A GC Troubleshooter's Toolkit - - Chromatography Online
A GC Troubleshooter's Toolkit


LCGC North America
Volume 7, Issue 30, pp. 570-577

Static Pad

A static pad is a grounded, conductive plastic sheet onto which it is safe to place electronic components that must be protected from damaging electrostatic discharge. Any circuit boards removed from an instrument should be placed on a grounded static pad, or in a static-proof bag.

Static Wrist Strap

A grounded static wrist strap prevents the technician from imparting a potentially harmful static discharge into instrumentation or components. Always wear one when working inside an instrument or removing components, and in all cases be quite sure that the instrument power has been removed while the instrument itself remains grounded.

Stopwatch, Digital

A digital stopwatch times bubbles in a bubble flowmeter, and also times an unretained peak. It's often more convenient to use a stopwatch when setting up an instrument than to operate the chromatography data system for each test injection. Select a stopwatch with readout to 0.01 s. Some GC systems include a stopwatch function on the display that includes flow, split ratio, and linear velocity calculations. These days I just use my smart phone's stopwatch and timer functions, and then its calculator to find flow rates or average linear velocities. Good phone applications are available with additional chromatography functions.

Syringe

I keep two syringes for setup purposes. One 10-L syringe is for injecting methane or butane to measure the unretained peak time and ascertain that the flame is lit and carrier gas is flowing. The other is for making liquid test-mixture injections as part of a column check-out. Sample syringes are kept separately.

Syringe-Cleaning Wires

Syringe cleaning wires may be used in an emergency to clear septum particles or other debris from syringe needles. I recommend discarding stubborn contaminated syringes; take steps to keep the syringe clean instead.

Test Mixtures

Column and detector test mixtures verify column performance and detector sensitivity. Keep a fresh vial of each type on hand. Column test mixtures are available for polar and nonpolar capillary columns, and there are test mixtures for each detector type. Some manufacturers provide a detector test mix that combines components for testing several different detectors. After they have been opened, test mixtures can be kept for a while in septum-sealed vials. Their lifetime is limited because of gradual evaporation. If you keep test mix in a vial, remove the vial cap rather than puncturing the septum when withdrawing liquid for injection. Some laboratories find it more convenient to keep dilute test mixtures on hand because these are more easily disposed of than the concentrated mixes. Many laboratories have their own qualification and validation standards, of course, but the manufacturer's mixtures allow easy comparison to the factory test results.

Tube Bender

I use this simple tool to make controlled bends of copper or stainless steel tubing for connecting the supply tanks to the filters and then to the back of the instrument. Tube benders come in sizes to fit standard tubing diameters.

Tube Reaming and Deburring Tools

These tools are used to remove burrs and irregularities from metal tubing after cutting. They are available for the standard tubing diameters, and I highly recommend using them to ensure leak-free connections.

Tubing, Plastic and Rubber

I keep several pieces of black and clear silicone rubber tubing on hand for connecting my flowmeter to column ends, split vents, and other flow sources. The narrower pieces of tubing fit inside the wider ones so that I can adapt the flowmeter fitting to a variety of connections. Of course, I never use plastic or rubber tubing for any gas at elevated pressure or for permanent supply or internal connections.

Tweezers and Hemostats

A pair of tweezers can hold small nuts or ferrules without risking contamination with skin oils or a burn from hot items. Some tweezers have a convenient locking feature that frees one hand for other tasks, as will a spring-loaded hemostat. Rubber tips help hold fragile capillary columns or inlet liners.


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