title: Sequential injection-bead injection-lab-on-valve coupled to high-performance liquid chromatography for online renewable micro-solid-phase extraction of carbamate residues in food and environmental samples.
abstract: A sequential injection-bead injection-lab-on-valve system was hyphenated to HPLC for online renewable micro-solid-phase extraction of carbamate insecticides. The carbamates studied were isoprocarb, methomyl, carbaryl, carbofuran, methiocarb, promecarb, and propoxur. LiChroprep(®) RP-18 beads (25-40 μm) were employed as renewable sorbent packing in a microcolumn situated inside the LOV platform mounted above the multiposition valve of the sequential injection system. The analytes sorbed by the microcolumn were eluted using 80% acetonitrile in 0.1% acetic acid before online introduction to the HPLC system. Separation was performed on an Atlantis C-18 column (4.6 × 150 mm, 5 μm) utilizing gradient elution with a flow rate of 1.0 mL/min and a detection wavelength at 270 nm. The sequential injection system offers the means of performing automated handling of sample preconcentration and matrix removal. The enrichment factors ranged between 20 and 125, leading to limits of detection (LODs) in the range of 1-20 μg/L. Good reproducibility was obtained with relative standard deviations of <0.7 and 5.4% for retention time and peak area, respectively. The developed method has been successfully applied to the determination of carbamate residues in fruit, vegetable, and water samples.
authors.affiliation: Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Jitlada
authors.initials: J
authors.lastname: Vichapong
authors.forename: Rodjana
authors.initials: R
authors.lastname: Burakham
authors.forename: Supalax
authors.initials: S
authors.lastname: Srijaranai
authors.forename: Kate
authors.initials: K
authors.lastname: Grudpan
mesh_terms: D002219:Carbamates / Q000032:analysis* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D007306:Insecticides / Q000032:analysis* / Q000302:isolation & purification; D010573:Pesticide Residues / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction / Q000379:methods*; D014675:Vegetables / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D002219:Carbamates; D007306:Insecticides; D010573:Pesticide Residues; D014874:Water Pollutants, Chemical