title: Automated milk fat extraction for the analyses of persistent organic pollutants.
abstract: We have utilized an automated acid hydrolysis technology, followed by an abbreviated Soxhlet extraction technique to obtain fat from whole milk for the determination of persistent organic pollutants, namely polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls. The process simply involves (1) pouring the liquid milk into the hydrolysis beaker with reagents and standards, (2) drying the obtained fat on a filter paper and (3) obtaining pure fat via the modified Soxhlet extraction using 100mL of hexane per sample. This technique is in contrast to traditional manually intense liquid-liquid extractions and avoids the preparatory step of freeze-drying the samples for pressurized liquid extractions. Along with these extraction improvements, analytical results closely agree between the methods, 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 dibenzofurans and the concentration of the marker polychlorinated biphenyls show a percent difference of 1% and 12%, respectively, compared to 315 previously analyzed milk samples at the same laboratory using liquid-liquid extraction. During our feasibility studies, both egg and fish tissue show substantial promise using this technique as well.
authors.affiliation: U.S. Food & Drug Administration, Arkansas Regional Laboratory, 3900 NCTR Road, Building 26, Jefferson, AR 72079, United States. Electronic address: Jeffrey.archer@fda.hhs.gov.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Archer
authors.affiliation: U.S. Food & Drug Administration, Arkansas Regional Laboratory, 3900 NCTR Road, Building 26, Jefferson, AR 72079, United States.
authors.forename: Roy G
authors.initials: RG
authors.lastname: Jenkins
mesh_terms: D000818:Animals; D001331:Automation; D004147:Dioxins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D005223:Fats / Q000737:chemistry / Q000302:isolation & purification*; D006868:Hydrolysis; D059625:Liquid-Liquid Extraction / Q000379:methods*; D008892:Milk / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D015203:Reproducibility of Results
chemical_list: D004147:Dioxins; D004785:Environmental Pollutants; D005223:Fats; D011078:Polychlorinated Biphenyls
keywords: Acid hydrolysis; Automated; Dioxins; Extraction; POPs