Sample injectors

The sample injection hardware is designed to introduce a small (1-100 pL) and reproducible volume of sample into the ion chromatograph. The injection system may be manual or automated. An automated system (often called an autosampler) permits the storage of multiple samples for unattended injection and analysis. 

Sample loop starting from right side end. No more 

Full loop Injection. Loop is completely filled with excess going to waste. 

At the same time that the sample loop is loaded with sample, the eluent travels in the by-pass channel of the injection valve and to the coluirm. Injection of the sample is accomplished by turning the valve and placing the injection loop into the eluent stream. Usually the flow of the eluent is opposite to that of the loading of the sample into the loop. The injected sample travels to the head of the column as a slug of fluid. The ions in the sample interact with the coluirm and the separation process is started with the eluent pushing the sample components down the column. 

Injection valves require periodic maintenance and usually have to be serviced after about 5000 injections. The instrument manual should be consulted for details on service. 

Remote control communication One-line contact closure 

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Parts that are common in SEC, but should not be used in HOPC are a sample injector (including an autosampler) and a guard column. 

Model GC6890, Hewlett-Packard Pulsed splitless sample injector. Column head pressure, 98 kPa pulse pressure, 240 kPa pulse time, 0.5 min... 

Splitless sample injector. Column head pressure ... 

Model GC5890, Hewlett-Packard Splitless sample injector... 

Gas chromatograph Sample injector Injection port Injection mode Column... 

Series 100 comprising CE 1100 pump, CE 1200 variable wavelength monitor, CE 1300 gradient programmer, CE 1400 refractive index detector, CE 1500 electrochemical detector, CE 1700 computing integrator, CE 1710 recorder and 1720 recorder, CE 1800 sample injector, 1200, 2000 column monitoring panel and sample valve. 

Sample Injector for HPLC 7725/7725i/9725/9725i, Product Bulletin 209, Rheodyne, Rohnert Park, CA, http //www.rheodyne.com/lit/docs/2320617A.pdf... 

Figure 5. HPLC profiles of products from reactions catalyzed by secreted pectate lyase activities from Erwinia chrysanthemi after 66 min and 192 min. Reaction mixtures contained 4 units of enzyme activity per ml and 0.1% PGA in 0.05 M Tris-HCl, pH 8.5, 0.2 mM CaClg. Injections of 0.05 ml were made from reaction mixtures with a WISP automatic sample injector and eluted at 2.0 ml/min with a run time of 60 min. Compounds eluting with retention times of 5.36, 6.40, 7.76, and 9.56 min corresponded to unsaturated oligogalacturonate reference standards with DP values of 2, 3, 4, and 5, respectively.

The experimental simplicity the common instruments can be utilized, preferably but not necessarily equipped with the column thermostat. An additional injecting valve can be easily mounted between the sample injector and the LC LC column in case of the LC LC procedures, which apply the zone of the barrier liquid injected in front of sample. 

Injection Syringe Loading Sample Injector Model 7125 (Rheodyne, USA)... 

HPLC system equipped with an automatic sample injector. 

Interstitial volume. Vj (Vg). The volume occupied by the mobile phase (carrier gas) in a packed column. This volume does not include the volumes external to the packed section, i.e., volume of sample injector and volume of the detector. In GC it corresponds to the volume which would be occupied by the carrier gas at atmospheric pressure and zero flowrate in the packed section of the column. 

Retention volume. VR. The product of the retention time of a sample component and the volumetric flowrate of the carrier gas (mobile phase). IUPAC recommends it be called the Total Retention Volume because it is a term used when the sample is injected into a flowing stream of the mobile phase. Thus, it includes any volume contributed by the sample injector and the detector. 

Sample injector. A device for introducing liquid or gas samples into the chromatograph. The sample is introduced directly into the carrier gas stream (e.g., by syringe) or into a chamber temporarily isolated from the system by valves which can be changed so as to instantaneously switch the gas stream through the chamber (gas sampling valve). 

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