Determination of Lead, Cadmium, Chromium, Arsenic, Copper and Nickel in Biogas Residues by Inductively Coupled Plasma Mass Spectrometry (Draft for Comments)

This standard applies to solid or semi-solid biogas residues produced through anaerobic digestion and solid-liquid separation of livestock and poultry manure, crop straw, organic waste from agricultural product processing, and similar feedstocks. It specifies acid microwave digestion and inductively coupled plasma mass spectrometry for determining lead, cadmium, chromium, arsenic, mercury, copper and nickel, for process monitoring, agricultural-use safety assessment, quality supervision and commissioned testing. Samples shall be properly collected, stored, reduced, freeze-dried, ground and sieved, while avoiding contamination from metal tools. Results shall generally be expressed on a dry basis; wet-basis results shall be converted as specified where needed. Laboratories shall implement safeguards for strong acids, oxidants, microwave digestion and heavy-metal exposure, and separately collect heavy-metal-containing liquids and wastes for disposal by qualified entities.