title: On-line renewable solid-phase extraction hyphenated to liquid chromatography for the determination of UV filters using bead injection and multisyringe-lab-on-valve approach.
abstract: For the first time, an automatic sample pre-treatment/detection method is proposed for the multiclass determination of UV filters (namely, benzophenone-3, ethylhexylmetoxycinnamate, butylmethoxydibenzoylmethane and homosalate) in environmental samples. The new methodology comprises in-line solid-phase extraction (SPE) of the target analytes by exploiting the bead injection (BI) concept in a mesofluidic lab-on-valve (LOV) format, with subsequent determination by liquid chromatography (LC). The proposed microanalytical system, using a multisyringe burette as propulsion unit, automatically performed the overall SPE steps, including the renewal of the sorbent in each analytical cycle to prevent sample cross-contamination and the post-extraction adjustment of the eluate composition to prevent chromatographic band broadening effects. In order to expedite the LC separation, a C(18) monolithic column was applied and an accelerated isocratic elution was carried out by using a cationic surfactant as mobile phase additive. The LOV-BI-LC method was proven reliable for handling and analysis of complex matrices, e.g., spiked swimming pool water and seawater, with limits of detection ranging between 0.45 and 3.2 microg L(-1) for 9 mL sample volume. Linear calibration was attained up to 160 microg L(-1) for homosalate and up to 35 microg L(-1) for the other target analytes, with good reproducibility (RSD<13%, for 5 different SPE columns). The hyphenated scheme is able to process a given sample simultaneously and within the same time frame than the chromatographic separation/determination of the formerly pre-treated sample, providing concentration values every 9 min. Hence, the sample throughput was enhanced up to 33 times when compared with previously reported off-line SPE methods. A drastic reduction in reagent consumption and effluent production was also attained, contributing to the development of an environment-friendly analyzer.
authors.affiliation: REQUIMTE, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4099-030 Porto, Portugal.
authors.forename: Hugo M
authors.initials: HM
authors.lastname: Oliveira
authors.forename: Marcela A
authors.initials: MA
authors.lastname: Segundo
authors.forename: José L F C
authors.initials: JL
authors.lastname: Lima
authors.forename: Manuel
authors.initials: M
authors.lastname: Miró
authors.forename: Victor
authors.initials: V
authors.lastname: Cerdà
mesh_terms: D002713:Chlorine / Q000737:chemistry; D002853:Chromatography, Liquid / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D016014:Linear Models; D015203:Reproducibility of Results; D012623:Seawater / Q000737:chemistry; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000295:instrumentation* / Q000379:methods*; D013473:Sunscreening Agents / Q000032:analysis* / Q000737:chemistry; D013551:Swimming Pools
chemical_list: D013473:Sunscreening Agents; D002713:Chlorine