What are the materials and methods for testing plastic levels in water?

[akrmn]

On wikipedia (https://en.wikipedia.org/wiki/Iron(III)_chloride) it says:
The ferric chloride test is a traditional colorimetric test for phenols, which uses a 1% iron(III) chloride solution that has been neutralised with sodium hydroxide until a slight precipitate of FeO(OH) is formed.[26] The mixture is filtered before use. The organic substance is dissolved in water, methanol or ethanol, then the neutralised iron(III) chloride solution is added—a transient or permanent coloration (usually purple, green or blue) indicates the presence of a phenol or enol.

So what materials do I need? Ferric chloride (saw it for sale on Amazon) and Sodium Hydroxide (I can check). Then how do I exactly neutralise it to satisfy the conditions and what do they mean by filter. Remove solids? With what?

I have a physics background but almost no chemistry background...
thanks

 

[jim mcnamara]

Materials:
1. pH test strip kit - the one meant for testing soils will work.
2. filter paper circles - used to filter out solids
3. funnel - line the inside of the funnel with moistened filter paper, folded so the it lays mostly flat against all the way round the inside of the funnel
4. some small glasses
5. Small cheapo eye dropper
6. distilled water; see comment below
7. some glass stirring rods - stainless steel spoons are okay too. Obviously plasticware is not okay.

Use distilled water only - in the grocery store in the laundry section. For ironing clothing (or playing chemist).
FeCl₂, ferric chloride dissolved in water:
1% sol'n = 1g FeCl₃ dissolved in 95g (95ml). After it is dissolved add quantity sufficient of water to make 100ml.

Make a 5% sol'n by weight of NaOH in water, 20ml H₂O using same technique. Note NaOH is nasty (it is lye), so use eye protection.

Drop-wise (eyedropper), place NaOH sol'n into Iron sol'n, stir, if you see slight cloudiness, check with test strip to see the pH is at or above 7. Continue dropping and stirring and testing until you get pH=>7.0

Remove the cloudiness from the iron sol'n by SLOWLY pouring the the iron sol'n through the filter paper. Pitch the paper, keep the iron sol'n.

Wash out the eyedropper, to use in your colorimetic tests

Run your tests.

 

[akrmn]

Thank you! I think that covers everything. I guess the other question on my mind is how to map color to concentration (ppm), at least roughly, but I will look around.

Edit: I think one way is to take a control sample of water I consider "clean" and see if there is a major difference.

 

[jim mcnamara]

Usually something like absorption spectrophotometry. So you need to be really careful about volumes of samples and volumes of the reagent you add to the samples.

Got an Android? https://play.google.com/store/apps/details?id=com.pasco.Spectrometry&hl=en_US See what that can do for you.

 

[akrmn]

By the way, if there is an easier or alternative way to give an indication of plastic levels in water, then someone please let me know. I already did a heavy metals test using a simple testing kit (with strips), but for this it is more complicated and also risky with the NaOH spilling... I just want some idea that the water in my rural area is safe for drinking compared with typical bottled water.

 

[Asymptotic]

By the way, if there is an easier or alternative way to give an indication of plastic levels in water, then someone please let me know. I already did a heavy metals test using a simple testing kit (with strips), but for this it is more complicated and also risky with the NaOH spilling... I just want some idea that the water in my rural area is safe for drinking compared with typical bottled water.

Once you've gone beyond commercially available strip tests such as those sold by Hach, methods like the one @jim mcnamara outlined are about as simple as they get, but also quite possibly insufficient for what you are trying to do.

There are a lot of different plastics, and likewise, a wide range of plasticizers, degradation products, etc. associated with them. Even a limited subset of plastics (food packaging) includes polystyrene, polyethylene, butadiene, PET, PLA, and so on, and the chemicals of interest associated with them are likely to be in the tens of parts per billion range down to 1 ppb and less.

My advice is to contact and consult with a local water testing lab, and have them do it. A basic test series may be $100 or less, but won't include any of the more esoteric tests used to detect VOCs and other organic compounds. Each additional test adds time ($), reagents ($), and other costs, which is why you'll want to consult to focus and tailor tests to your specific needs. If by rural you mean there are farms nearby, test for common insecticides, herbicides, e. coli, and other compounds and organisms typically found in farm run-off. What local industries have access your water table? What chemicals are used in their processes? If you have PVC piping, check for PVC-related compounds ... The final tab depends on how thorough you want to be - perhaps several hundred dollars for a reasonably restricted set of tests; a thousand or more if checking for everything under the sun.