PTScan - Automated Measurement Of Permanganate Time
•Brochure: PTScan - Automated Measurement Of Permanganate Time
Permanganate time is an industry standard test for product quality. It is used for determining the levels of impurities in a number of products: acetic acid, acetic anhydride, ethanol, methanol, pyridine, and tricresyl phosphate. This application was developed for BP Chemicals' acetic acid production facility at Hull, UK. PTScan is an automated permanganate time measurement that greatly improves the quality of the permanganate time measurement and significantly reduces the time required for the test. The test involves adding a standard solution of potassium permanganate to the product.
Oxidisable impurities discharge the pink permanganate colour over a period of time. The standard tests often call for the mixture to be left for periods up to 2 hours before checking the colour. If it is still pink then the sample has passed the test. The PTScan uses a Zeiss photodiode array spectrophotometer to monitor the colour of the mixture. Software isolates and monitors the permanganate absorption peak as a function of time. An equation is fitted to the first part of the decay curve. From this the 'permanganate time' is predicted. This reduces the analysis time to about 10 minutes. Under certain conditions the permanganate will oxidise the Manganese to Manganese dioxide. This brown precipitate obscures the pink of the permanganate. Pre-processing of the spectrum eliminates this interference and provides accurate estimates of the permanganate time, even in the presence of a heavy precipitate.
Benefits
- Dramatically reduces permanganate time measurement
- Eliminates operator error
- Provides more accurate data
- Suitable for at-line analysis improves process control
- Easy to use software
•Brochure: PTScan - Automated Measurement Of Permanganate Time