Digestion of inorganics

Matusiewicz, H. A review of acid vapour-phase sample digestion of inorganic and organic matrices for elemental analysis. Spectroscopy 6, 38 6 (1991)... 

Concentrated mineral acids (e.g., sulfuric acid or oleum) are often used in excess for digestion of inorganic raw materials or for production of reactive intermediates from relatively unreactive organic starting products. That proportion of acid not required for product formation must be either regenerated or disposed of in an environmentally friendly manner. Both routes are costly. Reprocessing is particularly difficult if the acid must be diluted or partially neutralized, or if salts have to be added to the solution in order to recover the product. 

Munoz O, Velez D, Montoro R (1999) Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) i- As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry. Analyst 124 601-607. 

Aspila et al. [60] have described a semi-automated method for the determination of inorganic, organic and total phosphorus in river and lake sediments. Total phosphorus is extracted from sediments with 1M hydrochloric acid after ignition at a high temperature (550°C) (method 1) or by digestion with sulphuric acid-potassium persulphate at 135°C in a sealed PTFE-lined Parr bomb (method 2). 

Olsen et al. [71] have reviewed the determination of inorganic, organic and total phosphorus in soil and sediments. Determination of total phosphorus in aqueous samples commonly involves a hot acid oxidation type digestion procedure, although various other dry-ashing, fusion and UV... 

It is interesting to note that exactly the same interference occurred for both organic and inorganic mercury standards, since methyl mercuric chloride does not directly react with sodium sulphide to form mercuric sulphide. Therefore the interference could not be the result of incomplete digestion of mercuric sulphide or CH3Hg+. 

Digestion is conveniently carried out in a Teflon-lined bomb (a sealed vessel) heated in a microwave oven.11 The vessel in Figure 28-8 has a volume of 23 mL and digests up to 1 g of inorganic material in up to 15 mL of concentrated acid or digests 0.1 g of organic material,... 

For chemical analysis, we used a mild acid-extraction procedure, based on recent experimental work (13, 26, 36, 37). We chose the extraction procedure over total digestion of the sample (35) because we are interested specifically in anthropogenic inputs by way of inorganic P and other elements, and not the total compositional chemistry (i.e., anthropogenic and diagenetic inputs). The extractant we used, composed of 20 ml of dilute 0.60 molar hydrochloric acid and 0.16 molar nitric acid, has been experimentally determined to remove soluble and readily labile P and other elements. While the extraction is not always proportional to the total P (or other elements) in soil, for activity area research we are concerned with the spatial patterns of elemental concentrations rather than absolute concentrations, as many variables affect elemental levels in soils (39, 40). 

Kimura and Miller and coworkers [5-18] determined low levels of inorganic plus volatile mercury. The soils were digested with sulfuric acid, hydrogen peroxide and potassium permanganate and then mercury swept of this mixture with air into an absorbing solution of potassium permanganate and sulfuric acid. Mercury is then determined in this solution by a dithizone-based spectrophotometric procedure at 605 nm. 

Gonzalez LaFuente, J.M., M.L. Fernandez Sanchez, J.M. Marchante-Gayon, J.E. Sanchez Uria, and A. Sanz-Medel. 1996. On-line focused microwave digestion-hydride generation of inorganic and organic selenium. Spectrochim. Acta Part B 51 1849-1857. 

International Standard Organization. 1994. Water quality. Determination of fluoride. Part 2 Determination of inorganically bound total fluoride after digestion and distillation. ISO 10359-2. International Organization for Standardization, Case Postale 56, CH-1211, Geneva 20 Switzerland. 

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