Method 5021A/8260B

Headspace Analysis for Volatile Organic Compounds by GC/MS

Method 5021 is a general purpose method for the preparation of volatile organic compounds (VOCs) purged into the headspace of soil/sediment and solid waste matrices and analyzed by GC/MS following Method 8260B procedures.  The method is applicable to a wide range of VOCs having high volatility.  A high volatility is required to effectively removethe VOCs from soil and solid matrices.

Typically, a 2 gram sample size is spiked with surrogate standards and allowed to equilibrate within the matrix at room temperature.  It is important to spike the standards into the sample prior to extracting the VOCs into the headspace.  The surrogate standards will give a measure of the efficiency of volatilizing the compounds.  The method does allow for the use of a matrix modifying solution to help preserve the samples but use of this solution is not required.  One hour prior to analysis the sample should be moved to the heated zone of the headspace analyzer.  The method does require collection and analysis of a field blank.

Samples that are high in oil content or organic sludge wastes will inhibit the partitioning of the VOCs into the headspace giving low surrogate recoveries.  Additionally, absorption potential of the soil, biological activity of the soil, and the soil composition may also affect the partitioning ability.

Once the VOCs are partitioned into the headspace, an aliquot of the headspace is analyzed using GC/MS.  Note that samples are also commonly analyzed by GC/FID (8015B).  Other GC techniques may be used as well.