Determination of free alkali content in concentrated laundry detergent?
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This post was last edited by jay853135070 on 2010-7-28 at 14:22. The determination of the free alkali content in laundry powder was carried out in accordance with GB T 13171-2004; the standardizing solution was prepared following GBT 601-2002 \"Chemical reagents – Preparation of standard titration solutions\". Except for the use of composite electrodes, all other instruments used complied with the standards specified. The value obtained through testing was around 20%, which is 100% above the limit. When the sample was sent to a provincial testing laboratory, the result was 8.3%. Why is there such a big difference between the results obtained through internal factory testing and those from the provincial laboratory? ? I hope some experts can help answer this!
If the standard solution is fine, the most likely issue is with the pH meter. Since the endpoint of the titration is set at a pH value of 9.0, it is crucial that the pH value at the endpoint be measured accurately; this is quite different from conventional potentiometric titrations, where the endpoint is determined based on a potential shift.
Reply 2# xwtsq: The pH meter was calibrated before use, and the calibration solution was also freshly prepared