Use of cryogenic trap and liquid chromatography-triple quadrupole mass spectrometry for indoor air analysis

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Title: Use of cryogenic trap and liquid chromatography-triple quadrupole mass spectrometry for indoor air analysis
Author: Barua, Shawon
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2019
Language: eng
Thesis level: master's thesis
Degree program: Kemian ja molekyylitieteiden maisteriohjelma
Master's Programme in Chemistry and Molecular Sciences
Magisterprogrammet i kemi och molekylära vetenskaper
Specialisation: ei opintosuuntaa
no specialization
ingen studieinriktning
Discipline: none
Abstract: Monitoring of indoor air quality (IAQ) is important because IAQ is directly related to human health and comforts. The purpose of this study was to develop a non-targeted approach for the screening of organic compounds present in indoor air. The sampling was done using cryogenic active and passive samplers, and the separation and analysis were done by using a liquid chromatograph coupled with a triple quadrupole mass spectrometer (LC-QQQ-MS). First, experimental design for sampling by variables, cooling temperature and sampling period was made and optimized to -15 ˚C and 120 minutes respectively to ensure efficient sample collection. For mass spectrometry in both positive and negative ionization modes, the ion source parameters, gas temperature, gas flow, nebulizer pressure and capillary voltage were optimized to 300 ˚C, 10 L/min, 45 psi and 4000 V respectively to enable as much detector response as possible facilitating detection and analysis of the compounds in the sample. The concentration of compounds in the raw sample being very low, one important step was to optimize the sample preparation method to enrich the sample for smooth detection and further analysis. Since the sample was collected in the form of condensate water, different sample preparation methods such as evaporation, liquid-liquid extraction (LLE) and solid-phase extractions (SPEs) with different cartridges were adopted for preconcentration. Comparing the outcomes from different sample preparation methods, it was found that sequential SPE using C2 and C18 cartridges gives maximum compound recovery, e.g., 1.5 and 2.6 times compared to evaporation and LLE respectively in positive ion mode, and 2.6 and 4.1 times in negative ion mode. Therefore, this methodology was adopted to analyze the condensate water samples from two sick houses in Finland. The results from the sick houses were compared with a reference house having no sick building syndrome (SBS) to look for potential compounds causing health issues. The data analysis was done using MZmine 2.3.4 software. Additionally, tandem mass spectrometric (MS/MS) acquisition parameters were optimized and product ions were determined as the initial step of identification of compounds in the sample of the first house. The methods developed in this work would be useful to analyze various natural samples including the analysis of outdoor air also.
Subject: Indoor air
cryogenic samplers
liquid chromatography-triple quadrupole mass spectrometry
condensate water
optimized sample preparation
tandem mass spectrometry

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