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Lecture 4

Lecture 4. Noise, signal/noise ratio, detection limit. Standard analytical terminology. Electronics. Value (mean, average) Standard deviation Relative standard deviation(RSD). Signal Noise Signal-to-noise ratio (S/N) . A noisy set of data.

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Lecture 4

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

  2. Standard analytical terminology Electronics Value (mean, average) Standard deviation Relative standard deviation(RSD) 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 bandwidth resistance Shot (quantum) current “Flicker”

  7. Environmental noise

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

  9. Removal of the amplifier noise by filtering

  10. Computer can help: Boxcar averaging

  11. c = a + b Random numbers aandb sc = ? c = a + a

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

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

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

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