Can two compounds have the same retention time?

Different compounds could lead to same retention times in HPLC and TLC. As previously suggested, you should try other protocols or better methods for the separation, if it is possible I recommend to use ultra-HPLC (UPLC).

Will the same compounds have similar retention times in gas chromatography?

Gaseous mobile phase carries gaseous compounds (analytes) through a long column with a stationary phase. Different compounds have different retention times. For a particular compound, the retention time will vary depending on: The boiling point of the compound.

What does retention time tell you in gas chromatography?

The concept of retention time was already introduced in Section 1.1. It indicates how long it takes for a compound to elute from the column, and the retention time of the last peak in a chromatogram is used to estimate the necessary length of the chromatographic run.

Why do different compounds have different retention times in gas chromatography?

Different compounds have different retention times. The more soluble a compound is in the liquid phase, the less time it will spend being carried along by the gas. High solubility in the liquid phase means a high retention time. the temperature of the column.

How do you separate closely eluting peaks in HPLC?

Some compounds of high molecular weight may not be separable on small pore size packings, but will be easily resolved on a column packed with larger-pore packing. Generally, the easiest way to resolve closely or co-eluting peaks is to change the bonded phase on the column packing.

How do you identify compounds in gas chromatography?

THE identification of unknown compounds separated by gas chromatography is often effected by comparison of their retention values with those of known compounds together with infra-red spectro-photometry or mass spectrometry.

What does a chromatogram show?

What Is a Chromatogram? A chromatogram is a representation of the separation that has chemically [chromatographically] occurred in the HPLC system. A series of peaks rising from a baseline is drawn on a time axis. Each peak represents the detector response for a different compound.

What does a gas chromatogram show?

What is gas chromatography? Gas chromatography (GC) is an analytical technique used to separate the chemical components of a sample mixture and then detect them to determine their presence or absence and/or how much is present. These chemical components are usually organic molecules or gases.

How do you separate co-eluting compounds?

Changing the chemistry of the mobile phase, stationary phase, temperature, and column or plane length are good methods to increase the separation. Techniques such as mass spectrometry and optical spectroscopy are common ways to distinguish between co-eluting compounds that cannot be resolved.

How do you separate co-eluting peaks?

Methods to separate co-eluting peaks

1. Switch column (not optimal due to delivery times and cost)
2. Change the method for my current column (BPX5, 50m, 0.32 mm, 1.0 um)
3. Ignore and analyse the two compounds combined.

How do you read a gas chromatogram?

How to Read GC/MS Chromatograms

1. The X-Axis: Retention Time. Usually, the x-axis of the gas chromatogram shows the amount of time taken for the analytes to pass through the column and reach the mass spectrometer detector.
2. The Y-Axis: Concentration or Intensity Counts.
3. Differences in Gas Chromatogram Models.