On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma–optical emission spectrometry

Abstract

An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 degrees C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L(-1) nitric acid at a flow rate of 1.5 mL min(-1), directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 microg L(-1). The precision for 10 replicate determinations at the 2.0 microg L(-1)Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 microg L(-1). The method was successfully applied to the determination of dysprosium in urine.

Doehlert matrix for optimisation of procedure for determination of nickel in saline oil-refinery effluents by use of flame atomic absorption spectrometry after preconcentration by cloud-point extraction

“…In procedures using CPE, Br-PADAP has been used for determination of vanadium [18] mercuric [20], dysprosium [36], and gadolinium [37]. This paper proposes a preconcentration procedure for determination of nickel in saline aqueous waste samples by FAAS.…”

Micellar mediated trace level mercury quantification through the rhodamine B hydrazide spirolactam ring opening process

“…30 It has been shown to be an effective sample preconcentration technique for improving the sensitivity and selectivity prior to flame AAS, HPLC, capillary electrophoresis and flow injection analysis. [31][32][33][34] Application of surfactant not only facilitates sensitivity enhancement but also avoids the use of toxic solvents in absorbance measurements. This aspect means that it is in agreement with ''Green Chemistry'' principles.…”

Enhancement in sample preconcentration by the on-line incorporation of cloud point extraction to flow injection analysis inside the chemiluminescence cell and the determination of total serum bilirubin

“…Therefore, compared to the results obtained by other authors [6][7][8][9][10][11][12][13], the present on-line CPE/FIA system had many advantages, such as high sensitivity, high sample throughput, high extraction efficiency and simplicity. Experimental factors which govern the magnitude of the preconcentration factors and the CL intensity were studied.…”

“…When compared to all the reported on-line CPE/FIA papers [6][7][8][9][10][11][12][13], the key difference/improvement of the present on-line CPE/FIA system was that the collection column served a dual function: (1) to entrap the analyte-containing surfactant aggregates and (2) to provide CL emission (i.e., the collection column was mounted directly adjacent to the detector). Table 1 shows the effects on the CL intensity as a function of the presence (or absence) of the analyte (bilirubin), surfactant (Triton X-114), salting-out agent (Na 2 SO 4 ) and/or filtering material (cotton).…”

“…The analytical capability of this automated system was demonstrated for the determination of coproporphyrin in pretreated urine samples. Subsequently, this on-line CPE/FIA methodology was adopted by other researchers for the rapid and sensitive determination of metal species [7][8][9][10][11][12] and PAHs [13]. However, the preconcentration/enhancement factors reported were lower than that predicted by theoretical calculations [14].…”