Perchloric acid hclo4

For chromatographic investigation, some plasma samples were deproteinated by mixing 1:1 with 2 m perchloric acid (HClO₄, Fisher Scientific, Pittsburgh, PA, USA), centrifuging for 5 min at 16,100 g to remove protein precipitate and neutralizing with 1.5 m potassium carbonate (Sigma‐Aldrich, St Louis, MO, USA).

Sediment samples were first pre-grinded, sieved through 2-mm sieves and homogenized. Sub-samples of 0.25 g were accurately weighed using an analytical balance, 10 mL of conc. Hydrofluoric acid (HF, 47–51%, Fisher Chemicals, Waltham, MA, USA, Trace Metal Grade) was added and the mixtures were left for 24 h. Subsequent dissolution was performed using a sand bath after adding an additional amount of 10 mL conc. HF (47–51%, Fisher Chemicals, Waltham, MA, USA, Trace Metal Grade) and 5 mL conc. Perchloric acid (HClO₄, 70% Fisher Chemicals, Waltham, MA, USA, Trace Metal Grade). The samples were heated until the acid mixture was reduced to 1/3 of the initial volume. Then portions of 10 mL conc. HF were added and heating in a sand bath was performed until complete dissolution of the sediments. Then two portions of 10 mL conc. Nitric acid (HNO₃, 67–69%, Fisher Chemicals, Waltham, MA, USA, Trace Metal Grade) were added and the samples were heated in a sand bath until the volume was reduced to 0.5–1 mL. After cooling, the samples were quantitatively transferred to 50 mL polyethylene tubes by repeated washing with double deionized water. All samples were initially diluted to 50 mL, and immediately before instrumental measurement, an additional dilution of 1 mL to 14 mL was performed.

Cerium(III) nitrate hexahydrate (Ce(NO₃)₃ × 6H₂O, Sigma-Aldrich, ACS Reagent, 99.99%), sodium hydroxide (NaOH, POCH, ACS reagent), ammonium phosphate dibasic ((NH₄)₂HPO₄, Sigma-Aldrich, ACS reagent, ≥ 98%), potassium bromide (KBr, Sigma-Aldrich, FT-IR grade, ≥ 99%), hydrochloric acid (HCl, Chempur, 38%), perchloric acid (HClO₄, Fisher Chemicals 60%) potassium indigotrisulfonate (Sigma Aldrich > 60%), tert-butyl alcohol (TBA, Sigma-Aldrich, ≥ 99.5%), benzoic acid (BA, Sigma-Aldrich ≥ 99.5%). All chemicals were used without further purification. Deionized water was used during synthesis. In ozonation and adsorption experiments high purity (Merck-Millipore) water was used.