12. (15 points) Thiamine is not fluorescent; however, it can easily be oxidized to thiachrome which exhibits readily mea

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12 15 Points Thiamine Is Not Fluorescent However It Can Easily Be Oxidized To Thiachrome Which Exhibits Readily Mea 1 (110.49 KiB) Viewed 83 times

12. (15 points) Thiamine is not fluorescent; however, it can easily be oxidized to thiachrome which exhibits readily measured fluorescence. A single tablet of a thiamine supplement was dissolved in 1.00 L of 0.01 M HCL. This sample was further diluted by a factor of 100. A 10.00 mL portion of the diluted solution is added to 5.00 mL of a pH 6.6 phosphate buffer and then 5.00 mL of 4 percent cyanogen bromide are added. After adding the cyanogen bromide (oxidizing agent) the solution is allowed to react for 30 min. The fluorescence is then measured with excitation at 365 nm and emission at 444 nm. If the fluorescence reads 132 on an arbitrary scale, how many mg of thiamine are in a single tablet? The calibration of the method is shown below. The concentration is reported in ug/mL for the diluted sample solution. (You do not need to correct for the buffer and oxidizing agent) Response 300 250 y = 519.71x + 0.2381 R2 = 1 200 150 Fluorescence (Arbitrary Units) 100 50 0 0 0.1 0.2 0.3 0.4 0.5 0.6 ug/mL