Milli q integral 3

Pasteurized egg white was provided by Ovobest Eiprodukte GmbH & Co. KG (Neuenkirchen-Vörden, Germany). Whey protein isolate powder with a protein content of 94% was obtained from Davisco Foods International Inc. (Eden Prairie, MN, USA). Commercial sunflower oil was sourced from a local store (Bröckelmann + CO, Hamm, Germany). EtOH (99.95% purity) was obtained from VWR Chemicals (Leuven, Belgium). Hydrochloric acid and sodium hydroxide came from Merck KGaA (Darmstadt, Germany). Perchloric acid 60% to dissolve ions as well as sulfuric acid 0.4 mM and oxalic acid 2.3 mM as eluent for HPLC were purchased from Merck KGaA (Darmstadt, Germany). Sodium IC standard solution and potassium AAS standard solution came from Carl Roth GmbH (Karlsruhe, Germany) and calcium chloride dihydrate from Sigma-Aldrich (Saint Louis, MO, USA). All chemical agents were of analytical grade. Buffers and solutions were prepared with deionized water (Milli Q Integral 3, Merck KGaA, Darmstadt, Germany).

Fifty-three pesticide standards (high purity grade, >90%) were purchased from Dr. Ehrenstorfer GmbH. Acetonitrile (ACN, LC-MS grade), methanol (MeOH, LC-MS grade) for HPLC with 99.80% of purity, and formic acid (FA, ACS reagent) were from Merck (Merck, Singapore). ammonium formate (LC-MS grade, Sigma-Aldrich, Singapore) was also used for preparation of the mobile phase. Standard compounds were classified into 30 groups and used to prepare individual stock solutions around 1000 μg·mL⁻¹ in appropriate solvents such as acetone (GC-MS grade), methanol, n-hexane (GC-MS grade), acetonitrile, and ethanol (ACS reagent) in amber vials. The mixed standard solutions of all target analytes (10 μg·mL⁻¹) were prepared and diluted with acetonitrile. Stock standards were stored in the amber LC vial at 4°C. The working standard solutions were daily prepared by diluting the mixed standard solution in the mobile phase. The mobile phase was daily prepared by dissolving appropriate amount of ammonium formate in methanol/deionized water (Milli-Q Integral 3, Merck Millipore, France) containing 0.1% formic acid. The mobile phase was degassed in the ultrasonic bath (S 100H, Elma, Germany) to eliminate dissolved gas.

All chemicals used were of analytical grade
and used as received without any further purification. All solutions
were prepared with deionized water of resistivity not less than 18.2
MΩ cm from a Milli-Q Integral 3 (Merck Millipore, U.K.). Post-industrial
waste poly(lactic acid) (PI-PLA), from coffee machine pods, was purchased
from Gianeco (Turin, Italy). Hexaamineruthenium (III) chloride (RuHex,
98%), ferrocenemethanol (97%), potassium chloride (>99%), caffeine
(99%), sodium hydroxide (>98%), phosphate-buffered saline tablets
(pH = 7.4), hydrochloric acid, and poly(ethylene succinate) (PES,
MW: 10 000) were purchased from Merck (Gillingham, U.K.). Carbon
black (Super P, >99%) was purchased from Fisher Scientific (Loughborough,
U.K.). Heat-set inserts were purchased from McMaster-Carr (IL). The
commercial conductive PLA/carbon black filament (ProtoPasta, Vancouver,
Canada) was purchased from Farnell (Leeds, U.K.). Real samples of
Earl Grey Fine Tea (96% Black Tea) and Coffee Bags (100% Arabica Coffee)
were purchased from a local convenience store.

Ammonium sulfate (≥99.0%),
sodium chloride (≥99.5%), sodium sulfate (≥99%), potassium
chloride (≥99%), disodium hydrogen phosphate (≥99.0%),
sodium dihydrogen phosphate (≥99.0%), hydrogen peroxide solution
(30% w/w), sodium hydroxide solution (HPLC grade, 50.0%), and formic
acid (>98%) were purchased from Sigma-Aldrich (Bornem, Belgium).
Acetonitrile
(ACN, HPLC-MS grade) was purchased from VWR International (Shanghai,
China), and trypsin (porcine) was obtained from Promega (Mannheim,
Germany). Ultrapure water was produced in-house using a water purification
system (Milli-Q Integral 3, Merck/Millipore, Billerica).

Fmoc-amino acids were purchased from Merck Ltd. (Darmstadt, Germany). Fmoc-NH-SAL-MBHA resin (100–200 mesh); N,N-diisopropylethylamine (DIPEA); and trifluoroacetic acid (TFA) were purchased from Watanabe Chemical Industries Ltd. (Hiroshima, Japan). 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyl uronium hexafluorophosphate (HBTU) and 1-hydroxybenzotriazole (HOBt) were purchased from Kokusan Chemical Co., Ltd. (Tokyo, Japan). Triisopropylsilane (TIS) and xylenol orange were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). Hydrochloric acid (HCl); nitric acid; 1,2-ethanedithiol (EDT); CdCl₂·2.5H₂O; NiCl₂·6H₂O; MnSO₄·5H₂O; and tris(hydroxymethyl)aminomethane (Tris) were purchased from Nacalai Tesque Co. Ltd (Kyoto, Japan). ZnCl₂ and Multielement Standard Solution W-V were purchased from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). Water for the experiments was purified by Milli-Q Integral 3 (Merck Millipore, Darmstadt, Germany). Other solvents and reagents were obtained from commercial suppliers and used without further purification.