Sequential injection trace determination of iron in natural waters using a long-pathlength liquid core waveguide and different spectrophotometric chemistries

Ricardo N.M.J. Páscoa, Ildikó V. Tóth, António O.S.S. Rangel

Limnol. Oceanogr. Methods 7:795-802 (2009) | DOI: 10.4319/lom.2009.7.795

ABSTRACT: We developed a sequential injection analysis (SIA) method for the determination of iron in coastal, ground, and surface fresh waters using two different reagents (ferrozine and 1,10-phenathroline). The methodology uses a double-line SIA system to improve mixing conditions between sample and reagent solutions. A liquid waveguide capillary cell (LWCC) with 1.0 m pathlength, 550 µm i.d., and 250 µL internal volume was used to enhance the sensitivity of the determination. The detection limits for the ferrozine and 1,10-phenanthroline reagent were 0.15 and 0.35 µg L–1, respectively. The system provides a linear response up to 20 µg L–1 and has a high throughput rate (41 h–1), low reagent consumption, and also low effluent production for both reagents. The developed method was applied to natural waters (river, well, ground, potable, and sea waters) and one reference water sample.