Question: can a spectrometer be used to measure color of water ?

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thangvu asked on March 23, 2018 09:17
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color of water



16 Comments

Since H2O is a colorless fluid, 'color' appears not to be the correct intent of the question. The author would need to clarify the objective.

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Maybe colour of liquid compared to distilled water/plain iron water. Qn example: Dissolved tannins give water a brown hue.

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Yes, it can. You need to go to the spectrometer page for more information. It will show how to set up cuvette s to hold water and what to use as a light source. Then you need to go to the spectrometry page. You will need to learn to use spectralworkbench, but there are many examples of different colored water samples in the library. There are help videos showing how to use the software.

The old way to learn color was Roy G. Biv ( red orange yellow green blue indigo violet). You can see this in the picture taken by the diffraction grating. But it will be a good way to teach. Sorry for the delay answering.

Thanks for your helpful answers


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Try to avoid using blue water solutions, at least without doing some testing. The compact florescent lamps (CFL) loose intensity at the blue and of the spectrum. The cfls are one lamp often used with the cuvettes for water testing. The intensity lose could be a problem.

Depending on what information is needed from the spectrum (i.e. like the entire available spectrum, using a CLF will not be useful. A broadband source, such as Solux 4700K, would be a better choice.


My idea is to use a 430nm wavelength to measure the color of the water, so, I use a 430nm (+ - 10nm) led as the source, but the 430nm led seems to be a bad idea (-_-). http://www.chemtronic-gmbh.de/index.php/sitemap/79-ctr-english/95-colour-standards-inline-color-photometer-apha-hazen-pt-co-astm-saybolt-ebc


If you used the right lamp, you would be ok. You need to use a broadband source, as stoft noted.


Do you know what APHA values you will be observing? I was typically observing values under 25. And yes, a florescent light was very helpful against a white background, if doing the test visually.

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Thanks for your answer, I have the standard solution of 5-10-20..70 pt / cb (I borrowed), according to the standard method, when measured at 430nm, i observed its Abs too low (0.0004 - 0.0016 ...)


I have no solution for multi-wavelength source like a spectrometer. I will try with another wavelength.


Be careful! light in the 450-480nm range (royal blue) is dangerous to unprotected eyes! 430 is not as bad but be aware! http://www.cree.com/led-components/media/documents/XLamp_EyeSafety.pdf


We always went with the longest path length. The visual test was done with 50 cm color comparison tubes. Very long for visual. Maybe you could do something similar with the spectrometer. Good luck!


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sorry for saying it is unclear, with wastewater, the color of the water partly assesses the level of water pollution.

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Can you measure pure water? Probably so! While largely transparent in the visible water absorb in the 700-850nm range, note that to image in that range you will need an IR enabled camera as the IR blocking filter will block that range. A great book with a short excerpt on this is Optics in the Air, it refers to two papers: Pure water and The color of the pools at the Yellowstone National park

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Pollution comes in many forms and many of the worst contaminants will not alter the appearance so visible light spectrometers (i.e. PLab types) will not detect those chemicals. Measuring water conductivity and pH might provide a simpler and more sensitive measure. Note, none of these simple methods provides detection of specific contaminants or detection of contaminants which are toxic at very small concentrations.

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