Chemical speciation and sequential extraction of Mn in workroom aerosols: analytical methodology and results from a field study in Mn alloy plants.
Workers in the Mn alloy producing industry are exposed to aerosols containing a variety of Mn compounds (MnO, MnO,, Mn2O3, Mn3O4, FeMn and SiMn). This paper reports a novel four-step chemical speciation/ fractionation procedure developed for characterisation of workroom aerosols collected in Mn alloy producing plants. The following components of the aerosol have been quantified: "water soluble" Mn dissolved in 0.01 M ammonium acetate: Mn0 and Mn2+ dissolved in 25% acetic acid; Mn3+ and Mn4+ dissolved in 0.5%) hydroxylamine hydrochloride in 25%) acetic acid; and "insoluble" Mn digested in aqua regia and hydrofluoric acid. Dissolution of pure Mn compounds with well-defined stoichiometries were essentially complete in the respective leaching steps with detectable amounts of < 1% in others. Recoveries of a mixed quality control sample were also acceptable in the range 92-97% for the different oxidation states. The levels measured in the inhalable and respirable fractions in three Mn alloy producing plants were approximately 300 and 35 microg m(-3) of total Mn, respectively. The most obvious feature of the speciation results is that none of the work areas is characterised by a single Mn contaminant. The predominant oxidation states in the inhalable aerosol fraction are Mn0 and Mn2+ independent of job functions/departments. The occurrence of insoluble Mn compounds in both the inhalable and respirable aerosol fractions is significantly higher during production of SiMn.
Thomassen
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Y
National Institute of Occupational Health, Oslo, Norway. Yngvar.Thomassen@stami.no
Ellingsen
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DG
Hetland
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Sand
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D000336:Aerosols; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004784:Environmental Monitoring; D006801:Humans; D008345:Manganese / Q000737:chemistry*; D016273:Occupational Exposure; D010084:Oxidation-Reduction; D017132:Workplace
D000336:Aerosols; D008345:Manganese