The previously revised chapter <670> was published in Pharmacopoeial Forum 40(6), November-December 2014, and will become official on May 1, 2016 (USP 39-NF 34). This revision included the introduction of compendial standards for packaging desiccants. Common types of commercial desiccants are, for example, bentonite, calcium chloride, calcium oxide, molecular sieves, and silica gel. For these materials specific tests and assays are described in the general chapter.
Other desiccants are subject to appropriate testing to ensure suitability for the intended application. The desiccants may be incorporated directly into the wall or cap of packaging containers or bound by a carrier material.
On the basis of a comment received, in Pharmacopoeial Forum 42(1) it is proposed to cross reference general chapter Spectrophotometric Identification Tests <197>, to add the needed flexibility to the Infrared Spectroscopy section of paragraph Pharmaceutical Coil in chapter <670>. Therefore, the ATR technique can be used as alternative method.