Imported evaporative light scattering detectorIt is a universal detection device based on the principle of light scattering, widely used in separation and analysis fields such as high performance liquid chromatography (HPLC), ultra-high performance liquid chromatography (UHPLC), and capillary electrophoresis (CE). Its core advantage lies in breaking away from the dependence of traditional detection techniques on the optical properties of samples, and being able to detect substances without UV absorption, fluorescence, or electroactivity, such as sugars, lipids, surfactants, amino acids, drugs, and polymers.
Working principle: The detection process of ELSD consists of three key steps: atomization, evaporation, and light scattering detection. The liquid sample flowing out of the chromatographic column enters the atomizer and mixes with high-speed inert gas (such as nitrogen) to form tiny droplets, forming aerosols. Aerosols enter the heated drift tube, and the solvent in the droplets rapidly evaporates, leaving only sample particles. These particles generate light scattering when passing through a beam of light (such as a laser or LED light source), and the intensity of the scattered light is proportional to the concentration of the sample. The photoelectric sensor collects scattered light and converts it into an electrical signal, ultimately outputting a chromatogram.
Imported evaporative light scattering detectorMaintenance methods:
1、 Daily cleaning and inspection
Instrument surface cleaning: Use a towel dipped in soapy water or neutral cleaning products to wipe the surface of the instrument and keep its appearance clean.
Internal channel cleaning: Following the instrument's on/off program, the instrument will automatically perform internal channel cleaning. However, it should be noted that for stubborn stains or residues, manual cleaning may be necessary.
Nebulizer cleaning:
Regularly check if the atomizer is clogged. If poor atomization effect is found (such as uneven droplets or splashing), it should be cleaned in a timely manner.
When cleaning the atomizer, use a suitable solvent (such as isopropanol or chromatographic methanol) and carefully disassemble, rinse, and assemble according to the correct steps. Avoid damaging the fine components of the atomizer.
After cleaning, ensure that the inside of the atomizer is dry to prevent residual solvents from affecting the test results.
Drift tube and detection room cleaning:
The drift tube and detection chamber are the core components of the detector and need to be cleaned regularly to remove any accumulated pollutants.
When cleaning, pure water or ethanol can be used to rinse the entire flow path of the drift tube and detector. For stubborn pollutants, methods such as ultrasonic cleaning can be used.
After cleaning, ensure that the drift tube and detection chamber are dry to prevent residual solvents or moisture from affecting the detection results.
2、 Mobile phase and gas management
Mobile phase selection:
Use high-purity mobile phase and avoid solvents that may cause contamination or corrosion.
Prohibit the use of mobile phases containing non-volatile acids, bases, and salts to prevent crystallization damage to the atomizer and drift tube after the evaporation step.
If additives are needed to improve separation efficiency, solvents suitable for LCMS such as ammonium acetate, formic acid, and acetic acid can be selected.
Gas management:
Use high-purity nitrogen or air as the carrier gas to ensure that the gas is free of oil and dust.
Regularly check the pressure of the gas source and the connection of the pipeline to ensure stable supply of carrier gas and appropriate pressure.
Install a gas filter between the atomizer and the instrument, and regularly maintain and replace the filter components.
3、 Nebulizer and drift tube maintenance
Nebulizer maintenance:
Regularly check the atomization effect of the atomizer to ensure that the droplets are uniform and there is no splashing phenomenon.
If the atomizer is found to be blocked or damaged, it should be cleaned or replaced in a timely manner.
When replacing the atomizer, pay attention to following the correct steps for installation and debugging to ensure compatibility between the atomizer and the instrument.
Drift tube maintenance:
Regularly check whether the temperature setting of the drift tube is consistent with the actual temperature to ensure stable evaporation process.
If it is necessary to maintain and clean the drift tube, its temperature can be set to the maximum value (such as 100 ℃) to remove stubborn organic matter deposits.
When cleaning the drift tube, pay attention to using appropriate solvents and cleaning methods to avoid damaging the internal structure of the drift tube.
4、 Optical system maintenance
Light source maintenance:
Regularly check the intensity of the deuterium lamp light source. If the emitted energy is lower than 70% of the initial value, the lamp tube should be replaced in a timely manner.
When replacing the light source, pay attention to following the correct steps for installation and debugging to ensure compatibility between the light source and the instrument.
Maintenance of optical lenses and quartz window panels:
Regularly use a dust-free cotton swab dipped in a small amount of anhydrous ethanol to wipe the surface of the quartz window panel in one direction. It is strictly prohibited to rub back and forth to cause scratches.
Keep the optical lens cover sealed to prevent the accumulation of laboratory dust from affecting the test results.
5、 Operating standards and records
Operating standards:
Follow the on/off program of the instrument to ensure that it is not damaged during startup and shutdown.
After the test is completed, rinse the pipeline and atomizer in a timely manner to prevent residue from affecting the next test results.
Avoid using the instrument under conditions beyond the design range of the detector (such as using excessively high temperatures or inappropriate solvents).
Record management:
Establish a running parameter file to record key parameters such as baseline noise value, response factor, and drift tube temperature setting value at each startup.
Save complete maintenance logs, including replacement part batch numbers, comparison of spectra before and after repairs, and other information. This helps track the maintenance history of the instrument, identify potential issues in a timely manner, and take measures.
6、 Long term storage management
Regular startup and operation:
If the detector is not used for a long time, it should be started and operated regularly (such as once a month) to prevent component aging or corrosion.
Storage environment requirements:
Store the detector in a dry, ventilated, and non corrosive gas environment, avoiding direct sunlight and high temperatures.
Ensure that the detector is dry, clean, and free of residue before storage.