Tubing Teflon

Eig. 19. CME monopolar electrolyzer a, membrane b, cathode element c, half-cathode element d, current distributor e. Teflon tube f, CI2 + depleted brine manifold g, conductor rod h, CI2 + depleted brine outlet nozzle i, base frame j, recycled NaOH manifold k, recycled NaOH inlet nozzle 1, gasket (the gasket-to-element ratio is quite small) m, tie rod n, anode element o, H2 + NaOH manifold p, end plate, q, under cell bus bar (simplifies piping... 

Eig. 6. Schematic ofTeclmicon CHEAl I analy2er where P = aspiration AIV = metering valves CT = capillary Teflon tube M = reagent mixing zone ... 

The use of SPME for CE has not (yet) been studied widely. Li and Weber (170) reported an off-line SPME-CE approach for the determination of barbiturates in urine and serum, utilizing a sorbent of plasticized PVC coated around a stainless steel rod. Eor extraction, the coated rod was inserted for 4 min in a Teflon tube containing 50 p.1 of sample, and next the rod was repeatedly desorbed in another Teflon tube which each time contained 5 p.1 of desorption solution. This solution was transferred to an injection vial and an aliquot was injected into the CE system (Eigure 11.19). The extraction procedure appeared to be selective and effectively allowed the handling of very small samples. 

Recent innovations [19] have circumvented the heat dissipation and sample stream distortion inherent in most of the previous designs. In one apparatus, developed by R S Technologies, Inc. (Wakefield, RI, USA), Teflon capillary tubes are aligned close to each other in the electrophoretic chamber. Coolant is pumped through the Teflon capillary tubes during the electrophoretic run while the electrophoretic separation is accomplished in the interstitial volume between the Teflon tubes. 

Figure 10-8. Single-pass shell and tube Teflon tube heat exchanger, countercurrent flow. Tube bundles are flexible tube Teflon joined in integral honeycomb tubesheets. Shell-side baffles are provided for cross-flow. Standard shell construction is carbon steel shell plain or Teflon (LT) lined. Heads are lined with Teflon . Tube diameters range from 0.125-0.375 in. O.D. the temperature range is 80-400°F pressures range from 40-150 psig. (Used by permission AMETEK, Inc., Chemical Products Div., Product Bulletin Heat Exchangers of Teflon . )...

For duPont s Teflon tube (Vr-in. diameter) heat exchangers (Figure 10-8) for condensing, heating, and cooling service, the U values range from 15-35. Little or no fouling occurs on the Teflon surface. 

The reflux condenser was connected by an adaptor and Teflon tube to a trap of known weight which was cooled by a mixture of acetone and solid carbon dioxide. The flow of nitrogen was stopped, and an excess of water (about 15 ml.) was added dropwise through the dropping funnel to the stirred reaction product. The resulting mixture was heated at the reflux temperature, and the butane was collected in the trap. The weight of butane, b.p. —1° to 0°, was 4.23 1.35 g. (73-76% yield). 

Animal treatment. Male 100-g MRC-Wistar or Sprague-Dawley rats were fasted from the evening of the previous day but were given water. Non-fasted 30-35 g Swiss mice were used. Except where specified otherwise, the animals received a standard commercial diet (Wayne Lab Blox, Allied Mills). In the standard experiments, animals were gavaged with 25 mg morpholine (Fisher Scientific Co.) in 10 mL water/rat or 2 mg morpholine in 0.2 mL water/mouse. A stream of NO2 was prepared by suitable mixing (using Teflon tubing) of gas from a cylinder of 106 ppm N0 in N (Linde Division, Union Carbide Corp.) and compressed air. 

The importance of the linear arrangement of mixer/funnel/tubular reactor is shown when processing in a set-up with a curved flow element (0.3 m long bent Teflon tube of 0.3 mm inner diameter) in between the funnel and tubular reactor [78]. If a straight tube of equal dimensions as given above is used, plugging occius after 30 s. Hence even short curved flow passages are detrimental for micro-chan-nel-based amidation studies. 

A second fully automated device, the HPTLC applicator AS 30 (described earlier), can be employed in connection with a sampling device. Automated refilling of the syringe is performed by editing a volume factor, e.g., 10 for application of 10 times 100 pi. This device can be recommended if loss of sample is not relevant (e.g., owing to automatic rinsing operations that afford at least 70 pi dead volume for a minimal 20-cm tube connection). However, the fully automatic mode is not recommended for valuable samples. Sample volume still present in the Teflon tube between the sampler and AS 30 syringe will be wasted and lost because this operation cannot be circumvented by the user. 

Fig. 2.5.9 COSY spectra acquired at 600 MHz with an eight-coil probe along with the chemical structures of the compounds used. Each sample was a 10 mM solution in D20 loaded into the coil via the attached Teflon tubes, with the samples being (A) sucrose, (B) galactose, (C) arginine, (D) chloroquine, (E) cysteine, (F) caffeine, (G) fructose and (H)...

Fig. 7 Unit dose collection (A) teflon tube (B) glass samplers.

The sample loop, Vg, has a volume of 0.25 cc. To initiate injection at time zero of the experiment, the valve handle is rotated 60°, and the flows within the valve are redirected along the dashed lines as shown in the figure. The sample solution in the loop is then displaced through port F by the 1% acidified brine from the pump. The sample loop therefore must be long enough to contain a sufficient "slug" of sample solution. Here, the phrase "sample solution" refers to the surfactant solution prepared in 1% acidified brine solution. Teflon tubing and connections are used to minimize the uptake of any corrosion products into the 1% acidified brine solution. 

FIGURE 16.6 Schematic of the clear flow gating interface. The interface was constructed in-house from a 1 in. diameter, 0.5 in. thick Lexan disk. The disk is clear, which allows direct observation of the capillaries in the stream of flush buffer. The capillaries are sleeved in 0.0625 in. o.d. Teflon tubing and this tubing is held in place by Lite Touch fittings (not shown). The cross-flow of buffer prevents LC effluent from electromigrating onto the CZE capillary until an injection is desired (reprinted with permission from Analytical Chemistry). 

Teflon tubing, when used to conduct fluorine into a reaction mixture, sometimes ignites. Combustion stops when the flow of fluorine is shut off. 

For oxidative detection use teflon tubing instead of steel tubing when possible, to keep the iron content of the mobile phase low. Teflon tubing however increases the risk of bubbles in the pump and thus may give unstable flow rates and baselines. 

For reductive detection replace all teflon tubing by steel tubing to avoid diffusion of oxygen through the tubing into the mobile phase except the inlet tubing of the cell. 

Watanabe et al. published the first paper to appear in the literature dealing with the coupling of LC and NMR in 1978 [82], This early exploration of LC-NMR led to the modification of a standard NMR probe to include a flow cell comprised of a thin-wall Teflon tube with an inner diameter of 1.4 mm. The dimensions of this flow-cell were 1 cm in length and a total volume of 15 pi. This modification not only made the NMR spectrometer amenable to a flow system, but also overcame some of the inherent sensitivity issues associated with NMR as an LC... 

The counter-electrode (CE) was a 40 at.% RuC>2 (the remainder being Ti oxide) electrode, having more than 100 times the apparent surface area of the WE. It was positioned inside a Teflon tube to minimise the amount of hydrogen gas that could be released into the cell solution. An Ag/AgCl electrode was employed as the reference electrode (RE) at high temperatures, while a saturated calomel electrode (SCE) generally served as the RE at room temperature. 

Figure 11.1a shows a scheme of a widely used reaction vessel for isoperibol titration calorimetry [211]. It consists of a silvered glass Dewar A, which can be adjusted to a lid B supporting a stirrer C, a resistance D for electrical calibration, a thermistor E for temperature measurement, and a Teflon tube F for titrant delivery. The assembled Dewar and lid set-up is immersed in a constant... 

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