Biological samples digestion

Much of the research on biological sample digestion has included results from standard reference materials for validation purposes. Also, much of the development work has been conducted in parallel with a more traditional method such as conventional heating [157,158] and also with new methods such as pressurized ashing [117]. 

Achievable detection limits for direct Pd quantification in solutions employing ETAAS are in most cases in the pg 1 range, which is not sufficient for most environmental or biological sample digestions. Accordingly, preconcentration of analytes is necessary to reach adequate sensitivity. 

TABLE 1. The relative amounts of constitutents recommended for use when counting Na or biological samples digested in aqueous NaOH ... 

Two methods were examined for digestion of biological samples prior to trace element analysis. In the first one a nitric acid-hydrogen peroxide-hydrofluoric acid mixture was used in an open system, and in the second one nitric acid in a closed Teflon bomb. The latter method was superior for Ge determination, however, germanium was lost whenever hydrogen fluoride had to be added for disolving sihcious material. End analysis by ICP-AES was used for Ge concentrations in the Xg/g range13. 

A separation step is sometimes an essential part of an analytical method and may be as diverse as distillation, filtration, digestion, extraction, phase-separation or dialysis. These can all be performed by continuous flow analysers either by adding a specially designed glass fitting to the manifold or analytical cartridge or by the addition of a separate module to the analyser. Many biological samples contain protein and dialysis is often used to remove this protein, which would otherwise affect the analysis. 

Flame atomic absorption spectrometry can be used to determine trace levels of analyte in a wide range of sample types, with the proviso that the sample is first brought into solution. The methods described in Section 1.6 are all applicable to FAAS. Chemical interferences and ionization suppression cause the greatest problems, and steps must be taken to reduce these (e.g. the analysis of sea-water, refractory geological samples or metals). The analysis of oils and organic solvents is relatively easy since these samples actually provide fuel for the flame however, build-up of carbon in the burner slot must be avoided. Most biological samples can be analysed with ease provided that an appropriate digestion method is used which avoids analyte losses. 

Biological samples Se Extraction, Digestion Both organoselenium and selenitefSelV) can be differentiated by the method developed 85)... 

Geological and biological sample preparation for subsequent analysis often involves digestion in highly oxidant media such as nitric or perchloric acid. This is a frequent... 

Normally, for determination in biological samples, the sample is digested in an oxidizing acid mixture followed by atomic spectrometric determination. Organotin can be extracted from biological samples and determined by atomic spectrometric methods or gas chromatography, usually after derivatization. 

Angerer J, Schaller KH. 1988. Digestion procedures for the determination of metals in biological samples. In Analysis of hazardous substances in biological materials. Vol. 2. Weinheim, FRG VCH, 1-30. 

A number of procedures for the determination of metals and biological samples call for the extraction of the metal with an organic chelating agent in order to remove interferences and concentrate the metal to enable detection of low levels. The urine or blood sample may be first subjected to wet ashing to enable extraction of the metal. Beryllium from an acid-digested blood or urine sample may be extracted by acetylacetone into methylisobutyl ketone prior to atomic absorption analysis. Virtually all of the common metals can be determined by this approach using appropriate extractants. 

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