Split injections

The last major decision is how to inject the sample. Split injection is best for high concentrations of analyte or gas analysis. Quantitative analysis is very poor Less volatile components can be lost during injection. Split injection offers high resolution and can handle dirty samples if an adsorbent packing is added to the injection liner. Thermally unstable compounds can decompose during the high-temperature injection. 

There are three injection techniques for introducing a sample into a GC equipped with a capillary column split injection, splitless injection, and on-column injection. Split injection is the most often used injection technique. When a certain amount of FAME sample (1 to 3 ll) is introduced into the GC injector that is normally set at a temperature much higher than the boiling point of the solvent, the solvent vaporizes instantly in the carrier gas and creates a large volume of gas that contains all of the injected FAME in it. The carrier gas that contains the FAME is then divided into two streams from the injector one is directed onto the column, and the second is vented to the atmosphere, clearing the sample out of the injection chamber momentarily. This way, only a limited amount of sample is introduced into the column, to avoid column overloading, and injection time is short, to avoid peak broadening. 

Analyses of the starting material and products were carried out by GC and GC-MS analyses. For GC analyses, a Shimadzu gas chromatograph, GC-17A, was used. A 60-m-long narrow bore (0.25-mm) DB5 with 0.25-gm phase thickness supplied by J W Scientific was used. The GC parameters were as follows split injection (split ratio of 50 1), carrier gas of hydrogen at 1 cm3/min at 30°C. The heating program was as follows initial temperature of 30°C, initial time of 2 min, rate of 30-250°C at 3°C/min, final time... 

Ideally, a sample is introduced into a chromatograph as a perfect plug. In practice, this is not the case, and diffusion occurs because of the injector. For narrow-bore and microbore applications, injectors capable of introducing the required sample volumes are commercially available and optimized to reduce dispersion. This is not the case for capillary LC, and homemade injection systems include the sample tube technique, in-column injection, stopped-flow injection, pressure pulse-driven stopped-flow injection (PSI), groove injection, split injection, heart-cut injection, and the moving injection technique (MIT). Of the injection techniques, only the split injector, MIT and PSI approaches can introduce subnanoliter sample volumes accu-... 

Injection split/splitless) No information available. Gases Carrier gas (helium) 1.5 mL/min inlet pressure 11 p.s.i.g. 

First station usually has multiple preform injection molds where preforms are formed over core pins. The preforms have hemispherical closed ends (resembles a laboratory test tube). The other ends have an open bore, formed by the core pin. External details, such as the thread and neck flange for a screw-top container, are directly produced by injection molding. While the preform is still hot, the injection split mold is opened and the preforms, still on the core pins, are rotated to the blowing station two. Here the preforms are enclosed within the blow mold, and introducing blowing air through the core pins followed with cooling produces the BM. Blow molds opened and the finished products, still on the core pins, are rotated to an ejection station where they are stripped off mechanically and/or air. 

Gas Chromatographic Conditions. All analyses were performed on a Hewlett Packard 5890 GC equipped with a 5970 Mass Selective Detector or a Hewlett Packard 6890 GC equipped with a Nitrogen Phosphorous Detector (Hewlett Packard, Inc., Avondale, PA). A DB 35 (35% phenyldimethylpolysiloxane), 30 m x 0.25 mm ID X 0.25 [im column (J W Scientific, Inc., Folsom, CA) was used for all analyses. Carrier gas was helium at a linear velocity of 30 cm/sec. Samples were analyzed using split injections (split ratio = 30 1) with injector and detector (NPD) temperatures of 260°C and 250°C, respectively. Oven temperature programming was as follows initial temperature of 80°C for 1 min increase temperature at 3.5°C/min to 115°C increase at 15°C/min to 180°C increase at 60 C/min to 190°C hold at 190°C for 6 min. 

The inactivated influenza vaccine preparations generally contain 45 meg antigen in 15-mcg trivalent units per 0.5 mL and are administered by IM injection. Split-virus vaccine must be used for children from 6 months to 12 years of age. Children 6 to 35 months old receive 0.25 mL of split-virus vaccine. Two doses of vaccine administered at least 1 month apart are necessary for all children younger than 9 years of age who are receiving the vaccine for the first time. Split-virus vaccine is less reactogenic than whole-virus vaccine, particnlarly in children. Whole- or split-virus vaccine can be administered to individuals older than 12 years of age. However, whole-vims vaccines are not available in the United States. ... 

The most common injection methods in the determination of FRs are splitless injection and on column injection. On column injection is suitable especially to thermally labile analytes, and it suits very well to quantitative analysis. However, the sample extract should be clean from nonvolatile matrix components in on column injection. Split injection is not recommended because of its low sensitivity and strong discrimination effects which can occur during the injection. Large volume injection techniques have also been applied in the analysis of FRs. ... 

Figure 3. SFC-MS response vs. probe tip temperature for Triton X-100. Conditions 10 m X 50 urn i.d. X 0.1 um film DB-17 column, column temperature = 90 C, probe stem temperature = 90 C, 0.1 uL of a 25 mg/ml Triton X-100 in methylene chloride solution split injected, split ratio 1 2, pressure program = 100 atm for 3 min, ramp to lAO atm in 3 min, ramp to 325 atm in 23 min, methane Cl, MS source temperature = 200 C.

Fig. 16.5 Reconstructed total ion current (RTIC) chromatograms of a test mixture of 10 compounds, each at a concentration of 0.1 g (1 iL injected split 1 40). Conditions (top) El and (bottom) Na" ionization conditions.

Fig. 8. Gas Chromatogram of volatile oil from rhizomes of C. aeruginosa, 1 pL of volatile oil solutions was injected (split mode 1 50) at 270°C onto a HP-5 column using nitrogen as carrier gas at a flow rate of 2 mL.min-i. The oven temperature was programmed for 60-240° C (4°C.min-i) and 240-270°C (10°C.min-i) then held for 2 min. The FID detector was maintained at 275°C.

Copolymer" PS/PC blend PU Dibufyl sebacate, tributyl acetylcitrate TPP Mixture of didecyl phthalate esters 700°C 30 m X 0.25 mm I.D., 1.0 p-m film hold for 18 min mass range) injection split ... 

General Various waxes, stearic acid, butyl stearate, zinc stearate, butyl oleate, butyl palmitate, stearamide, AcraWax C 0.5 mg sample at 950°C DB-5 fused silica capillary, 30 m X 0.25 mm I.D., 1.0 p-m film 40°C for 4 min, ramp at 10°C/minto320°C, hold for 18 min MS (El, 15 50 mass range) Injector T = 300°C detector T = 300°C 30/1 injection split [50] - ... 

Column 25 m x 0.53 mm, fused silica, PoraPLOT U, Df = 20 (im Oven 25 °C Carrier H2, 60kPa Injection Split, 100 cq/min Detection p-TCD Sample 1-10% of each component in inert gas Peaks 1 — helium 2— nitrogen + oxygen + carbon monoxide 3 — carbon dioxide 4 — ethane. 

Column 10 mx 0.32 mm, fused silica, PoraPLOTQ, Df = 10nm Oven -50-150 °C, 20 7min Carrier H2, SOkPa Injection Split Detection n-TCD Peaks 1 — nitrogen 2 — oxygen 3 — methane 4 — carbon dioxide ... 

Carrier H2, 30kPa Injection Split, lOOml/min Detection FID, 64x10" Afs ... 

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