Selection of a reference standard

Selection of a reference standard for most analytical methods is a straightforward task, involving acquisition of the relevant analyte in a state of known composition and purity. However, some analytes are not available in pure form, and structurally similar analogs (e.g. free base) may be used instead. Standard materials should be of a known purity, and the source, lot number, expiration date and certification of identity should be recorded (FDA, 2001). 

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Both Sing [3, 4] and Kaneko [5, 6] have published data which are accepted as standard reference data, however their CSU are unpublished. Uncertainty in micropore and/or pore volumes derived from comparison plots analyses are developed from CSU in the primary standard data and from the CSU in the test adsorption data. A second important consideration for an a, -analysis is an appropriate selection of a reference standard whose surface chemistry simulates that of the test adsorbent. Thus, a comparison plot uncertainty analysis needs to differentiate between the contributions of experimental uncertainty and adsorbent chemistry differences. 

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