ATR-FTIR and LC-Q-ToF-MS analysis of indoor dust from different micro-environments located in a tropical metropolitan area

Our plain-English summary of ATR-FTIR and LC-Q-ToF-MS analysis of indoor dust from different micro-environments located in a tropical metropolitan area, by M. Vishnu Sreejith, K.S. Aradhana, M. Varsha, et al (The Science of the Total Environment, 2021).

The study

• Authors: M. Vishnu Sreejith, K.S. Aradhana, M. Varsha, M.K. Cyrus, C.T. Aravindakumar, U.K. Aravind
• Journal: The Science of the Total Environment
• Published: 2021;783:147066
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Indoor dust is an important matrix that exposes humans to a broad spectrum of chemicals. The information on the occurrence of contaminants of emerging concern (CECs), their metabolites, and re-emerging contaminants in indoor dust is rather limited. As the indoor environment is exposed to various chemicals from personal care products, furniture, building materials, machineries and cooking/cleaning products, there is a high chance of the presence of hazardous contaminants in indoor dust. In the present study, dust samples were collected from four different micro indoor environments (photocopying centres, residential houses, classrooms, and ATM cabins) located in an urban environment located in India's southwestern part. The collected samples were subjected to ATR - FTIR and LC-Q-ToF-MS analyses. The ATR - FTIR analysis indicated the presence of aldehydes, anhydrides, carboxylic acids, esters, sulphonic acids, and asbestos - a re-emerging contaminant. A total of 19 compounds were identified from the LC-Q-ToF-MS analysis. These compounds belonged to various classes such as plasticisers, plasticiser metabolites, photoinitiators, personal care products, pharmaceutical intermediates, surfactants, and pesticides. To the best of our knowledge, this is the first report regarding the presence of CECs in indoor environments in Kerala and also the suspected occurrence of pesticides (metaldehyde and ethofumesate) in classroom dust in India. Another important highlight of this work is the demonstration of ATR-FTIR as a complementary technique for LC-Q-ToF-MS in the analysis of indoor pollution while dealing with totally unknown pollutants. These results further highlight the occurrence of probable chemically modified metabolites in the tropical climatic conditions in a microenvironment.

Copyright © 2021. Published by Elsevier B.V.

In plain English

This laboratory study screened settled indoor dust from the Greater Cochin area of Kerala, India, a warm and humid tropical metropolitan area. The authors collected 20 dust samples, five each from photocopying shops, residential houses, classrooms and ATM cabins. They analysed them with infrared spectroscopy (ATR-FTIR) and with liquid chromatography and high-resolution mass spectrometry (LC-Q-ToF-MS). In the residential house samples, an infrared signal (a silicon-oxygen vibration at 1033 cm−1) pointed to the presence of asbestos. The houses had asbestos-sheet roofing, and the authors suggested that breakdown of this roofing could be the source. No asbestos fiber type was named, and the article reported no asbestos amount or fiber count. Mass spectrometry identified 19 organic compounds, using online databases for tentative identification. They included phthalate breakdown products rather than the parent phthalates, benzophenone in dust from photocopying centres and ATM cabins, and triethyl phosphate in dust from photocopying centres. Fungal metabolites and kynurenic acid were found in the houses, and the pesticides metaldehyde and ethofumesate in classroom dust. The authors concluded that the infrared data supported the mass spectrometry results.

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 chemical screening (infrared spectroscopy and non-target mass spectrometry) of collected indoor dust samples; no human health outcomes studied
• Who was studied: 20 settled indoor dust samples from the Greater Cochin area, Kerala, India: photocopying shops (n = 5, S1), residential houses (n = 5, S2), classrooms (n = 5, S3), ATM cabins (n = 5, S4); sampling dates not given
• Exposure: Chemical contaminants in indoor dust. Asbestos was indicated only by an infrared spectroscopy signal in residential house dust, where roofs were made of asbestos sheets. No fiber type was named and no asbestos amount or fiber count was reported.
• Main results:
  • In residential house samples (S2), a silicon-oxygen stretching vibration at 1033 cm−1 in the infrared spectrum pointed to the presence of asbestos
  • Mass spectrometry identified a total of 19 organic compounds across the four types of indoor environment
  • Phthalate metabolites (phthalic acid, phthalic anhydride, monobutyl phthalate) were detected rather than parent phthalates
  • Benzophenone was detected in dust from photocopying centres (S1) and ATM cabins (S4)
  • Triethyl phosphate, a flame retardant, was detected in samples from photocopying centres (S1)
  • Suspected fungal metabolites and kynurenic acid were detected in residential house samples (S2)
  • Two pesticides, metaldehyde and ethofumesate, were detected in classroom samples (S3)
• The authors' conclusion: The authors concluded that the ATR-FTIR data supported the results from LC-Q-ToF-MS analysis
• Limitations the authors state:
  • Compound identities from mass spectrometry were tentative, based on online databases (ChemSpider and PubChem) rather than confirmed with standards

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