CEM’s closed vessel microwave digestion instruments are designed to allow for fast, simple, and safe sample preparation of pharmaceutical samples for metals analysis in line with USP Chapter 233 Elemental Impurities – Procedures.
In 2014 the United States Pharmacopoeia (USP) replaced the outdated USP chapter 231, which has been used since 1905 for the determination of heavy metals in pharmaceutical products.
Given the toxicity of some metals, such as arsenic, mercury and lead, even at low concentrations, this is clearly an important change.
Traditional aggressive sample preparation techniques, which may involve sample ignition in a muffle furnace, or open vessel acid digestion, have raised concerns because of the need for large sample sizes, the potential loss of dangerous volatiles and the inability to differentiate between metals and elemental species.
The new USP Chapters 232 and 233 set out the maximum limits for heavy metals in active pharmaceutical ingredients and drug products, and the sample preparation and analysis procedures for the determination of heavy metals in both products and raw materials.
Four sample preparation techniques are outlined: Neat, Direct Aqueous Solution, Direct Organic Solution, and Indirect Solution, where the optimal approach is the Neat technique.
Direct Aqueous Solution or Direct Organic Solution are also straightforward approaches, however many samples cannot be completely dissolved using these techniques.
The Indirect Solution technique, involving closed vessel digestion in a concentrated acid solution, is therefore required for most pharmaceutical raw materials. Microwave digestion offers several advantages over other digestion techniques with microwave energy directly heating the acid and sample through the kinetic transfer of energy directly to the sample matrix.
CEM Corporation has two microwave digestion systems, the Discover SP-D and MARS 6, which it has used to analyse three different pharmaceutical product samples.
Results indicate that both the MARS 6 and the Discover SP-D are well suited for fast, simple, and safe sample preparation of pharmaceutical products and raw materials for metals analysis.
Each instrument provides multiple advantages, particularly in time saved, and since both systems use completely sealed vessels, as opposed to caps, the possibility of cross contamination is eliminated and recovery of both non-volatile and volatile metals is possible.
Both instruments offer specific benefits, depending upon laboratory sample throughput, and include pre-programmed methods and intuitive software; expert applications assistance and CEM’s Complete Guide to Implementing USP 232, 233, & 223.
To download the associated whitepaper from the CEM website please click here.
