Syringe operation

If the system contains three constituents with different mobilities, three boundaries will form a rate of movement equal in magnitude, but opposite in direction, to that of the middle boundary is now imparted to the whole liquid. The fastest moving constituent moves ahead, whereas the slowest constituent is given an apparent negative velocity after electrophoresis has proceeded for some time, one limb of the section C contains the former constituent and the other contains the latter in a pure form. Several devices have been employed to impart a movement to the liquid one method is to withdraw gradually, by means of clockwork, a plunger which fits loosely into one of ihe electrode vessels, while another is to keep one electrode vessel closed, e.g., the left-hand one in Fig. 131, and to force buffer solution into it at the desired rate by means of a syringe operated by a constant speed motor. 

A fully automated, personal computer-controlled spotter (e.g., the Camag Automatic TLC Sampler III), which consists of a stainless steel capillary connected to a dosage syringe operated by a stepper motor, can sequentially apply constant or variable volume samples, chosen from a rack of vials, within the range of 10 nl to 50 pi as spots or bands. 

The column is next washed with Milli-Q water to remove sea salt the wash is also directed to the waste container. The elution step follows the eluting solvent is delivered from a 50-mL syringe operated by a displacement pump (Sage Instrument Co.). In this manner, a precisely measured volume of solvent is directed through the column and through a special, low-dead-volume eluant path into a sealed, acid-cleaned linear polyethylene vial. 

Samples and calibration standards are prepared for analysis using a 10-mL syringe. Add 10.00 mL of each sample and standard to separate 14-mL screw-cap vials containing 2.00 mL of pentane. Shake vigorously for 1 min to effect the separation. Wait 60 s for the phases to separate. Inject 3.0-pL aliquots of the pentane layer into a GC equipped with a 2-mm internal diameter, 2-m long glass column packed with a stationary phase of 10% squalane on a packing material of 80/100 mesh Chromosorb WAW. Operate the column at 67 °C and a flow rate of 25 mL/min. 

Ease of use 2-6°C storage. Multiple application devices (linear, spray tips, endoscopic, etc.), 20 min preparation time. Set-up time = 30 s-3 min. May wash away in presence of active bleeding. Requires trained personnel to operate equipment. Preparation time required to obtain plasma component. Room temperature storage. 5 min preparation time. Single syringe applicator per kit. Set-up time - 3 min. Effective at site of active bleeding. 

For dealing with smaller volumes of solution, micropipettes, often referred to as syringe pipettes, are employed. These can be of a push-button type, in which the syringe is operated by pressing a button on the top of the pipette the plunger travels between two fixed stops and so a remarkably constant volume of liquid is delivered. Such pipettes are fitted with disposable plastic tips (usually of polythene or polypropylene) which are not wetted by aqueous solutions, thus helping to ensure constancy of the volume of liquid delivered. The liquid is contained entirely within the plastic tip and so, by replacing the tip, the same pipette can be employed for different solutions. Such pipettes are available to deliver volumes of 1 to 1000 pL, and the delivery is reproducible to within about 1 per cent. 

Micrometer syringe pipettes are fitted with a micrometer head which operates the plunger of the syringe, and when fitted with a stainless steel needle tip can be used for the dropwise addition of liquid the volume added is recorded by the micrometer. 

The sampling of solution for activity measurement is carried out by filtration with 0.22 pm Millex filter (Millipore Co.) which is encapsuled and attached to a syringe for handy operation. The randomly selected filtrates are further passed through Amicon Centriflo membrane filter (CF-25) of 2 nm pore size. The activities measured for the filtrates from the two different pore sizes are observed to be identical within experimental error. Activities are measured by a liquid scintillation counter. For each sample solution, triplicate samplings and activity measurements are undertaken and the average of three values is used for calculation. Absorption spectra of experimental solutions are measured using a Beckman UV 5260 spectrophotometer for the analysis of oxidation states of dissolved Pu ions. 

Nitrogen is introduced via a syringe needle that pierces the septum. A positive pressure of nitrogen is maintained in the apparatus during the following operations. 

The general operation of the pilot scale reactor has be previously described by Pareek et. al. [3]. However, modifications were required to allow the injection of the gas and liquid tracers, and their subsequent detection at the outlets. The liquid tracer, 5mL Methyl blue solution (lOgL" ), was injected via a syringe inserted into the liquid feed line. Outlet samples were measured with a Shimadzu 1601 UV-Vis Spectrophotometer at a wavelength of 635nm. A pulse (20mL) of helium gas tracer was introduced using an automated control system, with the outlet concentration monitored in real-time with a thermal conductivity detector. Runs were carried out based on a two-level... 

The hydrophilic Au SR (RSH = GSH, h-GSH, (PG)SH, (SA)SH) clusters were ionized by the ESI method [15,16,18,23,24] (Figures 2 and 3c). The details of the ESI source are depicted in Figure 3c, together with typical pressures of the chambers under operation. A 50%(v/v) water-methanol solution of the fractionated Au SR cluster with a typical concentration of 0.5mg/mL was electro-sprayed into the ambient atmosphere through the stainless steel needle of a syringe biased at ca. — 3kV. The solution was delivered by a syringe pump (SP310I, World Precision... 

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. 

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