Analysis and solution of the problems reflected by

  • Detail

Analysis of problems reflected in the chromatogram and solutions

1. Sieve plate blockage: A. recoil the chromatographic column B, replace the sieve plate C, replace the chromatographic column

2. Column collapse: fill the chromatographic column

3. Interference peak: A. use a longer chromatographic column B, change the mobile phase or replace the chromatographic column

4. Wrong choice of mobile phase pH: adjust pH value. For alkaline compounds, low pH value is more conducive to obtain symmetrical peaks

5. The sample reacts with the active point on the surface of the filler:

a, adding ion pair reagent or alkaline volatile modification

b, changing the chromatographic column

b, peak front extension

1, low column temperature: increasing the column temperature

2, improper selection of sample solvent: using mobile phase as sample solvent

3, sample overload: 3, reducing the sample content

4 Chromatographic column damage: see A1, A2

c, peak bifurcation

1, protective column or analytical column pollution: remove the protective column for re analysis. The protective column can also be replaced. Remove it for cleaning. If the problem still exists, it may be that the column is polluted by strongly retained substances, and appropriate regeneration measures can be used. If not, the inlet may be blocked. You can replace the sieve plate or chromatographic column

2. The sample solvent is insoluble in the mobile phase: change the sample solvent. If possible, take the mobile phase as the sample solvent

component peak with high content of d

1. Improper selection of sample solvent: reduce the sample load

e, peak deformation of early emergence

improper selection of sample solvent:

A, reduce the injection volume

b, use low polarity sample solvent

F The tailing degree of the early peak is greater than that of the late peak

out of column effect:

a, adjust the system connection (use a shorter pipeline with a smaller inner diameter)

b, use a small volume of flow cell

g, when k 'increases, tailing is more serious

1, secondary retention effect, reverse phase mode:

a, add triethylamine B, add acetic acid C, add salt or buffer d first, replace a column

2, secondary retention effect, Normal phase model: A. add triethylamine B, add acetic acid C, add water D, try another method

3, secondary retention effect, ion pair: add triethylamine

h, peak tailing of acidic or alkaline compounds

the concentration of buffer is inappropriate: A. use buffer with concentration of mmol/l B, use buffer with PKA equal to the pH value of mobile phase

i, additional peak

1, other components in the sample: normal

2 Elution peak of the previous injection: A. increase the printing of the experimental report; Running time or gradient B, using buffer solution with pH equal to the pH of the mobile phase

3, vacancy or including the latest halogen-free brand (expansion of its thermal conductive resin series), new polymer series with good electrical properties, innovative rubber ghost peak for wire and cable mixture manufacturers: A, check whether the mobile phase is pure B, use the mobile phase as sample solvent C, reduce the injection volume

j, retention time fluctuation

1 Improper temperature control: reset the column temperature

2. Change of mobile phase components: prevent changes (evaporation, reaction, etc.)

3. The chromatographic column is not balanced: give enough time to balance the chromatographic column before each operation

Copyright © 2011 JIN SHI