Precolumn Derivatization-HPLC Analysis Method For Heavy Metal Mercury Ion And Its Application

Analytical methods for lead,zinc,cadmium and copper in heavy metals are Atomic Fluorescence Spectrometry?AFS?,Atomic Absorption Spectroscopy?AAS?,Inductively coupledplasma mass spectrometry?ICP-MS?,High Performance Liquid Chromatograghy?HPLC?.Due to the high sensitivity of HPLC,enriched analysis of complex components,high analytical efficiency,the reaction of RP-HPLC in the analysis of heavy metals has been widely used.This article compares two methods for the analysis of Hg²⁺by precolumn derivatization reagents sodium diethyldithiocarbamate?NaDDTC?and 4.6-2 methyldithiopyrimidine?DMMP?.Respectively,the pH at the time of derivatization,the bath temperature,the bath time,and the stability of the metal complexes.The chromatographic mobile phase pH,ion pair reagent concentration,and organic solvent ratio were examined.In the former method,sodium pentanesulfonate was used as the ion pair reagent,and the derivatization conditions were as follows:pH=9.0?NH₄Cl-NH₃H₂0?,the bath temperature was 25°C,the reaction time was 20 min,and the chromatographic conditions were:Thermo Hypersil GOLD chromatographic column C₁₈?5?m,150×4.6 mm?;chromatographic conditions:mobile phase methanol/water=?V/V 76:24?,containing 10.0 mmol/L sodium pentanesulfonate,injection volume 20?l,flow rate At 1.50mL/min,column temperature 33°C,the maximum absorption wavelength of the metal complex Hg-DDTC is 254 nm.After derivatization,the stability of Hg-DDTC is better within 3 h.The analysis of Hg-DDTC showed a good linear relationship,with a regression coefficient R²>0.99,RSD<5%,and a detection limit of 0.09-32.4?g/L.In the other method,DMMP was used as the derivatization reagent.The derivatization conditions were:pH=6.0,?CH₃COOH-CH₃COONa?,water bath temperature 25°C,reaction time 25 min,chromatographic conditions:Thermo Hypersil GOLD column C₁₈?5?m,150×4.6mm?.Mobile phase methanol/water?V/V 60:40?,flow rate:1.00mL/min,column temperature 33°C,injection volume 20?l.The maximum absorption wavelength of Hg-DMMP,a metal complex formed between Hg²+and DMMP,was 270 nm,and the stability was good within 6 h.The linear relationship was good.The regression coefficient was R²>0.99,RSD<5%.The detection limit of the method was0.08-2.11 ug/L.After comparison,the results showed that the effect of DMMP as a derivatizing agent was better.In order to reduce magazine interference,enrich target analytes,and increase sensitivity,heavy metal analysis often requires sample pretreatment.In terms of heavy metal detection,the most commonly used pretreatment methods are dry and wet ashing and solid phase extraction.In this thesis,the two pretreatment methods were established.The effect of solution pH on the recovery of ion-exchange SPE and the difference in spike recovery were investigated.The results showed that the use of strong cation exchange column,the pH value of the active solution when the pH=5.0,Hg²⁺ion exchange SPE method has a higher recovery rate.