WEIGHTS AND BALANCES 砝碼和天平（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] 本節(jié)的目的是使對砝碼的要求符合美家標準 ANSI/ASTM E617“實驗室砝碼和精密質(zhì)量標準物”。此標準以索引的方式整合在起，砝碼的容許公差和構(gòu)造應參考完整的說明和資料。
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.
藥典測試和檢測所需的天平要求多種負荷、靈敏度和可重現(xiàn)性。除另有規(guī)定，否則當物質(zhì)被要求在含量測定中“稱定”時，用來稱重的設備在測量中的不確定性（隨機加系統(tǒng)誤差）不過讀數(shù)的0.1%。如果不少于十次重復稱重的標準差乘以三除以稱得的重量，結(jié)果不過0.001，則測量的不確定性令人滿意。 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.
除另有規(guī)定，對于滴定法限定檢測，需行稱重以提供與滴定液濃度有效數(shù)字位數(shù)相對應的待分析物重量的有效數(shù)字位數(shù)。 The class designations below are in order of increasing tolerances.
以下的類別標號是按照容許公差的升序排列。 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級砝碼是用于校準低負荷、高靈敏度的天平。它們有多種類型，從1 mg 到500mg 不等。對此級內(nèi)任何種類砝碼的容許公差都是5 μg。他們被建議用于校準以光學或電子方法精密稱定低于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級砝碼被稱為用于校準的標準物。它們可用于稱定低于20mg 的重量。（對于10g 或更輕的砝碼，1級的要求可被 美藥典 XXI M 級滿足 。 ） 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類砝碼被用于作為校準的工作標準，分析天平的內(nèi)置砝碼，以及常規(guī)分析工作的實驗室砝碼。（2類要求可被 美藥典 XXI S 級滿足 。 ） 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類和4類砝碼與中等的實驗室天平起使用。（3類要求可被 美藥典 XXI S-1級滿足；4類要求可被 美藥典 XXI P 級滿足。） 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.
對砝碼的類別行選擇，以便所用砝碼的容許公差不過稱重物重量的0.1%。通常，2類砝碼可用在于20mg 的重量，3類砝碼可用在于50mg 的重量，4類砝碼可用在于100mg 的重量。砝碼必須定期行校準，的基于個的標準砝碼。 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 標準 E 617-81副本（1985年再次審定）可從美測試和材料組織中獲得，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 請注意，所用的名稱 S 和 P 不再指砝碼類別，而是指砝碼等級，即設計的限度，如材料的密度范圍，表面積，表面拋光，耐蝕性，和堅硬度 |
