美国材料测试协会ASTM 标准 D11 - 橡胶和橡胶制品中工业级标准品--- IRM 021 硬脂酸（十八酸）标准品
有关背景：
工业标准品简称（IRMs）用于美国材料测试协会ASTM 标准 D11，采用ASTM D4678测试标准。
Industry Reference Materials (IRMs), used for a number of test methods under the jurisdiction of ASTM Committee D11, are prepared according to ASTM D4678, "Preparation, Testing, Acceptance and Documentation for Industry Reference Materials (IRM)". Refer to this for details not covered in this document. Candidate materials that are intended as IRMs are tested and accepted on the basis if (1) homogeneity of the lot and (2) an Accepted Reference Value or AR-value, for the appropriate properties for any IRM. The AR-value is the test value that should be obtained (within specified limits) for the selected one or more properties. AR-values are of two types: Global AR-values, obtained as an average (with specified 3 s limits) from an interlaboratory test program and Local AR-values, obtained as an average (with specified 3 s limits) for the laboratory involved with the preparation and testing.

如何评价IRM
This lot of stearic acid is a Local AR-value IRM. It was produced in June 1998 by Henkel Corp. and the blending was done by Akron Dispersions, Inc. Homogeneity testing was conducted via the procedures as outlined in ASTM D 4678 Annex A.3 on the basis of Acid Number analysis via ASTM D1980-91, for eight individual samples taken from the beginning to end of the lot production. The lot was declared to be homogeneous using the procedure as outlined in Annex A.3. The Local AR-value for Acid Number as obtained for the homogeneity testing is given below. Two secondary properties, Iodine Number and heavy metal content were deemed important and an analysis was conducted for Iodine Number via ASTM D1959-89 and for heavy metal content via ICP Atomic Absorption on a composite stearic acid sample obtained by blending all individual homogeneity samples.

技术参数
酸值  (D1980-91) +/- 3s= 194.36 +/- 0.38 
碘价  (D1959-89) +/- 1s= 0.56 +/- 0.29
重金属(Co, Cu, Fe, Mn, Ni, Zn) 小于10 ppm
(The 3 s limits are based on 15 DF; 1 s limits are approximate, 3 DF)

补充信息
处于干燥冷藏环境下保质期一般为5年。 可以通过ASTM官方网站查询保质期。

包装
IRM-021 硬脂酸（十八酸）工业级标准品, 3200 克/听
1 听 包括 4 小包准 (800 克/小包装)