WEIGHTS AND BALANCES 砝码和天平(中英文) The intent of this section is to bring the requirements for weights intoconformity with American National Standard ANSI/ASTM E617, “LaboratoryWeights and Precision Mass Standards.” This standard is incorporated byreference and should be consulted for full descriptions and information on thetolerances and construction of weights.[1] 本节的目的是使对砝码的要求符合美家标准 ANSI/ASTM E617“实验室砝码和精密质量标准物”。此标准以索引的方式整合在起,砝码的容许公差和构造应参考完整的说明和资料。 Pharmacopeial tests and assays require balances that vary in capacity,sensitivity, and reproducibility. Unless otherwise specified, when substancesare to be “accuray weighed” for Assay, the weighing is to be performedwith a weighing device whose measurement uncertainty (random plussystematic error) does not exceed 0.1% of the reading. Measurementuncertainty is satisfactory if three times the standard deviation of not less thanten replicate weighings divided by the amount weighed, does not exceed0.001.
药典测试和检测所需的天平要求多种负荷、灵敏度和可重现性。除另有规定,否则当物质被要求在含量测定中“称定”时,用来称重的设备在测量中的不确定性(随机加系统误差)不过读数的0.1%。如果不少于十次重复称重的标准差乘以三除以称得的重量,结果不过0.001,则测量的不确定性令人满意。 Unless otherwise specified, for titrimetric limits tests, the weighing shall beperformed to provide the number of significant figures in the weight of theanalyte that corresponds to the number of significant figures in theconcentration of the titrant. 除另有规定,对于滴定法限定检测,需行称重以提供与滴定液浓度有效数字位数相对应的待分析物重量的有效数字位数。 The class designations below are in order of increasing tolerances. 以下的类别标号是按照容许公差的升序排列。 Class 1.1 weights are used for calibration of low-capacity, high-sensitivitybalances. They are available in various denominations from 1 to 500 mg. Thetolerance for any denomination in this class is 5 μg. They are recommendedfor calibration of balances using optical or electrical methods for accurayweighing quantities below 20 mg. 1.1级砝码是用于校准低负荷、高灵敏度的天平。它们有多种类型,从1 mg 到500mg 不等。对此级内任何种类砝码的容许公差都是5 μg。他们被建议用于校准以光学或电子方法精密称定低于20mg 重量的天平 Class 1 weights are designated as high-precision standards for calibration.They may be used for weighing accuray quantities below 20 mg. (Forweights of 10 g or less, the requirements of class 1 are met by USP XXI classM.) 1级砝码被称为用于校准的标准物。它们可用于称定低于20mg 的重量。(对于10g 或更轻的砝码,1级的要求可被 美药典 XXI M 级满足 。 ) Class 2 weights are used as working standards for calibration, built-in weightsfor analytical balances, and laboratory weights for routine analytical work. (Therequirementsof class 2 are met by USP XXI class S.)[2] 2类砝码被用于作为校准的工作标准,分析天平的内置砝码,以及常规分析工作的实验室砝码。(2类要求可被 美药典 XXI S 级满足 。 ) 2 Class 3 and class 4 weights are used with moderate-precision laboratorybalances. (Class 3 requirements are met by USP XXI class S-1; class 4requirements are met by USP XXI class P.)2 2 3类和4类砝码与中等的实验室天平起使用。(3类要求可被 美药典 XXI S-1级满足;4类要求可被 美药典 XXI P 级满足。) 2 A weight class is chosen so that the tolerance of the weights used does notexceed 0.1% of the amount weighed. Generally, class 2 may be used forquantities greater than 20 mg, class 3 for quantities of greater than 50 mg, andclass 4 for quantities of greater than 100 mg. Weights should be calibratedperiodically, preferably against an absolute standard weight. 对砝码的类别行选择,以便所用砝码的容许公差不过称重物重量的0.1%。通常,2类砝码可用在于20mg 的重量,3类砝码可用在于50mg 的重量,4类砝码可用在于100mg 的重量。砝码必须定期行校准,的基于个的标准砝码。 Auxiliary Information— — Please check for your question in the FAQs before contacting USP. [1] Copies of ASTM Standard E 617-81 (Reapproved 1985) may be obtained from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103. 1 美 ASTM 标准 E 617-81副本(1985年再次审定)可从美测试和材料组织中获得,地址:1916RaceStreet, Philadelphia, PA19103。 [2] Note that the designations S and P no longer designate weight classes but rather weight grades, that is, design limitations such as range of density of materials, surface area, surface finish, corrosion resistance, and hardness. 2 请注意,所用的名称 S 和 P 不再指砝码类别,而是指砝码等级,即设计的限度,如材料的密度范围,表面积,表面抛光,耐蚀性,和坚硬度 |