Determination of vanadium (V) employing a new combined single drop micro-extraction and diffuse reflectance Fourier transform infrared spectroscopy technique

Abstract

The present work deals with a new micro-extraction mode for the selective separation and determination of vanadium in the form of a metaloxy anionic species viz. vanadate (VO þ 2 ) using N 1 -hydroxy-N 1 ,N 2 -diphenylbenzamidine (HDPBA) reagent in to a single drop of dichloromethane and its subsequent and rapid diffuse reflectance Fourier transform infrared spectroscopic (DRS-FTIR) determination on potassium bromide matrix. The vibrational infrared peak at 500 cm À1 is selected for the quantitative analysis for the determination. The vanadate combines with the nitrogen and oxygen atoms of N 1 -hydroxy-N 1 ,N 2 -diphenylbenzamidine (HDPBA) and forms a selective 1 : 2, V(V) : HDPBA binary complex in acetic acid medium. The chemistry of pure vanadate and that of its HDPBA complex is discussed. The limit of detection (LOD) and the limit of quantification (LOQ) of the method are found to be 40 mg L À1 and 130 mg L À1 V(V), respectively. The precision of the method, in terms of standard deviation and relative standard deviation value, at a level of 10 mg V(V)/5 mL aqueous phase for n ¼ 10 is found to be 0.26 mg V(V) and 2.6%, respectively. The relative standard deviation (n ¼ 6) for the determination of vanadate (VO þ 2 ) in some environmental and real human biological fluid samples is observed to be in the range 4.6-7.8%.Keywords: single drop micro-extraction; DRS-Fourier transform infrared spectroscopy; quantitative determination of V(V); environmental and biological samples