Split-splitless injectors

For GC, the injector is most frequently a small heated space attached to the start of the column. A sample of the mixture to be analyzed is injected into this space by use of a syringe, which pierces a rubber septum. The injector needs to be hot enough to immediately vaporize the sample, which is then swept onto the head of the column by the mobile gas phase. Generally, the injector is kept at a temperature 50 C higher than is the column oven. Variants on this principle are in use, in particular the split/splitless injector. This injector can be used in a splitless mode, in which the entire injected sample goes onto the column, or in a split mode, in which only part of the sample goes onto the column, the remainder vented to atmosphere. For other less usual forms of injector, a specialist book on GC should be consulted. 

Application developed by using a Fisons GC 8000 chi omatogi aph where the two columns were installed and coupled via a moving capillary stream switching (MCSS) system. The chi omatogi aph was equiped with a flame-ionization detector on the MCSS system outlet and a Flame-photometric detector on the main column outlet, and a split/splitless injector. 

Automated gel permeation chromatograph (Cleanup XL, Abimed Gilson) equipped with 5-mL loop and chromatographic tube, 25-mm i.d., 600-mm long, filled with 52-g of Bio-Beads, S-X3, 200 00 mesh, 33-cm gel bed length GC Gas chromatograph equipped with a split/splitless injector, autosampler, DB-1 fused-silica column, 30 mx 0.25-mm i.d., 0.25-p.m film thickness and electron capture detector... 

Gas chromatograph. Model 3400 (Varian, San Jose, CA, USA) equipped with split/ splitless injector and a niAogen-phosphorus detector (GC/NPD) or equivalent Heater, HPLC column... 

Varian 3400 gas chromatograph with split/splitless injector and nitrogen-phosphorus detector (GC/NPD)... 

Gas chromatograph. Model 6890 (Agilent Technology) equipped with split/splitless injector and a mass spectrometer. Model 5973, or equivalent Tissumizer, Model SDT 1810 SI with S25N probe (Tekmar, Cincinnati, OFl, USA) or equivalent... 

Hewlett-Packard 6890 gas chromatograph with split/ splitless injector... 

The waxes, the organic phase, and the aqueous products, on the contrary, were unloaded daily from the collection traps and analyzed with an off-line GC (Hewlett-Packard model 6890) equipped with two flame ionization detectors and two identical columns (Hewlett-Packard HP-5), one connected to an on-column injector and dedicated to the analysis of waxes (dissolved in CS2 before the injection), and the other connected to a split/splitless injector and used for the analysis of the liquid reaction products (aqueous and organic phases). CH3CN was added to the aqueous sample prior to the injection as internal standard. 

FID ECD FTD FPD TCD 2 Split-splitless injector 3 Direct on column injector ... 

Chromatographic Conditions. GC/MS-MS analyses were performed on a Varian 3800 gas chromatograph (Varian Chromatography Systems, Walnut Creek, CA) equipped with a 1079 split/splitless injector and a ion trap spectrometer (Varian Saturn 2000, Varian Chromatography Systems) with a waveboard for MS-MS analysis. The system was operated by Saturn GC/MS Workstation v5.4 software. The MS-MS detection method was adapted from reference. PCBs were separated on a 25 m length x 0.32 mm i.d., CPSil-8 column coated with a 0.25-pm film. The GC oven temperature program was as follows 90 °C hold 2 min, ramp 30 °C/min to 170 °C, hold for 10 min, rate 3 °C/ min to 250 °C, rate 20 °C/min to a final temperature of 280 °C, and hold for 5 min. Helium was employed as the carrier gas, with a constant column flow of 1.0 mL/min. 

For ee determination Hewlett-Packard HP 4890 gas chromatograph, split/ splitless injector, jS-DEX 225, 30 m, internal diameter 0.25 mm, film... 

The GC operating conditions are as follows split/splitless injector and detector are held fixed at 260°C and 290°C, respectively. After injection, the oven temperature is kept at 100°C for 2 min, and then programmed at a rate of 35°C/min to a final temperature of 278°C. Helium is used as a carrier gas. 

Gas chromatograph equipped with a split/splitless injector, a capillary column (30 m,... 

In quantitative analyses, the use of the split/splitless injector can cause concentration errors because of the discrimination of compounds that are of different volatility. The composition of the fraction that enters the column can be very different from that which is eliminated. This mode of operation should be excluded when an external standard is used (cf. 4.9). However, this problem can be corrected, up to a point, by use of a proper glass sleeve inserted into the injector. 

Figure 2.5—Injectors, a) A split/splitless injector (the split is regulated by valve 2). The exit labelled 1 is called the septum purge, b) A cold on-column injector. A typical feature of a chromatogram obtained in the splitless mode is the interference of the solvent with the analytes. This can be avoided using a selective detector.

Dilute samples can also be introduced into the GC system by on-column injection however, this technique requires special syringes or other devices and therefore will not be disci xp I in detail. Split or splitless injection, on the other hand, can be performed in a GC system equipped with a split/splitless injector without the need for additional devices. Investigators can simply change the control of the split/splitless valve and the oven temperature for the column to choose between the two injection techniques. 

Capillary Gas Chromatography (HRGC). Analytical separations were performed on a Varian 3700 GC instrument as well as on a Carlo Erba type 5360 Mega Series gas chromatograph. The Varian 3700 GC system was modified with a hot split/splitless injector and additionally equipped with a commercially available inlet splitter (Gerstel, Mulheim/Ruhr) in order to install two capillary columns... 

The instrument can also be equipped with a desorber module, a dual desorber/split/splitless injector module or an automatic air sampler module. But these are not used in the current configuration of the system, which is approved for on-site analysis. 

Figure 1. Bruker EM 640S modular GC/MS system A - mass spectrometer, B - split/splitless injector, C -GC module, D - gas supply, E - electronic module, F -ruggedized PC, G - Printer, H - external power supply...

Hewlett Packard 5840A gas chromatograph equipped with a 63Ni electron capture detector (ECD), an HP 7672A autosampler (Hewlett-Packard, Palo Alto, CA, USA) and an temperature-programmable split/splitless injector (Gerstel, Muhlheim/Ruhr, Germany). The needle tip of the autosampler dipped only into the upper third of a sample bottle to prevent the injection of any of the aqueous phase into the GC column. 

Identification of phenolics in different subvarieties of currants was performed by GC-MS with split splitless injector set at a split ratio of 1 20. This study was able to determine the profile of the phenolics present, how the sub-varieties differed in polyphenols present (Vostizza did not have 3,4-dihydroxy-phenylacetic acid, while the other Gulf and Provincial did), and the amount of each phenolic present. This study demonstrated the potential of GC-MS to profile subtle differences among similar products (Chiou et ah, 2007). 

Split/splitless injector in the split mode only a portion of the injected sample (typically, 1 part in 50) reaches the column. The rest is vented to waste. A split injector is used for concentrated samples (> 0.1 mgmL for FID see p. 215). In the splitless mode all the sample volume injected passes through to the column. It is used, in this mode, for trace samples (< 0.1mgmL for FID). 

---