Selective Determination of Iron in River Water and Standard Bovine Liver by Solvent Extraction with N‐Benzoyl‐N‐Phenylhydroxylamine Followed by Reversed‐Phase HPLC

Abstract

A selective method for determination of iron ions in river water and iron in standard bovine liver has been developed by reversed‐phase HPLC. An Iron (Fe) ion was quantitatively extracted into 4‐methyl‐2‐pentanone at pH 3.0±0.5 as N‐benzoyl‐N‐phenylhydroxylamine (BPHA) chelate. The extracted Fe‐BPHA chelate was then separated on a ODS column with an eluent of methanol/water/0.2 mol/L BPHA (78∶21∶1), and detected at 443 nm. The correlation coefficients of the calibration curves obtained with 5 mL Fe standards were more than 0.999 over the range of 10 ng/mL (ppb) to 10 µg/mL (ppm). The detection limit of Fe ion in 5 mL water was 2 ppb, which corresponded to 3 times the standard deviation of the blank peak area. Relative standard deviations of peak areas (N=5) for 5, 0.5, and 0.05 ppm Fe standards were 0.9, 0.8, and 0.9%, respectively. Analytical results of Fe ion in river water obtained by the presented method, showed good agreement with those by inductively coupled plasma‐atomic emission spectrometry (ICP‐AES). Fe concentration in standard bovine liver was determined to be 193 µg/g, which was coincident with the reference value (194±20 µg/g). Effects of foreign ions on the method were investigated with 55 metal ions. Almost none of the ions interfered, except for V(V), Ti(IV), and Sn(II).

Keywords:

• N-Benzoyl-N-phenylhydroxylamine
• Iron ion
• Solvent extraction
• High-performance liquid chromatography
• Bovine liver
• River water
• Photometric detection