Formation of a Liquid Organic Ion Associate in Aqueous Solution and Its Application to the GF-AAS Determination of Trace Cadmium in Environmental Water as a Complex with 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol

Micro-organic Ion-associate Phase Extraction/micro-volume Back-extraction for the Preconcentration and GF-AAS Determination of Cadmium, Nickel and Lead in Environmental Water

“…The effect of the pH on chelation formation is considered to be almost the same as in previous studies. 17,18 However, at pH 10 or higher, the IAP extraction/MVBE technique was affected by the alkali component, it seems that the alkaline component attached to the IAP lowered the acidity of the nitric acid solution and interfered with the back extraction. For further experiments, pH 9.0 ± 0.5 was selected.…”

“…5-Br-PAPS was chosen as a chelating reagent, as reported concerning a previous study. 17,18 The effect of the chelating reagent on the relative intensities of the metals was investigated by increasing the concentration of 0.4% 5-Br-PAPS from 0.1 to 0.8 mL (from 0.02 to 0.15 mmol/L). The chelating reagent solutions of 0.3 mL or less were not sufficient for complex formation with trace metals.…”

“…After discarding the aqueous phase, an additional cleanup step was performed to eliminate any interference from sea salt by washing the ionassociate by the supernatant liquid obtained by the centrifugation of a mixture of phenolsulphonate and benzethonium solutions, as reported in a previous study. 17 The entire preconcentration procedure was performed in 40 min.…”

“…In the present study, as an organic anion to form IAP, the phenolsulfonate anion was recommended because it served as a pH buffer component in previous studies. 17,18 As an organic cation to form IAP, the effect of the benzethonium cation's concentration was studied ranged from 0.1 to 2 mmol/L. The amount of the IAP formed increased with increasing the concentration of the benzethonium cation.…”

“…IAP extraction [14][15][16][17][18] is a unique technique for separating, enriching, and determining traces in water. This method was already applied for the separation and spectrophotometric determination of ammonia in river water, 14 nitrite in river water and seawater, 15 the HPLC determination of di(2-ethylhexyl)phthalate in river water, 16 the GF-AAS determination of Cd in river water and seawater, 17 and the liquid electrode plasma emission spectrometry (LEP-AES) determination of trace metals in waste water. 18 In the present work, to avoid the use of organic solvent for extraction and to reduce coexisting components in the concentrate, IAP extraction was combined with a micro-volume back-extraction technique (MVBE) with acids.…”