自动牛奶脂肪萃取测定POPs
We have utilized an automated acid hydrolysis technology, followed by an abbreviated Soxhlet extractiontechniqueto obtain fat from whole milk for the determination of persistent organic pollutants, namelypolychlorinateddibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls. Theprocesssimply involves (1) pouring the liquid milk into the hydrolysis beaker with reagents and stan-dards,(2) drying the obtained fat on a filter paper and (3) obtaining pure fat via the modified Soxhletextractionusing 100 mL of hexane per sample. This technique is in contrast to traditional manually intenseliquid-liquidextractions and avoids the preparatory step of freeze-drying the samples for pressurizedliquidextractions. Along with these extraction improvements, analytical results closely agree betweenthemethods, thus no quality has been compromised. The native spike (n = 12) and internal standard(n= 24) precision and accuracy results are within EPA Methods 1613 and 1668 limits. While the median(n= 6) Toxic Equivalency Quotient (TEQ) for polychlorinated dibenzo-p-dioxins/polychlorinated diben-zofuransand the concentration of the marker polychlorinated biphenyls show a percent difference of 1%and12%, respectively, compared to 315 previously analyzed milk samples at the same laboratory usingliquid-liquidextraction. During our feasibility studies, both egg and fish tissue show substantial promiseusingthis technique as well