Ultrasonic Extraction

2015-03-16

ULTRASONIC EXTRACTION

SW846 is not intended to be an analytical training manual. Therefore, methodprocedures are written based on the assumption that they will be performed by analysts who areformally trained in at leastthe basic principles of chemical analysis and in the use of the subjecttechnology.In addition, SW846 methods, with the exception of required method use for the analysisof methoddefined parameters, are intended to be guidance methods which contain generalinformation on howto perform an analytical procedure or technique which a laboratory can useas a basic starting pointfor generating its own detailed Standard Operating Procedure (SOP),either for its own general useor for a specific project application. The performance dataincluded in this method are for guidancepurposes only, and are not intended to be and mustnot be used as absolute QC acceptance criteriafor purposes of laboratory accreditation.

1.0 SCOPE AND APPLICATION

1.1

This method describes a procedure for extracting nonvolatile and semivolatileorganic compounds from solids such as soils, sludges, and wastes. The ultrasonic processensuresintimate contact of the sample matrix with the extraction solvent.

1.2

This method is divided into two procedures, based on the expected concentrationof organic compounds. The low concentration procedure (Sec. 11.3) is for individual organiccomponentsexpected at less than or equal to 20 mg/kg and uses the larger sample size andthree serial extractions(lower concentrations are more difficult to extract). The medium/highconcentration procedure (Sec. 11.4)is for individual organic components expected at greaterthan 20 mg/kg and uses the smaller sample anda single extraction.

1.3

It is highly recommended that the extracts be subject to some form of cleanup(e.g., using a method from the 3600 series) prior to analysis.

1.4

Because of the limited contact time between the solvent and the sample, ultrasonicextraction may not be as rigorous as other extraction methods for soils/solids. Therefore, it iscriticalthat themethod (including the manufacturer's instructions) be explicitly, inorder to achieve the maximumextraction efficiency. See Sec. 11.0 for a discussion of thecritical aspects of the extraction procedure.Consult the manufacturer's instructionsregarding specific operational settings.

1.5

This method describes at least three extraction solvent systems that may beemployed for different groups of analytes (see Sec. 7.4). Other solvent systems may beemployed, providedthat adequate performance can be demonstrated for the analytes ofinterest. The choice of extraction solventwill depend on the analytes of interest and no singlesolvent is universally applicable to all analyte groups.As a result of concerns about theefficiency of ultrasonic extraction, particularly at concentrations near or belowabout 10 µg/kg, itis imperative that the analyst demonstrate the performance of the specific solvent system andoperating conditions for the analytes of interest and the concentrations of interest. Thisdemonstration applies toany solvent system that is employed,includingthose specifically listedin this method. At a minimum, such a demonstration will encompass the initial demonstration ofproficiency described in Method 3500, using a clean referencematrix. Method 8000 describes