Turbulent flow chromatography

A new on-line approach to SPE is the use of so-called turbulent flow chromatography which combines rapid mobile phase linear velocities with larger particle sizes this approach was discussed in Section 3.5.9 in the context of breakdown of the conventional (van Deemter) rate theory. Whether or not the flow can truly be described as turbulent (Ayrton 1998), there is no question that eddies are formed that enhance the interactions of smaller molecules with the stationary phase. In contrast the large proteins and other biopolymers have rates of mass transfer from the liquid to stationary phase (C term in the van Deemter equation) that are too 

There are two different modes in which on-line extraction/clean-up by turbulent flow chromatography is performed (Zhou 2005). In the simpler mode, single column extraction, the analytical sample or primary extract is injected directly onto the extraction column and extracted directly onto the analytical column by the turbulent flow mobile phase that has high eluent strength (Section 4.4.2a), i.e., high organic content in the case of analytes to be analyzed by reverse phase HPLC. This 

Liquid samples can be directly injected onto the system, while tissue samples require a crude extraction and sedimentation prior to analysis. TFC is also effective at separating residues that are bound to sample proteins. The use of TFC eliminates time-consuming sample cleanup in the laboratory and results in a much shorter analysis time, higher productivity, and reduced solvent consumption without sacrificing sensitivity or reproducibility. 

Despite these advantages, only a limited number of TFC applications for residue analysis have been reported in the literature. This is most likely due to the cost of the instrumentation and the limited number of vendors. Mottier et al. reported a TFC-LC-MS/MS method for 16 quinolones in honey. The method is particularly 

Stolker et al. described an analytical method based on TFC-LC-MS/MS for the direct analysis of 11 veterinary drugs (belonging to seven different classes) in milk. The method was applied to a series of raw milk samples, and the analysis was carried out for albendazole, difloxacin, tetracycline, oxytetracycline, phenylbutazone, salinomycin-Na, spiramycin, and sulfamethazine in milk samples with various fat contents. Even without internal standards, results proved to be linear and quantitative in the concentration range of 50-500 (xg/1, as well as repeatable (RSD 14% sulfamethazine and difloxacin 20%). The limits of detection were between 0.1 and 5.2 xg/l, far below the maximum residue limits for milk set by the EU. While matrix effects, namely, ion suppression or enhancement, were observed for all the analytes, the method proved to be useful for screening purposes because of its detection limits, linearity, and repeatability. A set of blank and fortified raw milk samples was analyzed and no false-positive or falsenegative results were obtained. 

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Direct injection of pretreated biological samples (also called online sample cleanup) greatly simplified sample preparation for LC/MS/MS analysis. The normal process involves sample aliquot steps, internal standard addition, and centrifugation. Compared to traditional off-line LLE and SPE sample preparation procedures, online methods are easier and faster. Two types of online SPE columns are commercially available. One is the restricted access media (RAM) column. The other is the turbulent flow chromatography (TFC) column. 

In some cases, so called direct plasma injection techniques may be used23 83 104 108 instead of protein precipitation for loading plasma samples onto an HPLC/MS/MS system. Some direct plasma injection systems use a column switching technique in which the plasma is loaded onto an extraction column that retains the small molecules. The other plasma components are sent to waste and the flow is switched so that the small molecules are eluted onto an analytical column that connects to the MS/MS.23 83 108 One variation of the column switching method is turbulent flow chromatography commercialized by Cohesive Technologies (now part of Thermo, San Jose, CA).23... 

Turbulent flow chromatography uses large particle packing materials and high flow rates to separate small molecules from proteins and other matrix components in plasma. In one example, Herman et al.109 reported that turbulent flow chromatography was useful for a series of discovery compounds as the online extraction step in LC/MS/MS analysis. As an alternative, Hsieh et al.89-104 107 described the use of a single mixed function column as a simpler process for direct plasma injection applications. 

The most common (off-line) sample preparation procedures after protein precipitation are solid phase extraction and liquid-liquid extraction. Multiple vendors and available chemistries utilize 96-well plates for solid phase extraction systems and liquid-liquid extraction procedures. Both extraction process can prepare samples for HPLC/MS/MS assay. Jemal et al.110 compared liquid-liquid extraction in a 96-well plate to semi-automated solid phase extraction in a 96-well plate for a carboxylic acid containing analyte in a human plasma matrix and reported that both clean-up procedures worked well. Yang et al.111 112 described two validated methods for compounds in plasma using semi-automated 96-well plate solid phase extraction procedures. Zimmer et al.113 compared solid phase extraction and liquid-liquid extraction to a turbulent flow chromatography clean-up for two test compounds in plasma all three clean-up approaches led to HPLC/MS/MS assays that met GLP requirements. 

Asperger A. et al., 2002. Trace determination of priority pesticide in water by means of high-speed online solid-phase extraction-liquid chromatography-tandem mass spectrometry using turbulent-flow chromatography columns for enrichment and a short monolithic column for fast liquid chromatographic separation. J Chromatogr A 960 109. 

Ayrton J. et al., 1997. The use of turbulent flow chromatography for the rapid, direct analysis of a novel pharmaceutical compound in plasma. Rapid Commun Mass Spectrom 11 1953. 

Ceglarek U. et al., 2004. Rapid simultaneous quantification of immunosuppressants in transplant patients by turbulent flow chromatography combined with tandem mass spectrometry. Clin ChimActa 346 181. 

Herman J.L., 2002. Generic method for online extraction of drug substances in the presence of biological matrices using turbulent flow chromatography. Rapid Commun Mass Spectrom 16 421. 

Pretorius V. and Smuts T.W., 1966. Turbulent flow chromatography A new approach to faster analysis. Anal Chem 38(2) 274. 

Ynddal L. and Hansen S.H., 2003. Online turbulent-flow chromatography-high-performance liquid chromatog-raphy-mass spectrometry for fast sample preparation and quantitation. J Chromatogr A 1020 59. 

Zimmer D. et al., 1999. Comparison of turbulent-flow chromatography with automated solid-phase extraction in 96-well plates and liquid-liquid extraction used as plasma sample preparation techniques for liquid chromatography-tandem mass spectrometry. J Chromatogr A 854 1999. 

Ceglarek et al.45 reported the rapid simultaneous quantification of immmunosuppressants (cyclosporine A, tacrolimus, and sirolimus) in transplant patients by turbulent flow chromatography (TFC) coupled with HPLC-MS/MS. TFC is an online extraction technique involving the direct application of human plasma onto a turbulent flow column where protein is washed from the samples before the retained drug is backflushed onto an analytical column. 

High-Flow HPLC and Turbulent Flow Chromatography, Fast Elution and UHPLC... 

High flow rate is generally the basis for the high-throughput efficiency of several Turbulent Flow Chromatography (TFC), Restricted Access Material (RAM), and monolithic columns methodologies. 

Among the new techniques that have been developed to improve the throughput, turbulent-flow chromatography (TEC) coupled with MS has... 

Takino, M., Daishima, S., and Nakahara, T. (2003). Determination of perfluorooctane sulfonate in river water by liquid chromatography/atmospheric pressure photoionization mass spectrometry by automated on-line extraction using turbulent flow chromatography. Rapid Commun. Mass Spectrom. 17, 383—390. 

Recently, turbulent flow chromatography (TFC) has shown a great potential for online sample pre-treatment in the analysis of PFCs. Up to now, the use of this technique in food and environmental analysis is scarce, but some successful applications have been developed. Among them, the analysis of PFCs has been carried out in cord blood and also in less invasive human samples, hair and urine. In these works, the main advantages presented were the simplified sample preparation, robustness and sensitivity. In addition in the case of cord blood, a low volume of sample was required. 

Farrhurst RE, Chassaing C, Venn RE, Mayes AG. A direct comparison of the performance of ground, beaded and siUca-gtafted MIPs in HPLC and turbulent flow chromatography applications. Biosens Bioelectron 2004 20 1098-1105. 

Ayrton, J., Dear, G. J., Leavens, W. J., Mallett, D. N., and Plumb, R. S. (1997). The use of turbulent flow chromatography/mass spectrometry for the rapid, direct analysis of a novel pharmaceutical compound in plasma. Rapid Commun. Mass Spectrom. 11 1953-1958. 

Smalley, J., Marino, A. M., Xin, B., Olah, T., and Balimane, P. V. (2007). Development of a quantitative LC-MS /MS analytical method coupled with turbulent flow chromatography for digoxin for the in vitro P-gp inhibition assay. J. Chromatogr. B Anal. Technol. Biomed. Life Sci. 854 260-267. 

Chassaing, C., Luckwell, J., Macrae, P., Saunders, K., Wright, P., and Venn, R. F. (2001). Direct analysis of crude plasma samples by turbulent flow chromatography/tandem mass spectrometry. Chromatographia 53 122-130. 

Chassaing, C., Stafford, H., Luckwell, J., Wright, A., and Edgington, A. (2005). A parallel micro turbulent flow chromatography-tandem mass spectrometry method for the analysis of a pharmaceutical compound in plasma. Chromatographia 62 17-24. 

Isocratic focusing techniques, in conjunction with turbulent-flow chromatography, are also explored in this chapter. Isocratic focusing is used to improve chromatographic peak shape, enhance sensitivity, and optimize reproducibility. Isocratic focusing has also led to the development of generic methodologies that eliminate the need... 

Turbulent-flow chromatography (TFC) was first described in the 1960s. Sternberg and Poulson (1964) showed how turbulent-flow increases the effective diffusivity of... 

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