Determination and speciation of inorganic As in homeopathic medicines by HG-ICP OES method with no or minimal sample treatment before measurements

Abstract

The analysis of homeopathic medicines for the content of total inorganic As by hydride generation (HG) hyphenated with the ICP OES detection was presented. Various forms of medicaments (sugar pellets, tablets, alcohol-based drops), containing Arsenicum album or Arsenicum iodatum in several potencies (C9–200, D6–10), as well as different sample preparation approaches (wet digestion, extraction, dissolution, dilution, direct analysis) before spectrometric measurements were studied. The influence of the undecomposed sample matrix (mainly sugar and alcohol) on the HG process of As was examined in detail. Under optimal conditions found, simplified sample preparation procedures for the determination of As traces were proposed. The suitable sensitivity, the limit of detection of As < 0.1 ng g−1, the precision within 0.31–7.4 % (as RSD), and the adequate trueness (94.9–113 % as confirmed by the recovery test) were achieved. Using the species-selective HG conditions and the developed direct analysis method, the speciation of As in arsenic drops without any prior chromatographic separation of As(III) and As(V) was carried out. The applicability of the developed strategies was demonstrated by the determination of As in 13 homeopathic products available on the Polish market.