Simultaneous Determination of Arsenic, Cadmium, Calcium, Chromium, Cobalt, Copper, Iron, Lead, Magnesium, Manganese, Molybdenum, Nickel, Selenium, and Zinc in Fertilizers by Microwave Acid Digestion and Argon Inductively Coupled Plasma-Optical Emission Spectrometry Detection: Single-Laboratory Validation, First Action 2017.02.

A single-laboratory validation method for the simultaneous determination of nutrient and non-nutrient metals in commercial fertilizers was reviewed by the AOAC Expert Review Panel (ERP) and Stakeholder Panel for Fertilizers at the 2017 midyear AOAC INTERNATIONAL meeting. In addition to using 15 of the original 30 fertilizer materials from the previous Method 2006.03 collaborative study, NIST Standard Certified Reference Material 695 and Magruder check sample 2009-06 were also incorporated as accuracy, recovery, and repeatability materials. Method 2017.02 is suitable for the simultaneous determination of arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, and zinc in all major types of commercial fertilizer products by microwave digestion and inductively coupled plasma-optical emission spectroscopy analysis. With recoveries ranging from 92.8 to 103.2% for analytes above the LOQs, improved RSDs, and enhanced efficiency as compared with the previous method, Method 2006.03, the ERP recommended this method for First Action Official MethodsSM Status.