H. Retention time drift 1 Temperature change Check the temperature of the column thermostat 2. Gas flow rate change Inject methane and measure the carrier gas linear velocity 3. Sample inlet leak check sample pad; Judge other leaks 4. Solvent conditions change sample, standard The product uses the same solvent 5. Chromatographic column is contaminated and cut off the column head 10cm; high temperature aging, cleaning
I. Decrease in resolution 1. The column is contaminated by the same method as above 2 The stationary phase is damaged (column bleed) Replacement 3 Failure of sampling, leak detection, maintenance, purge time, temperature suitability; liner 4. Sample concentration Too high dilution; reduce injection volume; use high split ratio
J. Widening of solvent peak 1. Failure of chromatographic column installation 2. Leakage of injection 3. High injection volume increases vaporization temperature 4. Low flow ratio increases split ratio lower than 5 OVEN 6 When split injection, the initial OVEN is too high to reduce the initial column Temperature, use high boiling point solvent 7. Purge time is too long (splitless injection) Define the short-term purge procedure baseline problem
K. The baseline drifts downwards 1 The newly installed column, the baseline continues to drift for a few minutes and continues to age 2 The detector does not reach equilibrium and the equilibration time of the detector is extended 3 Deposits in the detector or other parts of the GC system are baked out and cleaned
L. The baseline drifts upwards. 1. The stationary phase of the chromatographic column is destroyed. 2 The flow rate of the carrier gas decreases. Adjust the carrier gas pressure; purge pressure and flow control valve.
M. Noise 1. Insert the end of the capillary into the detector too deep and reinstall the column. 2. Use ECD, TCD gas leak to cause baseline noise inspection, repair the gas line 3 FID, NPD, FPD gas flow rate or gas selection improper high purity gas, adjust the flow rate . The inlet is contaminated to clean the inlet; replace the cushion; replace the glass fiber or silanization in the tube. 5. The capillary chromatographic column is contaminated and cut off the first end 10cm; clean the column with solvent; replace 6. The detector occurs Failure repair, replacement 7. Failure of the detector circuit Contact the manufacturer or maintenance organization (professional)
N, Offset (Sudden change of the baseline position 1. The power supply voltage fluctuates using the voltage regulator 2 The connection of the circuit interface is not well checked, clean the interface, tighten the interface 3. The inlet is contaminated
4. The column is contaminated 5. The end of the capillary is too deep into the detector 6 The detector is contaminated
O. Burr 1 Electromagnetic interference Turn off the electromagnetic interference source 2. Particle contamination enters the detector 3. The air circuit seal is loose, gas leakage is tightened and the loose seal is tightened 4. The detector internal circuit interface or input, output signal interface is loosely inspected, cleaned and tightened , Dust or corrosion of replacement
P, Wander (low frequency noise)
1. Fluctuations in environmental conditions such as temperature and pressure find the relationship between changes in environmental factors and the baseline, and then stabilize 2. Temperature control drift to measure the temperature of the detector 3 Carrier gas contains impurities (when the temperature is stable) Replace the carrier gas or gas purifier 4. The inlet is contaminated 5. The capillary is contaminated 6. The gas flow rate control fails to clean or replace the gas
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