VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS
Commonly used techniques for VOC analysis are Purge & Trap and Static Head space. These conventional methods for VOC analysis often either fail, under estimate or over-estimate the true concentrations of VOCs, due to matrix effects. EPA Method 8261A or 5032 using Vacuum Distillation was developed as an alternate technique (to Methods 8260 / 5035 / 8240)for VOC analysis in non-water matrices such as soil, sediment, sludge, solid waste, biota, fish tissue, milk, pine needles, plastics, soft drinks, BTEX, MTBE and other Oxygenates. Method 8261A compensates for the matrix effects by using surrogate based matrix correction.
1,4 -Dioxane is a compound that has gained considerable analytical interest, ever since the US EPA classified it as a carcinogen. Most commonly used Method 8260 using Purge and Trap, provides very unreliable data for 1,4 -Dioxane analyses. Being a polar volatile organic compound (VOC), 1,4 -Dioxane has a low purge efficiency from water as compared to non-polar VOCs. Consequently, 1,4 -Dioxane has a poor purge and trap/GC-MS response. In addition, 1,4 -Dioxane gives poor response with headspace sample introduction technique due to its low volatility from water. EPA Method 8261A / 5032 using Vacuum Distillation is the most suitable & efficient technique to determine 1,4 -Dioxane in water, ground water and soil samples. Method 8261A is routinely able to achieve a detection level of less than 1 ppb for 1,4 -Dioxane.
Volatile organic compounds (VOCs) or Volatile organic analytes (VOAs) are some of the most ubiquitous and mobile surface contaminants found in our environment. Soil VOCs are of concern primarily as a potential source of groundwater contamination.
Many of the plastic materials used today outgas volatile organic compounds (VOCs) during light or heat exposure, due to de polymerization process. Several monomers such as vinyl chloride and styrene used in the polymerization reactions are toxic or even carcinogenic. VOC analysis in polymers is usually done by static head space. Although widely used, static head space lacks sensitivity, especially for those compounds that have very low vapor pressure.
Most plants and vegetation have the ability to emit volatile organics compounds (VOCs) from flowers, fruits and leaves. VOCs emitted from plants belong to low-molecular classes of terpenes, non-terpene aliphatics, phenylproponoids and benzenoids. Essential oils extracted from plants and containing these VOCs are widely used as flavorings and fragrances. Static headspace is normally used for their analysis in the food and perfume industry.
In all of the above applications, although the analytical requirements have increased dramatically, the sample preparation technology has not kept pace or changed since the early 1970s. With the introduction of the New Vacuum Distillation technique using EPA Method 8261, there will now be a dramatic improvement in the data quality related to VOC analysis.