Lc ms ammonium formate

Folin−Ciocalteu reagent was purchased from Kemika (Zagreb, Croatia); 2,2-diphenyl-1-picrylhydrazyl, catechin (CAS: 154–23–4, ≥99.0%), epicatechin (CAS: 490–46–0; ≥98%), gallic acid (CAS: 149–91–7, ≥97.5), p-cumaric acid (CAS: 501–98–4, ≥98.0%), phloretin (CAS: 60–82–2, ≥99.0%), phloridzin (CAS: 60–81–1, ≥98%), chlorogenic acid (CAS: 327–97–9, ≥95%) and caffeic acid (CAS: 331–39–5, ≥98.0%) were obtained from Sigma Chemical Co. (St. Louis, MO, USA). Methanol (HPLC grade) and orthophosphoric acid (85%) were obtained from Panareac (Barcelona, Spain). Certified standard of patulin and MycoSep^® 228 AflaPat columns were obtained from Romer Labs Biopure (Romer Labs, Tulln, Austria). Certified pesticide standard solutions were obtained from CPAchem (CPAchem, Stara Zagora, Bulgaria). LC-MS and HPLC grade acetonitrile was purchased from J.T. Baker (J.T. Baker, Deventer, The Netherlands), while LC-MS grade formic acid and LC-MS ammonium formate were produced by Sigma–Aldrich (Sigma-Aldrich, St. Louis, MO, USA). Ammonium hydroxide solution, ≥25% NH₃ in H₂O, was purchased from Honeywell (Offenbach, Germany). Nylon syringe filters, 0.2 µm pore size and 13 mm diameter, were obtained from Agilent (Santa Clara, CA, USA). Ultrapure water was generated by Niro VV system (Nirosta d.o.o., Osijek, Croatia).

Certified standards of mycotoxins were produced by Romer Labs Biopure (Romer Labs, Tulln, Austria), while certified pesticide and heavy metal standard solutions were obtained from CPAchem (CPAchem, Stara Zagora, Bulgaria). All standard solutions were stored according to manufacturer’s instructions and tempered to room temperature before use. LC-MS and HPLC grade acetonitrile and methanol were produced by J.T. Baker (J.T. Baker, Deventer, The Netherlands). LC-MS grade formic acid, LC-MS ammonium formate, nitric acid (65.0%) of trace analysis grade and hydrogen peroxide (30%) of extra purity were produced by Sigma–Aldrich (Sigma-Aldrich, St. Louis, MO, USA). Ultrapure water was generated by Niro VV system (Nirosta d.o.o., Osijek, Croatia). A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) buffer-salt mixture was produced by Agilent (Agilent Technologies, Santa Clara, CA, USA) and each portion consisted of 1 g trisodium citrate dihydrate, 1 g sodium chloride, 0.5 g disodium hydrogen citrate sesquihydrate, and 4 g of anhydrous magnesium sulfate. dSPE salt mixture was obtained from the same producer and consisted of 900 mg of anhydrous magnesium sulfate, 150 mg of primary secondary amine, and 150 mg graphitized carbon black.