The Research Of Rapid Detective Method About Lead,Cadmium Ion In Contaminated Vegetables

In recent years, food safety issues are becoming increasingly serious, and the pollutional degree of heavy metal in vegetables is more serious. The traditional heavy metal detective methods need sample nitrified by strong acid; the acid need high temperature to evaporat, the cost time is generally about24h, and also need for expensive testing equipment,which can not meet the real-time monitoring of the vegetable samples.This study focused on lead and cadmium ions in pollutive vegetables. We developed rapid detective method by ion-selective electrode and rhodamine6G spectrophotometry, also selected representative samples, respectively, determined the sample pretreatment steps and the details of testing process.Ion selective electrode:(1) Sample preparation:5g of fresh sample was dried for20min under130℃, extracted with (1+11) hydrochloric acid for1hour, filter, adjusted the pH=3.0, at last the test solution was obtained.(2) Linear range: considering the maybe existed Pb, Cd ion concentrations (ug/mL) in the samples, lead has good linear relation in concentration range of0.1～5.0ug/mL and0.06～2.0ug/mL for cadmium, both of correlation coefficient were greater than0.99, also greater than the correlation coefficient (r=0.990) which is required by99%confidence level.(3) The electrode response time:2min.(4) The ionic strength reagent:potassium nitrate (0.1mol/L).(5) The buffer solution:potassium hydrogen phthalate buffer solution.Rhodamine6G spectrophotometry:(1) Sample preparation:5g of fresh sample was dried for20min under130℃. extracted with (1+11) nitric acid for1hour, filter, adjusted the pH=9.0. active carbon was added with twice (boiling), filter, adjusted the pH=5.0, at last the test solution was obtained.(2) Linear range:lead has good linear relation in concentration range of0.1～1.0ug/mL and0.01～0.1ug/mL for cadmium, both of correlation coefficient were greater than0.99. also greater than the correlation coefficient (r=0.990)which is required by99%confidence level.(3) Reaction time:5min.(4) stabilizer:3mL1%gelatin solution.(5) Masking agent: sodium citrate solution (0.1mol/L).(6) The buffer solution:Six subunits of four amine buffer solution.Compared to traditional detective methods, both methods could detect lead, cadmium ion in the cropland and vegetable market, obtained data with fast, steady reached the requirements of rapid detection.