【国外标准】 Standard Specification for Reagent Water

This specification describes the required characteristics of reagent waters. Four types of waters have been specified, with three additional grades that can be applied to the four types. The grade specifications specifically address contaminants of microbiological origin. Historically, reagent water types I, II, III, and IV have been linked to specific processes for their production. Starting with this revision, these types of waters may be produced with alternate technologies as long as the appropriate constituent specifications are met. The electrical conductivity and resistance, pH, silica, sodium, chlorides, TOC, endotoxins, and microbiological contamination shall be tested to meet the requirements prescribed.1.1 This specification describes the required characteristics of waters deemed suitable for use with the standards under the jurisdiction of ASTM.1.2 The alphanumeric characters ascribed to water types and grades are specified in the manual, Form and Style for ASTM Standards. These have been assigned in order of historical precedence and should not be taken as an indication of a progression in water purity.1.3 Four types of waters have been specified, with three additional grades that can be applied to the four types. The grade specifications specifically address contaminants of microbiological origin.1.4 All applicable ASTM Standards are expected to reference one or more of these reagent water types where reagent water is needed as a component of an analytical measurement process. Where a different water type or grade is needed for an ASTM Standard, it may be added to this Specification through the ASTM Standard revision process.1.5 Although these water types and associated grades have been defined specifically for use with ASTM Standards, they may be appropriate for other applications. It is the responsibility of the users of this specification to ensure that the selected water types or grades are suitable for their intended use. Historically, reagent water Types I, II, III, and IV have been linked to specific processes for their production. Starting with this revision, these types of waters may be produced with alternate technologies as long as the appropriate constituent specifications are met and that water so produced has been shown to be appropriate for the application where the use of such water is specified. Therefore, the selection of an alternate technology in place of the technology specified in Table 1 should be made taking into account the potential impact of other contaminants such as microorganism and pyrogens. Such contaminants were not necessarily considered by the performance characteristics of the technology previously specified.(A) Type I grade of reagent water shall be prepared by distillation or other equal process, followed by polishing with a mixed bed of ion-exchange materials and a 0.2-µm membrane filter. Feed water to the final polishing step must have a maximum conductivity of 20 µS/cm at 298K (25°C). Type I reagent water may be produced with alternate technologies as long as the appropriate constituent specifications are met and that water so produced has been shown to be appropriate for the application where the use of such water is specified.(B) Type II grade of reagent water shall be prepared by distillation using a still designed to produce a distillate having a conductivity of less than 1.0 µS/cm at 298 K (25°C). Ion exchange, distillation, or reverse osmosis and organic adsorption may be required prior to distillation, if the purity cannot be attained by single distillation. Type II reagent water may be produced with alternate technologies as long as the appropriate constituent specifications are met and that water so produced has been shown to be appropriate for the application where the use of such water is specified.(C) Type III grade of reagent water shall be prepared by distillation, ion exchange, continuous electrodeionization, reverse osmosis, or a combination thereof, followed by polishing with a 0.45-µm membrane filter. Type III reagent water may be produced with alternate technologies as long as the appropriate constituent specifications are met and that water so produced has been shown to be appropriate for the application where the use of such water is specified.(D) Type IV grade of reagent water may be prepared by distillation, ion exchange, continuous electrodeionization, reverse osmosis, electrodialysis, or a combination thereof. Type IV reagent water may be produced with alternate technologies as long as the appropriate constituent specifications are met and that water so produced has been shown to be appropriate for the application where the use of such water is specified.(E) Electrical conductivity at 25°C.(F) Electrical resistivity at 25°C.(G) pH at 25°C, not applicable to higher resistivity waters.(H) Total organic carbon.(I) Sodium.(J) Chloride ion.(K) Heterotrophic bacteria count.(L) Endotoxin in endotoxin units per mL.1.6 Guidance for applications, the preparation, use and monitoring, storage, handling, distribution, testing of these specified waters and validation of the water purification system is provided in Appendix X1 of this specification.1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.8 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.1.9 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.