cFI: Colorimetric Assay of Chloride
This assay is an example of a single reagent method characterized by a fast reaction rate, which uses the simplest one line manifold and a constant flow rate. (cFI). The sampling frequency of 110s/hr is typical with repeatability of +/- 1%. Higher sensitivity and better LOD will be obtained by using flow cell with a longer light path and by flow programming (pFI).
1.1.5.
Chloride ions react with mercury thiocyanate reagent, liberating thiocyanate which in turn reacts with iron(III), forming a red-colored complex.The analog output on the left shows a series of chloride standards, each injected four times to document reproducibility of the measurement. Injected sample volume was 30 mL, reagent consumption and waste generation was less than 0.5 mL per assay. 1 cm light path. A single peak displayed on the right, obtained with 75 ppm Cl standard, shows less than 1% carryover, 38 seconds after sample injection. Reproduced from student laboratory experiments (Ruzicka & Hansen 1988).
J. Ruzicka & E.H. Hansen, “Flow Injection Analysis” 2nd ed. J. Wiley, N.Y. 1988
