Unexpected peak after up & down sampling

1. What causes extra peaks in gas chromatography?
2. What causes ghost peaks in HPLC?
3. How do you identify unknown peaks in HPLC?
4. What is the reason for RSD failure in HPLC?

What causes extra peaks in gas chromatography?

A contaminated syringe could easily cause additional peaks to be present in a chromatogram. The rinse solvents should be first replaced and either rinse or replace the syringe if the syringe continues to contaminate.

What causes ghost peaks in HPLC?

The ghost peak is most likely coming from column shedding during injection, and to a lesser degree, coming from your HPLC system (filters, frits, injectors, tubing, etc.) or mobile phase.

How do you identify unknown peaks in HPLC?

The best way I know is to connect the HPLC directly to a mass spectrometer (LC-MS). This method provides a simple characterization of peaks observed by UV-HPLC. By doing this, you have an additional detection method that can distinguish molecules by their molecular mass – which is perfect for stability studies [1].

What is the reason for RSD failure in HPLC?

It could also be due to blockage in the HPLC column frit, HPLC guard column, injector, or in-line filter; the use of the wrong HPLC column or the wrong mobile phase; low column temperature; or controller malfunction.