Vitamin C 1 (1)

BCH 367 Results Six different dilutions of Vitamin C in a 1% phosphate-citrate buffer were created by using the equation C1V1=C2V2 with the total volume of 1 mL. Example of equation for the dilution of 3 ug/mL is as demonstrated below: C1= 50 ug/mL V1=? C2= the dilution ( 3) V2= 1 ml total 50 ug/mL x V1 = 3x 1 mL = 0.06 mL ( This is what V1 equals to) . The same steps were completed for all 6 dilutions in the chart below (figure 1). Figure 1: Standard curve Vitamin C (ug/ mL ) DCPIP (mL) Phosphate citrate buffer (mL) Vitamin C stock ( mL) Total Volume (mL) Absorbance 0 0.67 0.33 0 1.00 0.625 A 3 0.67 0.27 0.06 1.00 0.624 A 6 0.67 0.21 0.12 1.00 0.575 A 9 0.67 0.15 0.18 1.00 0.574 A 12 0.67 0.09 0.24 1.00 0.445 A 15 0.67 0.03 0.3 1.00 0.384 A The dilutions created with the values obtained, the spectrophotometric assay was taken of each sample at an absorbance of 518 nm ( 0.683 A). DCPIP absorbance vs the concentration of Vitamin C is shown in the graph below: Figure 2: Absorbance vs. Concentration of Vitamin C

The first point ( 0.625 ) and the fourth point ( 0.574) were excluded from the linear equation used to calculate the Vitamin C concentration. This was done in order to get a linear trendline as you can see in figure 2. Figure 3: Spectrophotometric analysis of samples Unknown sample Background absorbance (no DCPIP ) Concentration Absorbance at 518 nm Actual Absorbance Vegetable ( green bell pepper ) 0.024 A 0.368 A 0.344 A Fruit ( orange ) 0.004 A 0.423 A 0.419 A The concentration of Vitamin c was calculated using the following equations: Calculation of concentration of cuvette: ● Vegetable ( green bell pepper)