Reference material for analysis of alkali leaching from pharmaceutical glass containers
A certified reference material for the determination of alkali leaching from pharmaceutical glass containers is now available from IRMM. The use of pharmaceutical containers intended for parenteral preparations is regulated by the European Pharmacopoeia, which prescribes aqueous injectables to be distributed in borosilicate glass containers. As borosilicate glass is known to be very inert, the only observed interaction between the glass and the contained liquid is the release of traces of alkaline substances - mainly NaOH - from the glass surface. These traces are harmless from the health point of view but at the same time many pharmaceuticals are dissolved in pure unbuffered water and very sensitive to changes in pH. The presence of only traces of alkaline substances can be sufficient to affect the properties of pharmaceuticals through increased pH. Therefore, the European Pharmacopoeia set limit values to the release of alkaline substances during a temperature cycling, specified also by the standard ISO 4802.
Extensive studies of a Technical Committee of the International Commission on Glass have shown that the reproducibility of the standard test method can be further improved by imposing requirements beyond the standard ISO 4802, accompanied by strict quality control and a certified reference material. Therefore, the certified reference material IRMM-435 has been produced. It is based on a type of glass used for pharmaceutical purposes whose alkali release rate is sufficiently high to allow certification using a titration method and flame atomic absorption spectrometry. The reference material is certified for release of sodium (and Na2O) per volume of leachate and indirectly for total alkali release.