Study on the application of graphite tube in detecting plumbum and chromium in dairy products
To study the accuracy of lead and chromium detection in dairy products was improved by reasonable use of graphite tube.The mixed solution with chromium content of 0.03 mg/kg and lead content of 0.02 mg/kg was prepared,the lead and chromium items were determined by graphite furnace atomic absorption spectrometry.Reasonable aging graphite tubes were used to directly determine lead and chromium items in dairy products,and graphite tubes with chromium detec-tion were used to detect lead items,and the detection accuracy was evaluated by recovery rate and precision.The results showed that when the reasonable aging graphite tube was used to directly determine the lead content in dairy products,the sample recovery rate was 0.02 mg/kg,and the precision did not meet the requirement.When the reasonable aging graphite tube is used to determine the chromium in dairy products,the recovery rate and precision of chromium meet the require-ments of 60％-120％recovery rate and 20％precision.When the absorbance value of 30 ng/mL chromium standard working fluid is reduced to 0.31±0.1,the lead recovery rate and precision are in line with the lead project,and the determination of lead project can be continued several times.When using a reasonably aged graphite tube to determine lead and chromium in dairy products,the chromium item can be measured first,and when the performance of the graphite tube decreases to a certain extent,it is then used to detect lead.The accuracy can meet the requirements,which improves the service life of the graphite tube and greatly reduces the detection cost.
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