Acs reag ph eur

Acetonitrile was of HPLC grade and was purchased from Sigma (Milano, Italy). Orthophosphoric acid (ACS ISO, for analysis, 85%) and ethanol (ACS-Reag. Ph.Eur.) were purchased from Carlo Erba Reagents S.r.l. (Milano, Italy). Water was distilled and filtered through a Milli-Q apparatus (Millipore, Milan, Italy). Standards of malvidin-3-O-glucoside, cyanidin, ascorbic acid, chlorogenic acid, α-solanine and α-chaconine were purchased from Sigma (Milano, Italy). C18 SPE columns (500 mg 3 mL, Supelco, Bellefonte, PA, USA) were used.

For the analysis of the finished dosage forms, a pH 5.6 buffer solution was prepared with 0.1 M sodium acetate (ACS Reag. Ph Eur, Merck, Darmstadt, Germany) adjusted to pH with acetic acid (glacial 100%, ACS.ISO reag. Ph Eur, Merck, Darmstadt, Germany). Methanol (LiChrosolv^®, Merck, Darmstadt, Germany) was used as solvent and eluent for the LC separations. Triethylamine (Sigma-Aldrich, Taufkirchen, Germany) and formic acid (98–100%, ACS Reag. Ph Eur, Merck, Darmstadt, Germany) were added to the mobile phases for the LC analysis. Water was prepared in house with a Milli-Q system (Millipore, Bedford, MA, USA). Acetonitrile (LiChrosolv^®, Merck, Darmstadt, Germany) was used as mobile phase for the LC analysis.
Pravastatin 1,1,3,3-tetramethyl amine (European Pharmacopoeia reference standard catalogue code Y0000201, batch 2) was used as a reference compound. Pravastatin sodium salt hydrate for NMR studies was purchased from Sigma-Aldrich (Germany, P4498).
Simvastatin (Ph. Eur. Reference standard CRS) and dihydroSimvastatin (impurity K, Ph. Eur. Reference standard CRS) were obtained from the European Directorate for the Quality of Medicines & Health Care (edqm).
Deuterated methanol (Cambridge Isotope Laboratories, Andover, MA, USA) was used as a solvent for the NMR analysis.