Suggest analytical procedures which can solve the problems described below. You

Question

Suggest analytical procedures which can solve the problems described below. You will need to take into account the required selectivity, sensitivity, accuracy, throughput, portability, and the cost of the analysis. There are no restrictions of what type of techniques you can use (feel free to use those that you studied in Quantitative Analysis too). You will get a full credit if you propose a technique that would do the job, and if you address all the steps named below (when relevant): sampling sample preparation, preconcentration, matrix removal, etc. all chemical reactions, including derivatization. separation (stationary phase., mobile phase, mass-analyzer, etc.) detection (type of detector, light source, monochromator, etc.) calibration: calibration curve, standard addition, internal standard: matrix for standards and sample. You will get bonus points if your answer is the best solution for the particular situation. Be brief. 5-8 sentences should be enough. i) Resveratrol (F-la below) is believed to be responsible for positive health effect of red wine and it is currently marketed as a nutritional supplement. If you are hired as a consultant by a winery that wants to analyze the concentration of resveratrol in its wines, what method would you suggest? You need to determine the total concentration of resveratrol (both trans- and cis-isomers together). The expected concentration is in the 0.1-20 mg/L range and the customer wants to analyze 5-10 samples a day.

Explanation / Answer

Following method will be followed for determining the concentration of resveratrol.

First we would be needing a solution of known conc. of resveratrol , which can be obtained by extracting it from grapes and purifying it.

Next we deal with the uknown samples, that is, wines.

Sample preparation would include steps of extraction using ethyl acetate combined with distilled water. Following this freezing is done to decrease the water content, after which the sample is filtered to remove the ice crystals. Then the sample is dried by rotary evaporation, and then absorbed in methanol.

Since the conc. range is 0.1-20 mg/L, HPLC technique can be used to bring out the separation effectively.

The above prepared sample is injected into HPLC and then eluted with a proper mobile phase. The known conc. solution of resveratrol is also injected alongside. And when this known solution elutes we take some fraction of unknown sample simultaneously.

This sample collected is then visualised using UV-spectroscopy using a radiation of 280 nm.

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