The use of infrared spectrophotometry for the estimation of small quantities of single varieties of U.I.C.C. asbestos

Our plain-English summary of The use of infrared spectrophotometry for the estimation of small quantities of single varieties of U.I.C.C. asbestos, by S.T. Beckett, A.P. Middleton, J. Dodgson (The Annals of Occupational Hygiene, 1975).

The study

• Authors: S.T. Beckett, A.P. Middleton, J. Dodgson
• Journal: The Annals of Occupational Hygiene
• Published: 1975;18(4):313-20
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

An i.r. technique has been developed to measure small quantities (down to less than 10 ng) of single varieties of asbestos. This has been used to monitor airborne fibre concentration and to measure the asbestos recovered from the lungs of rats. The method has the advantages that it is relatively simple to perform and requires minimal labour, whilst its precision for estimating micro quantities of asbestos ( < 200 ng) is much greater than by direct weighing.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This laboratory methods paper from the Institute of Occupational Medicine, Edinburgh, described using infrared spectrophotometry to measure small amounts of a single variety of UICC asbestos (chrysotile, amosite or crocidolite). It supported rat inhalation experiments, measuring asbestos in exposure chambers and in rats' lungs. Airborne dust was measured directly on membrane filters. Asbestos recovered from ashed rat lungs was pressed into potassium bromide discs. Below about 500 micrograms, the infrared method was much more reproducible than direct weighing. No effect of the tested size fractions on the reading per unit weight was apparent, but their fibre lengths were similar. The authors cautioned that results might differ for much longer or shorter fibres. When relatively large amounts of asbestos were added to unexposed rat lungs, recovery showed negligible loss after correcting for lung salts. Lung residues from crocidolite-exposed rats appeared to contain amorphous silica, which interfered and required correction. The authors concluded the method was sensitive when only one mineral was present. The abstract reads less than 10 ng but the conclusion says under 10 micrograms, and the scanned text does not show which is meant.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory analytical methods development paper (infrared spectrophotometry technique for measuring asbestos mass), developed for use in animal inhalation experiments
• Who was studied: Airborne dust samples from animal exposure chambers and lungs of rats exposed by inhalation to UICC asbestos, plus lungs of unexposed rats used for calibration. Work at the Institute of Occupational Medicine, Edinburgh. The number of rats is not given.
• Exposure: UICC standard reference samples of chrysotile, amosite and crocidolite, each measured as a single variety in the absence of other minerals
• Main results:
  • On airborne dust filters, at weights of about 500 micrograms or more, direct weighing and infrared measurement were comparable. At lower weights the infrared technique gave much greater reproducibility.
  • Samples were reasonably uniform across the filters. The coefficient of variation between different areas of the filters ranged from 4% at weights over 500 micrograms to 17% at 35 micrograms.
  • Across samples of total dust and of smaller size fractions, no effect on the infrared absorbance per unit weight was apparent for chrysotile, amosite or crocidolite. Table 2 values were roughly 0.21 to 0.23 per mg for chrysotile and 0.26 to 0.28 per mg for amosite and for crocidolite. The fibre-length distributions of the fractions tested were similar.
  • Nuclepore filters were not used for sampling because dust chamber experiments indicated they could undersample by as much as 36% due to electrostatic charge.
  • When relatively large amounts of asbestos were added to lungs of unexposed rats to obtain a weighable residue, a negligible loss was found during the recovery process after correcting for remaining lung salts.
  • Lung residues from rats exposed to crocidolite gave infrared absorptions suggesting amorphous silica was present. This interfered with the crocidolite band used, so corrections were applied.
• The authors' conclusion: The authors concluded that infrared spectrophotometry provides a sensitive method for estimating sub-milligram amounts of single varieties of UICC amosite, crocidolite and chrysotile in animal inhalation experiments, when only a single mineral species is involved.
• Limitations the authors state:
  • The fibre length distributions of the size fractions tested were similar, so sensitivity might differ for samples containing only much longer or much shorter fibres.
  • The method was considered applicable only where a single asbestos variety is present and other mineral interferences are absent.
  • Heating and acid washing during lung recovery broadened and reduced the intensity of the absorption bands, requiring separate calibration.
  • Uneven sample distribution on filters accounted for most of the variation in repeated measurements. Taking the mean of several measurements per filter could improve reproducibility.

Related studies

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