Sample preparation is an important, basic method in the analysis of inorganic and organic specimens. Acid dissolution, with or without an oxidizing agent has proved to be an efficient, commonly used procedure for the decomposition of solids, sediments and sludges.

In general, strong inorganic acids are employed such as nitric, perchloric, hydrochloric and sulfuric acid. In most cases the dissolution process requires more than one acid e.g. aqua regia, Leffort (Lunge) mixture, or the Dixon mixture in soil analysis with a certain, predominating acid, determining the rate and completeness of the decomposition.

Mercury and arsenic-free reagents are particularly suitable for the determination of those metal ions, in the presence of others, in e.g. industrial and waste waters, polluted soils, and sludge. They can be used for sample preparation (dissolution) and measuring the prepared samples with ICP-OES or –MS

Acid, Acid Mixture	Additive	Metal to be analyzed in matrix	Matrix to be analyzed	Method
HCl / HNO3	-	As, Hg	Waste sludge, soils, sediments, rocks	Extraction
HNO3 / H2SO4	Br2	As	Pb, Cu, Zn, Mo ores, concentrates	Dissolution
HNO3 / H2SO4 (2:1)	-	As	Soils	Decomposition
HNO3 / H2SO4	KMnO4	Hg	Soils	Decomposition
HNO3 / H2SO4	KMNO4	Hg	Water, waste-water, sludge	DIN 38406
HNO3 / H2O2	-	As	Water, wast-water, sludge	DIN 38406
1. HNO3 / HClO4 2. KMnO4 / K2S2O8	-	As	Materials rich in organic compounds	Two-step decomposition
1. HNO3 / HClO4 2. HCl	-	As	Sulfidic minerals	Decomposition
H2SO4	-	As	Allemontite	Dissolution