The water was ultrapure water obtained from a Milli-Q-system (Millipore Corporation, Bedford, MA, USA) and nitric acid (68 – 70%), hydrochloric acid (30%), ammonium carbonate (powder), hydrogen peroxide (30%) and formic acid (98%) were all from J. T. Baker (Deventer, Netherlands). In the arsenic speciation analysis arsenobetaine (AB) (Fluka Analytical, Italy), arsenic(III)oxide (As(III)) (Aldrich Chemistry, USA), dimethyl arsenic acid (DMA) (Chem Service, USA), monomethyl arsenic acid disodium salt (MMA) (Argus Chemicals, Italy) and arsenic(V) (As(V)) standard solution (Merck, Germany) were used.
nitric acid
68 – 70%
%
hydrochloric acid
30%
%
hydrogen peroxide
30%
%
formic acid
98%
%