Gas and liquid chromatography of metal chelates of pentamethylene dithiocarbamate

Capillary GC and HPLC of metal chelates of pentamethylene dithiocarbamate were examined. Copper(II), nickel(II), cobalt(III), iron(III), manganese(II) and chromium(III) chelates formed in slightly acidic media (pH 5) were extracted in methyl isobutyl ketone or chloroform. Capillary GC elution and separation was carried out on methylsilicone DB-1 column (25 m×0.2 mm I.D.) with film thickness 0.25 μm. Electron-capture detection was used. Elution was carried at initial column temperature 200 °C with an increment at a rate of 5 °C/min up to 250 °C and maximum temperature was maintained for 10 min. Symmetrical peaks with baseline separation were obtained with the metal chelates investigated with linear calibration range between 5 and 25 μg/ml for each metal ion and detection limits in the range of 0.5–6.0 μg/ml corresponding to 27–333 pg of metal ion reaching to the detector. HPLC separation was carried out from LiChrosorb ODS, 5 μm column and complexes eluted with methanol–water–1 mM sodium acetate (70:28:2, v/v) with a flow-rate of 1.2 ml/ml. UV detection was at 260 nm. The detection limits obtained were in the range 2–6 μg/ml. The methods were applied to the determination of metal ions in canal water and coal samples with RSD values within 4.15%. The results when compared with a standard flame atomic absorption spectrophotometric method and revealed no significant difference.