Gy sampling theory in environmental studies

Gerlach, Robert W; Nocerino, John M.; Ramsey, Charles A.; Venner, Brad

doi:10.1016/s0003-2670(03)00568-3

Cited by 23 publications

(11 citation statements)

References 12 publications

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“…Cereal F is a practical example of a material that laboratories may be required to evaluate, in which values from replicate bottles or packages do not agree as a result of material inhomogeneity. When analyzing what would be considered a real sample, a representative sample must be obtained [8, 20]. The mass of the processed sample may need to be increased to give a representation of the entire product or appropriately random samples need to be taken at intervals to assure chemical homogeneity between samples [5–7].…”

Section: Resultsmentioning

confidence: 99%

Breakfast cereal sampling study for nutritional elements

et al. 2013

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The National Institute of Standards and Technology (NIST) has established a Dietary Supplement Laboratory Quality Assurance Program (DSQAP) in collaboration with the National Institutes of Health Office of Dietary Supplements (NIH-ODS). The DSQAP invites laboratories twice annually to participate in interlaboratory studies where participants elect to measure concentrations of nutritional and/or toxic elements as well as active and/or marker compounds. One of these studies was designed to determine the effects of material granularity and sample processing techniques on measurement variability (precision) as well as to provide participating laboratories information on their performance relative to the NIST assigned values (bias) and to the other participants (concordance). Participants were asked to determine the mass fractions of Ca, Fe, and Zn, in mg/kg, in six breakfast cereal samples. Cereal samples consisted of three ground materials (homogenized wheat, wheat, and rice), two flake materials (wheat and rice) and a partially crushed material (a wheat/rice mixture). In general, approximately 25 % of the laboratories processed and analyzed the suite of six cereal materials with adequate to exemplary measurement precision. Over half of the laboratories (60 %) experienced measurement issues related to only a particular type of cereal matrix or for only a single element. A small number (15 %) of laboratories experienced significant sample processing or measurement problems. Future studies planned by the DSQAP may be designed to use commercial products to aid laboratories with their sampling and analytical techniques.

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Section: Resultsmentioning

confidence: 99%

Breakfast cereal sampling study for nutritional elements

et al. 2013

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“…Nevertheless, a parallel with the Gy sampling theory can be done to identify how to improve our sampling protocol in ecotoxicological evaluation of solid waste leachates. This theory delineates seven major categories of sampling error that cover differences within samples in addition to the error introduced by the analytical method (20). However, only three categories seem to be relevant to this study: the fundamental error, the segregation error, and the delimitation error.…”

Section: Resultsmentioning

confidence: 99%

Predicting Uncertainty in the Ecotoxicological Assessment of Solid Waste Leachates

Ferrari

Masfaraud

Maul

et al. 2006

Environ. Sci. Technol.

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Environmental managers need suitable technological methods to use in optimization studies to improve management of hazardous waste. One of the challenges to achieving a reliable hazardous waste classification is the improvement of procedures used forthe ecotoxicological characterization of solid waste leachates. Indeed, this step requires data that meet levels of acceptable quality if scientifically based decisions are to be made. In this study, we illustrate how the variability associated with the successive steps of a procedure used to assess ecotoxicological hazard of solid waste (i.e., primary sampling, laboratory sampling, toxicity measurements) can contribute to the overall variability of the ecotoxicity results. To this end, a municipal solid waste incinerator bottom ash and a slag from a second smelting of lead were studied using a nested experimental design. The results showed that the waste sampling design is of major importance for limiting the final variability of toxicity test parameters. At the opposite, increasing the number of replicates at the toxicity test level has negligible impact on this variability. Our approach could be of great practical interest in ecotoxicological studies not only for ensuring a safe classification for these materials, but also for improving sampling protocols and facilitating less time-consuming and less expensive ecotoxicological evaluations.

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“…The control measure is weighing the samples after each working step as drying, fragment removal, crushing/ grinding/milling, sieving, splitting/sub-sampling, and storing (Houba et al 1994). Sources of measurement instabilities are uneven drying and possible volatilization and cross-contamination for Hg and organics (Bartlett and James 1980;Bordas and Bourg 1998;Gillis and Miller 2000); discarding fine earth by removing fragments as stones; contamination, dilution, and loss by crushing/grinding/milling (Desaules 1989;Houba et al 1993); loss of soil crumbs by sieving residues; uneven and/or incomplete splitting (Gerlach et al 2002); and alterations during storing (Bartlett and James 1980;Berndt 1988;Billett et al 1990). The major errors to control are segregation, materialization, contamination, and sample alteration (Gy 1982;Pitard 1993).…”

Section: Physical Soil Sample Preparation and Storagementioning

confidence: 99%

Measurement instability and temporal bias in chemical soil monitoring: sources and control measures

Desaules

2011

Environ Monit Assess

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Concern that human impacts on the environment may be harmful to natural resources such as soils as well as to living conditions is the major motivation for long-term environmental monitoring. However, the evidence that measurement bias is not constant through time affects time series as an artifact; this also holds true for chemical soil monitoring. Measurement instabilities occur along the whole measurement chain, from soil sampling to the expression of results. The first step in controlling measurement instability is to identify its relevant sources, and the second is to control it by stabilizing, minimizing, or quantifying measurement instability. For all five steps in the measurement process, from soil sampling to the expression of the analytical results, sources of measurement instability are identified and measures of control discussed, leading to the main conclusion concerning the requirement to continuously control the relevant environmental and measurement boundary conditions that may affect measurement instability. The innovative aspect of this paper consists in explicitly addressing measurement instability in chemical soil monitoring and tracking it along the whole measurement chain. The paper is also a plea for a change of paradigm in long-term environmental monitoring, namely to consider temporal measurements as unstable unless their degree of stability is traceably demonstrated, adequately quantified, and included in interpretation.

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Gy sampling theory in environmental studies

Cited by 23 publications

References 12 publications

Breakfast cereal sampling study for nutritional elements

Breakfast cereal sampling study for nutritional elements

Predicting Uncertainty in the Ecotoxicological Assessment of Solid Waste Leachates

Measurement instability and temporal bias in chemical soil monitoring: sources and control measures

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