How do you troubleshoot gas chromatography?
How do you troubleshoot gas chromatography?
Verify steady flow rates and temperatures, then adjust settings and/or replace parts if needed. Remove contamination and use properly deactivated liner, seal, and column. Check for leaks at all connections and repair connections as needed. Verify injection technique and change back to original technique.
What causes GC retention time shift?
A change in the temperature program often causes a retention time shift of all the peaks. A change in the initial temperature, the initial hold time, or the ramp rate can affect all of the peaks. Retention times increase with a lower initial temperature, longer initial hold time, or a slower ramp rate.
What is septum purge in GC?
Most modern gas chromatographs have a septum purge flow that is designed to flow across the inward face of the septum, sweeping most of the volatiles away from the column.
What is HPLC troubleshooting?
In an HPLC system, problems can arise from many sources. First define the problem, then isolate the source. Use Table 1 to determine which component(s) may be causing the trouble. A process of elimination will usually enable you to pinpoint the specific cause and correct the problem.
What causes GC column bleeding?
High bleed is one of the most common issues you’ll encounter when doing gas chromatography. Excessive bleed is often caused by something damaging the stationary phase of the column, things like oxygen from a leak or some aggressive component in the sample.
How is GC column prevented bleeding?
The answer is careful column conditioning, and good quality carrier gas. At high column temperatures, traces of oxygen can damage column phases leading to increased column bleed. So before conditioning the column, it needs to be thoroughly purged with good quality carrier gas to ensure that no oxygen is present.
What is purge flow in GC?
Re: Purge Flow for Splitless Injection You need suffient flow to sweep the inlet clean quickly enough to stop transfer of any materials from the inlet to the GC column – like the tail of the solvent peak. With a purge rate of 100, you will exchange the carrier gas in the inlet in a couple of seconds or less.
How do you increase peak shape in GC?
Steps that can be taken to improve early eluting peak shape:
- Use a split injection. This limits the amount of solvent that gets onto the column and reduces how much analyte dissolves in pooled solvent.
- Decrease the injection volume.
- Use a pressure pulsed injection.
- Use a guard column.
- Increase the column film thickness.
What is split and splitless in GC?
If a split injection is used then there won’t be enough analyte injected on-column to detect. This is called the splitless mode and it’s used for trace because all the analyte mass in a 1 µL injection goes on column, and is not split; and so this is the most sensitive the method can be: a splitless injection.
