How do you overcome peak tailing in GC? Try changing your stationary phase or solvent. If peak tailing is occurring only in peaks closest to the solvent front or major component peak, consider the Reverse Solvent Effect. Try a retention gap or guard column to correct this.
How do you solve peak broadening in GC?
How do I improve early eluting peak shape for GC?
- 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 peak tailing?
Peak tailing is the most common chromatographic peak shape distortion. … Peak tailing occurs when the peak asymmetry factor (As) is greater than 1.2 — although peaks with As greater than 1.5 are acceptable for many assays.
What is tailing factor in GC?
Definition: Tailing factor
The tailing factor is a measure of peak tailing. It is defined as the distance from the front slope of the peak to the back slope divided by twice the distance from the center line of the peak to the front slope, with all measurements made at 5% of the maximum peak height.
What causes peak broadening?
The sample injection volume is related to broadening of the sample zone in the first stage of column separation. Therefore, increasing the injection volume can result in peak broadening. In particular, the higher the ratio of strong solvent in the sample solvent, the greater the effects.
Why is peak broadening bad?
The ideal is a Gaussian or symmetrical shaped peak, a narrow peak width at half-height when compared to its height and no peak fronting, tailing or broadening. Poor peak shape can cause integration and resolution errors in your analysis — which ultimately means poor analysis and wasted time and money.
What is Ghost Peak?
Ghost peaks are contaminant peaks that appear even when no sample is injected. There are many causes for ghost peaks and this note will describe how to troubleshoot these contaminant peaks, when you see them. The primary cause of a ghost peak is a dirty pre-column or column. … Improve sample cleanup prior to injection.
What causes peak shouldering?
Peak Shoulders and Split Peaks
Shoulder peaks and split peaks often result due to presence of two closely unresolved compounds. Splitting off peaks is also caused by frit blockage. Reverse flow with 20 – 30 ml of mobile phase often resolves the peak splits.
What is a ghost peak?
Ghost peaks are contaminant peaks that appear even when no sample is injected. There are many causes for ghost peaks and this note will describe how to troubleshoot these contaminant peaks, when you see them. The primary cause of a ghost peak is a dirty pre-column or column. … Improve sample cleanup prior to injection.
How do you increase peak resolution?
How to Improve Resolution in HPLC
- Increasing column length.
- Decreasing particle size.
- Reducing peak tailing.
- Increasing temperature.
- Reducing system extra-column volume.
What is Ghost peak in HPLC?
Ghost peaks are contaminant peaks that appear even when no sample is injected. There are many causes for ghost peaks and this note will describe how to troubleshoot these contaminant peaks, when you see them. The primary cause of a ghost peak is a dirty pre-column or column.
Why is it important for GC peaks to appear symmetrically?
Ideally, the peaks in the chromatogram display a symmetric shape (Gaussian curve). If too much of the sample is injected, the peaks show a significant tailing, which causes a poorer separation. Most detectors are relatively sensitive and do not need a lot of material in order to produce a detectable signal.
What is a good number of theoretical plates?
The number of theoretical plates is often used to establish the efficiency of a column. Plate numbers range from 100 to 106. The more theoretical plates available within a column, the more equilibrations between the stationary and mobile phases are possible and the better the quality of the separation.
How do you minimize peak broadening?
Buffers are considered capable of improving the shape of the peak when selected at the proper pH level to control ionization. You can reduce peak broadening by using different types of buffers such as acetate or phosphate buffer solutions, these adjusted to the suitable pH as per the pKa value of the molecule.
What causes peak broadening in XRD?
The broadening in the peaks of the XRD patterns arises due to the finite size of the crystals. If one has crystal of infinite size, the peaks in the XRD pattern will appear as very sharp and as size get reduces peak broadening increases.
How can excessive peak broadening be avoided?
Inject your sample into the same solvents (or very similar) to those used as mobile phase. Check out the age of your column. Too old columns give tailing peaks and other performance problems. Check out also the volume injected and the concentration of the target analyte in your sample.
How do you stop peak splitting?
2) Wash the column with 90% Organic phase such as Acetonitrile or Methanol. It eliminates the peak splitting by washing out the hydrophobic adulterant in the column. The column should be washed regularly with polar and non-polar solvents to prevent agglomeration of adulterants within the column for smooth analysis.
How do I get rid of ghost peaks?
The remedy is to devise a sample preparation procedure to eliminate the impurity, such as an extraction or use of a disposable filter, etc. Furthermore, when the appearance of a ghost peak is due to degradation of the sample, that degradation can be inhibited by using an autosampler with a vial cooling feature.
How do I get rid of ghost peak in HPLC?
If the ghost peak is seen even with a blank injection, then it is due to the system and is a true ghost peak. To eliminate or prevent these ghost peaks: Use an HPLC system with minimum pressure change during the load and inject steps.
What is peak fronting?
Peak fronting is the name given to asymmetric peaks having a wider front half of the peak compared to the back half.
How do you stop peak splitting?
The problem of the peak splitting can be solved by reverse flushing most of the times as it removes the contaminant from the column and may also dissolve the absorbed contaminants if the impurities in the column is soluble in the Mobile Phase. 2) Wash the column with 90% Organic phase such as Acetonitrile or Methanol.
What is peak splitting?
Peak splitting is when a Gaussian peak gets a shoulder or a twin. They have the same base, are unexpected and can be caused by a number of factors. The splitting can affect all peaks or just one, and different effects can be attributed to different causes.
How do I get rid of ghost peaks?
If the ghost peak is seen even with a blank injection, then it is due to the system and is a true ghost peak. To eliminate or prevent these ghost peaks: Use an HPLC system with minimum pressure change during the load and inject steps.
What causes peak?
The primary cause of peak tailing is the occurrence of more than one mechanism of analyte retention. … Secondary analyte interactions, with ionised silanols on the silica surface, give rise to peak tailing. These interactions need to be minimised to achieve acceptable peak shapes.
Why do we get negative peak in HPLC?
Negative peaks are most often caused by difference in refractive index between the sample solvent, sample and mobile phase. They are also caused after routine maintenance when the system has not been reconfigured correctly.
References
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