Valves ten-port

Figure 6.4 Schematic diagram of an on-line SPE-SFE-GC system (from ref. 40) 1, carbon dioxide 2, high-pressure syringe pump 3, gas cliromatograph 4, tliree-poit valve 5, oven 6, extraction cell 7, waste 8, ten-port valve 9-11 conditioning and washing solvents 12, sample 13, niti Ogen.

Figure 14.6 Schematic diagram of a five-column cliromatographic refinery analyser system SL, sample loop V1, two-way valve to block the sample line V2 and V5, ten-port valves V3 and V4, six-way valves Cl C5, packed columns R, restriction TCD, thermal conductivity detector-.

Figure 14.8 Schematic diagram of the natural gas analyser system SL, sample loop VI, two-way valve to block the sample lines V2, ten-port valve V3, V4 and V5, six-port valves R, restriction TCD, themial-conductivity detector FID, flame-ionization detector.

An eight-port or a ten-port valve with dual matching sample loops is generally used for automated comprehensive 2DLC so that solute is injected repetitively into the... 

Figure 1 is a schematic of one of the two supercritical flow reactors used in this work. The system is first brought up to the operating pressure by an air compressor. An HPLC pump forces the reactant solution through the reactor, the ten-port valve and dual-loop sampling system, and into the product accumulator, where the flow of products displaces air through a back-pressure regulator. The reactant inflow is rapidly heated to reaction temperature by an electric entry heater/water jacket combination, and maintained at isothermal conditions by a Transtemp Infrared furnace and an exit electric heater/water jacket combination. 

Equipment for column switching is available commercially but equally good results can be obtained from a do it yourself system. Six- or ten-port valves can be used, one ten-port valve being capable of replacing two six-port valves. 

Figure 18.10 Two-dimensional separation of a mixture of phenolic and flavone antioxidants [after P. Jandera, University of Pardubice, Czech Republic see also F. Cacciola et a ., J. Chromatogr. A, 1149, 73 (2007)]. Conditions in the first dimension column, 15 cm x 4.6 mm i.d. stationary phase, PEG silica 5 pm mobile phase, 0.3 ml min" water-acetonitrile, gradient 1-55% acetonitrile in 200 min. Interface ten-port valve with two storage columns X-Terra Cl8 2.5 pm, 3 cm x 4.6 mm i.d. which concentrate the eluate. Cycle time, 5 min. Conditions in the second dimension column, 10 cm x 4.6 mm i.d. stationary phase, SpeedROD RP-18e (monolith) mobile phase, 2 ml min" water-acetonitrile, gradient 1-40% acetonitrile in 5min. Diode array detector with 254 + 260 + 280 + 320 nm. Of the numerous identified analytes only the most important ones are specified in the figure.

To inject samples from two ducts of gases under analysis, a two-position, ten-port valve with two sample loops is used (Fig. 7). In position A, the carrier gas flows through sample loop 1, the gas under analysis (gas 2) flows through sample loop 2, and gas 1 flows through the valve, omitting... 

Fig. 7 Two-position, ten-port valve with two sample loops, taking sample from two gas tracks.

The above-mentioned sampling from two tracks of gases under analysis through the two-position, ten-port valve having two sample loops is limited to alternately successive operations. 

This shortcoming is absent in the three-position, ten-port valve having two sample loops, which is used for taking samples from two gas tracks (Fig. This valve can be used to analyze two gases in any order. The constructional solution of this valve makes it possible to simultaneously take two samples of different gases into two sample loops and perform their chromatographic analyses. 

The high-pressure switching valve is the most important part of the instrumentation in this technique. It must work reliably even after several thousand switches under high pressure, must have a very small dwell volume, and must be chemically inert to both the sample and the mobile phase. Normal switching valves have six ports, but four- and up to ten-port valves are commercially available as well. Their setup is very similar to the usual sample valve injectors, e.g., rheodyne valves (Section 12.2.4.2). They can be driven by hand or automatically either by pneumatic force or electronically. Pneumatically or electronically driven valves have the advantage that the entire analysis can be automated. 

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