First application of microwave-assisted extraction in the analysis of polybrominated diphenyl ethers in human milk

As a method, microwave-assisted extraction (MAE) has a number of advantages over other extraction methods, such as lower solvent consumption and analyte loss, shorter processing time, and higher sample throughput. So far, however, MAE has mostly been applied with solid samples like sediments and soil. This paper describes the first MAE of organic pollutants from human milk samples, the influence of sample preparation and pretreatment, and how extraction conditions (type and volume of solvent, extraction temperature) were optimized. The most efficient way to extract polybrominated diphenyl ethers (PBDEs) from human milk using MAE was dissolving a freeze-dried sample in ultrapure water and applying a solvent mixture of n-hexane and acetone (1:1, v/v) with formic acid and 2-propanol as denaturing agents at 105 degrees C for 20 min. Extracts were cleaned up with concen-trated sulfuric acid and on SPE column containing neutral and acidified silica with n-hexane and dichloro-methane (4:1, v/v) as elution solvent. The method was validated at two concentration levels through parallel analysis by gas chromatography with two detection techniques and application in real samples and a baby formula (similar matrix). It has shown great potential for the analysis of organic pollutants in important bio-logical matrices such as human milk. Further optimization could extend its application to other classes of persistent organic pollutants (POPs).