Speciation of chromium in edible animal oils after microwave extraction and liquid chromatography inductively coupled plasma mass spectrometry

• Speciation of Cr(III) and Cr(VI) in edible animal oils
• Microwave assisted extraction of Cr species using HF, TritonX-100, TBAP, EDTA
• Interference free measurements of Cr using DRC with NH3 reaction gas
• Method validation with NRCC SLRS-3 Riverine Water reference material
• A new Cr compound was found could be Cr complex with fatty acid.

Speciation of chromium has been carried out using reversed phase HPLC and ICP-MS in tandem. Isocratic elution using 0.5 mmol L− 1 tetrabutyl ammonium phosphate (TBAP) and 0.3 mmol L− 1 EDTA in 1% methanol (pH 6.9) as mobile phase separated Cr(III) and Cr(VI) in less than 110 s. Spectral interferences in ICP-MS at m/z 52 and 53 were reduced using NH3 in the DRC. Detection limits were 0.045 and 0.052 ng Cr mL− 1 for Cr(III) and Cr(VI), respectively. This method has been applied to determine Cr compounds present in selected edible animal oils and NRCC SLRS-3 Riverine Water reference material. The animal oils selected are used for different applications including cooking. Chromium species were extracted from oils using microwave heating with 0.4% v/v HF and 2% Triton X-100 in mobile phase. HPLC-ICP-MS results showed good agreement with total chromium concentrations in extracts obtained by ICP-MS analysis. An unknown chromium compound was found in all oil samples with the absence of Cr(VI).