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参照我国国标对海藻无机砷的测定方法及相关文献,摸索出一套适于复杂介质、高浓度干扰成分共存体系的测定方法——原子荧光光谱法测定海带提取物中的无机砷。主要研究内容为:优化酸度剂及还原剂的种类及用量;使用正辛醇为消泡剂对检测结果的影响;选择温和萃取无机砷的前处理条件,避免有机砷水解为无机砷。结论:标准曲线中标准物砷浓度测定范围在0~40 ng/m L;酸度剂为HCl,其在检测时浓度为5%;还原剂为硫脲-抗坏血酸,其在检测时浓度为5-5 g/L;不使用正辛醇;萃取无机砷的条件为5%HCl-石油醚(1:1)体系,在室温下萃取10 min。该法检出限为0.0823 ng/m L,变异系数(RSD)3.20%~3.70%,回收率91.29%~93.60%,达到产品检测所需的准确性。采用此法检测脱砷前后的海带提取物产品中无机砷含量,分别为10.3781 mg/kg及1.8507 mg/kg,后者达到国际标准对海带提取物中无机砷的含量要求。
Reference to China’s national standard method for the determination of seaweed inorganic arsenic and related literature, worked out a set of complex media for the interference of high concentrations of interfering components of the determination method - atomic fluorescence spectrometry for determination of inorganic arsenic in kelp extract. The main research contents are as follows: optimizing the types and amount of acidity and reducing agent; using octanol as antifoaming agent on the test results; selecting the pretreatment conditions of mild extraction of inorganic arsenic to avoid the hydrolysis of organic arsenic to inorganic arsenic. CONCLUSION: The standard curve for the determination of arsenic in the standard range of 0 ~ 40 ng / m L; acidity agent is HCl, which is detected at a concentration of 5%; the reducing agent is thiourea-ascorbic acid at a concentration of 5- 5 g / L; n-octanol was not used; the conditions for extracting inorganic arsenic were 5% HCl-petroleum ether (1: 1) system and extracted for 10 min at room temperature. The detection limit of the method was 0.0823 ng / m L, the coefficient of variation (RSD) was 3.20% -3.7% and the recovery rate was 91.29% ~ 93.60%, which met the accuracy of product testing. This method was used to detect inorganic arsenic contents of kelp extract products before and after arsenic removal, which were 10.3781 mg / kg and 1.8507 mg / kg, respectively. The latter reached the international standards for the content of inorganic arsenic in kelp extract.