A simple, sensitive and selective spectrophotometric method for determining iron in water samples

Abstract

We proposed a procedure for determining iron in various water samples employing molecular absorption spectrophotometry. The ligands used are 1-Nitroso-2-naphthol-3,6-disulphonic acid disodium salt (Nitroso R Salt) and Hexadecyl trimethyl ammonium Bromide (CTMAB). Iron can be determined by chromogenic reaction without redox pretreatment. The effects of temperature, acidity and the amount of reagent on the color reaction were studied. The linear correlation coefficient between iron concentration and absorbance is 0.9997. The limits of detection and quantification of method are 6.7 × 10−8 and 2.0 × 10−7mol/L, respectively. The molar absorption coefficient is 0.8 × 105 L. mol−1cm−1. Under selected conditions, common co-existing ions generally do not interfere with the determination of iron in water samples. Ten repeated determinations of Fe standard solution (8.0 × 10−6 mol/L) have shown that the relative standard deviation (RSD) is 0.61%. In the determination of the trace iron in actual samples, the RSDs are less than or equal to 3.1% (n = 4), and the recovery rate of standard addition method is between 92.8% and 108%. The proposed method is simple, economical, rapid, sensitive, accurate and highly selective, and can be used to determine iron contents in various water samples without pretreatment.