Fast GC Using Minibore Fused Silica Capillary Columns Introduction ...

Capacity Considerations• Amount on column• Overloading• Injection methodsSample CapacityA limiting factor of a minibore column is the amount of sample that can be injected onto the column.The table indicates that the sample capacity of a minibore column is ten times less than a 0.25mm IDcolumn. Therefore, the on-column injection should be at least ten times lower for a minibore column.Overloading Causes Problems:• Resolution• Integration• Retention timeLinearityOverloading can also be a concern when using a minibore column. When the column's samplecapacity is exceeded, peak fronting (overloading) can occur resulting in poor resolution, poorintegration, irreproducible retention times, and poor linearity.speed, resolution, flow rate, operating pressure, sample capacity and overloading are all factors thatmust be taken into consideration when choosing minibore columns and the correct injection mwhtodfor your analysis.Injection Technique• Compatible:• Split• Splitless• Incompatible:• Direct• On-ColumnInjector ConsiderationsDirect and on-column injection modes are not recommended due to the required low flow rates andsmall bore size of these columns. Therefore, trace analyses are difficult to perform with miniborecolumns. Split and splitless injections are the best alternatives. However, since minibore columnsrequire low flow rates, speed of sample transfer through the liner to the column is a concern. Due tothe high dead volume, poor peak shape, and response, loss of resolution will occur when 2 or 4mmID liners are used in conjunction with minibore columns. Thus, 1mm ID inlet liners are a must forsharp, well resolved, and recovered peaks. Not only is the inlet liner a consideration when usingminibore columns for split or splitless injections, but other parameters specific to the type ofinjection method must also be optimized.