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

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.

Spectrophotometric sensor system based on a liquid waveguide capillary cell for the determination of titanium: Application to natural waters, sunscreens and a lake sediment

“…To overcome these difficulties, in this work we propose the use of a liquid waveguide capillary cell (LWCC), a sample cell where the optical path length is increased without light attenuation [27], which enables to significantly increase sensitivity, in order to attain the direct determination (i.e., without a pre-concentration step) of trace levels of titanium in samples of different types (as natural waters, sunscreens and lake sediments). This approach was already successfully used in the determination of iron at low concentration levels [28]. The characteristics of this device permit total internal reflection of the light on the walls as the light conducting path is transparent to the wavelength of interest and has a refractive index higher than the walls material.…”