1. Lecture 4 Noise, signal/noise ratio, detection limit

2. Standard analytical terminology Value (mean, average) Standard deviation Relative standard deviation(RSD) Electronics Signal Noise Signal-to-noise ratio (S/N)

3. A noisy set of data

4. Less noisy measurements. Signal is well visible.

5. Sine wave – a primitive model of a noisy experiment Peak-to-peak noise = 3 s (approximately)

6. Noises: Thermal temperature resistance bandwidth Shot (quantum) current “Flicker”

7. Environmental noise

8. A simple filter What should I do to reduce the noise?

9. Removal of the amplifier noise by filtering

10. Boxcar averaging Computer can help:

11. c = a + b Random numbers a and b s c = ? c = a + a

12. This N stands for word “noise” And this is number of measurements

13. A: one measurement, S/N=4 B: 100 measurements(scans), S/N= 40

15. concentration intensity Limit of quantitation (limit of determination) Limit of detection (detection limit) 3s/slope 10s/slope 0 Limit of linearity