4.1. Materials

1,4-Dioxane, 3,3′,5,5′-tetramethylbenzidine, acetonitrile, ammonia, polyethylene-sorbitan monolaurate (Tween20), sodium hydrogen carbonate, tris-HCl, tris(hydroxymethyl)-aminomethane, and dialysis membranes (regenerated cellulose, molecular weight cutoff < 3.5 kDa) were obtained from Carl Roth GmbH & Co. KG, Karlsruhe, Germany. Sodium chloride and tert-butanol were purchased from VWR International GmbH, Darmstadt, Germany. Bovine α-lactalbumin (α-LA) as model protein, benzyl isothiocyanate (98%), citric acid monohydrate, dioctyl sulfosuccinate sodium salt, dithiothreitol (DTT), fluorescamine, hydrogen peroxide, and trypsin from porcine pancreas were purchased from Sigma-Aldrich GmbH, Steinheim, Germany. The polyclonal primary antibodies were raised in rabbit against bovine α-LA with a concentration of 1g/L and obtained from antibodies-online GmbH, Aachen, Germany. A polyclonal goat anti-rabbit antibody, conjugated to HRP, was used as secondary antibody (Dako GmbH, Glostrup, Denmark). The concentration of the purified antibodies was 0.25 g/L. Ethanol, formic acid, hydrochloric acid, pyridine, urea, and HPTLC silica gel 60 were purchased from Merck KGaA, Darmstadt, Germany. The stationary phase materials were glass-backed and had a size of 10 × 20 cm. C₁₈ solid phase extraction cartridges (1 mL, 100 mg) were purchased from Macherey-Nagel GmbH & Co. KG, Düren, Germany. All solvents were of HPLC grade, otherwise, ACS grade was used. Water was double distilled (ddH2O).