Mitsubishi Card Moisture MeterBased on the principle of Karl Fischer Coulomb method, it has the characteristics of wide measurement range (10 μ g~100mg H ₂ O), high accuracy, and strong automation. It can adapt to various types of samples such as gas, liquid, and solid, and is widely used in industries such as petroleum, chemical, pharmaceutical, and food. Mastering its applicable sample range and detection techniques can further improve the accuracy and repeatability of detection results.
1、 Applicable sample types and adaptation scenarios
1. Liquid sample
Common types: petroleum products such as engine oil, transformer oil, lubricating oil, organic solvents such as ethanol and methanol, and food and pharmaceutical liquids such as beverages, pharmaceuticals, and syrups.
Adaptation features: It can be detected directly by injection without complex pretreatment, especially suitable for detecting trace moisture (0.0001%~10%).
Caution: Viscous liquids need to be slightly heated and diluted in advance to avoid residual tube walls during injection; Samples containing volatile components need to be sealed for injection to reduce water evaporation loss.
2. Solid samples
Common types: plastic pellets, rubber, ore, welding rods, clay, metal oxides, inorganic salts, powdered foods (such as milk powder, flour), pharmaceuticals, etc.
Adaptation features: Combined with a fully automatic water vaporization device, it can achieve continuous automatic detection of 33 samples without the need for frequent manual injection.
Attention: Solid samples should be crushed to uniform particles (recommended sieving), and the quartering method should be used for sampling to ensure sample representativeness; Powder samples need to be pre mixed for 3-5 minutes to eliminate clumping.
3. Gas samples
Common types: industrial gases such as propane, butane, natural gas, and laboratory high-purity gases.
Adaptation features: It needs to be equipped with a dedicated gas injection device to introduce moisture into the titration cell through gas blowing, with high detection sensitivity.
Attention: Gas pipelines need to be dried in advance to avoid moisture adsorption on the inner wall of the pipeline affecting the detection results; Maintain stable gas flow rate to prevent impact on titration cell reagents.
2、 Core testing techniques
1. Precise control of sample size
Adjust the sampling amount based on the moisture content of the sample: for a moisture content of 0.0001%, take 10g or more; for 0.001%, take 5g-10g; for 1%, take 100mg-300mg; and for 50%, take 10mg-20mg to avoid errors caused by excessive or insufficient sample size.
Dry injection needles are used for liquid samples. Before sampling, the inner wall should be moistened and washed 1-2 times to remove any bubbles before rapid injection. The needle tip should be close to the reagent liquid level to reduce volatilization.
2. Instrument pre-processing and parameter setting
Preheat for 30 minutes after starting up, and wait for the background value of the instrument to stabilize below 0.3 (with higher accuracy below 0.1) before starting the detection to reduce the impact of baseline drift.
Adjust the stirring speed to 2-3 levels to ensure thorough mixing of reagents and samples; If the background value decreases slowly, briefly stop stirring and shaking the titration tank before resuming stirring.
3. Reagent and consumables management
Select Mitsubishi's original Karl Fischer reagent (anode solution AXI, cathode solution CXU) to ensure that the reagent liquid level remains at the same level, and replace it promptly when the reagent color turns dark brown.
If there are obvious pinholes or poor sealing after multiple uses of the injection pad, it should be replaced immediately; Check the contact surface of the titration cell weekly, apply special silicone grease to ensure sealing, and avoid contact between silicone grease and reagents.
4. Error control and calibration techniques
Regularly calibrate the instrument with standard reagents (38-42mg/L) or pure water. If the test result of the standard sample exceeds the standard value ± 25 μ g, the electrode needs to be cleaned (soaked in anhydrous ethanol or acetone and dried below 65 ℃).
After detecting high adsorption samples, the titration cell should be cleaned with anhydrous methanol to avoid residual samples affecting subsequent testing; The humidity in the laboratory environment should be controlled at ≤ 85%, and good ventilation should be maintained.
3、 Special sample testing precautions
Samples containing highly volatile and thermosensitive components: Sealed injection method is used to shorten the injection time and avoid simultaneous evaporation of moisture and sample components.
Oil contaminated or viscous solid samples: Pre treat the sample surface with anhydrous ethanol in advance, or use a dedicated sample boat for indirect injection to prevent electrode contamination.
Toxic or corrosive samples: Operate in a fume hood, wear protective gloves, and avoid contact of reagents with the skin; After testing, dispose of the waste liquid according to hazardous waste regulations.
4、 Summary
Mitsubishi Card Moisture MeterThe adaptability covers samples from multiple industries, and the core testing techniques focus on representative sampling of samples, instrument pretreatment, maintenance of reagents and consumables, and regular calibration. Adjusting the sampling volume and injection method according to the sample type, strictly controlling the environment and consumables status, can fully leverage the high-precision advantages of the instrument, and provide reliable data support for production quality control and scientific research testing.