Determination of iron(II) with 2-nitroso-5-diethylaminophenol by thermal lens spectrophotometry using a semiconductor laser as a light source

The concentration of Fe(II) ion is determined by chelation with 2-nitroso-5-diehtylaminophenol and liquid-liquid extraction into chloroform. Light absorption at 780 nm is measured with a thermal lens spectrophotometer equipped with a semiconductor laser as a light source. The enhancement factor achieved experimentally is 47. The detection limit of Fe(II) ion is 8.1 × 10^?9 M, which is 3–4 times better than that obtained by conventional absorption spectrometry, and is governed by the background signal originating from Fe(II) impurity in the reagent.