Suprapure 65 hno3

Sigma-Aldrich provided high purity grade nitric acid (Suprapure 65% HNO₃), calcium disodium ethylene-diaminetetraacetate hydrate (EDTA-Ca-Na₂), pepsin from porcine stomach mucosa (P-7000), pancreatin from porcine pancreas (P-1750), and bile extract porcine (B-6831) (St Louis, MO, USA). The National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA, provided stock solutions of Se (SRM3149), CRM SRM1566b (oyster tissue), and Rh (Rh SRM3144). In addition, this study made use of CRM from the National Metrology Institute of Japan (NMIJ7402-a, codfish tissue). Merck provided potassium hydroxide (KOH, 105033), sodium bicarbonate (NaHCO₃), and dialysis membrane (molecular weight cut-off 12–14 KDa, 13 mm internal diameter) (KGaA, Darmstadt, Germany). Medicell Membranes Ltd. provided flat dialysis membranes (MWCO 12–14 kDa, 15.9 mm wide) (Greenwich, London). In the study, deionized water from Milli-Q^® water (Millipore Sigma, Burlington, MA, USA) was employed.

The high purity grade nitric acid (Suprapure 65% HNO₃) was obtained from Sigma–Aldrich (St Louis, MO, USA). Stock solutions of Se (Se SRM3149), Rh (Rh SRM3144), and certified reference material (CRM) SRM1566b (oyster tissue) were obtained from the National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA. Another CRM was NMIJ7402-a (codfish tissue) obtained from the National Metrology Institute of Japan (NMIJ). Milli-Q^® water (Millipore Sigma, MA, USA) was used throughout the study.