HPLC basic maintenance fault diagnosis communication seminar
Sweep, welcome attention Official WeChat of Educational Equipment Procurement Network Master the latest and most authoritative information in the education equipment industry Copyright and Disclaimer: â‘ The copyright of all works on this website that indicate "Source: China Education Equipment Purchasing Network" belongs to China Education Equipment Purchasing Network, and may not be reproduced, edited or used in other ways without authorization from this website. Works that have been authorized by this website should be used within the scope of authorization, and indicate "Source: China Education Equipment Purchase Network". Violators of this website will be held accountable for legal liabilities. â‘¡ All works on this website that indicate "Source: XXX (non-this website)" are reproduced from other media. The purpose of this reprint is to transmit more information. This does not mean that this website agrees with its views and is responsible for its authenticity. Take direct responsibility and joint liability for infringement of such works. If other media, websites or individuals download and use it from this website, they must keep the "source of the manuscript" indicated on this website, and bear the legal responsibility of copyright and other. â‘¢ If the content of the work, copyright and other issues are involved, please contact this website within two weeks from the date of publication of the work, otherwise it is deemed to waive the relevant rights. Stainless Steel Coconut Shaver Stainless Steel Coconut Shaver,Coconut Shaver,Kitchen Coconut Shaver,Coconut Shaver Set HY-STAINLESS STEEL INDUSTRIAL CO.,LTD. , https://www.cnhuangyi.com
2. Solvent filter head can not be cleaned by ultrasonic. It can be soaked with 35% nitric acid for 1 hour and then cleaned with solvent;
3. EDTA, ethylenediaminetetraacetic acid, etc. will corrode the immortal steel of the liquid column; carbon tetrachloride, 2-isopropanol, and tetrahydrofuran can not be mixed, but can be used alone;
4. Use of solvent: change or re-filter the solvent every two days (especially water, which needs to be replaced every day); mobile phase filtration is to remove microorganisms, generally water should be placed in a brown bottle;
5. Determine whether the filter element of the purge valve needs to be replaced: when water is used as the mobile phase, the normal pump pressure should be 0 bar when the flow rate is 5 ml / min (if the purge valve is opened, the filter element needs to be replaced when the pump pressure exceeds 10 bar);
6. If a non-polar solvent is used as the mobile phase, it is necessary to replace the "black straw hat" that plays a sealing role in the pump (the material suitable for reverse phase is graphite + PTFE, and the one suitable for normal phase), and a pair of simultaneous Replace, otherwise damage will be faster;
7. Washing of the gasket: when the concentration of salt in the mobile phase is> 0.01M, the wear of the gasket can be reduced; the salt precipitated in the piston rod is washed with a 1% isopropyl alcohol solution (isopropyl alcohol is added to prevent bacterial growth), The flow rate is set to 3-5 drops / min; the pump is turned on, and the salt washing device must also be turned on;
8. The pump head can not be cleaned by ultrasonic (can be cleaned by ethanol and water), the gemstone rod can not be ultrasonic, and the quartz window can be cleaned by ultrasonic;
9. The buffer salt channel is placed under the proportional valve. If there are only two phases, only one side is used (salt is below, organic phase is above);
10. The dual element pump is a post-pump mixing method (high pressure mixing method, which is not easy to enter bubbles), while the quaternary pump is a low pressure mixing method;
11. The outlet ball valve can be cleaned with ultrasound;
12. Binary pump has a sieve to control low flow rate;
13. If the mobile phase uses a buffer salt, it must be a reversed phase column (do not flush with water for a long time). Generally, it can be washed for 20-30 minutes, and then add an organic phase (such as methanol), the concentration is gradually increased until 100% methanol;
14. When switching between reversed phase and normal phase, solvent transition is generally required (the best is isopropanol), because the viscosity is large, the flow rate should not be set too large, and should not exceed 1ml / min (volume of solvent required to completely replace the original solvent = system volume (column Volume + 1.5ml) × 5);
15. Leakage in proportional valve: lift the suspected passage to see if the volume of mobile phase in the tube decreases (open the purge valve at the same time when lifting);
16. Possible causes of abnormal pump pressure: bubbles, active valve failure, outlet valve failure, seal or plunger rod wear, leakage or blockage, proportional valve failure, sensor failure, salt concentration is too high when mixing with proportional valve;
17. Automatic injection: bypass state, main path state; manual injection: load state to inject state (preferably full-scale injection, it is recommended to aspirate more than 3 times the injection volume), small volume injection is less than 1/2 The sample valve volume is better; usually the injection valve is best kept in the inject state (the rightmost state);
18. Sampling process: pin insertion—inject state—load state—injection (slow) —inject state—pull out the needle (two waste tubes after the injection valve);
19. VWD (variable wavelength) detector: the out waste liquid pipe after the detector should not be too short, otherwise the flow cell is easy to enter bubbles, and it should not be too long, otherwise it is easy to crush the flow cell;
20. DAD detector (the advantage is that it is convenient to optimize the conditions): maximum wavelength selection-to select the position where the solvent does not absorb (avoid about 20nm); the sensitivity of the VWD detector is slightly higher than the DAD detector; the holmium glass in the filter is used Calibrate the wavelength; if you want to increase the sensitivity of the detector, you need to open a large slit (the slit in front of the diode array defaults to 4nm);
twenty one. The deuterium lamp of the DAD detector can be used for the VWD detector, but not vice versa; the tungsten lamp and the xenon lamp have a long life and can be used whenever they are turned on, but "the deuterium lamp needs to be warmed up (10 minutes) (lifetime is 1000 hours), 1 -2 hours without use, no need to turn off, it is better to turn on, the deuterium lamp is easy to decay for a long time ", the lamp can be tested;
twenty two. Setting of measurement conditions: reference wave (absorption of solvent in mobile phase) can be omitted. The reference wavelength should be set during gradient elution, otherwise it will cause baseline drift. DAD can select a wavelength that is not absorbed by the sample as the reference light; band width ( VWD is set to the half-band width of the spectrum, but the DAD detector does not need to be set) (making a chromatogram within this range can reduce noise, the signal-to-noise ratio is better, but the signal will be reduced); reference wavelength selection principle: the sample is not absorbed, However, it is close to the position of the maximum absorption of the sample; the wavelength bandwidth of the reference light must be greater than or equal to the wavelength bandwidth of the measurement light; all spectra should be stored when selecting conditions for DAD; the deuterium lamp (190-800nm), but the effective range is 190-600nm, Tungsten lamp (470-950nm), if 470-800nm ​​is used, the intensity will increase;
twenty three. Causes of large baseline noise: unstable pump pressure, bubbles, column contamination
twenty four. Cleaning the online degasser and proportional valve (especially the long-term use of water phase or buffer salt channels): first rinse with water, then with methanol, you can open the purge valve, use a flow rate of 5ml / min, or use IPA to clean: A, Buffer B, MeoH C, Water D, CH3CN Analysis: A: B: D = 20:
25. When the pH of the mobile phase is> 9.5 or <2.3, the injection valve should be replaced with a tefzel rotor seal, which can withstand pressure: VWD (40bar), MWD (120bar), FLD (20bar), RID (56bar); RID, FLD is always the last A detector
2. Pump maintenance:
1) Use mobile phase as clean as possible;
2) The sand core filter at the liquid inlet should be cleaned frequently;
3) Prevent precipitation during mobile phase exchange;
4) Avoid blockage or bubbles in the pump;
3. Sampler maintenance:
1) After each analysis, the sample inlet should be washed repeatedly to prevent cross-contamination of the sample;
4. Column maintenance:
1) The column must not collide, bend or vibrate strongly under any circumstances;
2) When the column is connected with the chromatograph, the valve parts or pipelines must be cleaned;
3) Pay attention to the degassing of the mobile phase;
4) Avoid using high viscosity solvents as mobile phase;
5) Purify the injected sample;
6) Strictly control the injection volume;
7) After the end of daily analysis work, the residual sample in the injection valve should be cleaned;
8) After the daily analysis and determination, the column must be cleaned with an appropriate solvent;
9) If the analytical column will not be used for a long time, it should be stored and closed with an appropriate organic solvent;
5. Maintenance of detector (UV):
1) Maintenance of the UV lamp: Before the analysis, when the column is almost balanced, turn on the detector; after the analysis is completed, turn off the detector immediately.
2) The sample cell should be maintained. 
