Liquid chromatography on-line

Hansen, S.H. et al.. High-performance liquid chromatography on-line coupled to high-field NMR and mass spectrometry for structure elucidation of constituents of Hypericum perforatum L., Anal. Chem., 71, 5235, 1999. 

Apffel, A. Chakel, J. Udiavar, S. Hancock, W. S. Souders, C. Pungor, E. Jr. 1995. Application of capillary electrophoresis, high-performance liquid chromatography, on-line electrospray mass spectrometry and matrix-assisted laser desorption ionization—time of flight mass spectrometry to the characterization of single-chain plasminogen activator. . /. Chromatogr. A, 717,41-60. 

Wu, S. L. Wang, Y. J. Hu, J. Leung, D. 1997. The detection of the organic extractables in a biotech product by liquid chromatography on-line with electrospray mass spectrometry. PDA J. Pharm. Sci. Technol., 51, 229-237. 

L. N. Liang, G. B. Jiang, J. G. Liu, J. T. Hu, Speciation analysis of mercury in seafood by using high-performance liquid chromatography on-line coupled with cold-vapor atomic fluorescence spectrometry via a post column microwave digestion, Anal. Chim. Acta, Ml (2003), 131-137. 

Wangkam, S., Pergantis, S. A. High-speed separation of arsenic compounds using narrow-bore high-performance liquid chromatography on-line with inductively coupled plasma mass spectrometry. J Anal At Spectrom 2000, 15, 627-633. 

Wei, M.-C., et al., Determination of organic acids in fermentation products of milk with high performance liquid chromatography/on-lined micro-dialysis, Chwmatographia, 54, 601, 2001. 

The content of this chapter focuses on the analysis of intact polar lipids by high-pressure liquid chromatography (HPLC) with flow or loop injection -and mass spectrometry (MS) or tandem mass spectrometry (MS-MS) using thermospray (TS), discharge-assisted TS [or plasmaspray (PSP)], electrospray (ES) and atmospheric pressure chemical ionization (APCI). It was intended to include only those papers describing the analysis of intact polar lipids by liquid chromatography on-line with MS. However, many papers describe flow or loop injection with MS and/or the analysis of derivatives of polar lipids. These papers, describing excellent applications of MS and/or MS-MS of polar lipids, are included since this chapter would not have been complete without them. 

The checkers used a 40-cm. spinning-band column. The product, n2bD 1.4237, was shown to be 98.9% pure by gas-liquid chromatography on a 6-ft. 20% fluorosilicone column. The retention time was 3.75 minutes with a flow rate of helium of 100 ml. per minute, and a column temperature of 125° with the injection port at 170°. The 19 F n.m.r. spectrum (56.4 MHz) consists of four lines of equal intensity centered at +3396 Hz from trichlorofluoromethane (internal) and two sets of two overlapping quartets centered at +4369 Hz and +4461 Hz, respectively. The integrated intensities of the three sets of fluorine resonances are 3 1 1. 

T. Storm, C. Hartig, T. Reemtsma and M. Jekel, Exact mass measurements on-line with high-performance liquid chromatography on a quadrupole mass spectrometer. Anal. Chem., 73 (2001) 589-595. 

Liquid chromatography on a chiral support occupies a special place in the study of atropisomers since analytical conditions may be easily scaled up to collect optically pure samples for off-line studies. Subambient... 

Another development arising from FAB has been its transformation from a static to a dynamic technique, with a continuous flow of a solution traveling from a reservoir through a capillary to the probe tip. Samples are injected either directly or through a liquid chromatography (LC) column. The technique is known as dynamic or continuous flow FAB/LSIMS and provides a convenient direct LC/MS coupling for the on-line analysis of mixtures (Figure 40.2). 

Figure 2.17 Schematic representation of the set-up used for on-line liquid-liquid exti action coupled with capillary GC when using a membrane phase separator. Reprinted from Journal of High Resdution Chromatography, 13, E. C. Goosens et al., Determination of hexachloro-cyclohexanes in gi ound water by coupled liquid-liquid extraction and capillaiy gas cliro-matography , pp. 438-441, 1990, with permission from Wiley-VCH.

Coupled liquid chromatography-gas chromatography is an excellent on-line method for sample enrichment and sample clean-up. Recently, many authors have reviewed in some detail the various LC-GC transfer methods that are now available (1, 43-52). For the analysis of normal phase eluents, the main transfer technique used is, without doubt, concurrent eluent evaporation employing a loop-type interface. The main disadvantage of this technique is co-evaporation of the solute with the solvent. 

Figure 5.2 Schematic representation of the final column-switching system (a) foi ward-flush position (b) back-flush position (further details are given in the text). Reprinted from Journal of Chromatography, A 828, A. K. Sakhi et al. Quantitative determination of endogenous retinoids in mouse embiyos by high-performance liquid cliromatography with on-line solid-phase exti action, column switcliing and electi ochemical detection , pp. 451 -460, copyright 1998, with permission from Elsevier Science.

Figure 5.3 Analysis of 100 ml of (a) surface water and (b) drinking water sample spiked with 0.1 pig/ml of microcystins, using column-switching HPLC 1, microcystin-RR 2, microcystin-YR 3, microcystin-LR. Reprinted from Journal of Chromatography A, 848, H. S. Lee et al, On-line trace enrichment for the simultaneous determination of microcystins in aqueous samples using high performance liquid chromatography with diode-array detection , pp 179-184, copyright 1999, with permission from Elsevier Science.

W. Haasnoot, M. E. Ploum, R. J. A. Paulussen, R. Schilt and F. A. Huf, Rapid determination of clenbuterol residues in urine by high perfoi mance liquid cliromatography with on-line automated sample processing using immunoaffinity chromatography , 7. Chromatogr. 519 323-335 (1990). 

G. S. Rule, A. V. Moi dehai and J. Henion, Determination of carbofuran by on-line immunoaffinity cliromatography with coupled-column liquid chromatography/mass spectrometiy . Aim/. Chem. 66 230-235 (1994). 

S. Palmarsdottir and L. E. Edholm, Enhancement of selectivity and concentration sensitivity in capillary zone electrophoresis by on-line coupling with column liquid chromatography and utilizing a double stacking procedure allowing for microliter injections , 7. Chromatogr. 693 131-143 (1995). 

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