On-line sample pretreatment

Figure 11.16 Chromatograms of plasma samples obtained by using SPE-SFC with super-aitical desorption of the SPE cartridge (a) blank plasma (20 p.1), UV detection at 215 nm (b) blank plasma (20 p.1), UV detection at 360 nm (c) plasma (1 ml) containing 20 ng mitomycin C (MMC), UV detection at 360 nm. Reprinted from Journal of Chromatography, 454, W. M. A. Niessen et al., Phase-system switching as an on-line sample pretreatment in the bioanalysis of mitomycin C using supercritical fluid cliromatography, pp. 243-251, copyright 1988, with permission from Elsevier Science.

Scalia S, Pazzi P (1994) HPLC assay of conjugated bile acids in human fluids using on-line sample pretreatment on a standard isocratic chromatograph. Clin Chim Acta 224 181-190... 

Kim, C. S., Kim, C. K., Lee, J. I., and Lee, K. J., Rapid determination of Pu isotopes and atom ratios in small amounts of environmental samples by an on-line sample pretreatment system and isotope dilution high resolution inductively coupled plasma mass spectrometry, J. Anal. At. Spectrum., 15, 247-255, 2000. 

A. Farjam, R. de Vries, H. Lingeman and U. A. Th Brinkman, Immuno precolumns for selective on-line sample pretreatment of aflatoxins in milk prior to column liquid chromatography , Int. J. Environ. Anal. Chem. 44 175-184 (1991). 

W. M. A. Niessen, P. J. M. Bergers, U. R. Tjaden and J. van der Greef, Phase-system switching as an on-line sample pretreatment in the bioanalysis of mitomycin C using supercritical fluid chromatography , J. Chromatogr. 454 243 -251 (1988). 

Proper sample pretreatment methods are important to reduce or eliminate matrix effects. In this section, advances in sample pretreatment methods in relation to LC-MS quantitative bioanalysis are briefly reviewed (see also Ch. 1.5). Contrary to environmental analysis, where on-line sample pretreatment is often used (Ch. 7.3.2), off-line sample pretreatment appears to be preferred in quantitative bioanalysis. This is partly due to the composition of biological samples, where the presence of especially proteins may cause clogging of the SPE columns, cartridges or disks used, and partly due to the fact that decoupling sample pretreatment and LC-MS analysis generally allows for a higher sample throughput. 

A Farjam, GJ De Jong, RW Frei, UA Brinkman, W Haasnoot, ARM Hamers, R Schilt, FA Huf. Immunoaffinity pre-column for selective on-line sample pretreatment in high-performance liquid chromatography determination of 9-nortes-tosterone. J Chromatography 452 419-433, 1988. 

J. De Jong, A.J.F. Point, U.R. Tjaden, S. Beeksma and J.C. Kraak, Determination of catecholamines in urine (and plasma) by hquid chromatography after on-line sample pretreatment on small alumina or dihydroxyborylsilica columns, J. Chromatogr., 414, 285-300 (1987). 

V. Cerda, J.M. Estela, On-line sample pretreatment dissolution and digestion. Ch. 6, p. 129, in S.D. Kolev, I.D. McKelvie (Eds.), Advances in Flow Injection Analysis and Related Techniques, Wilson and Wilson s Comprehensive Analytical Chemistry, vol. 54, Elsevier, Amsterdam, 2008. 

Ohta, T. Takamiya, I. Takitani, S. Carbonic anhydrase-inunobilized precolumn for selective on-line sample pretreatment in high-performance liquid chromatographic determination of certain sulphon-amide drugs. Biomed.Chromatogn, 1994, 8, 184-188... 

Schoneshofer, M. Kage, A. Weber, B. New "on-line" sample-pretreatment procedure for routine liquid-chromatographic assay of low-concentration compoimds in body fluids, illustrated by triamcinolone assay. Clin.Chem., 1983, 29, 1367-1371 [column-switching LOD 5 ng/mL urine for triamcinolone]... 

Burguera JL and Burguera M (1998a) On-line sample pretreatment systems interfaced to electro-thermal atomic absorption spectrometry. Analyst (London) 123 561-569. 

Other on-line sample pretreatment methods can be combined with MS directly or before the separation column. For example, on-line hydrogen/deuterium exchange (UDX) could... 

Trojanowicz, M., P. Kozmiriski, H. Dias et al. 2005. Batch-injection stripping voltammetry (tubeless flow-injection analysis) of tracer metals with on-line sample pretreatment. Talanta 68 394-400. 

A variety of on line sample pretreatment procedures have been described for the coupling to on-line capillary zone electrophoresis (CZE)-MS, including capillary isotachophoresis, electrodialysis, liquid-liquid electroextraction and SPE on Empore disks. The latter system was applied to the analysis of the neuroleptic drug haloperidol in patients urine by on-line Empore-disk SPE-CZE-MS. 

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