【国外标准】 Standard Practice for Handling of High Purity Water Samples

4.1 The determination of trace impurities (on the order of parts per billion) in high purity water places extreme requirements on all aspects of the analytical system. This is particularly true when ubiquitous species such as sodium and chloride are of interest because they can potentially be introduced as contaminants at almost every step of an analytical procedure. Contamination can occur during sample collection, during sample storage by leaching of improperly cleaned containers, during sample transfer, and by handling with pipets, syringes, etc., and during the actual analysis by contaminated reagents and sample cells and loop systems. It is also possible that trace contaminants can be lost from samples by volatilization or precipitation, by diffusion into the matrix of the container material, and by “plating out” on the walls of sampling lines by flow phenomena.4.2 Strict adherence to a given procedure is necessary to achieve good results at trace levels of analysis because very small differences in procedure execution will affect precision and the addition or loss of nanogram amounts of analyte may affect the accuracy of a determination.1.1 This practice2 covers concepts for handling high purity water samples needed for the measurement of ever-decreasing levels of specified impurities that are encountered in the operation of modern high-pressure boilers and turbines. The handling of blanks associated with the analysis of high purity water samples is also covered by this practice. The techniques presented can help the investigator increase the accuracy of analyses performed.1.2 This practice is applicable to water and steam samples from “zero solids treated” once-through or drum-type boilers, reactor coolant water, electronic grade water, or any other process water where analyte concentrations are in the low parts per billion (micrograms per litre) range.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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 and health practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in 6.2.3.5, 6.1, and 6.3.7.