【国外标准】 Standard Guide for Laboratory Subsampling of Media Related to Waste Management Activities

4.1 This guide discusses options for taking a subsample from a sample submitted to a laboratory. If followed, it will minimize the bias and variance of the characteristic of interest of the laboratory sample prior to analysis.4.2 The guide will describe appropriate instructions to be submitted to the laboratory with the field sample.4.3 This guide is intended for use in the laboratory to take a representative subsample or specimen of the whole field sample for direct analysis or sample preparation for analysis. It is intended for field personnel, data users, laboratory sample reception personnel, analysts, and managers.4.4 To obtain a representative subsample, layer analysis, grinding, mixing, and changing the physical state such as digesting, drying, melting, or freezing may be required. This guide considers cone and quartering, riffle splitting, and particle size reduction.1.1 This guide covers common techniques for obtaining representative subsamples from a sample received at a laboratory for analysis. These samples may include solids, sludges, liquids, or multilayered liquids (with or without solids).1.2 The procedures and techniques discussed in this guide depend upon the sample matrix, the type of sample preparation and analysis performed, the characteristic(s) of interest, and the project-specific instructions or data quality objectives.1.3 This guide includes several sample homogenization techniques, including mixing and grinding, as well as information on how to obtain a specimen or split laboratory samples.1.4 This guide does not apply to air or gas sampling.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.