The detection principle of cleaning validation TOC cotton swabs is mainly based on the total organic carbon (TOC) analysis technology, which is detailed as follows:

Oxidation Process

The TOC analyzer is used to oxidize the organic carbon in the samples collected by the cotton swabs and convert it into carbon dioxide (CO₂). Common oxidation techniques include photocatalytic oxidation, chemical oxidation, and high-temperature combustion. For photocatalytic oxidation, under specific catalyst and light conditions, organic substances undergo oxidation reactions. Chemical oxidation involves using strong oxidants to react with organic substances and oxidize them into carbon dioxide. High-temperature combustion makes organic substances burn at high temperatures to generate carbon dioxide.

Detection Process

After the organic carbon is oxidized into carbon dioxide, the TOC analyzer measures the content of the generated carbon dioxide. Through specific detection techniques, such as non-dispersive infrared absorption method and conductivity method, the content of carbon dioxide is detected. The non-dispersive infrared absorption method utilizes the characteristic that carbon dioxide absorbs infrared light of specific wavelengths, and the content of carbon dioxide is determined by measuring the degree of infrared light absorption. The conductivity method calculates the content of carbon dioxide by measuring the conductivity of the carbonic acid solution formed after carbon dioxide dissolves in water.

Quantification Process

Based on the corresponding relationship between the carbon content in carbon dioxide and total organic carbon, the total organic carbon in the aqueous solution is quantitatively determined. Since a carbon dioxide molecule contains one carbon atom, by measuring the amount of carbon dioxide, the content of total organic carbon in the sample can be calculated, and thus the situation of organic residue on the equipment surface can be obtained to evaluate the cleaning effect.