Ammonium acetate nh 4 ch 3 co 2

Individual certified standards of ARs and PhACs (purity 95.19% to 99.9%) were acquired from Dr. Ehrenstorfer (Augsburg, Germany), Sigma-Aldrich (Augsburg, Germany) and European Pharmacopoeia Reference Standards (Strasbourg, France). Atrazine-d5, Carbendazim-d3, Coumachlor, Cyromazine-d4, Linuron-d3 and Pirimicarb-d6 (Dr. Ehrenstorfer and Sigma-Aldrich, 99.3–99.9% purity) were used as procedural internal standards (P-IS) and were maintained as described in the reference method [41 (link)]. These internal standards were added to the samples at the beginning of the procedure to account for various sources of errors throughout all stages in the method [58 ]. The list of the selected analytes, their classification, and their legal status are in Table 1.
LC-MS grade methanol (MeOH), acetonitrile (ACN) and formic acid (FA, HCOOH) were obtained from Honeywell (Morristown, NJ, USA). Ammonium acetate (NH₄CH₃CO₂) was purchased from Fisher Scientific (Loughborough, UK). AOAC method QuEChERS salts [59 (link)] (6 g of MgSO₄ and 1.5 g of CH₃COONa) were acquired in commercial premixes from Agilent Technologies (Palo Alto, CA, USA). The ultrapure water was produced in the laboratory using a Gradient A10 Milli-Q System (Millipore, Bedfore, MA, USA).