title: Extraction of pesticides, dioxin-like PCBs and PAHs in water based commodities using liquid-liquid microextraction and analysis by gas chromatography-mass spectrometry.
abstract: Water based samples such as flavored drinks, juices and drinking water may contain contaminants at ultra trace level belonging to different chemical classes. A novel, simple, low-cost and fast method was developed and validated for trace residue extraction of pesticides, dioxin-like PCBs and PAHs from water and water based samples followed by analysis through gas chromatography (GC) coupled with time-of-flight mass spectrometry (ToFMS). The extraction solvent type, volume; sample volume and other extraction conditions were optimized. This was achieved by extracting 10 mL sample with 250 μL chloroform by vortexing (1 min, standing time of 2 min) followed by centrifugation (6000 rpm, 5 min). The bottom organic layer (200 μL) was pipetted out, evaporated to near dryness and reconstituted in 20 μL of ethyl acetate+cyclohexane (1:9) mixture resulting in an enrichment factor of 400. The recoveries of all compounds were within 76-120% (±10%) with the method detection limit (MDL) ranging from 1 to 250 ng/L depending on the analyte response. The MDLs were 400 times lower than the instrument quantification limits that ranged from 0.4 to 100 ng/mL. The method was further validated in water based drinks (e.g. apple, lemon, pineapple, orange, grape and pomegranate juice). For the juices with suspended pulp, the extraction was carried out with 400 μL chloroform. The extract was analyzed by GC-ToFMS at both 1D and GC×GC modes to chromatographically separate closely eluting interfering compounds the effect of which could not be minimized otherwise. The resulting peak table was filtered to identify a range of compounds belonging to specific classes viz. polycyclic aromatic hydrocarbons, chlorinated, brominated, and nitro compounds. User developed scripts were employed on the basis of identification of the molecular ion and isotope clusters or other spectral characteristics. The method performed satisfactorily in analyzing both incurred as well as market samples.
authors.affiliation: National Research Centre for Grapes, P.O. Manjri Farm, Pune 412 307, India.
authors.forename: Soma
authors.initials: S
authors.lastname: Dasgupta
authors.forename: Kaushik
authors.initials: K
authors.lastname: Banerjee
authors.forename: Sagar
authors.initials: S
authors.lastname: Utture
authors.forename: Parijat
authors.initials: P
authors.lastname: Kusari
authors.forename: Sameer
authors.initials: S
authors.lastname: Wagh
authors.forename: Kondiba
authors.initials: K
authors.lastname: Dhumal
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kolekar
authors.forename: Pandurang G
authors.initials: PG
authors.lastname: Adsule
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D004147:Dioxins / Q000032:analysis / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D010575:Pesticides / Q000032:analysis / Q000302:isolation & purification*; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000302:isolation & purification*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000302:isolation & purification*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D004147:Dioxins; D010575:Pesticides; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls