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International Journal of Food Science, Nutrition and Dietetics, 2014 ©
4
Gabriel A Agbor (2014) Folin-Ciocalteau Reagent for Polyphenolic Assay 3:801
Single reagent assay
Standard Catechin Sample Preparation and Analysis.
Weigh 2.9 mg of catechin powder in 10mL of methanol making
a solution of 1mM. This is stable in the refrigerator at 4
o
C for at
least one month.
Prepare standard curve by taking 0, 10, 20, 40, 50, 100 µl of the
1mM catechin solution to each of 6 micro cuvettes (10 to 100 µM
in the cuvette).
Table 2. Free Polyphenolic concentration (mg/g catechin equivalent) of herbs and spices as determined by single and dual
reagent method.
Herbs and spices
Single Reagent Poly-
phenol (μM)
Single reagent preci-
sion (%)
Dual Reagent Poly-
phenol
Dual reagent preci-
sion (%)
P nigrum (leaves)
7.29
4.12
22.91
7.16
±0.30
±1.64
P nigrun (black pep-
per, seed)
7.14
1.12
22.04
1.86
±0.08
±0.41
P umbellatum
(leaves)
10.38
1.45
39.73
2.06
±0.15
±0.82
H cannabinus
(leaves)
5.44
1.47
12.76
3.21
±0.08
±0.41
R. heudelotti (seeds) 5.86
3.92
15.08
8.16
±0.23
±1.23
S zenkeri (seeds)
7.97
1
26.68
1.54
±0.08
±0.41
S zenkeri (bark)
5.38
4.65
12.47
10.75
±0.25
±1.34
A lepidophyllus
(seeds)
6.34
5.05
17.69
13.05
±0.32
±2.31
C mannii (seeds)
5.7
7.89
14.21
17.31
±0.45
±2.46
I gabonensis (seeds) 4.69
4.9
8.7
14.14
±0.23
±1.23
T vulgaris (seeds)
9.05
2.54
32.48
6.87
±0.23
±2.23
G africanum (seeds) 7.72
5.83
25.23
9.75
±0.45
±2.46
P nigrum (white pep-
per, seeds))
4.32
9.95
6.67
8.1
±0.43
±0.54
0.2
0.4
0.6
0.8
0
0
50
100
200
Concentration of catechin statndard (uM)
Average absorbance against concentration
Absorbance (750 nm)
Figure. 2. Standard curve: Concentration of catechin against absorbance for the single reagent method
y=0.007x-0.0324
R
2
=0.9971