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Many problems with used liquid chromatographs can be reflected in the chromatogram
.
Recently, many users have inquired about various problems of liquid chromatography, and they have been solved in a timely manner.
Today, we summarize the solutions to the problems of second-hand liquid chromatography, and hope that everyone can use liquid chromatography to prevent problems before they happen! The following is a summary of 11 solutions to the problems of second-hand liquid chromatograms: (1) Reasons and solutions for peak tailing of second-hand liquid chromatograms Column; 2.
Collapse of the chromatographic column: fill the chromatographic column; 3.
Interference peaks: use a longer chromatographic column, change the mobile phase or replace the chromatographic column; 4.
Wrong choice of mobile phase PH: adjust the PH value
.
For basic compounds, low pH value is more conducive to obtaining symmetrical peaks; 5.
The reaction diagram of the melting point between the sample and the surface of the filler: Add ion-pairing reagent or basic volatile modifier to change the chromatographic column
.
(2) Causes and solutions of second-hand liquid chromatogram peak extension 1.
Low column temperature: increase column temperature; 2.
Inappropriate selection of sample solvent: use mobile phase as sample solvent; 3.
Sample overload: reduce sample content ; 4.
Damage to the chromatographic column: backflush the chromatographic column and fill the chromatographic column
.
(3) Reasons and solutions for peak bifurcation in second-hand liquid chromatograms 1.
Contamination map of guard column or analytical column: remove the guard column and conduct analysis
.
Replace the guard column if necessary
.
If the analytical column is clogged, remove it for cleaning
.
If the problem persists, the column may be contaminated with strongly retained material, apply appropriate regeneration measures
.
If the problem persists, the inlet may be blocked, replace the frit or replace the column
.
2.
The sample solvent is insoluble in the mobile phase: change the sample solvent
.
Use mobile phase as sample solvent if possible
.
(4) Reasons and solutions for peak deformation in second-hand liquid chromatograms Sample overload: reduce sample load (5) Reasons and solutions for early peak deformation in second-hand liquid chromatograms Inappropriate choice of sample solvent: reduce the injection volume, Use low polarity sample solvents
.
(VI) Reasons and solutions for the tailing degree of early peaks in second-hand liquid chromatograms greater than that of late peaks Extra-column effects: adjust the system connection (use shorter and smaller inner diameter pipes), use a small volume flow cell
.
(7) Causes and solutions for more serious detailing when the second-hand liquid chromatogram K' increases ), add salt or buffer (or ionized sample), replace one pillar; 2.
Secondary retention effect, normal phase mode: add triethylamine (or basic sample), add acetic acid (or acidic sample), add Water (or multifunctional compound), try another method; 3.
Secondary retention effect, ion pair: add triethylamine (or basic sample)
.
(8) Reasons and solutions for peak tailing of acidic or basic compounds in second-hand liquid chromatograms Inappropriate buffering: use a buffer with a concentration of 50-100 mM and a buffer with Pka equal to the pH value of the mobile phase
.
(9) Reasons and solutions for the extra peaks in the second-hand liquid chromatogram 1.
There are other components in the sample: normal; 2.
The elution peak of the previous injection: increase the running time or gradient slope, and increase the flow rate; 3.
Vacancy or ghost peaks: Check that the mobile phase is pure, use the mobile phase as the sample solvent, and reduce the injection volume
.
(10) Reasons and solutions for fluctuations in retention time of second-hand liquid chromatograms 1.
Improper temperature control: adjust the column temperature; 2.
Changes in mobile phase components: prevent changes (evaporation, reaction, etc.
); 3.
The column is not balanced : Allow sufficient time to equilibrate the column before each run
.
(11) Reasons and solutions for the changing retention time of second-hand liquid chromatograms 1.
Change of flow rate: reset the flow rate; 2.
Air bubbles in the pump: remove air bubbles from the pump; 3.
Inappropriate selection of mobile phase: replace Appropriate mobile phase; choose an appropriate mixed mobile phase
.
.
Recently, many users have inquired about various problems of liquid chromatography, and they have been solved in a timely manner.
Today, we summarize the solutions to the problems of second-hand liquid chromatography, and hope that everyone can use liquid chromatography to prevent problems before they happen! The following is a summary of 11 solutions to the problems of second-hand liquid chromatograms: (1) Reasons and solutions for peak tailing of second-hand liquid chromatograms Column; 2.
Collapse of the chromatographic column: fill the chromatographic column; 3.
Interference peaks: use a longer chromatographic column, change the mobile phase or replace the chromatographic column; 4.
Wrong choice of mobile phase PH: adjust the PH value
.
For basic compounds, low pH value is more conducive to obtaining symmetrical peaks; 5.
The reaction diagram of the melting point between the sample and the surface of the filler: Add ion-pairing reagent or basic volatile modifier to change the chromatographic column
.
(2) Causes and solutions of second-hand liquid chromatogram peak extension 1.
Low column temperature: increase column temperature; 2.
Inappropriate selection of sample solvent: use mobile phase as sample solvent; 3.
Sample overload: reduce sample content ; 4.
Damage to the chromatographic column: backflush the chromatographic column and fill the chromatographic column
.
(3) Reasons and solutions for peak bifurcation in second-hand liquid chromatograms 1.
Contamination map of guard column or analytical column: remove the guard column and conduct analysis
.
Replace the guard column if necessary
.
If the analytical column is clogged, remove it for cleaning
.
If the problem persists, the column may be contaminated with strongly retained material, apply appropriate regeneration measures
.
If the problem persists, the inlet may be blocked, replace the frit or replace the column
.
2.
The sample solvent is insoluble in the mobile phase: change the sample solvent
.
Use mobile phase as sample solvent if possible
.
(4) Reasons and solutions for peak deformation in second-hand liquid chromatograms Sample overload: reduce sample load (5) Reasons and solutions for early peak deformation in second-hand liquid chromatograms Inappropriate choice of sample solvent: reduce the injection volume, Use low polarity sample solvents
.
(VI) Reasons and solutions for the tailing degree of early peaks in second-hand liquid chromatograms greater than that of late peaks Extra-column effects: adjust the system connection (use shorter and smaller inner diameter pipes), use a small volume flow cell
.
(7) Causes and solutions for more serious detailing when the second-hand liquid chromatogram K' increases ), add salt or buffer (or ionized sample), replace one pillar; 2.
Secondary retention effect, normal phase mode: add triethylamine (or basic sample), add acetic acid (or acidic sample), add Water (or multifunctional compound), try another method; 3.
Secondary retention effect, ion pair: add triethylamine (or basic sample)
.
(8) Reasons and solutions for peak tailing of acidic or basic compounds in second-hand liquid chromatograms Inappropriate buffering: use a buffer with a concentration of 50-100 mM and a buffer with Pka equal to the pH value of the mobile phase
.
(9) Reasons and solutions for the extra peaks in the second-hand liquid chromatogram 1.
There are other components in the sample: normal; 2.
The elution peak of the previous injection: increase the running time or gradient slope, and increase the flow rate; 3.
Vacancy or ghost peaks: Check that the mobile phase is pure, use the mobile phase as the sample solvent, and reduce the injection volume
.
(10) Reasons and solutions for fluctuations in retention time of second-hand liquid chromatograms 1.
Improper temperature control: adjust the column temperature; 2.
Changes in mobile phase components: prevent changes (evaporation, reaction, etc.
); 3.
The column is not balanced : Allow sufficient time to equilibrate the column before each run
.
(11) Reasons and solutions for the changing retention time of second-hand liquid chromatograms 1.
Change of flow rate: reset the flow rate; 2.
Air bubbles in the pump: remove air bubbles from the pump; 3.
Inappropriate selection of mobile phase: replace Appropriate mobile phase; choose an appropriate mixed mobile phase
.
