The liquid‐solid flotation separation behaviors of Cd2+ in ammonium sulfate‐potassium iodide‐cetylpyridine chloride‐water system and the conditions for the separation of Cd2+ from other metal ions were studied. The results showed that in the presence of 1.0 g (NH4)2SO4 and when the dosage of 0.1 M potassium iodide was 2.0 mL and 0.01 M cetylpyridine chloride (CPC) solution was 1.0 mL respectively, the formed water‐insoluble ternary association complex of KI‐CPC‐Cd floated above water phase and liquid‐solid phases were formed with clear interface. In this condition, Zn2+, Mn2+, Fe2+, Co2+, Ni2+ and Al3+ could not be floated and Cd2+ was floated quantitatively at pH 5.0. Therefore, the quantitative separation of Cd2+ from the above metal ions could be achieved. The quantitative flotation separation determination of Cd2+ in the sample of synthetic water and industrial waster water was performed, and the results agreed well with those by AAS method. The recoveries were 97.2%∼102.4%, and the RSD was 1.8%.

Fe3+ can react with penicillamine to form Fe2+, the amount of Fe2+ is directly proportional to the addition of penicillamine in system, and then Fe2+ reacted with the chromogenic reagent of phenanthroline to form a stable complex which its maximum absorption wavelength is 511nm. The content of penicillamine is determinated by measuring the absorbance of the stable orange red complex. The method for the indirect determination of penicillamine using Fe(II)-phenanthroline spectrophotometry has been established. The method is used to the determination of penicillamine in tablets, and the results are satisfactory.

The paper presents a novel method for the flotation separation of Zn2+ with ternary association complex system prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of NH4SCN and dodecyl trimethyl ammonium chloride (DTAC), various salts and acidity etc. on the flotation yield of Zn2+ have been investigated to select the experimental conditions. The possible flotation mechanism of Zn2+ was discussed. The results showed that by controlling pH 4.0, in the presence of 1.0 g NaBr, when the dosage of 0.1 molṁL−1 NH4SCN solution was 2.50 mL and 5.0 × 10−3 molṁL−1 DTAC solution was 2.00 mL respectively, the water‐insoluble ternary association complex of [Zn(SCN)4] (DTAC)2 which produced by Zn2+ and SCN−, DTAC cation (DTAC+) floated above water phase and liquid‐solid phases were formed with clear interface, while K+, Na+, Ca2+, Mg2+, Al3+, Fe2+, Mn2+, Cd2+, Co2+ and Ni2+ could not be floated, so Zn2+ was floated quantitatively at pH 4.0. Thereby, the quantitative separation of Zn2+ from the above metal ions could be achieved. A new method of determination of trace zinc by flotation separation was established. The proposed method has been successfully applied to the determination of Zn2+ in plating waster water, and the results agreed well with AAS method. The recoveries were 93.6%∼106.4%, and the RSD was 1.8%∼2.3%.

The paper presents a novel method for the flotation separation of Cu 2+ using microcrystalline adsorption system prior to the determination by spectrophotometry. could not be floated. Therefore, Cu 2+ was separated completely from the above metal ions. A new method of determination of trace copper by flotation separation was established. The proposed method has been successfully applied to the determination of Cu 2+ in plating waster water, and the results agreed well with AAS method. The recoveries were 93.3%~107.8%, and the RSD was 1.9%~2.1%.

An accurate and fast spectrophotometric method for the determination of acetylcysteine by silicomolybdenum blue has been established. The various effect factors on the determination of acetylcysteine by silicomolybdenum blue spectrophotometry are investigated in detail. The results show that under the optimum reaction conditions, SiO 3 2reacts with Mo 7 O 24 6to form silicon molybdenum heteropoly acid (H 4 Si(Mo 3 O 10 ) 4 ). Then H 4 Si(Mo 3 O 10 ) 4 is reduced by hydrosulfuryl (-SH) in acetylcysteine to form silicomolybdenum blue (H 4 Si(Mo 3 O 10 ) 2 (Mo 3 O 9 ) 2 ). The absorbance of silicomolybdenum blue is measured at the maximal absorption wavelength of 735 nm, and the content of acetylcysteine can be calculated based on this absorbance. A good linear relationship is obtained between the absorbance of silicomolybdenum blue and the concentration of acetylcysteine in the range of 5.040~25.20 mg·mL -1 . The linear regression equation is A = 0.0272 + 21.484C (mg·mL -1 ), with a linear correlation coefficient of 0.9995. This proposed method has been successfully applied to the determination of acetylcysteine in pharmaceutical samples, and the results agree well with those obtained by pharmacopoeial method.