Analysis of Microbial Volatile Organic Compounds (MVOCs)

“Sick Building Syndrome” (SBS) occurs frequently in airtight buildings, but there are also a wide variety of factors that triggers the health problems. Numerous investigations have shown that micro-organisms may play an important role. Studies have shown that there was a high correlation between home dampness indicators and respiratory health problems. There were also indications that volatile organics from microbial cultures has an impact on cilial cells in respiratory airways.

Typically, a musty and earthy odour is the first sign of microbial activity. The microbial activities usually result in the decomposition of complex organic compounds into simpler compounds, and, in so doing, producing a wide range of by-products including the MVOCs. Some of these compounds are unique to micro-organisms; some can be the natural components of building materials that they grow on; and others are the same as common indoor air pollutants. The microbial volatile organics are so diverse that they encompass many chemical classes. In addition, there is no fixed MVOC pattern as the microbial emissions are different depending on the specific species, the substrates and the environment.

Determination of MVOCs is a useful way to check for the presence of mold. In many situations where spores of the micro-organisms are absent, the presence of unique MVOCs can be used to indicate the microbial activities.

Although many MVOCs have been reported in the literature, a lot of them are also known from indoor sources such as furnishings and building materials. In order to distinguish microbial volatiles from other sources, it is of utmost importance to choose compounds that are unique to microbial origin to determine the presence of microbial activities. Currently, other laboratories have used a list of VOCs as markers of the microbial activities, however, more often only a few of them were found in the air sample and the results are not conclusive. When MVOCs are present, there are often a number of higher molecular weight microbial compounds present. The detection of these compounds (listed in Table 2) in conjunction with some of the compounds in the target list will give a clear indication of microbial growth.

Normally, the concentrations of MVOCs in indoor air are very low. The use of a solvent extraction technique will often lead to false negative results. The thermal desorption GC/MS technique offers full scan capability with a thousand-fold increase in sensitivity. Not only can MVOCs be detected, but sesquiterpenes from micro-organisms activities can also be identified. Below is a summary of the method used and the MVOCs/Sesquiterpenes that are targeted for:

Microbial Volatile Organic Compounds Method

Data Analysis

Table 1 Target MVOC List

3-Methyl Furan
2-Methyl Isoborneol

Table 2 Qualitative List

1Furan, 3-methyl1,6,10,12,18,19
21-Propanol, 2-methyl-1,2,3,10,11,12
4Furan, 2-ethylIH
6Furan, 2,4-dimethyl1
10Fenchyl alcohol9
133-Hexanone, 4-methyl1
14Benzene, methoxy-9
211-Hexanol, 2-ethyl1,5,6,20
22Cyclohexanone, 3-butylIH
251-Octanol, 2-methyl8
302-Boranone (Camphor)IH
312-Norpinone, 3,6,6,-trimethylIH
33Octanoic acid2,21
37Bornyl acetateIH

References for Microbial Volatile Organic Compounds

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  14. Kaminski, E. et al. Identification of the Predominant Volatile Compounds Produced by Aspergillus flavus. Applied Microbiology. Nov. 1972, Vol. 24, 3, 721-726
  15. Kaminski, E. et al. Volatile Flavor Compounds Produced by Molds or Aspergillus, Penicillium, and Fungi imperfecti. Applied Microbiology. June 1974, Vol. 27, 6 1001-1004
  16. Norrman, J. A Gas Chromatographic Investigation of the Influence of Different Carbon Sources on the Production of Volitile Comounds by Dipodascus aggregatus. Arch. Mikrobiol. 1971,Vol. 28, 75, 145-162
  17. Bjurman, J., Release of MVOCs from Microorganisms in Organic Indoor Air Pollutants: Occurrence –measurement – evaluation T. Saithammer, Ediditor, Wiley-VCH: Weinheim, 1999, p. 259-273
  18. Gao, P. et al. Determination of Unique Microbial Volatile Organic Compounds Produced by Five Aspergillus Species Commonly Found in Problem Buildings, AIHA Journ. (63), 2002, p. 135 – 140
  19. Wessen, B and Schoeps, K., Microbial Volatile Organic Compounds – What Substances Can Be Found in Sick Buildings? Analyst, 1996 121 1203-1205
  20. Karahadian, C. et al. Volatile Compounds from Pencillium sp. Contributing Musty-Earthy Notes to Brie and Camembert Cheese Flavors, J. Agric Food Chem. 1985, 33 339-343
  21. Bjurman, J, Kristensson, J., Volatile Production by Aspergillus Versicolor as a Possible Cause of Odor in Houses Affected by Fungi, Mycopathlogia, 1992, 118:173-178