光度法测定小麦粉中过氧化苯甲酰研究

Spectrophotometric Determination of Flour Benzoyl Peroxide

基于过氧化苯甲酰的氧化性,将Fe2+氧化成Fe3+,生成的Fe3+与硫氰酸盐在酸性乙醇介质中发生显色反应,建立小麦粉违禁添加剂过氧化苯甲酰检测新方法。对该方法进行试验条件研究,包括光谱吸收曲线、反应介质、酸含量、反应温度、反应时间、Fe2+浓度、KSCN浓度、共存干扰物质等因素对检测结果的影响。最佳试验条件下,过氧化苯甲酰线性范围0.1～15 mg/L,相关系数R2=0.999 4,505 nm处表观摩尔吸光系数ε=2.136 5×104L.mol-1.cm-1,检出限0.025 mg/L。利用该方法对市售小麦粉样品进行测定,回收率在97.2%～104.4%之间。

A new method for benzoyl peroxide detection was proposed. It was based on the principle that benzoyl peroxide oxidize ferrous iron to ferric ion, then color reaction between ferric ion and thiocyanate in ethanol and acid system can be quantified. Experimental conditions of the benzoyl peroxide detection method including absorption curve, reaction medium, acid content, reaction temperature, reaction time, ferrous iron content, thiocyanate contentand interfering substances were studied in the research. Under the optimum conditions, the linear range of benzoyl peroxide concentration was 0.1 - 15 mg/L, with a correlation coefficient （ R2 ） of 0.999 4 and a lower detection limit of 0. 025 mg/L. The apparent molar adsorptivity of the coordination complex was 2.136 5×10^4L·mol-1·cm^-1 The recovery was at the range of 97.2% to 104.4% by this method to detect commercial flour samples.