Hydrostatic injection system

Samples are introduced into the capillary by either electrokinetic or hydrodynamic or hydrostatic means. Electrokinetic injection is preferentially employed with packed or monolithic capillaries whereas hydrostatic injection systems are limited to open capillary columns and are primarily used in homemade instruments. Optical detection directly through the capillary at the opposite end of sample injection is the most employed detection mode, using either a photodiode array or fluorescence or a laser-induced fluorescence (LIF) detector. Less common detection modes include conductivity [1], amperometric [2], chemiluminescence [3], and mass spectrometric [4] detection. 

Injection volumes are in the nanoliter range to avoid system overloading, since the total volume of the capillary is in the /rl range. Direct injection techniques have been developed to ensure efficient and reproducible injection. Techniques employed are electrokinetic injection (i.e., electromigration injection), hydrodynamic injection by pressure or vacuum, and hydrostatic injection by gravity. Organic acids are almost exclusively detected with indirect UV, whereas other analytes have been measured by direct or conductivity detection. 

Hgure 4 Electropherogram of 100-fold dilution of urine from a subject supplementing with creatine. The separation was carried out at 17kV with hydrostatic injection for 20 s, using a 30 mmol r phosphate-150 mmol r sodium dodecyl sulfate buffer, pH 6, and detection by absorbance at 214nm. The unlabeled peak is a system peak. 

Injection pump. An injection pump is used to force the waste into the injection zone, although in very porous formations, such as cavernous limestone, the hydrostatic pressure of the waste column in the well is sufficient. The type of pump is determined primarily by the well-head pressures required, the volume of liquid to be injected, and the corrosiveness of the waste. Single-stage centrifugal pumps are used in systems that require well-head pressures up to about 10.5 kg/cm2 (150 psi), and multiplex piston pumps are used to achieve higher injection pressures. 

Garcia-Leiner and Lesser (2004) have studied the use of SCCO2 in the processing of a variety of polymers (s-PS, PEP, and PIPE) using a modified single-screw extruder with a CO2 injection (Fig. 5). The present of CO2 significantly enhanced the processability of the polymer-C02 system by plasticization effect and the hydrostatic contribution. This presented an effective alternative to process intractable or high melt viscosity polymers. 

From the point of view of nucleosynthesis, explosive burning in such binary systems proves to be especially important as nuclides created in such an environment can be injected into the interstellar medium by the explosion. Furthermore, the nucleosynthetic signature will be different from stellar hydrostatic and explosive scenarios due to the different initial and burning conditions. Thus, different isotopic ratios can be obtained and, in some cases, it is possible to synthesize nuclides not accessible in other sites. In the following, therefore the main focus is put on outlining only such scenarios, which might have an impact on the abundances... 

P. Kuban, P. Kuban, V. Kuban, Flow injection-capillary electrophoresis system with contactless conductivity detection and hydrostatic pressure generated flow. Application to the quantitative analysis of inorganic anions in water samples. Electrophoresis 24 (2003) 1935—1943. 

The scram system of the CIRENE reactor consists, as previously mentioned, in a number of tubes passing through the core and allowing injection of a poisoned liquid. Each of these tubes is a branch of a U-shaped duct, the other branch being placed outside the core. In operation the liquid column is maintained in the outside branch by an overpressure of the cover gas inside the in-core branch, which balances the hydrostatic head. 

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