Question

1. There are three sets of assay data obtained from a set of standard solution in an ELISA experiment (triplicate assay). Use Excel to draw a calibration curve. Then do the following:

(a) Calculate the Lower Limit of Detection (LLOD)

(b) Calculate the Limit of Quantitation (LOQ)

(c) Calculate the Sensitivity of the assay

(d) If an unknown sample gives an assay reading of 1.35. Use the calibration curve to determine the concentration of this sample.

Concentration (ng/mL)	Assay1	Assay2	Assay3
0	0.04	0.02	0.03
0.1	0.05	0.03	0.04
0.5	0.15	0.18	0.16
1	0.25	0.29	0.27
2	0.50	0.48	0.52
5	1.20	1.10	1.18
10	1.98	1.89	2.20
20	3.95	3.90	4.20

Answer 1

Since the curve is linear therefore the sensitivity is between two linmits

(a) Calculate the Lower Limit of Detection (LLOD)=0.1ng/ml

(b) Calculate the Limit of Quantitation (LOQ)= 0.1ng/ml

(c) Calculate the Sensitivity of the assay=0.1ng/ml to 20 ng/ml

(d) If an unknown sample gives an assay reading of 1.35. Use the calibration curve to determine the concentration of this sample.

               =0.5OD corresponds to 5ng/ml

             1 OD will correspond to 5/0.5

             1.35 will correspond to 5/0.5×1.35=13.5ng/ml