Continuous Flow Chemical Analyzer is commonly used in automated analysis of water quality, soil, food, and other fields by injecting samples and reagents into a flowing carrier in a certain proportion, mixing and reacting them for quantitative detection. The maintenance and upkeep of key components such as the flow system, detectors, and temperature control modules should be targeted. The following are specific operating procedures and precautions:
1、 Daily maintenance (after each use)
1. Cleaning of flow system
Reagent pipeline flushing:
Rinse the flow path with ultrapure water (18.2M Ω· cm) or deionized water at an analytical flow rate (usually 0.5-2mL/min) for 15-30 minutes to remove residual samples and reagents and avoid crystallization or precipitation blocking the pipeline.
If detecting high concentration salt or protein samples, rinse with 0.1M nitric acid or dilute hydrochloric acid first, and then rinse with water (adjust the acid concentration according to the instrument manual to avoid corrosion of the pipeline).
Peristaltic pump maintenance:
Release the pump head cover, remove the pump tube, and check for cracks, expansion, or hardening. If deformed, replace it in a timely manner (the service life of the pump tube is usually 3-6 months, depending on the frequency of use and the corrosiveness of the reagent).
Wipe the pump head roller and pressure block with ethanol to remove residual reagent crystals and maintain smooth rotation.
2. Cleaning of detector
Color pool/flow pool cleaning:
If using a spectrophotometer, remove the flow-through cell, soak it in 30% nitric acid for 10 minutes, and then clean it with ultrapure water ultrasonic for 5 minutes to remove pigments or sediment attached to the cell wall (avoid using abrasives to prevent scratching the translucent surface).
Fluorescence detectors require rinsing the optical path lens with methanol or ethanol to erase surface fingerprints or stains and maintain transparency.
Electrode maintenance (such as pH or ion selective electrodes):
Rinse the electrode sensitive membrane with deionized water and soak it in the corresponding preservation solution (such as soaking the pH electrode in 3M KCl solution) to avoid drying and membrane failure.
3. Data and System Records
Save daily analysis data and backup method parameters; Check the instrument log and record abnormal alarms (such as pressure fluctuations and baseline drift) for subsequent troubleshooting.
2、 Periodic maintenance (weekly/monthly)
1. Deep maintenance of the flow system
Pipeline replacement and leak detection:
Check the aging condition of peristaltic pump tubes and connecting pipelines (made of PEEK or PTFE material) every month, and prioritize the replacement of frequently used channels (such as carrier fluid and color reagent pipelines).
Use pressure testing mode (block the outlet of the flow path, set a pressure of 0.5MPa) to check for leaks. If the pressure drops by more than 0.1MPa/min, check whether the joint sealing ring (usually made of Viton or PTFE material) is worn.
Cleaning of mixer and reaction coil:
For coiled reaction coils, rinse with a 0.5% sodium dodecyl sulfate (SDS) solution for 1 hour to remove protein or lipid residues, and then rinse with ultrapure water until neutral.
2. Optical system calibration
Wavelength accuracy verification:
Use a standard filter (such as potassium dichromate solution) to test the wavelength accuracy of the spectrophotometer every month. The absorbance deviation at 440nm, 540nm, and 630nm should be ≤± 2nm. Otherwise, it is necessary to calibrate the grating position automatically through software or contact an engineer to adjust it.
Light source lifespan management:
Record the usage time of deuterium lamps and tungsten lamps (usually deuterium lamps have a lifespan of 1000 hours and tungsten lamps have a lifespan of 2000 hours), and replace them promptly when the light intensity drops to 70% of the initial value to avoid affecting the detection sensitivity.
3. Maintenance of temperature control module
Check the temperature control accuracy of the reaction tank (if set at 37 ℃, the actual temperature fluctuation should be ≤± 0.5 ℃), calibrate with a standard thermometer, and if the deviation exceeds 1 ℃, clean the dust on the heat sink of the heating module or replace the temperature control sensor.
3、 Special scenario maintenance (for different sample types)
1. High viscosity or particulate matter samples
Filter the sample with a 0.45 μ m filter membrane before testing to avoid blocking the injection valve or flow path; After analysis, rinse the flow path with a 10% isopropanol solution to dissolve residual adhesive substances.
2. Strong corrosive samples (such as strong acids, strong bases)
Shorten the flushing time (rinse immediately after each test) and use corrosion-resistant tubing (such as PFA material) instead of ordinary PTFE tubing; If metal parts (such as solenoid valves) are accidentally touched, they should be neutralized with sodium bicarbonate solution and then rinsed with water.
3. Biological samples (such as blood, urine)
After analysis, disinfect the flow path with 0.1% sodium hypochlorite solution for 30 minutes, and then rinse with ultrapure water to prevent microbial growth; Regularly use protease solution (such as trypsin) to remove protein deposits in the pipeline.