abstract
A novel microvolume UV–vis spectrophotometry method was proposed for the rapid determination of
total iron coupling with an efficient pretreatment method known as dispersive liquid–liquid microextraction
(DLLME). The basis of the method is a quantitative colorimetric reaction between ferrous iron and 2-
(5-bromo-2-pyridylazo)-5-(diethyl amino) phenol (5-Br-PADAP) after the reduction of Fe(III) to Fe(II) by
using ascorbic acid as reducing agent. Parameters related to the efficiency of microextraction, such as pH,
complexant concentration, the volume ratio of disperser solvent and extraction solvent were discussed
and optimized in detail. Under the optimized conditions, the absorbance was in proportion to iron concentration
in the range of 5–400 lg L1 with a correlation coefficient (R) of 0.9993. The limit of detection
(LOD) and limit of quantitation (LOQ) were 1.5 lg L1 and 5.2 lg L1
, respectively. The relative standard
deviation (RSD) for samples were 1.37– 4.42% (n = 3). Good recoveries of iron were obtained in the range
of 95.4–103.2% in food samples, 96.9–103.6% in water samples and 98.8–102.3% in Certified Reference
Material. The proposed method was rapid, reliable and high-selective for the determination of total iron
in food and water samples.