Development of an Enzyme-Linked Immunosorbent Assay Method for the Detection of Rhein in Rheum officinale

Table 3

Recovery of rhein determined by icELISA in spiked samples.

Spiked level (μg)	Mean amount^a (μg)	Recovery^b (%)
0	3.17 ± 0.29^c	0
1	4.06 ± 0.05	89.17 ± 4.56
2	5.38 ± 0.23	102.90 ± 6.96
5	7.38 ± 0.29	84.19 ± 5.72
10	13.15 ± 0.10	99.77 ± 1.00

^aData were mean ± SD from triplicate samples for each level. ^bThe percentage of recovery was calculated as follows: recovery (%) = (measured amount − control)/spiked amount × 100. ^cThe zero spiked level was obtained by the HPLC method and used as a control.