- 15 Points Vitamin K1 Can Be Measured Using Staircase Voltammetry Ins One Tablet Of A Nutritional Supplement Is Dissol 1 (60.84 KiB) Viewed 76 times
(15 points) Vitamin K1 can be measured using staircase voltammetry. ins One tablet of a nutritional supplement is dissolved into 25 mL of 60% acetonitrile. The solution is filtered, and 10.00 mL of this solution is transferred to beaker. A glassy carbon electrode is placed in the beaker and the electrode is allowed to equilibrate with the solution for 12 minutes. During the equilibration the polished glassy carbon adsorbs the analyte. The electrode is then transferred to a measurement cell containing 10 mL of O.IM HCI. The electrode is hooked to a potentiostat that is equipped with a platinum counter electrode and Ag/AgCl reference electrode. The potentiostat is programmed to hold the electrode for a period 60 seconds at -0.1 V and then using staircase voltammetry the electrode is programmed to 0.6 V in 5 mV steps using square wave voltammetry. A peak in current is observed at 0.19 volts and the peak increased with the increase is the amount of standard added. The standard was added in the form of a 0.01 M solution of vitamin K . The square wave had an amplitude of 25 mV and a frequency of 20 Hz. The results of a series of standard additions of a solution of 0.0100 M vitamin K is shown below. Note that the volumes added are very small and to a good approximation you can consider the total volume to be constant at 10 ml. Vitamin K1 Analysis 00 y=0.1688x+0.7412 R=0.9963 Response (UA) ON 0 un 5 10 30 35 15 20 25 ul of 0.01 M std a. a. Based on the structure of the compound, why is the 60 second period at -0.1 V required for this analysis? You can write out the reaction to explain your answer. b. If the molecular weight of vitamin K, is 450.7 g/mol what is the content (mg per tablet) in a single tablet (be careful of the units)?