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目的建立在炉内直接消解的石墨炉原子吸收分光光度法测定速溶咖啡中铅的方法。方法样品用体积分数为0.5%的硝酸和质量分数0.2%的曲通X-100溶解,0.5%硝酸定容后再在超声波中处理5 min后直接进样,采用硝酸钯作基体改进剂,在283.3 nm波长下测定其吸光度,利用标准加入法求得工作曲线。结果工作曲线为A=0.00211C,相关系数为0.998,方法的线性范围0μg/L~62.5μg/L,加标12.5μg/L和25.0μg/L时其回收率分别为99.3%和89.8%,相对标准偏差分别为5.37%和3.99%;样品批处理检测其相对标准偏差在2.10%~3.88%。结论本法样品前处理简单,试剂耗费少,灵敏度高,准确度好,分析结果可靠,稳定性好,分析速度快,能满足食品卫生应急的需要。
Objective To establish a method for the determination of lead in instant coffee by graphite furnace atomic absorption spectrometry with direct digestion in the furnace. Methods The sample was dissolved with 0.5% HNO3 and 0.2% Triton X-100. After 0.5% nitric acid was fixed, the sample was directly treated with ultrasonic wave for 5 min. The sample was treated with palladium nitrate as matrix modifier. The absorbance was measured at 283.3 nm and the working curve was obtained using the standard addition method. Results The calibration curve was A = 0.00211C with a correlation coefficient of 0.998. The linear range of the method was 0μg / L ~ 62.5μg / L. The recoveries were 99.3% and 89.8% when spiked with 12.5μg / L and 25.0μg / The relative standard deviations were 5.37% and 3.99%, respectively. The relative standard deviations (RSDs) of samples were 2.10% ~ 3.88%. Conclusion The sample pretreatment is simple, less reagent consumption, high sensitivity, good accuracy, reliable analytical results, good stability, fast analysis, and can meet the needs of food hygiene emergency.