Milli q integral 10 system

All reagents were of analytical grade. Ultra-pure water (resistivity > 18.2 MΩ cm) was obtained from a Milli-Q® INTEGRAL 10 system (Millipore, MA, United States). Nitric acid (Vetec, Rio de Janeiro, Brazil) was purified by sub-boiling followed by distillation in a quartz still (Kürner Analysentechnik, Rosenheim, Germany). The multi-element standard solution Merck IV (Merck, São Paulo, Brazil), comprising 29 elements in diluted Nitric acid, was employed to prepare standard analytical curves. Two reference materials, certified Skimmed Milk Powder ERM®-BD150 (European Commission, Belgium) and Milk Powder 1549 (NIST SRM, United States) were used to assess method accuracy.

All reagents were of analytical grade. Ultra-pure water (resistivity > 18.2 MΩ cm) was obtained from a Milli-Q^® INTEGRAL 10 system (Millipore Co., Billerica, MA, USA). Nitric acid (Vetec, RJ, BRA) was purified by sub-boiling followed by distillation in a quartz still (Kürner Analysentechnik, ROS, DEU). A multi-element standard solution Merck IV (Merck, SP, BRA), comprising 29 elements diluted in Nitric acid, was employed to construct the calibration curves.

Standard solutions and reagents were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). All solvents, including methanol (MeOH), ethanol and acetonitrile with HPLC grade were purchased from Tedia Company Inc. (Rio de Janeiro, RJ, BRA). Agar yeast, extract glucose, chloramphenicol (YGC) and agar glucose and yeast extract were purchased from Hexis Científica (São Paulo, SP, BRA). Agar Man, Rogosa and Sharpe (MRS) was purchased from Acumedia (Lansing, MI, USA); 3M PetrifilmTM Salmonella Express Sy and 3M PetrifilmTM E. coli Count Plate were purchased from 3M Health Care (São Paulo, SP, BRA). All reagents were analytical grade. Nitric acid (Vetec, Rio de Janeiro, RJ, BRA) was purified by sub-boiling followed by distillation in a quartz still (Kürner Analysentechnik, Rosenheim, BY, DEU). The multi-element standard solution Merck IV (Merck, São Paulo, SP, BRA) comprising 29 elements in Nitric acid was employed to prepare standard analytical curves. Two reference materials, certified Skimmed Milk Powder ERM^®-BD150 and Milk Powder 1549 were used to assess method accuracy (St. Louis, MO, USA). Ultra-pure water (resistivity > 18.2 MΩ cm) obtained from a Milli-Q^® INTEGRAL 10 system (Millipore, Burlington MA, USA) was used to prepare all reagents.

The following compounds used for preparing extracts by targeted analysis of phenolic compounds and eluents were obtained commercially: resorcinol (Fluka, Germany), methanol (HPLC grade, VWR BDH Chemicals, Poole, United Kingdom), tetrahydrofuran (HPLC grade, VWR BDH Chemicals, Poole, United Kingdom), formic acid (Merck KGaA, Darmstadt, Germany), and orthophosphoric acid (85%, VWR BDH Chemicals, Poole, United Kingdom). Water used for extract and eluent preparation was purified by a Milli-Q Integral 10 system (Millipore, MA, United States).

HPLC grade acetonitrile (ACN, Sigma–Aldrich) was used in all UPLC mobile phases. All water used in these experiments was 18 MΩ water generated from an in-house system (Millipore Milli-Q Integral 10 system). UPLC vials were ‘Total Recovery’ 1 ml vials (Waters). 100 mM trieythl ammonium acetate (TEAA) was made by dilution of a commercial 2 M stock solution (Transgenomic). 100 mM tetraethyl ammonium bicarbonate (TEAB) was prepared by dilution of a 2 M TEAB stock. The 2 M TEAB was prepared by the drop wise addition of 278 ml of triethylamine to 700 ml of water while simultaneously bubbling carbon dioxide through the solution. The stock 2 M TEAB solution is stored at 4°C.