Volatile organic compounds (VOCs) are organic substances that evaporate at room temperature due to their low boiling point. Most VOCs are harmful to humans and the environment, so the Environmental Protection Agency (EPA) uses VOC analyzers to monitor and analyze VOCs for regulatory purposes. VOC monitoring can be performed using a handheld detector and a fixed monitor.
The analysis (and detection) is performed using a gas chromatograph, a liquid chromatograph, a mass spectrometer, and an autosampler with a balanced pressure injection. In this device, VOCs are analyzed using the following methods established by the EPA in the third update of “Test Methods for Assessing Solid Waste, Physical / Chemical Methods” (SW-486). Will be done.
Solvent extraction and direct injection
This method is highly regarded for its reliability and ability to reanalyze samples multiple times. Due to the low incidence of carryover between one sample and another, liquid extraction and direct infusion are commonly used for high concentration samples.
Headspace analysis (method 5021)
This method is used for compounds with high Henry’s law constants (the solubility of a compound is proportional to the pressure of the gas on the liquid). Examples of compounds for which this method of headspace analysis is not intended are methyl tert-butyl ether (MTBE) and ethylene dibromid (EDB).
Purge and trap (method 5035B)
This method is similar to the previous purge and trap methods promulgated by the EPA, except that raw soil cannot be added to the purge and trap mechanism. Instead, the soil needs to undergo a methanol extraction, adding an aliquot from the extraction to the mechanism. This improves the detection of low range hydrocarbons and high range halogen compounds.
Closed system purge and trap (method 5035)
This method is used to preserve the VOCs of soil samples between the time the soil samples are collected and the time they are analyzed in the laboratory. The soil is sealed in an airtight vial and analyzed without removing the seal. This is the process of detecting low VOC concentrations. However, detection of high VOC concentrations is limited to concentrations below 200 ug / kg.
These methods are the most common methods of VOC analysis, but they are not the only ones. Three infrequently used but approved SW-486 methods are vacuum distillation, azeotropic distillation, and hexadecane dilution-direct injection EPS compliant VOC analysis with comparable success in new or used laboratory equipment. I can.
Impact of VOCs on humans
In either case, VOCs can cause the following health conditions in the short term: dyspnea, dizziness, agitation. The impact of VOCs on humans is explained in several situations, including workplace practices, household items characteristics, and air quality. VOC analyzers are used to analyze air, water, soil, and product samples, responsible companies, and EPA. VOC analyzers are used to analyze air, water, soil, and product samples, responsible companies, and EPA. Reduces the threat of VOCs to the average person and the environment as a whole.