Characterization of Odorants in an Air Wet Scrubber Using Direct Aqueous Injection-Gas Chromatography-Mass Spectrometry (DAI-GC-MS) and Solid Phase Extraction (SPE-GC)

Nawaf Abu-Khalaf,Kim F Haselmann

doi:10.5923/j.ajee.20120203.04

Abstract

One of the biological methods to reduce odours emission from livestock buildings is bioscrubber. Characterization (identification and quantification) of key odorants from an air wet scrubber in livestock buildings is presented. The key odorants represent five chemical groups, i.e. sulphides, alcohols, volatile fatty acids (VFAs), phenols and indoles. Direct aqueous injection (DAI) and solid phase extraction (SPE) methods were used for sample preparation before injecting the samples into the gas chromatography. Gas chromatography-flame ionization detection (GC-FID) was used for identification and quantification of samples prepared by DAI and SPE. The SPE method had a high recovery (i.e. 89-100%). However, DAI showed a better linearity, a lower limit of detection (LOD) and a lower limit of quantification (LOQ) than the SPE method. The DAI method was preferred for identification and quantification as it is cheaper, easier to handle, without sample preparation and highly applicable. For at least two odorants, i.e. phenol and 1-butanol, LOD and LOQ were below literature values for odorants detection limits in livestock buildings. Gas chromatography-mass spectrometry (GC-MS) was used to verify the identification of odorants, prepared by DAI, according to their m/z values.

Highlights

Odour is an important environmental pollution issue[1]
The objective of this study is to characterize the key odorants in an air wet scrubber, according to their odorants detection threshold cited by O’Neil and Philip[16] and Schiffman et al [3], by using Direct Aqueous Injection (DAI)-Gas chromatography-flame ionization detection (GC-FID) and SPEGC-FID and to compare the two methods with respect to the air wet scrubber application
The results of this study show that DAI is a convenient method for identification and quantification of odorants in the air wet scrubber

Summary

Introduction

Odour is an important environmental pollution issue[1]. An odour is defined as a sensation resulting from the reception of a stimulus by the olfactory sensory system[2, 3], whereas an odorant is the compound imparting an odour[4]. Due to the huge numbers of odorants, seven key odorants, representing five chemical groups, i.e. dimethyl sulphide represents sulphides, 1-butanol represents alcohols, n- butyric acid and iso-valeric acid represent volatile fatty acids (VFAs), phenol and 4-methyl phenol represent phenols and 3-methyl indole represents indoles (Table 1), were chosen as key odorants in this study They have an offensive odour, despite their presence in low concentrations in various livestock buildings[3, 16]. The objective of this study is to characterize the key odorants in an air wet scrubber, according to their odorants detection threshold cited by O’Neil and Philip[16] and Schiffman et al [3], by using DAI-GC-FID and SPEGC-FID and to compare the two methods with respect to the air wet scrubber application

Materials

Results and Discussion

Identification and Quantification of Compounds by DAI

Recovery and Breakthrough

Identification and Quantification of Compounds by SPE

Application and Perspectives