Speciation of Cr (III) and Cr (VI) Ions via Fabric Phase Sorptive Extraction for their Quantification via HPLC with UV Detection

Simultaneous extraction of the morpholino dithiocarbamate (MDTC) chelates of Cr(III) and Cr(VI) ion from aqueous samples was accomplished by applying fabric phase sorptive extraction (FPSE) using a cellulose fabric modified with a sol-gel/polytetrahydrofuran composite. Following extraction, the chelates were separated by HPLC on a reverse phase C18 column with acetonitrile:water (65:35; v/v) as the mobile phase and UV detection at 320 nm. A single peak is found for the Cr(MDTC)3 but two peaks are caused by Cr(VI) due to the formation of the complexes Cr(MDTC)2(OMDTC) and Cr(MDTC)3 (where OMDTC stands for oxy-MDTC). The limits of detection for the Cr(III) and Cr(VI) complexes are 0.001 and 0.003 ng∙mL‾1, respectively. The method can be used for the determination of chromium species in aqueous samples and displays high precision, sensitivity and reliability.