53


Item


Sample Introduction and Inlets Syringes and needles


Inlet liner Liner O-rings Inlet septum Inlet hardware


Inlet gold or stainless steel seal


Columns


Front-end maintenance


Solvent rinse


Replacement Ferrules


Detectors


FID/NPD jets and collector


NPD bead TCD ECD FPD


Mass selective detectors Clean the ion source


Gas Management


Gas purifiers (carrier gas and detector gas)


Every 6 to 12 months


Replacement schedule is based on capacity and grade of gas. In general, replace non-indicating traps every 6 to 12 months or when indicating traps start to change colour. Replace indicating traps when indicating material is starting to change colour.


Table 2: GC and GC/MS cleaning schedule for average use. Frequency can vary widely depending on application and sample.


source prevents active compounds from attaching to metal surfaces. The best inert sources are constructed of a solid inert material, as opposed to an inert coating that can wear away over time. Stainless steel construction alone is not sufficient, as can be seen in Figure 4.


5. Purify your gases


Contaminants in gases can significantly affect your analysis. Moisture, oxygen, and hydrocarbons contribute to loss of sensitivity


and undermine the accuracy of the GC. Impurities activate glass wool in liners and accelerate septa degradation, causing high background signals and ghost peaks, which lead to time-consuming troubleshooting. Supply gases can pick up contaminants from every part of the gas line, so you need a gas filter system even if your supply gas is of the highest quality. It is not economical to buy expensive, high purity gases if their quality is downgraded by impurities in the gas line. Gas filters help to provide a clean, high-


quality gas supply that is free of oxygen and contaminants. Use these filters to reduce the risk of column damage, sensitivity loss, and downtime. In addition, it’s important to change gas filters when they become exhausted. This is usually indicated by a change of colour of the filter material. All GC applications benefit from the use of gas filters, whether your GC is connected to an FID or MS, or any other type of detector such as flame photometric, thermal conductivity, electron capture, nitrogen-


As needed As needed As needed Every 6 months or as needed Every 6 months or as needed


Clean when deposits are present. Replace when they become scratched, bent, or damaged, or when having difficulty lighting FID or keeping flame lit.


Replace when signal drifts or there is a dramatic change in sensitivity.


Thermally clean by "baking-out" when a wandering baseline, increased noise, or a change in response is present. Replace when thermal cleaning does not resolve the problem.


Wipe test. Thermally clean by "baking-out" when baseline is noise, or the output value is abnormally high. Replace when thermal cleaning does not resolve the problem.


Measure hydrogen, air, and makeup gas flows. Clean/replace FPD windows and seals when detector sensitivity is reduced.


Clean when performance deteriorates to remove contamination and to As needed


restore the electrostatic properties of the ion lens system. Replace scratched parts to maintain optimal performance.


Weekly-monthly As needed


As needed As needed


Remove 1/2 to 1 m from the front of the column when experiencing chromatographic problems (peak tailing, decreased sensitivity, retention time changes, etc.). Replace inlet liner and septum, and clean inlet as necessary. Guard column may be useful for increasing column lifetime.


Perform when chromatography degradation is due to column contamination. Only for bonded and cross-linked phases.


Replace when trimming and/or solvent rinsing no longer restore chromatographic performance.


Replace when changing columns and inlet/detector parts.


Typical Schedule


Comments Every 3 months


Weekly Monthly


Daily Every 6 months Monthly


Replace syringe if dirt is present, if it cannot be cleaned, if the plunger does not slide easily, or if clogged. Replace needle if septa wear is abnormal or the needle becomes clogged.


Check often. Replace when dirt is visible in the liner or if chromatography is degraded. Replace with every liner change.


Check often. Replace when signs of deterioration are visible (gaping holes, fragments in inlet liner, poor chromatography, low column pressure, etc.)


Check for leaks and clean. Check parts and replace when parts are worn, scratched, or broken.


For highest level of reproducibility, change inlet seal with every liner change, but at a minimum replace monthly or when scratched, corroded, or if there is build-up of nonvolatile sample components.


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