Key points for sampling electronic-grade products
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We produce electronic-grade ethyl acetate products, requiring a purity level of over 99.99% with a moisture content of less than 20 ppm. However, the moisture levels obtained from each sample are unstable – sometimes they exceed 50 ppm while at other times they are 0 ppm. The process control is proper; therefore, what are the appropriate methods for sampling such products with low moisture levels? Are there any specific requirements regarding the sampling procedures, sampling bottles, or sampling valves? Thank you
It depends on how you take the samples – whether the air humidity is high during sampling, or whether the sample introduction method is incorrect when conducting the measurements. Trace amounts are inherently difficult to parallelize, and there are also many interfering factors. For the determination of trace moisture, we use Karl Fischer reagent along with the coulometric method
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If process control is confirmed to be satisfactory and the moisture level in the samples varies between 0–50 ppm, attention can be focused on humidity control within the sampling box. Rinse the sampling bottle several times with the material. It is also necessary to pay attention to whether moisture in the air will enter before the sample reaches the analysis instrument How are humidity and cleanliness controlled in the laboratory?
A glove box is used at the sampling point; before sampling, the area is purged with nitrogen to ensure the appropriate humidity level. Then, the pipelines and sample bottles need to be rinsed during sampling； Only then can formal sampling be carried out.