Our research

VOC analysis using TD-GC-MS

TD-GC-MS is used for identification and quantification of non-methane volatile organic compounds (NMVOC’s). Thermal desorption (TD) provides analyte pre-concentration; gas chromatography (GC) allow analyte separation; mass spectrometry (MS) provided analyte identification and quantification. 

The UNSW Odour Lab operates a variety of these systems with varying capabilities for sample preparation (SPME, headspace, sorbent tubes) as well as mass spectroscopy set-ups (single tof, Q-tof, MS/MS).  

When coupled with an Odour Detection Port (ODP) it can provide additional functionality of odorant identification and prioritisation within a gas phase sample.

Applications 

This method allows the identification and quantification of VOCs from complex mixtures from a variety of sources. Analyses can run as targetted (SIM) or non-targetted (SCAN) depending on study purposes.   

VOC emissions from industrial processes, waste management systems, consumer products and packaging, food products, ambient conditions among others have been analysed.  

To find out more about these methods and potential applications, get in touch with Odour@unsw.edu.au

Relevant Publications 

• Fisher RM; Le-Minh N; Sivret EC; Alvarez-Gaitan JP; Moore SJ; Stuetz RM, 2017, 'Distribution and sensorial relevance of volatile organic compounds emitted throughout wastewater biosolids processing', Science of the Total Environment, vol. 599-600, pp. 663 - 670, http://dx.doi.org/10.1016/j.scitotenv.2017.04.129
  
• Sivret E.C., Wang B., Parcsi G., Stuetz R.M. 2016, Prioritisation of odorants emitted from sewers using odour activity values. Water Research 88, 308 – 321 https://doi.org/10.1016/j.watres.2015.10.020
• Murphy K.R., Parcsi G., Stuetz R.M. 2014, Non-methane volatile organic compounds predict odor emitted from five tunnel ventilated broiler sheds. Chemosphere 95, 423 – 432 https://doi.org/10.1016/j.chemosphere.2013.09.076

Olfactory-gas chromatography analysis

Odour detection ports have been coupled with a variety of analysis units to aid the identification of odour relevant compounds in complex mixtures.

The output of the gas chromatograph is split between the detector (usually MS) and the odour detection port (ODP).   

The ODP provides humidified flows of the GC output which can be sniffed by trained pannelists. Panellists note the times at which specific odour events occur and provide a description of the odour and an intensity rating. This can be conducted at the press of a button using GERSTEL software and instrument set-up. 

Applications

This technique has great potential in the identification of specific odorants in complex mixtures. Examples of its use include:  

• Identification of key odorants from industrial processes (biosolids processing, rubber processing) to inform odour management methods using Odour Wheels.  

• Identification of ‘unknown’ nuisance odorants that are challenging to identify analytically (e.g nuisance or musty type odours from drinking water, or packaging contamination).  

• Confirming the efficacy of odour control devices.  

To find out more about this technique, get in touch with Odour@unsw.edu.au

Relevant Publications 

• Kamarulzaman NH; Le-Minh N; Fisher RM; Stuetz RM, 2019, 'Quantification of VOCs and the development of odour wheels for rubber processing', Science of the Total Environment, vol. 657, pp. 154 - 168, http://dx.doi.org/10.1016/j.scitotenv.2018.11.451
• Fisher RM; Barczak RJ; Suffet IHM; Hayes JE; Stuetz RM, 2018, 'Framework for the use of odour wheels to manage odours throughout wastewater biosolids processing', Science of the Total Environment, vol. 634, pp. 214 - 223, http://dx.doi.org/10.1016/j.scitotenv.2018.03.352
  
• Barczak RJ; Fisher RM; Wang X; Stuetz RM, 2018, 'Variations of odorous VOCs detected by different assessors via gas chromatography coupled with mass spectrometry and olfactory detection port (ODP) system', Water Science and Technology, vol. 77, pp. 759 - 765, http://dx.doi.org/10.2166/wst.2017.569

Volatile sulfur compounds are a cause of many nuisance odour impacts. Quantification of these odorants can be complicated by transformation and non-targeted analysis.   

As such the UNSW Odour Lab has a specific unit targetting 11 key common volatile sulfur compounds. Coupled with the use of specific gaseous sulfur standards this allows for reliable quantification.  

Sulfur chemiluminescence converts sulfur compounds in the GC eluant to sulfur dioxide which can be detected by a photomultiplier.  

The unit is also coupled with an NCD for the analysis of nitrogen containing odorants. The unit allows for direct gas sampling using Markes AirServer and has a cold trap appropriate for sulfur compounds. 

Applications

This technique is widely used for the targetted analysis of challenging organic volatile sulfur compounds including mercaptans (methyl mercaptan, ethyl mercaptan) and sulfides (DMS, DMDS, DMTS). These are very common odorants in a variety of waste management industries (wastewater treatment, landfills, livestock).  

The method has been used to determine baselines for process operation as well as odour control device effectiveness 

To find out more about this technique, get in touch with Odour@unsw.edu.au, opens in a new window

Relevant Publications 

• Fisher RM; Le-Minh N; Alvarez-Gaitan JP; Moore SJ; Stuetz RM, 2018, 'Emissions of volatile sulfur compounds (VSCs) throughout wastewater biosolids processing', Science of the Total Environment, vol. 616-617, pp. 622 - 631, http://dx.doi.org/10.1016/j.scitotenv.2017.10.282
• Wang B., Sivret E.C., Parcsi G., Stuetz R.M. 2015, Determination of VOSCs in sewer headspace air using TD-GC-SCD. Talanta 137, 71 – 79 https://doi.org/10.1016/j.talanta.2014.11.072

Prior to the analysis of emissions, samples need to be collected from sources and transported to the laboratory.    

Emission collection  

Flux hood methods  

Fluxhoods are a common method for collecting emissions from passive surface such as liquid surfaces (lagoons, settling ponds) and porous media (biosolids, soils). They use a consistent sweep flowrate of an inert gas (N2) to generate an emissions in a controlled setting, removing effects of concentration and equilibria associated with headspace or passive systems.  

Wind tunnels are similar however use higher directionals sweep gas flowrates to simulate the effect of wind.   

Gas storage and transportation  

Gas sampling bags  

A variety of materials can be used to prepare gas sampling bags, in the UNSW Odour Lab, Nalophan and Tedlar bags are predominantly used. However, the stability of certain samples should be initially tested to determine the effect of transportation or storage times on compound recovery.  

Sorbent tubes 

Sorbent tubes allow the preconcentration and storage of volatile compounds. A variety of sorbent materials including Tenax TA, Carbotrap are available in the laboratory. Emissions can be collected in-situ or from sampling bags using vacuum pumps. However, stability of compounds, size of target analytes and humidity of samples should be evaluated prior to use.  

To find out more about these methods, get in touch with Odour@unsw.edu.au

Relevant Publications 

• Liu L; Abdala Prata Junior A; Fisher RM; Stuetz RM, 2022, 'Measuring volatile emissions from biosolids: A critical review on sampling methods', Journal of Environmental Management, vol. 317, pp. 115290, http://dx.doi.org/10.1016/j.jenvman.2022.115290
  
• Le H.V., Sivret E.C., Parcsi G., Stuetz R.M. (2015) Impact of storage conditions on the stability of volatile sulfur compounds in sampling bags. Journal of Environmental Quality 44, 1523 – 1529 https://doi.org/10.2134/jeq2014.12.0532

Siloxane analysis using Q-Tof (Targeted analysis)

The UNSW Odour Lab operates a variety of GC-MS systems that can be set-up for the targeted analysis of key analytes for different applications.  

An example of which is the identification and quantification of siloxane type compounds, which are common problematic contaminants in biogas.  

Applications 

Based on industry requirements, a method was developed in-house for the accurate quantification of siloxanes in biogas produced from wastewater treatment plant anaerobic digesters and landfills.   

Siloxanes are found in many consumer and laboratory products, and volatile components can become concentrated in biogas streams. When these compounds are combusted to recover energy, it can lead to increased maintenance due to silica deposition in equipment.  

To find out more about these methods and potential applications, get in touch with Odour@unsw.edu.au.