Rapid and Low Cost Determination of Total Mercury in Cat Foods by Photochemical Vapor Generation Coupled to Atomic Absorption Spectrometry

A rapid and low-cost method for determination of total mercury (THg) in cat food was developed based on photochemical vapor generation (PVG) coupled to cold vapor atomic absorption spectrometry (CVAAS). Cat food samples with ingredients based on tuna fish and other seafood were investigated. Organic acid precursor and concentration for radical generation and Hg photoreduction, sample UV irradiation time, and carrier gas flow were optimized. Highest PVG efficiency was achieved using 10% v v(-1)formic acid, 4-s UV irradiation time, and a carrier gas flow of 50 mL min(-1). The calibration function presented a correlation coefficient of 0.99. Accuracy was confirmed by analysis of Certified Reference Materials with recoveries of 93-110% and relative standard deviation lower than 6%. Under optimized conditions, a procedural detection limit of 0.28 mu g kg(-1)was obtained. Determination of THg in 10 samples of cat food purchased in local markets revealed a concentration range of 0.035-0.388 mg kg(-1). Highest concentrations were found in cat foods. Only one sample presented a concentration close to the regulatory limit of the European Commission Directive. Assuming the estimated daily food intake (EDI) calculated in a range of 0.0021 to 0.023 mg of THg per day per kg body weight, it is concluded that it remains below that considered lethal for cats. The methodology is efficient, simple, low cost, and fit for purpose.

Automated summary

A rapid and low-cost method for determination of total mercury in cat food was developed using photochemical vapor generation combined with cold vapor atomic absorption spectrometry. The method showed high efficiency and accuracy under optimized conditions, with good calibration function and confirmed accuracy through analysis of Certified Reference Materials. The concentration range of THg in cat food samples purchased in local markets was determined, showing highest concentrations in certain products but overall below lethal levels for cats. The methodology proved to be efficient, cost-effective, and fit for purpose.