An in-tube SPME device for the selective determination of chlorophyll a in aquatic systems

We report a new device for the estimation of the content of chlorophyll a pigment in water samples as an indicator of water quality. The extraction of the pigment from water was also optimized. 10 mL of water was filtered through a nylon filter (45 microm pore size and 13 mm of diameter), after the chlorophylls were dissolved by immersing the filter in 1 mL of a low non-hazardous solvent as ethanol. An in-valve in-tube SPME device coupled to capillary liquid chromatography with diode array detection was designed. A capillary column of 70 cm in length (0.32 mm i.d. coated with 5% diphenyl-95% polydimethylsiloxane, 3 microm coating thickness) was used as the loop of the injection valve for preconcentration and a Zorbax SB C(18) (SiO(2)-based) 150 mm x 0.5 mm i.d., 5 microm column (Agilent) was used as analytical column. The achieved detection limit was 0.05 microg L(-1) and the working range of concentrations was 0.1-1 microg L(-1). % RSD values between 2 and 11 were obtained. Chlorophyll a in several water matrices was determined with good results in presence of other pigments such as chlorophyll b, pheophytin a and pheophytin b.