Sample tangential flow

Tangential-flow ultrafiltration was used with approximately 150-L samples of centrifugate from the ship-based centrifuges. 

These samples were processed through a large tangential-flow cell (regenerated cellulose membrane, Millipore Pellicon) while on station. 

H NMR spectra have been used to analyze 11 DOM samples that were isolated from seawater using tangential-flow ultrafiltration and one sample that was isolated using dialysis (Aluwihare et al., 1997). A linear combination of three endmembers (carbohydrates, lipids, and acetate) was sufficient to account in some detail for the... 

Whenever the analyte of interest is soluble in the liquid phase or part of the gas phase, sample removal via a filtering device is the most reasonable solution. Filters mounted in situ are ideal provided they do not foul within an unreasonably short period. If this is the case, a filter operating in bypass must be used because this can be repeatedly exchanged with a freshly prepared one. In our experience, bypass filters should be operated with a high tangential flow, say > 2 m s 1 of superficial liquid velocity. Then, a useful lifetime of a few weeks can be achieved even in cultures of filamentous organisms. 

Powell, M. J., and Timpermann, A. T. (2005). Quantitative analysis of protein recovery from dilute, large volume samples by tangential flow ultrafiltration. J. Memb. Sci. 252(1-2), 227-236. 

In the cyclonic spray chamber droplets are discriminated according to their size by means of a vortex produced by the tangential flow of the nebulizer. Smaller droplets are transferred with the sample aerosol into the ICP-MS, while the larger droplets collide with the walls and exit by gravity via a drain tube. If compared to the Scott design, the cyclonic spray chamber typically shows higher sensitivity. 

Samples with particulate matter may present quite serious problems, and it may be desirable to remove particles, for example, by centrifugation, and examine this fraction by procedures applicable to solid phases which are discussed in Section 2.2.5. Tangential-flow high-volume filtration systems have been used for analysis of particulate fractions (>0.45 jum) where the analytes occur in only low concentration (Broman et al. 1991). Attention has already been drawn to artifacts resulting from reactions with cyclohexene added as an inhibitor to dichloromethane. It has also been suggested that under basic conditions, Mn2+ in water samples may be oxidized to Mn(III or IV) which in turn oxidized phenolic constituents to quinones (Chen et al. 1991). Serious problems may arise if mercuric chloride is added as a preservative after collection of the samples (Foreman et al. 1992) since this has appreciable solubility in many organic solvents, and its use should therefore be avoided. 

The sample aliquot is introduced into the main analytical channel and the established sample zone undergoes tangential flow filtration (see below). The unfiltered portion is directed towards waste while the filtrate is directed towards the detector. The manifold architecture is analogous to that for in-line dialysis, as both processes tends to occur simultaneously consequently, the approach is also useful for in-line dilution. 

Adams and Byrne, 1989 Pant et al., 1999 Turrion et al., 2000, 2001). However, given the risk of hydrolysis with higher temperatures (Cade-Menun et al., 2002 Turner et al., 2003b), lyophilization may be the safest method. Water samples have been concentrated by tangential-flow ultrafiltration (Nanny and Minear, 1994a,b, 1997a,b ... 

The concentration of viruses in water is much lower than that of bacteria therefore their preconcentration and separation from other suspended matter is important in virological analysis. Viruses may be enriched by UF by use of tangential-flow or hollow-fiber filtration units most suitable for preconcentration from large-volume water samples. Another possibility consists in adsorption of the viruses on the microfilter matrix followed by elution with diluents containing cell extracts, serum, or surfactants. 

Online collection/concentration of samples through the use of cross (tangential) flow ultrafiltration has also found a number of applications. 

Nearly all ICP torches consist of three concentric quartz tubes surrounded by a coil carrying radiofrequency (r.f.) power, referred to as the load coil. The middle tube carries the Ar that forms the plasma while Ar flow in the inner tube serves as a carrier for sample introduction. This punches a hole in the center of the plasma, creating a toroidal plasma with a central axial channel that acts as the atomization-ionization cell. The plasma forms under the load coil, past the exit of the inner and middle tubes. The outer tube extends beyond the coil and carries a tangential flow of Ar that serves as a coolant layer to prevent the torch from melting in addition to centering the plasma. 

This problem seems to be overcome by the tangential flow filtration system, specifically developed for a large sample size (1-2 m ) by Broman and coworkers in order to collect water from Baltic Sea, where the suspended particulate generally occurs at concentrations of 0.2-0.3 mg/L [10]. The system is made of a microporous poly(vinylidene difluoride) membrane, where the filtrate is separated from the retentate with a constant cutoff of 0.45 xm. A tangential flow of water sweeps the surface of the membrane so that the particles are kept in suspension avoiding membrane plugging. The retentate (liquid) each of volume 3-5 L is collected and centrifuged the supernatant and pellet are thereafter extracted and analyzed. 

Kuwabara, J.S., and R.W. Harvey. 1990. Application of hollow fiber, tangential flow device for sampling suspended bacteria and particles from natural waters. J. Environ. Qual. 19 625-629. 

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