Determination of metal-containing components of airborne particles

In addition to the gravimetric determination of airborne particles (total concentration), it is often necessary to selectively determine metals and their compounds in particle fractions because of their toxicological relevance. Usually, the total metal concentration is determined independently of the type of binding or oxidation state in a sample. From an occupational medical and toxicological point of view it makes sense to distinguish between different compounds of a metal, because type and extent of the toxic effect of metals depend considerably on their binding type and their solubility in the human body. In addition to the limit values of the respirable and inhalable particle fraction that must be complied with, many metals have an OEL (occupational exposure limit) or MAK value that has to be checked and complied with, too. For carcinogenic compounds the exposure-risk relationship has to be considered. Analysis for metals and their compounds predominantly resorts to methods which The MAK Collection for Occupational Health and Safety 2020, Vol 5, No 4 1 Air Monitoring Methods – Determination of metal-containing components of airborne particles require that the dust particle sample is brought into solution.That means the metals and their compounds contained in the sample need to be extracted, dissolved or digested. Aim of the sample preparation is the complete solution of all relevant substances to be analysed. Common digestion methods are for example acid digestion, which uses an acid mixture to digest the sample, and the suspension method, in which acetone is used to suspend the sample. An alternative sample preparation method is the microwave-assisted pressure digestion with acid/acid mixture. In this chapter the different digestion methods are presented, discussed and compared, taking into account recent developments, in particular microwave-assisted digestion.