est tube Ascorbic acid stock (20 μg/mL) Citrate buffer Final Concentrations 1 0 μL 1000 μL 0.0 μg/mL 2 125 μL 875 μL 2.5 μg/mL 3 250 μL 750 μL 5.0 μg/mL 4 500 μL 500 μL 10.0 μg/mL 5 750 μL 250 μL 15.0 μg/mL 6 1000 μL 0 μL 20.0 μg/mL 7 1 mL of the fresh orange juice (20x diluted) 8 1 mL of the heated orange juice (20x diluted) 9 1 mL of the pre-citrus urine sample (5x diluted) 10 1 mL of the post-citrus urine sample (5x diluted) Plot a graph in which y-axis represents for absorbance and x-axis represents for concentration From graph, y=mx + c Calculate the vitamin C concentrations of samples by the equation with consideration of dilution factors. 1. StandardCurve Sample (μg) Absorbance (520 nm) 0.0 0.621 2.5 0.599 5.0 0.556 10.0 0.469 15.0 0.418 20.0 0.291 2. Analysis of orange juice or urine Samples Absorbance (520 nm) Ascorbic (μ g/mL) Dilution Ascorbic Corrected (μ g/mL) Orange Juice (fresh) 0.515 Orange Juice (heated) 0.540 Pre-citrus urine 0.626 Post-citrus urine 0.633
|
Test tube |
Ascorbic acid stock (20 μg/mL) |
Citrate buffer |
Final Concentrations |
|
1 |
0 μL |
1000 μL |
0.0 μg/mL |
|
2 |
125 μL |
875 μL |
2.5 μg/mL |
|
3 |
250 μL |
750 μL |
5.0 μg/mL |
|
4 |
500 μL |
500 μL |
10.0 μg/mL |
|
5 |
750 μL |
250 μL |
15.0 μg/mL |
|
6 |
1000 μL |
0 μL |
20.0 μg/mL |
|
7 |
1 mL of the fresh orange juice (20x diluted) |
|
8 |
1 mL of the heated orange juice (20x diluted) |
|
9 |
1 mL of the pre-citrus urine sample (5x diluted) |
|
10 |
1 mL of the post-citrus urine sample (5x diluted) |
Plot a graph in which y-axis represents for absorbance and x-axis represents for concentration
From graph, y=mx + c
Calculate the vitamin C concentrations of samples by the equation with consideration of dilution factors.
1. StandardCurve
|
Sample (μg) |
Absorbance (520 nm) |
|
0.0 |
0.621 |
|
2.5 |
0.599 |
|
5.0 |
0.556 |
|
10.0 |
0.469 |
|
15.0 |
0.418 |
|
20.0 |
0.291 |
2. Analysis of orange juice or urine
|
Samples |
Absorbance (520 nm) |
Ascorbic (μ g/mL) |
Dilution |
Ascorbic Corrected (μ g/mL) |
|
Orange Juice (fresh) |
0.515 |
|||
|
Orange Juice (heated) |
0.540 |
|||
|
Pre-citrus urine |
0.626 |
|||
|
Post-citrus urine |
0.633 |
In linear regression analysis, we examine whether one variable (called independent variable) can be used to predict the value of another variable (called dependent variable) accurately or not. y = mx +c (the straight line equation) is the simplest linear regression equation, where y is our dependent variable and x is our independent variable.
The analysis generates an R2 value. An R2 of 1.0 means the independent variable can accurately predict the value of the dependent variable.
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