Instrument: 7000 Headspace Autosampler
Analysis of BTEX Compounds by USEPA Method 5021/8020 Using
Static Headspace
Method 5021 is a new method using static headspace for the analysis of soils that has been approved by the USEPA as an alternative to purge and trap Method 5030. This method addresses various characteristics of liquid and soil matrices. The analytes are separated from the matrix by way of thermodynamic equilibrium, where optimizing heat and time drives the BTEX compounds from the matrix into the headspace. Upon equilibrium, a fixed volume of headspace is taken and the analytes are transferred from Tekmar’s 7000 Headspace Autosampler to the Varian 3300 Gas Chromatograph with a Photoionization Detector (GC/PID). Data is processed by a PE Nelson 900 Interface module and quantitated with Turbochrome software in Windows. Static headspace coupled with Gas Chromatography/Mass Spectrometry has been used extensively in many applications, but this experiment proves that static headspace with a GC/PID gives results which surpass the requirements of USEPA Method 5021 and may be used by laboratories without access to mass spectrometers.
To monitor amounts of BTEX compounds in soils, a qualitative and quantitative method of analysis is needed. Tekmar’s 7000 Headspace Autosampler with GC/PID is the ideal instrumentation for BTEX compounds. Static headspace may also be used for the analysis of very dirty and foamy samples, high level samples, and for the laboratory in need of screening techniques. Applications of static headspace include trace analysis of volatiles, and the ability to analyze liquid matrices, solid matrices, and chemicals with boiling points up to 300ºC. Static headspace may be used as a gauge for partial pressure and is useful in industries of latex, resins, petroleum, food and flavors, medical, toxicological, and pharmaceutical specimens, and in the detection of analytes in chemical and environmental streams.
USEPA Method 5021 allows for the use of a GC or a GC/MS for the analysis of BTEX compounds. This study verifies that a GC/PID produces linear results for the initial calibration curve and excellent quality control data.
Matrix effects of soils can be measured by static headspace using average response factors. These results will explain the necessity of Matrix Modifying Solution (MMS) and support its importance.
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