New sample collection and dissolution tools for point-of-need analysis of Pb and Hg in fish tissues

The quantification of contaminants in indigenous food is a significant consideration for food safety and security. This is particularly critical for remote communities that rely on local agriculture, fishing, and hunting as their primary food supply. While point-of-need technologies have been proposed to facilitate on-site detection and quantification of contaminants, sample preparation steps remain mandatory for most contaminants, especially inorganic ones. This study presents innovations to facilitate sample preparation at the point-of-need. First, the repeatability and reproducibility of two biopsy punch tools used to sample fish tissues (fillets) are assessed and compared. The first punch tool is commercially available (69039; Hatfield, PA) while the second was custom made. They were both simple to use and their results showed limited variability for mass collection. Second, a new, portable, low-energy-consumption ultrasonic probe for the rapid dissolution (< 10 min) of fish tissues in tetramethyl ammonium hydroxide (TMAH) is presented. The dissolution rate, and Hg and Pb recovery rates in fish tissues are also reported and compared to those obtained with an ultrasonic bath. Finally, the analytical performances of both tools were validated on certified reference materials for mercury after analysis by GC-ICP-MS. These new tools will improve chemical sampling success even for inexperienced users at the point-of-need.