Automatic syringe pump

The first design of LIS (Figure 1.27) [30] consisted of an automatic syringe pump equipped with a three-way solenoid valve at the head and two optical fibers mounted to the syringe, enabling the whole procedure (i.e. microextraction and detection) inside a glass syringe, connected to the central port of a selection valve. 

For regional profihng experiments, relatively large matrix spots can be deposited directly on the sample by the use of either a low volume automatic pipette or an automatic syringe pump attached to a small capillary (Fig. 2B). Matrix solution is typically deposited in volumes ranging from 50 nL to 1 p,L. Stained histology... 

Figure 11 -5 shows an autotitrator, which performs the entire operation automatically.4 Titrant from the plastic bottle at the rear is dispensed in small increments by a syringe pump while pH is measured by electrodes in the beaker of analyte on the stirrer. (We will learn how these electrodes work in Chapter 15.) The instrument waits for pH to stabilize after each addition, before adding the next increment. The end point is computed automatically by finding the maximum slope in the titration curve. 

Briefly the positions of the valve are used in a manner illustrated in Figure 3. Position 1 is fitted to a 1/16" stainless steel tee (T3) fitting for delivery of fluid from the system syringe pump to the two 6-port tandem selectors for 12 column operation. In the 6 column system, this tee is eliminated. If six column operation is desired on the twelve column system, an on/off valve placed in line with one of the exit tubes (OU-4) from the stainless steel tee is manually closed and single delivery to one tandem selector is achieved. Position 2 of the VALCO selector valve delivers modifier from the liquid pump to each one of the extraction vessels automatically. 

Most flow-based analytical procedures rely on constant flow rates (Fig. 3.4a). These have also been used in model systems designed for studying sample dispersion, in order to simplify the related mathematical models. Uniform solution delivery is accomplished by exploiting pumping devices relying on pistons such as automatic burettes or syringe pumps, peristaltic pumps with dampeners, or gravity as fluid propellers. 

A typical laboratory preparation recipe for this coprecipitation route is provided hereafter. The experimental setup consists of a computer-controlled automatic titrator, a syringe pump, and a reactor, heated by a thermostat. 

Figure 1 Schematic illustration of flowing stream manifolds devised for the automatic determination of relevant environmental parameters in water samples using various flow techniques (A) flow injection analysis, (B) sequential injection analysis, (C) multicommutation flow injection analysis, (D) multisyringe flow injection analysis. The sequential injection-lab-on-valve configuration is depicted in previous article Flow injection analysis-detection techniques. S, sample R, reagent C, carrier D, detector IV, injection valve HC, holding coil RC, reaction coil MV, multiposition valve SV, solenoid valve SP, syringe pump MP, multisyringe pump PP, peristaltic pump St, stopper W, waste.

Cells are brought into focus and a distinct field is chosen for injection. The capillary is lowered by the manipulator and an individual cell is approached. The cell is injected by further lowering the capillary, and the test material is transferred into the cell by a low pressure exerted with a 50-ml syringe (air-filled) or an automatic injection pump. A small dent is seen at the cell surface when the capillary touches the cell. When the capillary is lowered further, the tip enters into the cell and the dent disappears. Appearance of a white spot indicates that the capillary has penetrated the entire cell and killed the cell. Successful microinjection is marked by slight enlargement of the cell or of the nucleus. 

The automatic relative viscometer is ideally suited for measuring dilute polymer viscosities. It provides faster analysis and greater precision than is obtainable with conventional glass tube viscometers (Ubbelohde or Cannon-Fenske), which it replaces. The principle of operation is based on measurement of pressure drops due to the continuous forced flow of solvent and sample through two stainless steel capillary tubes placed in series. The pressure drop across each capillary tube obeys Poiseuille s law. The pressme drop is measured by a differential pressure transducer. The sample solution is loaded into a sample loop via a syringe pump and then pushed into one of the two capillaries. A steady-state condition is reached when the sample solution completely fills capillary 2, solvent remaining in capillary 1 at all times. The relative viscosity of the sample solution is determined simply and directly by the ratio of the pressure drops. From the measured relative viscosity, all other solution viscosity measurements can be calculated. Solution viscosities are determined by the viscosity of the sample relative to the reference solvent. The relative viscometer measures the solvent and sample viscosity simultaneously, so errors due to temperatme fluctuation and solvent variations are avoided. The main advantages of this approach are ... 

Fig. 7-3. Illustration of two automatic systems for the determination of pH by multi-wavelength measurements. In (A) the mixing ratio of the sample (SW) and indicator stock (ISS) solutions is determined by a peristaltic pump (PP), while in (B) it is determined by a syringe pump (SP). Other abbreviations are Ml and M2 for magnetie three-way valves, RV for rotating valve, TP for temperature probe, C for computer control and W for waste.

The instrumentation for SFE can be relatively simple as shown in Figure 29-10. Instrument components include a fluid source, most commonly a lank of carbon dioxide a syringe pump having a pressure rating of at least 400 atm and a flow rate for the pressurized fluid of at least 2 mL/min a valve to control the flow of the critical fluid into a heated extraction cell having a capacity of a few milliliters and an exit valve leading to a flow restrictor that depressurizes the fluid and transfers it into a collection device. In the simplest instruments, the flow restrictor is 10 to 50 cm of capillary tubing. In modern sophisticated commercial instruments, the restrictors are variable and controlled manually or automatically. Several iastrument manufacturers offer various types of SFE apparatus. ... 

Fig. 24.4 Flow sheet of the used SAS plant (SI solvent, 52 solution, FI filter, VI, V2 automatically driven needle valve, PI syringe pump, V3 hand valve, F2 filter, HPV high-pressure vessel, F3 particle filter (with sinter metal Mt), F5 three-way valve, V6 metering valve, DM demister, AS antisolvent stream, 5 solvent stream, P2 diaphragm piston pump, V4 three-way valve, CV check valve, PRV pressure relief valve) (from [1])...

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