Lead sampling procedures methods

As microwave sample preparation has evolved, standard microwave procedures have been developed and approved by numerous standard methods organisations (ASTM, AOAC International, EPA, etc.), see ref. [64]. Examples are standard test methods for carbon black/ash content (ASTM Method D 1506-97), lead analysis in direct paint samples (ASTM Method E 1645-94), etc. Table 8.15 shows some microwave ashing references (detection weight). A French AFNOR method utilises the atmospheric pressure single-mode microwave method as an alternative sample preparation procedure for Kjeldahl nitrogen determination [84], The performance of a microwave-assisted decomposition for rapid determination of glass fibre content in plastics for QC has been described [85]. 

Another short note For samples that are relatively clean, one could always resort to employing (and frequently replacing) a guard column. This might be a bit more costly, but it greatly simplifies any sample preparation procedure and will probably lead to better method precision. One should always keep in mind that the largest contributor to poor method precision is usually manual sample preparations. 

Observance of these rules, coupled with an understanding of the manner in which segregation takes place, leads to the best sampling procedure. Any method that does not follow these rules should be regarded as a second-best method liable to lead to errors. Finally, the need for care and skill in abstracting samples cannot be over-emphasized. 

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. 

This method of detecting traces of lead can also be used in the examination of certain "high purity" chemicals. Dissolve 1-6 g of the sample in 10 ml water and apply the procedure just described. Alkali salts of the highest purity were tested for traces of lead by this method. The packages bore labels reading, "Heavy metals as Pb. ..0.0003. 0.0005 respectively. 

Lead detection kits are useful as a quick check for screening areas for lead abatement. A positive response is evidence of the presence of lead or a positive interference. A negative response, however, is not conclusive evidence of the absence of lead. The test provides presumptive evidence for the presence of lead, not its absence. A more thorough determination may need to be performed by a quantitative laboratory analysis of any representative bulk material available to substantiate the absence of lead. Samples are analyzed for lead at OSHA s Salt Lake Technical Center (SLTC) using OSHA methods ID-121 with Atomic Absorption Spectroscopy (AAS), ID-125 G with Inductively Coupled Plasma (ICP), or ID-206 (Solders by ICP). If necessary, lower limits of detection for lead may be achieved using ICP Mass Spectrometer procedures. 

Hyphenated analytical methods provide more complementary information in a shorter time period leading to faster and more reUable results, than data obtained from traditional instmmental methods. The types of analytical instmments that can be joined is very large depending only upon the nondestmction of samples after the initial analytical procedure and the ability of the manufacturer to interface the instmmental techniques. Combinations include separation—separation, separation—identification, and identification—identification techniques (see Analytical methods, survey). 

This method is used for the determination of total chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), manganese (Mn), beiylhum (Be), copper (Cu), zinc (Zn), lead (Pb), selenium (Se), phosphorus (P), thalhum (Tl), silver (Ag), antimony (Sb), barium (Ba), and mer-cuiy (Hg) stack emissions from stationaiy sources. This method may also be used for the determination of particulate emissions fohowing the procedures and precautions described. However, modifications to the sample recoveiy and analysis procedures described in the method for the purpose of determining particulate emissions may potentially impacl the front-half mercury determination. 

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