Sampling for chemical analysis

Abstract

As analytical methodology improves and instrumental methods allow, or often require, the use of smaller and smaller analytical test portions, the error in the sampling operations becomes increasingly significant. Also, heterogeneity of trace components can introduce major sampling problems. Sampling errors cannot be controlled by use of blanks, standards, or reference samples and so are best treated independently.

Semiquantitative Analysis of Biological Materials by Inductively Coupled Plasma–Mass Spectrometry

“…Often in practical analytical applications, the amount of biological material available for analysis is limited. However, sample errors resulting from heterogeneous analyte distributions, particle size differences, sample amount used, and analyte concentrations could influence the analysis (22)(23)(24). Although the minimum analytical sample aliquot recommended to ensure sample homogeneity for most NIST SRMs is 250 mg, satisfactory results have been demonstrated previously with microamounts of SRMs and samples (22,(25)(26)(27).…”

The effects of homogenisation method and freezing on the determination of quality parameters in red grape berries of Vitis vinifera

“…Sample storage and processing are common procedures in laboratory analysis for quality assessment, aiming to preserve the condition of samples before analysis by standard chemical and physical methods (Pomeranz and Meloan 1987). One objective of sample preparation for analysis is to convert the original sample to a stable and homogeneous form that will facilitate the taking of representative sub-samples (Bowman and Remmenga 1965, Kratochvil and Taylor 1981, Pomeranz and Meloan 1987, Horwitz 1988). In general, samples might suffer changes in their composition as a result of various factors such as loss of one of the constituents (e.g.…”

Progress in the quality assurance of environmental trace organic analysis

“…Attempting to reducing the analytical variance with a large inherent sampling variance will not improve the detection of the environmental trend [21,22]. Provided that the between laboratory agreement can be controlled and maintained as outlined in this paper then any effort in attempting to address the problems associated with these MMPs should be directed towards processing greater numbers of replicated samples from the same site.…”