Probenahme und Bestimmung von Aerosolen und deren Inhaltsstoffen – Bestimmung von metallhaltigen Staubinhaltsstoffen [Air monitoring methods in German language, 2019]

Abstract

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, many metals have an OEL (occupational exposure limit) or MAK value that has to be checked and complied too. For cancerogenic compounds the exposure‐risk relationship has to be considered. Analysis for metals and their compounds predominantly resorts to methods, which 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.

Atomic Spectrometry Update – a review of advances in environmental analysis

“…A review (141 references) on new approaches in microwave-assisted digestions included 21 the following topics: digestions involving dilute acids; reactants such as O 2 ; UV-mediated reactions; high-pressure FIA digestions and microwave-initiated combustion procedures. The development of a new microwave method, using HNO 3 heated to 240 °C, for the dissolution of workplace air filter samples was reported 22,23 Although the measurement of the bioaccessible metal fraction of workplace aerosols is of interest from a health perspective, the lack of standardised methods and associated performance data has hampered progress until now. An interlaboratory study assessed 24 the performance of a procedure described in ISO 15202-2 which advocated leaching air filter samples into water at 37±2 °C for 60 minutes.…”