盐和硅酸盐的测定一般都用分光光度法中的钼黄法和钼蓝法。钼黄法相当稳定,但灵敏度低;钼蓝法的灵敏度虽有所提高,但这些有色配合物的摩尔吸光系数都未超过1×10~4。近年来用结晶紫—杂多酸分光光度法同时测定磷、硅和砷,然而砷和硅的含量只能用减差法求出,误差较大。由于地表水中含磷、硅较多而含砷较 The determination of phosphate and silicate are generally spectrophotometric molybdenum yellow method and molybdenum blue method. Molybdenum yellow method is quite stable, but its sensitivity is low. Although the sensitivity of molybdenum blue method is improved, the molar absorptivity of these colored complexes does not exceed 1 × 10 ~ 4. In recent years, crystal violet - heteropoly acid spectrophotometry simultaneous determination of phosphorus, silicon and arsenic, but the content of arsenic and silicon can only be calculated by the subtraction method, the error is large. As the surface water contains phosphorus, silicon and more arsenic than