中英文對照資料—天平與砝碼
The intent of this section is to bring the requirements for weights into conformity with American National Standard ANSI/ASTM E617, “Laboratory Weights and Precision Mass Standards." This standard is incorporated by reference and should be consulted for full descriptions and information on the tolerances and construction of weights.1 本節(jié)的目的是使對砝碼的要求符合美家標(biāo)準(zhǔn)ANSI/ASTM E617“實(shí)驗(yàn)室砝碼和精密質(zhì)量標(biāo)準(zhǔn)物"。此標(biāo)準(zhǔn)以索引的方式整合在起，砝碼的容許公差和構(gòu)造應(yīng)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 substances are to be “accuray weighed" for Assay, the weighing to be performed with a weighing device whose measurement uncertainty (random plus systematic error) does not exceed 0.1% of the reading. Measurement uncertainty is satisfactory if three times the standard deviation of not less than ten replicate weighings divided by the amount weighed, does not exceed 0.001. Unless otherwise specified, for titrimetric limits tests, the weighing shall be performed to provide the number of significant figures in the weight of the analyte that corresponds to the number of significant figures in the concentration of the titrant. 藥典測試和檢測所需的天平要求多種負(fù)荷、靈敏度和可重現(xiàn)性。除另有規(guī)定，否則當(dāng)物質(zhì)被要求在含量測定中“稱定"時(shí)，用來稱重的設(shè)備在測量中的不確定性（隨機(jī)加系統(tǒng)誤差）不過讀數(shù)的0.1%。如果不少于十次重復(fù)稱重的標(biāo)準(zhǔn)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。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(yīng)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(biāo)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-sensitivity balances. They are available in various denominations from 1 to 500 mg. The tolerance for any denomination in this class is 5 μg. They are recommended for calibration of balances using optical or electrical methods for accuray weighing quantities below 20 mg. 1.1級砝碼是用于校準(zhǔn)低負(fù)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5μg。他們被建議用于校準(zhǔn)以視覺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 class M.) 1級砝碼被稱為用于校準(zhǔn)的標(biāo)準(zhǔn)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 weights for analytical balances, and laboratory weights for routine analytical work. (The requirements of class 2 are met by USP XXI class S.)2 2類砝碼被用于作為校準(zhǔn)的工作標(biāo)準(zhǔn)，分析天平的內(nèi)置砝碼，以及常規(guī)分析工作的實(shí)驗(yàn)室砝碼。（2類要求可被美藥典21 S級滿足。）2 Class 3 and class 4 weights are used with moderate-precision laboratory balances. (Class 3 requirements are met by USP XXI class S-1; class 4 requirements are met by USP XXI class P.) 2 3類和4類砝碼與中等的實(shí)驗(yàn)室天平起使用。（3類要求可被美藥典21 S-1級滿足；4類要求可被美藥典21 P級滿足。）2
A weight class is chosen so that the tolerance of the weights used does not exceed 0.1% of the amount weighed. Generally, class 2 may be used for quantities greater than 20 mg, class 3 for quantities of greater than 50 mg, and class 4 for quantities of greater than 100 mg. Weights should be calibrated periodically, 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(zhǔn)，基于個(gè)標(biāo)準(zhǔn)砝碼。 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(biāo)準(zhǔn)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：1916 Race Street, Philadelphia, PA 19103。
Note that the designations S and P no longer designate weight classes but rather weight grades, that is, design limitation 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(shè)計(jì)的限度，如材料的密度范圍，表面積，表面拋光，耐蝕性，和堅(jiān)硬度。
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