SIMULTANEOUS DETERMINATION OF HEAVY-METAL S AT PPM LEVEL IN BOVINE LIVER BY AUTOMATED REVERSED-PHASE HPLC INVOLVING PRECOLUMN CHELATION WITH HEXAMETHYLENEDITHIOCARBAMATE AND ONLINE COLUMN ENRICHMENT

Various procedures for reversed-phase HPLC determination of Cd, Ni, Pb , Zn, Cu, Hg, Co, and Bi as their hexamethylenedithiocarbamate (HMDC) chelates have been automated. The optimum analytical conditions were i nvestigated for determination of the heavy metals in the standard refe rence material (Bovine Liver) of National Institute of Standards and T echnology (NIST). A 100 mg sample was ashed with nitric and perchloric acid, and the residual acids evaporated. The resulting residue was th en dissolved with diluted hydrochloric acid, and an aliquot of the sol ution was used for the HPLC analysis. The preparation of the standard solutions for calibration curves, chelation of metal ions, on-line enr ichment of the HMDC chelates on a Capcell C-18 mini-column (10 X 4.0 m m i.d.), separation of the chelates on a Cosmosil 5C(18)-MS analytical column (250 X 4.6 mm i.d.), and detection at 260 nm were all carried out with an optimum pretreatment program and a rime program. The analy tical results of Zn and Cu (Zn: 124 +/- 2, Cu: 156 +/- 3 mu g/g) were in good agreement with the certified values of NIST (Zn: 123 +/- 8, Cu : 158 +/- 7 mu g/g), and the precision of the present method was also good (about 2%).