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

摘要

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_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 500cm~(-1) 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 40μg L~(-1) and 130 μg L~(-1) V(V), respectively. The precision of the method, in terms of standard deviation and relative standard deviation value, at a level of 10μgV(V)/5mL aqueous phase for n = 10 is found to be 0.26μgV(V) and 2.6%, respectively. The relative standard deviation (n = 6) for the determination of vanadate (VO_2~+) in some environmental and real human biological fluid samples is observed to be in the range 4.6-7.8%.