Volatile organic compounds (VOC) are organic chemicals that have a high vapor pressure at ordinary room temperature, which means these compounds can evaporate or sublimate from the liquid or solid form and enter the surrounding air. Figure 1 shows the sources of Volatile Organic Compounds (2005. https://www.epa.gov/ ). Solvent and transport emissions are the major anthropogenic sources of VOC emission, which together account for roughly 60% of the total sources. For now, more than 180 organic pollutants have been found in groundwater, and the quantity and type of these compounds are still increasing as time goes on. Since many VOCs include alkanes, olefins in aliphatic and aromatic groups, oxygenated hydrocarbons, and halogenated hydrocarbons are strong oxidants (such as OH radicals, O₃) and toxic substances, they can cause environmental and side human health problems. These VOCs in water are carcinogenic, stable, and not easy to decompose, therefore, there is an urgent need to use effective detection methods to monitor the total content of the VOC.

Fig.1. Sources of Volatile Organic Compounds

Alfa Chemistry has experts with extensive experiences in the detection of VOC in water. We can provide various types of methods including gas chromatography, liquid chromatography and mass spectrometer to determine the content of VOC in water, and ensure the accuracy and reliability of the results.

Detection Service for VOC:

Detection Methods for VOC:

Fig.2. Gas Chromatograph-Mass Spectrometer（GC-MS）

Due to the low concentrations (few ppb to less than 1ppt) of VOC, the large diversity of VOC compounds and their different physical and chemical characteristics, measurements of VOC are challenging. A common technique is gas chromatographic (Fig.2) coupled with flame ionization detectors (FID) or a mass spectrometer (MS). We can optimize and specify the instrumentation as you need. Here are some technical introductions.

• Headspace gas chromatography:

  Headspace means that the gas sample can be transfered into the instrument under the protection of shielding gas by the special approach of heating samples. The technology convergence of headspace and gas chromatography significantly extends the application range of traditional gas chromatography.

• Liquid-liquid extraction gas chromatography:

  As a traditional method, it is still in use today. Although many original technologies of liquid-liquid extraction have been replaced, it is still widely used in chemical and pharmaceutical fields owing to its unique advantages.

• Gas chromatography mass spectrometer:

  Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. This is quite a breakthrough in the fields of biochemistry, organic chemistry, pharmaceutical chemistry as well as synthesis and catalysis, and it is also an analytical method with high sensitivity and specificity.

• A purge and trap with gas chromatography mass spectrometry:

  It is an efficient and highly sensitive technique in combination with gas chromatography mass spectrometry, which can separate numerous compounds simultaneously. Such technology integration provides a favorable basis for the detection of volatile organic compounds in water.

Alfa Chemistry is the technology leader of VOC detection and quantification. Our experts and chemists have been developing and implementing a wide variety of methods for testing VOC in water. Please contact us if you have any problems, we can also design a particular method for your special requirements. We have a dedicated custom analysis team, as well as well-equipped and advanced instruments. Glad to hear from you and look forward to cooperating with you.

References

• X Y Xu, Q Zhu. An Overview on Analytical Method of Volatile Organic Compounds in Water [J]. ENVIRONMENTAL SCIENCE. 2011 (12): 1-2.

• S Wang, J C Sun. The present situation and countermeasures of organic pollution in water in China [J]. M Marine Geology Letters. 2005, 21 (10): 5-10.