Formic acid ulc ms grade

Ammonium hydroxide solution (28% NH₃ in H₂O, ≥99.99% purity), ammonium bicarbonate (99–101% purity) and sodium chloride were purchased from Sigma-Aldrich (St Louis, MO, USA). HiPerSolv CHROMANORM for LC-MS acetonitrile (≥99.9% purity) was obtained from VWR Chemicals (Lutterworth, UK), and LiChrosolv hypergrade for LC-MS methanol and chloroform were obtained from Merck (Darmstadt, Germany). ULC/MS grade formic acid (≥99% purity) and ammonium acetate (≥99% purity) were obtained from Biosolve (Valkenswaard, The Netherlands). Ultrapure water was obtained from a water purification unit (Millipore). High glucose Dulbecco’s Modified Eagle Medium (D-MEM), penicillin–streptomycin, dialyzed fetal bovine serum (FBS), l-glutamine, and non-essential amino acids were purchased from Thermo Fisher, Life Technologies (Bleiswijk, the Netherlands).

HPLC grade Methanol was purchased from Finar Ltd. India; LC/MS grade Acetonitrile by Fisher Chemicals. Ascorbic acid, Gallic acid, vanillic acid, Syringic acid Ellagic acid was supplied by (TCI India) chemical Pvt. Ltd. and Quercetin by MP Biomedicals LLP, Germany. ULC/MS grade formic acid was supplied by Biosolve B.V., Netherlands. Ethanol was supplied by Merck. The HPLC analysis was carried out using Shimadzu Prominence UFLC system (Shimadzu, Kyoto, Japan) equipped with LC-20AD and LC-20AT prominence liquid chromatography pumps, DGU-20A3 prominence degasser, CBM-20A prominence communications bus module, SPD-20A prominence UV/VIS detector. LC-MS/MS experiments were performed in LTQ XL™ Linear Ion Trap Mass Spectrometer.

Acetonitrile and methanol HPLC grade (≥99.9%) were purchased from Fisher scientific (Merelbeke, Belgium). Trifluoroacetic acid HPLC grade was purchased from Fisher scientific (Loughborough, UK). C₁₈ grafted silica for flash high throughput purification was purchased from Supelco (Bellefonte, PA, USA, batch SP98226). Fontainebleau sand, hydrochloric acid 37%, hydrogen peroxide 30% and sodium sulfite were purchased from VWR Chemicals (Leuven, Belgium). Formic acid ULC/MS grade (99%) was purchased from Biosolve (Valkenswaard, The Netherlands). Sodium hypochlorite 9.6% was purchased from Notilia (Nîmes, France). Sepia officinalis eumelanin was purchased from Sigma-Aldrich (Burlington, MA, USA, batch #103H1023). Ultrapure water (0.055 μS/cm) was obtained by pre-filtration and reverse osmosis system (Labostar Pro TWF, Evoqua water technologies, Pittsburgh, PA, USA). Xanthurenic acid was purchased from Interchim (Montluçon, France, batch V0226P002).