Why are the results from field and laboratory analyses different?
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We analyzed the organic chlorine content in the circulating water on-site, and it was 0.6. But the laboratory value is only 0.2 – why is there such a big difference? Thank you for the advice.
There are various factors that cause this problem: 1. Whether the analysis methods and instruments are consistent； 2. Is there any error in sampling? ； 3. Is the operation correct? ； 4. Circulating water contains organic substances and microorganisms. Chlorine is added to this water in order to kill these organic substances and microorganisms, thereby preventing scaling and corrosion. However, the process of disinfection also takes time; the results of testing the water right after chlorine has been added are different from those obtained after waiting some time, as part of the chlorine is consumed during the disinfection process
The original poster didn’t explain clearly; first, it is necessary to state whether the analytical instruments and methods are the same, and second, the sampling method. I think if the difference is extremely large, the most likely reason is that the sample wasn’t mixed properly at the time of sampling, assuming that there are no errors in the measuring instruments or methods
If the analysis method is the same and the samples taken do not change over time, then the samples are not homogeneous; you can take samples from several different points, mix them together, and then try analyzing the mixture
There are three points: whether the analysis methods and instruments are consistent, whether the same sample is used for testing, and whether the sample is stored properly.
There are various factors that cause this problem: 1. Whether the analysis methods and instruments are consistent； 2. Is there any error in sampling? ； 3. Is the operation correct? ； 4. Circulating water contains organic substances and microorganisms; chlorine is added to this water in order to kill these organisms and substances, thereby preventing scaling and corrosion. However, the process of disinfection takes time. The results of testing the water right after chlorine has been added are different from those obtained after waiting some time, as part of the chlorine is used up during the disinfection process. 5. Was it done by one person?
1: Different environments 2: Different instruments 3: Different stabilization times for the instruments 4: Reagents
If your supervisor is strong enough and confident enough, the laboratory doesn’t need to pay any attention to this issue at all! Haha, if it wasn’t impressive, then you guys would have a lot of work to do. . . .