Speciation analysis of organoarsenic compounds in livestock feed by microwave-assisted extraction and high performance liquid chromatography coupled to atomic fluorescence spectrometry

- Total As and phenylarsenic compounds are analyzed in feed samples.
- A microwave-assisted extraction method with 1.5 M H3PO4 is applied.
- The HPLC-UV/HG-AFS technique presents low-cost, simplicity, sensitivity and reproducibility.
- ASA compound is found in chicken feed samples studied.
- Unknown arsenic species are usually found in feed samples evaluated.

The development of a new method to determine the presence of the organoarsenic additives p-arsanilic acid (ASA), roxarsone (ROX) and nitarsone (NIT) in livestock feeds by high performance liquid chromatography coupled to ultraviolet oxidation hydride generation atomic fluorescence spectrometry (HPLC-UV/HG-AFS) after microwave assisted extraction (MAE) was proposed. Chromatographic separation was achieved on a C18 column with 2% acetic acid/methanol (96:4, v/v) as the mobile phase. The limits of detection (LODs) were 0.13, 0.09 and 0.08 mg L−1, and the limits of quantification (LOQs) were 0.44, 0.30 and 0.28 mg L−1. The relative standard deviations (RSDs) for ASA, ROX and NIT determined from five measurements of the mixed calibration standard were 3.3, 5.3, and 5.4%, respectively.MAE extraction of phenylated arsenic compounds using 1.5 M H3PO4 at 120 °C for 45 min allowed for maximum recoveries (%) of total arsenic (As) and organoarsenic species, with no degradation of these compounds. The extraction of total As was approximately 97%, and the As species recoveries were between 95.2 and 97.0%. The results of the analysis were validated using mass balance by comparing the sum of extracted As with the total concentration of As in the corresponding samples. The method was successfully applied to determine the presence of these compounds in feed samples. ASA was the only As species detected in chicken feed samples, with a concentration between 0.72 and 12.91 mg kg−1.