Liquid–liquid extraction and cloud point extraction for spectrophotometric determination of vanadium using 4-(2-pyridylazo)resorcinol

Abstract

Liquid-liquid extraction (LLE) and cloud point extraction (CPE) of vanadium(V) ternary complexes with 4-(2-pyridylazo)resorcinol (PAR) and 2,3,5-triphenyl-2H-tetrazolum chloride (TTC) were investigated. The optimal conditions for vanadium extraction and spectrophotometric determination were identified. The composition (V : PAR : TTC) of the extracted species was 1 : 2 : 3 (optimal conditions; LLE), 2 : 2 : 2 (low reagents concentrations; LLE), 1 : 1 : 1 (short heating time; CPE), and 1 : 1 : 1 + 1 : 1 : 0 (optimal extraction conditions; CPE). LLE, performed in the presence of 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid and NH4F as masking agents, afforded the sensitive, selective, precise, and inexpensive spectrophotometric determination of vanadium. The absorption maximum, molar absorptivity, limit of detection, and linear working range were 559 nm, 1.95 × 10 5 dm 3 mol −1 cm −1 , 0.7 ng cm −3 , and 2.2-510 ng cm −3 , respectively. The procedure thus developed was applied to the analysis of drinking waters and steels. The relative standard deviations for V(V) determination were below 9.4 % (4-6 × 10 −7 mass %; water samples) and 2.12 % (1-3 mass %; steel samples).

Application of 4-(2-pyridylazo)resorcinol for flotation-spectrophotometric determination of iron

“…It forms colored complexes with many metal ions and can be used for their spectrophotometric determination. A well-known disadvantage of this reagent is its insufficient selectivity [1]. Commonly used approaches for increasing the selectivity are masking, precise pH control, introduction of additional reagents for the formation of ternary/multicomponent complexes, derivative spectrophotometry, and application of separation/preconcentration steps, which often demand expensive equipment, high running costs, and well-trained personnel.…”

Extraction-spectrophotometric and theoretical (Hartree-Fock) investigations of a ternary complex of iron(II) with 4-nitrocatechol and 2,3,5-triphenyl-2H-tetrazolium

“…The results showed that the extracted ternary complex has a composition of 1 : 1 : 2 (Fe-4NC-TTC). One can conclude that the Fe(II)-4NC anionic chelate has a double negative charge, since TTC forms monovalent cation (TT + ) [13,[15][16][17][18][19][20][21][22][23][24][25][26] and the Fe(II)-to-TTC molar ratio is 1 : 2 ( Fig. 5, 2).…”

“…We previously reported [13] a liquid-liquid extraction-chromogenic system containing Fe(III), 4NC, and a widely used [15][16][17][18][19][20][21][22][23][24][25][26] cationic ion-association reagent, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC). The next step, study of a similar system containing Fe(II) instead of Fe(III), is accomplished here.…”

Preconcentration and Determination of Trace Vanadium(V) in Beverages by Combination of Ultrasound Assisted-cloud Point Extraction with Spectrophotometry

“…In general, the most commonly used analyti-cal techniques are flame atomic absorption spectrometry (FAAS), 10,11,12 electrothermal atomic absorption spectrometry (ET-AAS), which is also known as graphite furnace AAS (GF-AAS), 13 inductively coupled plasma mass spectrometry (ICP-MS), 14,15 neutron activation analysis (NAA), 16 inductively coupled plasma-optical emission spectrometry (ICP-OES), 17 fluorometry, 18,19 requiring sample pretreatment steps such as ion-exchange, 20 solid phase extraction (SPE), 21,22 liquid phase microextraction (LPME), 23 and cloud point extraction (CPE). [24][25][26][27][28] CPE is superior to traditional solvent extraction because of its high extraction yield and preconcentration factor, and has several advantages such as simplicity, inexpensiveness, operational safety and use of non-toxic rea gents. 29,30 Before detection, CPE is used as a separation and preconcentration method using a surfactant to cause the generation of micellar surroundings and phase separation when a nonionic surfactant solution (or its mixture with cationic or anionic surfactant) as extractant is heated above the critical temperature.…”