Separation and determination of vanadium in fertiliser by capillary electrophoresis with a light-emitting diode detector

Abstract

A method has been developed for determination of vanadium, as an anionic ternary complex of vanadium(V) with 4-(2-pyridylazo) resorcinol (PAR) and hydrogen peroxide, after separation by capillary electrophoresis (CE). The optimum conditions for the formation of the ternary complex were acetate buffer (3 mmol L(-1)) at pH 6 containing 0.15 mmol L(-1) PAR and 7.1 mmol L(-1) H(2)O(2). The CE separation was conducted using 15 mmol L(-1) acetate buffer at pH 6 as the background electrolyte; the separation potential was -30 kV and the injection time 100 s. The vanadium complex was detected photometrically at 568 nm, by use of a light-emitting diode (LED); the detection limit was 19 ppb. The method was applied to the analysis of vanadium in fertilisers. Clean-up of the digested fertiliser sample, with Sep-Pak C(18) coated with tetrabutylammonium hydroxide, before analysis was used to remove matrix ions which otherwise caused electrophoretic de-stacking. Vanadium levels found in the fertiliser samples by use of the CE method were found to be comparable with results obtained by HPLC and ICP-MS.

Water Quality of Medium Size Watercourse Under Baseflow Conditions: The Case Study of River Sutla in Croatia

“…The comparison of the metal concentrations obtained at October 14th with the average concentrations obtained in three remaining samplings within the same site revealed 14-17 times increased concentrations of Ti and Cr, and 2-4 times increased concentrations of Co, Cu, Rb, K, and V. The presence of corn fields in the immediate vicinity of the last two sampling sites indicated that temporary concentration increases of specific metals could be the consequence of sporadic emissions or leaching of the waste manure in the river water. It can be further corroborated by the fact that K 2 O, copper sulfate, Co, and Ti are commonly used ingredients in fertilizers (Anke 2004b;Momčilović 2004;Schrauzer 2004;Anke and Seifert 2004), whereas some of the metals which were found increased are common contaminants of NPK fertilizers, e.g., V and Rb (Vachirapatama et al 2002;Senesi et al 1983). The number of enterococci in the river water at the sites 7 and 8 was also appreciably increased at October 14th (approximately 50 times; Fig.…”

Design and performance of a light‐emitting diode detector compatible with a commercial capillary electrophoresis instrument

“…A study of solute-wall interactions using this system was also performed [24]. Vachirapatama et al [18] achieved direct detection of vanadium-PAR (4-(2-pyridylazo)resorcinol) complexes at 568 nm. LODs of 19 ppb were reported and analysis of vanadium in fertilizer samples was performed.…”

“…One approach at optimizing the potential benefits of using highly absorbing probes is to use a light source with better characteristics in the visible region. Light-emitting diodes (LEDs) have found some use for this purpose [13,[15][16][17][18] because they emit strongly in the visible region (and for some recent examples, also in the high-UV region [17]), have near monochromatic output, are highly stable, have long lifetimes, and are very affordable. Unfortunately, there are currently no commercially available LED-based detectors for CE.…”

Sensitive determination of carbohydrates labelled with p‐nitroaniline by capillary electrophoresis with photometric detection using a 406 nm light‐emitting diode

“…The recent development of light-emitting diodes (LEDs) has been shown to offer considerable advantages over conventional light sources due to their superior stability and exceptionally low noise. We have made extensive use of LEDs in CE and our studies have shown that these two factors combine to provide a significant enhancement in sensi-tivity over conventional light sources [11][12][13][14][15][16][17][18]. In addition, LEDs are cheap, small and have an extended lifetime, thus enhancing their potential as light sources, particularly in the development of portable microfluidic systems.…”