Preconcentration on-line

Li, J. Thibault, P. Martin, A. Richards, J. C. Wakarchuk, W. W. der Wilp, W. Development of an on-line preconcentration method for the analysis of pathogenic lipopolysaccharides using capillary electrophoresis-electrospray mass spectrometry—Application to small colony isolates. J. Chromatogr. A 1998, 817, 325-336. 

V. Pichon, L. Chen, and M.C. Hennion, On-line preconcentration and liquid chromatographic analysis of phenylurea pesticides in environmental water using a silica-based immunosorbent. Anal. Chim. Acta 311, 429-436 (1995). 

P. Britz-McKibbin and S. Terabe, On-line preconcentration strategies for trace analysis of metabolites by capillary electrophoresis. J. Chromatogr.A 1000 (2003) 917-934. 

Quirino, J. P., Dulay, M. T, and Zare, R. N. (2001). On-line preconcentration in capillary electrochromatography using porous monolith together with solvent gradient and sample stacking. Anal. Chem. 73, 5557—5563. 

Starkey, J. A., Mechref, Y, Muzikar, J., McBride, W. J., and Novotny, M. V., Determination of salsolinol and related catecholamines through on-line preconcentration and liquid chromatography/atmospheric pressure photoionization mass spectrometry. Analytical Chemistry 78(10), 3342-3347, 2006. 

Ni [161] On-line preconcentration and simul- Natural water ICP-OES Super-modified ... 

M. C. Yebra and S. Cancela, Continuous ultrasound-assisted extraction of cadmium from legumes and dried fruit samples coupled with on-line preconcentration-flame atomic absorption spectrometry, Anal. Bioanal. Chem., 382(4), 2005, 1093-1098. 

M. Zougagh, P. C. Rudner, A. Garcia-de-Torres and J. M. Cano-Pavon, Application of Doehlert matrix and factorial designs in the optimisation of experimental variables associated with the on-line preconcentration and determination of zinc by flow injection inductively coupled plasma atomic emission spectrometry, J. Anal. At. Spectrom., 15(12), 2000, 1589-1594. 

H. Karami, M. F. Mousavi, Y. Yamini and M. Shamsipur, On-line preconcentration and simultaneous determination of heavy metal ions by inductively coupled plasma-atomic emission spectrometry. Anal. Chim. Acta, 509(1), 2004, 89-94. 

J. P. Quirino, M. T. Duylay, B. D. Bennett, and R. N. Zare, Strategy for On-Line Preconcentration in Chromatographic Separations, Anal. Chem. 

The calibration of atomic spectrometers can be handled much easier than that of conventional IC detectors using the large dynamic range of ICP techniques. Those simple off-line calibrations had been used for ICP-AES and ICP-MS in on-line preconcentration applications. With its ability to decide between isotopes the ICP-MS is well suited for isotope dilution analysis (IDMS), a calibration tool which increases the accuracy, the results and saves time due to reduced calibration work. The use of IDMS in combination with on-line coupling methods allows a significant speedup of the usually to IDMS applied time consuming separation processes. 

Epov, V. N., Benkhedda, K., Cornett, R. J., and Evans, R. D., Rapid determination of plutonium in urine using flow injection on-line preconcentration and inductively coupled plasma mass spectrometry, J. Anal. At. Spectrom., 20, 424-430, 2005. 

J. J. Vreuls, A. J. Bulterman, R. T. Ghijsen and U. A. Th Brinkman, On-line preconcentration of aqueous samples for gas chromatographic-mass spectrometric analysis , Analyst 117 1701-1705 (1992). 

Ion chromatography using spectrophoto-metric detection and on-line preconcentration gives an effective detection limit <1 g/L in aqueous samples. GFAAS is the method of choice for measuring low-ppb levels of aluminum in dialysis fluids (Andersen 1987, 1988 Woolfson and Gracey 1988). 

Tapparo A, Bombi GG. 1990. Ion chromatographic determination of trace amounts of aluminum with on-line preconcentration and spectrophotometric detection. Clin Chim Acta 238 279-284. 

Sperling, M., Xu, S. and Welz, B. (1992) Determination of chromium (III) and chromium (VI) in water using flow injection on-line preconcentration with selective adsorption on activated alumina and flame atomic absorption spectrometric detection. Anal. Chem., 64, 3101-3108. 

Spectrophotometric techniques combined with flow injection analysis (FIA) and on-line preconcentration can meet the required detection limits for natural Fe concentrations in aquatic systems (Table 7.2) by also using very specific and sensitive ligands, such as ferrozine [3-(2-bipyridyl)-5,6-bis(4-phenylsulfonic acid)-l,2,4-triazine], that selectively bind Fe(II). Determining Fe(II) as well as the total Fe after on-line reduction of Fe(III) to Fe(II) with ascorbic acid allows a kind of speciation.37 A drawback is that the selective complexing agents can shift the iron redox speciation in the sample. For example, several researchers have reported a tendency for ferrozine to reduce Fe(III) to Fe(II) under certain conditions.76 Most ferrozine methods involve sample acidification, which may also promote reduction of Fe(III) in the sample. Fe(II) is a transient species in most seawater environments and is rapidly oxidized to Fe(III) therefore, unacidified samples are required in order to maintain redox integrity.8 An alternative is to couple FIA with a chemiluminescence reaction.77-78... 

Blain, S. and R Treguer. 1995. Iron(II) and iron(BI) determination in sea water at the nanomolar level with selective on-line preconcentration and spectrophotometric determination. Anal. Chim. Acta 305 425-432. 

Wu, J.C.G. 1991. Interfacing HPLC and cold-vapor AA with on-line preconcentration for mercury speciation. Spectrosc. Lett. 24 681-697. 

Katarina, R.K., N. Lenghor, and S. Motomizu. 2007. On-line preconcentration method for the determination of trace metals in water samples using a fully automated pretreatment system coupled with ICP-AES. Anal. Sci. 23 343-350. 

Yebra, M.C., S. Cancela, and A. Moreno-Cid. 2005. Continuous ultrasound-assisted extraction of cadmium from vegetable samples with on-line preconcentration coupled to a flow injection-flame atomic spectrometric system. Int. J. Environ. Anal. Chem. 85 305-313. 

Morales-Munoz, S., J.L. Luque-Garcia, and M.D. Luque de Castro. 2004. Screening method for linear alkylbenzene sulfonates in sediments based on water Soxhlet extraction assisted by focused microwaves with on-line preconcentration/derivatization/detection. J. Chromatogr. A 1026 41 —46. 

I Ion exchange -resin column On-line preconcentration electrode Iodide selective electrode InM [328]... 

On-line preconcentration followed by liquid chromatographic separation and cold vapour atomic absorption spectrometry have been used to detect 0.5ppt methylmercuiy in non saline water [43],... 

Several different approaches to preconcentration and matrix elimination have been reported. A commercially available chelation system based on silica-immobilized 8-hydroxyquinoline has been used for on-line preconcentration and matrix separation [315,316]. Detection limits using a 90-fold concentration were 0.04 ng/dm3 for U to 6.3 ng/dm3 for Zn. 

A. Limbeck, J. Rendl, H. Puxbaum, ETA-AAS determination of palladium in environmental samples with on-line preconcentration and matrix separation, J. Anal. Atom. Spectrom., 18 (2003), 161D165. 

As regards fractionation methodologies for the selective determination of Pb and other metals compounds in wines, Lemos et al. [57] have developed a FIA method for the direct determination of available free Pb(II) and total Pb content in wine samples. Lead (II) was chemically retained on a packed polyurethane foam microcolumn, modified by immobilization of 2-(2-benzothiazolyazo)p-cresol (BTAC) and eluted with 0.1 M HC1. The eluate was determined on-line by FAAS. Total Pb was quantified after sample digestion with HN03 and H202, whereas free Pb was determined by direct sample on-line preconcentration and elution. No effect of ethanol on the enrichment procedures was observed. With a preconcentration factor of 26 an LoD of 1 xg l-1 was reached. Four red and three white wines of different origins were analyzed and the total Pb content varied from 8 to 42 p,g 1 1. 

The use of GC-MIP-AES is advantageous because it avoids the predecomposition step required in the AAS detection mode. The first applications of the MIP-AES detector for Hg speciation and detection were reported in the 1970s [27-29]. Despite the overall good detection ability of the detectors, however, most of the above methods require large sample volumes, tedious solvent extraction procedures, and usually lead to the final determination of only the Me-Hg species. The description of the feasibility of quantitative in situ aqueous ethylation of Hg2-1- and Me-Hg followed by on-line preconcentration and detection by atomic fluorescences pectro-metry (AFS) or AAS certainly produces a wealth of information since it allows all Hg species to be detected in the same chromatographic run. Also on-line speciation of Hg and Me-Hg by chromatography-AFS hydride generation (HG) was used [30]. 

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