Determination of Co and Cr in wet animal feeds using direct solid sample analysis by HR-CS GF AAS

The present study proposes the determination of Cr and Co in wet animal feeds for employing direct solid sample analysis (SS) and high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For determination of Cr and Co, the analytical lines 357.8687 nm and 240.7254 nm were used, respectively. The pyrolysis temperatures were 1500 and 1400 °C and atomization temperatures were 2500 and 2400 °C for Cr and Co, respectively. The limits of quantification (LoQ) obtained for Cr was 0.03 μg g− 1 and 0.17 μg g− 1 for Co. The characteristic masses (m0) also obtained were 2.2 pg for Cr and 2.9 pg for Co. The accuracy of the proposed methods was performed by analysis of standard reference materials (SRM) of tomato leaves (NIST 1573), bovine muscle powder (NIST 8414) and apple leaves (NIST 1515) for Cr and bovine liver (NIST 1577b) for Co. The trueness obtained were between 102 ± 9 and 116 ± 7% for Cr and 94 ± 8% for Co for analyzed of the SRM. Precision, expressed as relative standard deviation (RSD), was better than 8.7% for Cr and 8.3% for Co (n = 5). Thirteen wet animal feed samples for dogs and cats were analyzed. The concentrations values found for Cr in the samples ranged from 0.17 ± 0.01 to 0.59 ± 0.06 μg g− 1 with an average of 0.36 ± 0.13 μg g− 1 (n = 13). On the other hand, the obtained concentrations for Co ranged between < 0.18 and 12.57 ± 1.11 μg g− 1, with an average of 5.92 ± 3.19 μg. The optimized analytical methods were simple, fast, efficient, precise and accurate for determination of Cr and Co in wet animal feeds for cats and dogs by HR-CS SS-GF AAS. Additional advantage of the method was no dissolution of the samples, no use of harmful reagents and consequently no generation of residues, besides the use of an effective analytical technique that allows optimization of fast and reliable screening procedures.