Lc ms grade acetonitrile mecn

LC-MS grade acetonitrile (MeCN) and methanol (MeOH) were obtained from E. Merck (Darmstadt, Germany). LC-MS grade water were purchased from Sigma-Aldrich (St. Louis, MO, USA). Moreover, deionized water (0.07–0.09 µS cm⁻¹) was obtained by means of Hydrolab System (Gdansk, Poland) in our laboratory.
Solvents and reagents were also avoided to contact with plastic materials. Furthermore, the polypropylene material used for sample analysis and reagents (including QuEChERS) were checked previously for BPA contamination. All glassware was cleaned with methanol prior to the analysis. Moreover, quality control blanks were periodically prepared and analyzed. All solvents were checked for the presence of the target analytes before use.
Individual stock standard solutions were prepared in methanol and were stored in screw capped glass tubes at −4 ± 2 °C in the dark. A bisphenols standards mixture containing all the analytes was prepared by combining suitable aliquots of each individual standard stock solution and diluting them methanol and was stored at 4 ± 2 °C for up to one month. This mixture was used for the calibration preparation, as well as for fortification of the breast milk samples.

Fourteen reference standards of ginsenosides Rb1, Rb2, Rb3, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rh1, Rh2, F2, and 24(R)-pseudoginsenoside F11 (p-F11) were purchased from Star Ocean Ginseng Ltd. (Suzhou, China). The purities of the fourteen standards were no less than 98.0%. Their structures are shown in Figure 1. LC–MS-grade acetonitrile (MeCN) and water were supplied by Merck (Phillipsburg, NJ, USA). LC-grade methanol (MeOH) and formic acid (HCOOH) were purchased from Fisher Chemical (Pittsburgh, PA, USA). Water (for extraction) was obtained from a Milli-Q Ultra-pure water system (Millipore, Billerica, MA, USA). Other reagents used in this study were of analytical grade.

Thirteen reference standards of ginsenosides Rb1, Rb2, Rb3, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rh1, Rh2, and F2 were purchased from Star Ocean Ginseng Ltd. (Suzhou, Jiangsu, China). The purities of all reference standards were above 98.0%. HPLC-grade methanol (MeOH) and formic acid (HCOOH) were purchased from Fisher Chemical (Pittsburg, PA, USA). LC-MS-grade acetonitrile (MeCN) and water were obtained from Merck (Phillipsburg, NJ, USA). Water (for extraction) was obtained from a Milli-Q Ultra-pure water system (Millipore, Billerica, MA, USA). Other reagents used in this study were of analytical grade.