Column separation and preconcentration

Actinide isotope analysis method development using FI technique for column separation and preconcentration ICP-MS 138... 

Schuster M and Schwarzer M (1998) A new online column separation and preconcentration system... 

FI manifolds for column separation and preconcentration in spectrophotometry are diverse, and there is hardly one which may be considered typical. However, the reader may refer to the manifold used in the determination of boron just mentioned (63]. Another interesting contribution by Novikov et al.[ll] combined ion-exchange column preconcentration with on-line solvent extraction followed by spectrophotometric detection. The eluate from the column preconcentration was released into an on-line liquid-liquid extraction system. An advantage of this approach is that interferences from Schlieren effects are avoided, since the eluate does not flow directly to the detector. Selectivity and sensitivity are also enhanced due to the combination of two separation procedures. The system has been used successfully for the determination of lead in alloys, soil leachates and sea water. 

Abstract A preconcentration method using Amberlite XAD-16 column for the enrichment of aluminum was proposed. The optimization process was carried out using fractional factorial design. The factors involved were pH, resin amount, reagent/metal mole ratio, elution volume and samphng flow rate. The absorbance was used as analytical response. Using the optimised experimental conditions, the proposed procedure allowed determination of aluminum with a detection limit (3o/s) of 6.1 ig L and a quantification limit (lOa/s) of 20.2 pg L, and a precision which was calculated as relative standard deviation (RSD) of 2.4% for aluminum concentration of 30 pg L . The preconcentration factor of 100 was obtained. These results demonstrated that this procedure could be applied for separation and preconcentration of aluminum in the presence of several matrix. 

Miniaturization of HPLC-ICP-MS is an important issue in bioanalytical chemistry when small amounts of sample (e.g., single cells) need to be investigated.33 ICP-MS (with an octopole collision cell) in combination with nano-HPLC (75 pun column) was optimized for the detection of selenopeptides in a selenium-yeast protein digest after 100-fold preconcentration on a C18 capillary precolumn (300 (im column for salt removal and cleanup).34 Under identical separation and preconcentration conditions, electrospray MS/MS (using Nanospray qQqToF-MS - QSTAR from Applied... 

In 1994, Dadfarnia and McLeod described the analysis of uranium in surface waters and sea water using a simple FI system with an alumina column for preconcentration.77 Species eluted from this column were delivered to an ICP-MS as the detector. Also in 1994, Hollenbach et al. described the automation of extraction chromatographic methods based on TRU-Resin and TEVA-Resin to separate and preconcentrate U, Th, and Tc from soil samples, using ICP-MS for detection.49125 In 1996, Aldstadt et al. described the use of FI and extraction chromatography using TRU-Resin to determine U in environmental samples by ICP-MS.78... 

Guedes da Mota, M. M., Rdmer, F. G., Griepink, B. Automated separation and preconcentration of copper II from natural waters using a column treatment. Z. Anal Chem. 287, 19(1977)... 

Many different trace/matrix separation procedures are also applied prior to the ICP-MS determination, or even on-line (e.g. Muller and Heumann 2000). ID finds increasing application in combination with ICP-MS, thereby reducing the problems of analyte losses in sample preparation, but not the problem of interferences in the ICP-MS measurements (e.g., Yi and Madusa 1996) and that of contamination during sample preparation. Schuster and Schwarzer (1998) have described a new very versatile online capable column t/m-separation and preconcentration procedure for the selective separation and preconcentration of Pd even from solutions containing high concentrations of the other PGM. Moldovan et al. (2003) recently published another method for on-line preconcentration and determination of Pd using ICP-MS. 

The general merits of FI separation and preconcentration summarized in Chapter 1 are all well demonstrated by FI sorption column techniques. The technique is inherently easier to operate than other separation methods, and the equipment generally more robust. An additional benefit over other separation techniques is its extremely high versatility, owing to the availability of a broad range of choice for different sorbents, complexing systems, and eluents. However, there are some restrictive features which are characteristic... 

FI on-line column separation and/or preconcentration have been applied to various detection systems, including atomic absorption and ICP spectrometers, spectrophotometers and electrochemical detectors. The basic components of the manifolds for different detection systems are quite similar, usually consisting of the following parts ... 

Although applications for column separation or preconcentration systems coupled to chemiluminescence determinations are few, published reports show no particular difficulties in such applications, except for the requirement of an adjustment of the chemical conditions of the eluate to suit the chemiluminescence reaction. Interferences due to refractive index effects are not likely to occur, owing to the often used spiral shape of the chemiluminescence flow-cell and to the fact that light emission is measured perpendicular to the direction of the flow. Therefore, column washing is usually not as important as for spectrophotometric applications, so that time-based sample loading manifolds such as those used for flame AAS may be used to advantage for improving the concentration, efficiencies. 

Sperling el al.IlO] determined nickel in CASS-1, CASS-2, NASS-2 standard reference sea water samples by ETA AS after on-line separation and preconcentration of its DDC complex on Cig column, achieving a detection limit of 0.04 /ig The method is sufficiently sensitive to determine nickel in de-ionized water. Almost the same detection limit was obtained by Porta et al.fll] in the determination of nickel in Antarctic sea water, using a similar approach which involved sorbing the APDC complex on a Cix column. 

A standard ASTM method for the determination of Np, Th, and in urine is based on ICPMS measurement of these radionuclides after the sample is wet-ashed and the nuclides are separated and preconcentrated on a chromatographic resin column (C1614 2010). It is stated that due to isobaric interferences and limits on sensitivity some of the other actinides of interest ( Pu, Am, and U) cannot be assayed by this ICPMS procedure. In this case, the main advantage of ICPMS over... 

Packed columns have been used ever since the earliest flow techniques were developed for purposes such as treating samples with solid reagents, saving reagents (e.g. immobilized enzymes) or, especially, separating and preconcentrating analytes. 

The use of LOV allows the bead injection process, so that the replacement of the resin packing was performed automatically. Contrary to the longer manual protocol to isolate Sr which lasts days, the automatic separation and preconcentration system allowed analyzing up to five samples per hour depending on the preconcentrated volume. The analytical protocol started with the automatic filling of the microcolumn with Sr-resin. Then it was conditioned with 2 ml of 8 mol/1 nitric acid. Once the column was ready, a variable volume of sample was dispensed toward the column. An additional volume of 0.5 ml of conditioning solution was propelled in order to eliminate interferences. After that, the elution of Sr was carried out dispensing 5.1 ml of 0.01 mol/1 nitric acid. For the radiostrontium quantification, the eluate was dried and measured in a LBPC. 

Online separation and preconcentration of thorium and uranium was carried out by means of UTEVA resin. LOV made possible the full automation of the system by the online regeneration of the column. Figure 8.10 shows a scheme of the flow system configuration. 

Fig. 19. Separation of ethanol and water from an ethanol—water—benzene mixture. Bottoms and are water, B is ethanol, (a) Kubierschky three-column sequence where columns 1, 2, and 3 represent the preconcentration, azeotropic, and entrainer recovery columns, respectively, (b) Material balance lines from the azeotropic and the entrainer recovery columns, A and E, respectively, where represents the overall vapor composition from the azeo-column, 2 1SP Hquid in equiUbrium with overhead vapor composition from the azeo-column, Xj, distillate composition from entrainer...

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