How to determine calorimetrically? HPLC methods exist but can one determine using UV spec or fluorometry?
Dear Mr John, salycilic acid is possible to determine by potentiometry and spectrophotometry. A purple complex between salycilic acid and Fe+3 (Trinder method) occurs at 540 nm. Besides, salycilic acid absorbs in the ultraviolet about 238 nm at pH 1-2. However, when the pH changes the peak undergoes a shift. Potentiometrically, it is possible to manufacture an ion selective sensor for salycilate ion using the ion-exchanger named Aliquat. However, the sensor based on Aliquat can response to other anions. In this case, is necessary a separation method. We studied the determination of salycilate for both methods. See the articles:
1) Application of two- and three-way chemometric methods in the study of
acetylsalicylic acid and ascorbic acid mixtures using ultraviolet spectrophotometry;
2) Determination of acetylsalicylic acid by FIA-potentiometric system in drugs after on-line hydrolysis
You can download these papers in my profile. Maybe may help you. Although, we applied the methods for acetylsalycilic acid determination, you can easily adapt them. But, we tested the methods above for pharmaceutical analysis. Plants are more complex samples, interferents must be a critical problem. Finally, jasmonic acid maybe you can determine using UV spectrophotometry once has a chromophore group. However, I never worked with this product. How your sample is complex, I suggest to use multivariate calibration associated with UV or near infrared (NIR) spectrophotometry. You will need a mathematical software such as matlab or scilab. A good book about this subject is Harald Martens, Tormod Næs, Multivariate Calibration (http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471930474.html). I hope that this answer helps you.
Salicylic acid gives violet color with FeCl3 & the optical density can be measured colorimetrically. One can estimate by applying Beer-Lambert low & drawing the standard plot & measuring the optical density of the unknown solution.
You can use visible light in spectrophotometry itself. It will fall in violet range. Use ferric chloride as reagent
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