Sample Holder Version 1, 100 ml +- 0.1 pH

The sample holder supports the light source leds and light sensor modules.  A 100 ml sample jar containing the water sample is shown in the right rear of the shot.  The sample jar is placed in the sample holder cup during operation, and the assembly is placed under a lightproof shield.

Everything depends on the kind of hardware/glassware to be used to hold the water samples to be tested which in turn, depends on the measurement protocol.   The sample holder is then designed around the sample container.

Dimensions of sample jar:   6.5mm diam  6.5 depth

Would a rectagnular container be better?   TBD

Functional Requirements:

  1. rigid fixed support for water sample jar
  2. support adjustable optics alignment
  3. support/protect led assembly
  4. support/protect light support assembly
  5. support and protect wiring from water
  6. easy insertion / removal of sample jar
  7. integrate with light shield
  8. protect electronics from water and accidental spills

The sample in the prototype is contained in a covered plastic 100 ml jar for testing in accordance with the sampling protocol prescribed by Yang et.al.  Briefly, raw sea-water to be sampled is read to provide the “blank” reading from the photometer.  Then the die is introduced to take the absorbance reading.  The absorbance numbers are then used to compute pH by plugging them into the calibration equations.

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