Accurate determination of trace moisture in various substances is a crucial quality control indicator in multiple fields such as petrochemicals, pharmaceuticals, food, electricity, and scientific research. The fully automatic micro moisture analyzer is precisely designed as a precision analysis equipment for this purpose. It mainly works based on the principle of Karl Fischer Coulomb coulometric method and can accurately and efficiently detect trace moisture in liquid, gas, and solid samples.

1、 Core detection principle: Karl Fischer Coulomb coulometric method

The core technology of this instrument is based on the classic Karl Fischer reaction and adopts modern electrochemical measurement methods such as Coulomb coulometric analysis.

Electricity measurement method (Coulombic method): Unlike the traditional volumetric method that calculates moisture content by titrant volume, this instrument uses the Coulombic method. There is a special electrolytic cell inside the instrument, which is filled with Karl Fischer reagent containing iodine ions. When the moisture in the sample is introduced into the electrolytic cell, it immediately participates in the above chemical reaction, consuming the iodine in the reagent.

Electrolysis produces iodine: In order to maintain the concentration balance of iodine ions in the reaction system, the instrument applies current through a pair of electrolysis electrodes, and the iodine ions (I ⁻) in the electrolysis solution are regenerated into iodine (I ₂). The electrolysis reaction is: 2I ⁻ → I ₂+2e ⁻.

The quantitative relationship between electricity and moisture: According to Faraday's law of electrolysis, there is a strict quantitative relationship between the amount of electricity consumed (Coulomb) to electrolyze iodine and the amount of iodine produced. Since the generated iodine is used to supplement the iodine consumed by reacting with water, the total amount of electricity consumed is directly proportional to the amount of water in the sample.

Endpoint determination and calculation: The instrument monitors the concentration of iodine in the electrolytic cell in real time through precision sensors (such as dual platinum electrodes). When the system detects that all moisture has reacted and there is a small, stable change in the concentration of free iodine, it determines that the titration endpoint has been reached and automatically stops electrolysis. The microcomputer system automatically calculates the mass of moisture in the sample based on Faraday's law and the total amount of electricity consumed during the electrolysis process.

2、 Technical Implementation and Instrument Characteristics

Based on this core principle, the instrument achieves convenient and reliable analysis by integrating microcomputer control technology, high-precision electricity measurement module, and automation process.

Automation and Intelligence: Users only need to input parameters and inject samples through the touch screen, and the instrument can automatically complete the entire process of stirring, electrolysis, endpoint judgment, data calculation, and result printing. The system has automatic balancing and deviation correction functions, ensuring the stability of the measurement.

High sensitivity and wide range: Thanks to the precise measurement of electricity by Coulomb method, the instrument has a high resolution (such as 0.1 micrograms) and can detect moisture as low as several micrograms. At the same time, the upper limit of the range can reach tens of milligrams, making it suitable for samples with different moisture contents.

Data management and compatibility: The instrument has a built-in clock that can record analysis time and has data printing function. Some models also support data exchange with external computers or networks for easy laboratory information management.

3、 Application and standard adaptability

The fully automatic micro moisture analyzer based on Karl Fischer Coulomb coulometric method has a scientific detection method and objective results. Its design and performance meet or reference the technical requirements of multiple national standards, such as relevant standards for petroleum products, insulating oils, chemical products, and general experimental methods. This enables it to be widely applied in production analysis, quality inspection, and scientific research in the above-mentioned industries while ensuring the compliance of detection methods.

In summary, the fully automatic micro moisture analyzer combines the classic Karl Fischer chemical reaction with modern Coulomb coulometric analysis technology and microcomputer automatic control to achieve rapid, accurate, and fully automatic determination of micro moisture in samples. It is an important tool for moisture analysis in modern laboratories.