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目的建立微波消解-混合基体改进剂石墨炉原子吸收光谱法测定含明胶食品中总铬的方法。方法微波消解处理样品,通过试验确定不同基体改进剂时石墨炉的最佳仪器条件,并对比不同基体改进剂时样品的灵敏度和精密度,确立最优方案进行铬的测定。结果以2%磷酸二氢铵+2%抗坏血酸作为混合基体改进剂,能够使用较高的灰化温度和较低的原子化温度,标准曲线方程为A=1.51×10~(-2)C+4.37×10~(-3),r=0.997 2,方法线性范围为0μg/L~15.0μg/L,特征浓度为0.29μg/L,检出限为0.004mg/kg,加标回收率为90.0%~97.9%,相对标准偏差(RSD)小于5%。结论该法简单快速,灵敏度精密度高,可以有效去除基体干扰,改善吸收峰型,降低原子化温度延长石墨管工作寿命,能满足食品安全风险监测中大批量含明胶食品中铬监测要求。
OBJECTIVE To establish a method for determination of total chromium in gelatin-containing food by microwave digestion and mixed matrix modifier graphite furnace atomic absorption spectrometry. Methods Microwave digestion samples were processed to determine the best instrument conditions for graphite furnace with different matrix modifiers. The sensitivity and precision of samples were compared with different matrix modifiers to establish the optimal scheme for the determination of chromium. The results showed that using 2% ammonium dihydrogen phosphate and 2% ascorbic acid as a mixed matrix modifier, the higher ashing temperature and the lower atomization temperature could be used. The standard curve equation was A = 1.51 × 10 -2 C + 4.37 × 10 -3, r = 0.997 2. The linear range of the method was 0μg / L ~ 15.0μg / L, the characteristic concentration was 0.29μg / L, the detection limit was 0.004mg / kg and the recoveries were 90.0 % ~ 97.9%, relative standard deviation (RSD) less than 5%. Conclusion The method is simple, rapid and sensitive. It can effectively remove matrix interference, improve the absorption peak shape, reduce the atomization temperature and prolong the working life of graphite tube. It can meet the requirement of chromium monitoring in large quantities of gelatin-containing food in food safety risk monitoring.