Study On The Detection Technology Of Heavy Metals In Concentrated Apple Juice

Recently,concentrated juice industry is developing rapidly in China,The exports of concentrated juice in China surged to about 700,000 tons in 2018.With the increasing concern of the food safety,domestic and abroad,the content of metallic elements in apples will be more strictly demand.The limit standards of indexes affecting the safety of fruit juice such as heavy metal pollution is increasingly high.The detection of heavy metals has guiding significance for enterprises to monitor the content of heavy metals in juice.This paper studied the detecing methods of the content of heavy metallic elements by atomic absorption specrometry.Because of the national standard heavy metal detection method can not meet the requirements of heavy metal detection accuracy in concentrated apple juice.In the experiment,optimized design of instrument and reagent condition,by repeatedly test,analysis of test results under different conditions than differences,eliminate various interference factors in the process of test,and then by standard addition recovery test verifies the repeatability and accuracy of test results,the relevant parameters of experiments is to choose the best,and finally establish standard curve equation of linear regression.Finally,a method for the detection of heavy metal elements in concentrated juice with good accuracy,simple operation and fast was established.The conclusions of this paper were turned out as follows:?1?In the sample pre-treatment stage,all the glassware and microwave digestion tanks used shall be soaked with 10%HNO₃ solution for more than 24 hours,and then washed and dried with deionized water before use.This operation can effectively avoid the introduction of external interference and reduce the impact of pollution on the detection results.?2?Pb in apple juice concentrate was determined by Graphite Furnace atomic absorption spectrometry.The experimental results showed that the optimum determination conditions of Pb was found as follows:the pyrolysis temperature was 600?;the atomization temperature was 1800?;the clean temperature was 2000?.Linear range:0-25?g/L,the correlation coefficient was 0.9986;the recovery was 95.00%-104.50%and the precision test RSD was 1.7%-5.0%;the repeatability test RSD was 1.4%-2.9%.The detection limit at 11.5 Brix was 0.01 mg/kg.?3?As in apple juice concentrate was determined by hydride generation-atomic absorption spectrometry.The experimental results showed that the optimum determination conditions was found as follows:the lighting mode was bgc-d₂;the solution concentration of sodium borohydride was 0.4%;the solution concentration of hydrochloric acid was 5mol/L;the carrier velocity was 6-7 mL/min.Linear range:0-25?g/kg,the correlation coefficient was 0.9995;the recovery was 88.80%-95.80%and the precision test RSD was1.4%-2.8%;he repeatability test RSD was 2.8%-5.9%.The detection limit at 11.5 Brix was 0.008 mg/kg.?4?Cu in apple juice concentrate was determined by flame atomic absorption spectrometry.The experimental results showed that the optimum determination conditions of Cu was found as follows:linear range:0-2.5 mg/kg,the correlation coefficient was 0.9998;the recovery was 98.65%-106.00%and the precision test RSD was 0.6%-4.1%;he repeatability test RSD was 1.5%-4.2%.The detection limit at 11.5 Brix was 0.01 mg/kg.