Determination of UV Filters in Seawater by Stir Bar Sorptive Extraction and Liquid Chromatography Tandem Mass Spectrometry Università di Genova

Transcription

1 Determination of UV Filters in Seawater by Stir Bar Sorptive Extraction and Liquid Chromatography Tandem Mass Spectrometry E. Magi, K. Nguyen,, C. Scapolla, M. Di Carro Università di Genova Dipartimento di Chimica e Chimica Industriale Sezione di Chimica Analitica ed Ambientale

2 Protezione dai Raggi UV: gli UV filters (sunscreens) Pelle Senza Filtri Filtri Inorganici (Riflessione) Filtri Organici (Assorbimento) Meccanismo d azione d dei filtri organici

3 UV FILTERS: AMBIENTE E SALUTE

4 UV filters with ED activity

5 Analytes extraction from water: Stir Bar Sorptive Extraction (SBSE) Magnetic Rod Glass jacket PDMS coating Polydimethylsiloxane Film thickness : 0.5mm (24( μl); length : 10mm Volume Sample campionabile volume : 10-50mL

6 SBSE: recovery of the analytes

7 SBSE parameters logk OW

8 Instruments & conditions HPLC Agilent 1200 SL various LC columns sub-2 μm particle size MS Agilent 6430 QQQ Acquistion mode: MRM

9 Chromatographic conditions ZORBAX Rapid Resolution (RRHT) Agilent SB RP-C 18 : 50x2.1mm 1.8mm Injection: 10 µl Flow: 0.4 ml/ L/min Temperature : 30 C Mobile phase: H 2 O (A); Methanol (B) Isocratic elution: 80% B - 20% A

10 Ionization source and polarity mode

11 Ionization source and polarity mode BP-3 OC OD-PABA EHMC HMS EHS Polarity : +/- (polarity switching) ESI APCI

12 APCI and ESI full-scan mass spectra APCI ESI

13 Effect of modifiers on ionization Tested Modifiers (0.1% in the mobile phase): : HCOOH, AcOH and HCOONH 4

14 MS/MS experimental parameters First transition Second transition Analyte Precursor ion (m/z) Product ion (m/z) Product ion (m/z) BP (+) OC 362 (+) OD-PABA 278 (+) EHMC 291 (+) HMS 261 (-) EHS 249 (-)

15 Figures of merit of APCI and ESI LOD (ng/ml) RSD (%) Correlation coeff. (R 2 ) (S/N = 3) Within-day Interday APCI ESI APCI ESI APCI ESI APCI ESI BP OC OD-PABA EHMC HMS EHS

16 Seawater analysis Calibration curves drawn using SBSE Sea water (analyte free) spiked at six concentration levels: ng/ml for BP-3, OC, OD-PABA and EHMC; ng/ml for HMS and EHS Very good linearity for all the analytes (R 2 > 0.997)

17 Seawater analysis RSD values in the range 3%-5%, for analytes in positive mode, 9% and 7% for HMS and EHS respectively LODs: 8-31 ng/l (analytes pos.), about 1 µg/l (analytes neg.) Recoveries close to 100% except for BP-3 (83%) and OC (71%)

18 Seawater collected during summer 2010 Four seaside resorts in Liguria Santa Margherita San Fruttuoso Camogli Swimming-pool (seawater) Three sampling (June, July, August) Two analytes detected and quantified concentration range ng/l T. Rodil et al. (Anal.Chem.( 2008) reported the concentration range ng/l for BP-4 4 and PBSA in seawater BP-3 EHMC

19 Conclusions & perspective The propsed method for the determination of six UV filters in seawater is rapid and sensitive (low ng/l for BP-3, OD-PABA and EHMC) SBSE is a simple and effective technique for the extraction and simultaneous preconcentration of these contaminants in seawater APCI provided better results than ESI for all analytes, with higher reproducibility and lower detection limits An extension of the method to wastewater is in progress; it will be applied to monitor wastewater treatment plants