Lead sampling procedures

The lead sampling procedures described in Section 3.2 were evaluated in a European broad study (EUR19087,1999). The results of this study are described in this section. 

Whenever possible a powder should be sampled when in motion and the whole of the stream of powder should be taken for many short increments of time in preference to part of the stream being taken for the whole of the time. Observance of these rules coupled with an understanding of the manner in which segregation takes place leads to the best sampling procedure. Care and skill in abstracting samples is needed and cannot be overemphasized. 

Work on sample preparation for lead speciation has raised a number of questions about accuracy of results of analyses. Sampling procedures should be restricted to the minimum number of steps. TAL and other lead compounds are readily adsorbed on container surfaces, including glass from aqueous solutions. In... 

In addition to sampling procedures, sampling bias and sampling errors are introduced, leading to some guidance on sample handling, shipping, and chain-of-custody procedures. 

In many possible situations a sample has to be obtained under conditions that often necessitate the use of inferior sampling techniques, however, observance of these Golden Rules will lead to the best sampling procedure. 

An important property of wavelet bases is their lack of translational invariance. In other words, when a pattern is translated, its descriptors are not only translated but also modified. This is a direct consequence of the down-sampling procedure and leads to distorted reconstruction of the underlying signal features. A possible solution is to omit down-sampling, resulting in a redundant family of coefficients. 

One of the most important aspect of allergen detection is sampling, followed by preparation of the sample for analysis. Generally, the distribution of the allergen as contaminant in the food product is extremely heterogeneous, and for this reason an incorrect sampling procedure, which is one of the main sources of error, may lead to poor-quality results. To guarantee the representativeness of the sample, it is necessary ... 

Pre-treatment of the sample is especially important if lead particles are present in the sample. To obtain representative results, prescription of representative, reproducible, precise and accurate sampling, pre-treatment and methods of analysis are essential in the sampling procedure. 

Assessing/predicting the effect of measures A distinction should be made between measures taken at the treatment facility and measures taken at specific properties. To evaluate the effect of measures taken at the treatment facility (pH increase, orthophosphate dosing, etc.), both the RDT sampling procedure and the lead pipe test are appropriate. For predietion purposes the lead pipe test is most eonvenient. 

Can identify high short-term exposure that may lead to acute effects, e.g., facilitate confined space entry, and also provide estimates of long-term exposures with correct sampling procedures. 

ISO 12743 1998 Copper, lead, and zinc sulfide concentrates - sampling procedures for determination of metal and moisture... 

Sampling is employed to ensure that a representative sample is obtained. The purpose of the sampling procedure is to ensure the expected probability of sampling, i.e., to fulfill the requirement that all the parts of the bulk material have the same probability that they will be sampled and that they appear in the sample for testing. Any deviation from this basic requirement may lead to unacceptable bias and the creation of a sample that is not representative. 

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