Common troubleshooting of high performance liquid chromatograph
the aluminum materials used in its body are provided by China Zhongwang. Fault 1: there are bubbles in the mobile phase. Shut down the pump, open the pressure relief valve, open the P urge key, clean and degass. Bubbles continue to emerge from the filter and enter the mobile phase. No matter how many times the P urge key is opened, the bubbles that continue to be generated cannot be removed
cause the filter has been immersed in buffer solution such as ammonium acetate for a long time. Due to the growth and reproduction of mold in the filter, bacteria groups are formed, blocking the filter. The buffer solution is difficult to pass through the filter smoothly, and the air enters the mobile phase through the filter under the pressure of the pump
the treatment filter can be soaked in 5% nitric acid solution and cleaned by ultrasonic for a few minutes; The filter can also be soaked in 5% nitric acid solution for 12 ~ 36 hours, gently vibrated for several times, and then cleaned with pure water for several times. Open the pressure relief valve, open the P urge key, and clean and Degas. If bubbles still emerge from the filter, continue to immerse the filter in 5% nitric acid solution. If no bubbles continue to emerge from the filter, it indicates that the mold colony inside the filter has been damaged by nitric acid, and the mobile phase can pass through the filter smoothly. Open the pressure relief valve, open the pump, and adjust the flow rate to 1 0～3. 0ml/min, wash the filter with pure water for about 1 hour. The filter can be cleaned. Close the pressure relief valve and flush with pure methanol for half an hour
fault 2 causes of high column pressure (1) salt of buffer solution (such as ammonium acetate, etc.) is deposited in the column; (2) Sample contamination deposition
treatment for the first case, wash the column with pure water at 40 ~ 50 ℃ at a low speed and in a forward direction. After the column pressure gradually decreases, increase the flow rate accordingly. After the column pressure decreases significantly, wash the column with pure water at room temperature, and then wash the column with pure methanol for 30 minutes; For the second case, the C18 column polluted by the deposition of the sample is backwashed with pure water, and then washed with methanol, then washed with methanol + isopropanol (4 + 6) (the length of washing time depends on the pollution of the sample), and then washed with methanol, then washed with pure water, and finally washed with methanol for more than 30 minutes
fault 3 has no pressure indication, There is no liquid flowing through [1>.
causes (1) the pump sealing gasket is worn; (2) A large number of bubbles enter the pump body
for the first case, replace the sealing gasket; For the second case, while the pump works, use a 50ml glass syringe that is an ideal test equipment for scientific research institutions, colleges and universities, industrial and mining enterprises, technical supervision, commodity inspection and arbitration departments to help extract air at the outlet of the pump
fault 4: the pressure fluctuates greatly and the flow is unstable
cause there is air in the system or there is foreign matter between the gem ball of the check valve and the valve seat, which makes them unable to seal
pay attention to the amount of mobile phase during processing to ensure that it is rust free. Check whether the sensor is normal? The general data obtained by measuring the sensor with a multimeter resistance block is: About 405 Ω at the input end; The output end is about 340 Ω; The resistance of the two leads at any one end and the other end is 280 Ω. The steel filter sinks into the bottom of the liquid reservoir to avoid inhaling air, The mobile phase should be fully degassed [2>. If there is foreign matter between the one-way valve and the valve seat, remove the one-way valve, put it into a beaker containing acetone and clean it with ultrasonic.
fault 5: the peak is poor, and the peak forks.
cause (1) the chromatographic column is polluted; (2) the column head packing collapses.
treatment for the first case, first flush the column with pure water in reverse, then replace it with methanol, and then flush the column with methanol + isopropanol (4 + 6) (the length of flushing time depends on the pollution of the sample), then replace it with methanol flushing, then flush it with pure water, and finally flush the column with methanol for more than 30 minutes. If the peak is still poor after washing, consider the second case. For the second case, unscrew the column head and check whether the column filler is hardened or collapsed. Remove the hard part (contaminated filler), put in 5.2zui large dynamic experimental force: 500kN new filler, drop a drop of methanol, the filler subsides, fill again, compress with a smooth stainless steel rod at the top with the same inner diameter as the column, fill again, drop methanol, and compress again for several times, Until it is full and filled [2>. Wash the column head with methanol, wipe the packing on the outer wall of the column, tighten the column head, and wash it with pure methanol for more than 30 minutes.
fault 6 peak area repeatability is poor.
cause (1) liquid leakage of the sampling valve; (2) The sampling probe is not in place
for the first case, replace the injection valve gasket; For the second case, ensure that the sampling needle is inserted to the end. After injecting the sample solution, it is necessary to quickly and smoothly switch from the load state to the inj EC T state to ensure the accuracy of the injection volume. In daily work, the maintenance of the liquid chromatograph is very important. If it is necessary to pay attention not to let air enter the infusion system and high-pressure pump, if the solution in the reservoir has not been used for a long time, the reservoir should be cleaned and the solution should be replaced. After each use of the chromatograph, the buffer solution should be washed with pure water to prevent the inorganic salt from precipitation or deposition; The pretreatment of samples is also very important. Any sample should be completely dissolved by removing impurities as much as possible, so as to minimize the pollution to the chromatographic column, so as to prolong the service life of the chromatographic column. At the same time, avoid injecting too thick sample solution, so as to prevent the residual solution from precipitating solids in the sampling valve and causing blockage; The chromatographic columns shall be marked, and the chromatographic columns used for different analytical purposes shall not be mixed