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The Analytical Process

All instrumental analysis follows the same process of stimulus and response

  • To do this, they must transfer information across data domains through conversions.

Data Domains

  • Data domains can either be Electrical or non electrical
  • Within the electrical domain, the can be stored as:
  • Time - frequency, pulse width, phase
    • Analog signals - current, voltage, charge
    • Digital media - count, serial, parallel, number

Data Conversion

  • Relies on three primary types of devices:
  • Detectors - indicates change in the environment
    • Sensors - converts chemical data to electrical
    • Transducers - converts non-electrical data to electrical
    • Also contain a sensor
      • Contain a signal conditioning unit that will make it strong enough for further processing and turn the signal into useful information. E.g. may include amplification.

Domain Conversion

To get from a non-useful to useful data type, the information must be converted. This can be intra-domain or inter-domain.

E.g. process - the Thermocouple

  1. Physical, temperature information is read by transducer that amplifies the electrical signal into something useful
  2. The voltage is converted into a current
  3. The current is read on an ammeter
  4. The scale position is read by a human and converted into a number value

This is:

  1. Physical \(\ce{->}\) Voltage (inter-domain)
  2. Voltage \(\ce{->}\) Current (intra-domain)
  3. Current \(\ce{->}\) Scale position (inter-domain)
  4. Scale position \(\ce{->}\) Number (intra-domain)