GC Glass Insert
The GC inlet functions as the interface between the syringe and the GC capillary column, where the sample is introduced, vaporized, mixed with carrier gas and transferred to the column. Shimadzu instruments offer several types of inlets - split, splitless, programmable temperature vaporization (PTV) and on-column. The glass insert prevents the sample contacting the metal walls of the injector block. Glass insert geometry and packing materials enable the glass insert to achieve greater heated surface area; this additional surface area can often improve sample vaporization. Conversely, choosing the wrong glass insert geometry can signi cantly decrease the reproducibility and quality of analysis.
Injection Technique
Sample Types
Glass insert Geometry
Function
A bottom taper focuses sample onto the head of the column and minimizes sample contact with metal parts of the inlet. The addition of quartz wool to your glass insert promotes mixing of analytes, aids the vaporization of liquid samples, and works as a trap to collect non-volatile residue in the sample (i.e. protects capillary column from ‘dirty’ samples). Ensures quartz wool remains in the correct position in the liner. Excellent reproducibility results from the wiping of the sample from the syringe needle and the prevention of droplet formation. Minimiz- es high molecular weight discrimination. Bottom taper focuses sample onto the head of the column and minimizes contact with metal parts of the inlet. Excellent reproducibility results from the wiping of the sample from the syringe needle and the prevention of droplet formation. Minimizes high molecular weight discrimination. Direct glass inserts facilitate maximum transfer of sample by connecting directly to the GC column and inhibiting sample degradation due to hot metal components inside inlet. Straight glass inserts facilitate higher split ows. Narrow bore straight glass inserts facilitate fast GC work. Small injection volumes of less than 0.5 μL are best used with a narrow bore. Narrow bore straight glass inserts improve focussing of gaseous samples (purge, trap & headspace).
Taper
Trace Level Analyses/ Active Compounds
Splitless
FocusLiner™
General Purpose/ Concentrated Samples/ Dirty Samples
Split
Taper FocusLiner™
Trace Level Analyses/ Dirty Samples/ Wide Boiling Point Range
Splitless
Direct Taper
Trace Level Analyses/ Active Compounds
Direct
General Purpose/ Concentrated Samples/ Dirty Samples (only if quartz wool is present)/ Gaseous Samples (also purge & trap, headspace)
Straight
Split/Splitless
Glass Insert Deactivation
Every batch of glass inserts are tested for inertness using the EPA 8081B method. This standard method ensures that each batch of glass inserts has less than 3 % Endrin breakdown from a 1 ppm injection.
Pg C-67
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