GolamMostafa:
This is a good idea; but, the sensor output is analog signals. Therefore, the signals should be stored in some kind of peak-reader circuit consisting of low-leakage capacitors being interfaced with the ADC through a buffer. The peak-readers have to be discharged before making the next measurements.
That is some 'old school' stuff. In the 70's, I bought an old emission spectrometer - it looked like a locomotive. Among the other electronica fantastica, it included an analog integrator. Light was aimed (using small mirrors, lenses and shift plates) from the exit slit for an element, into a photo multiplier tube. The current generated by the tube was amplified and stored in a capacitor. During integration, a timer was run as the capacitor was discharged through a suitable resistor. The elapsed time was proportional to the intensity of the light, which in turn, was proportional to the amount of a particular element. We were making stainless steel rebar, two and a quarter inches in diameter for the largest nuclear power plant ever. So the steel analysis had to be accurate.