water testing

Discussion in 'Chemistry' started by fionn, Jul 12, 2013.

  1. fionn Registered Member

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    3
    I am interested in testing a number of water samples from different sources and determining what chemicals/pollutants may be in the samples. Would I be able to do this with an IR spectrometer? I used one years ago as a biology major but it has been a long time. I think I could re-educate myself on their use.
     
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  3. Trippy ALEA IACTA EST Staff Member

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    Probably not.

    A better approach might be to make some educated guesses about what might be in the samples and proceed from there. What kind of sources are you looking at? Do you have any idea of what pollutants are likely to be there?
     
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  5. fionn Registered Member

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    I don't have a good idea of what might be in the samples. One idea I had was to test water samples from various restaurant espresso machines and see what might be concentrated in the boilers.

    Do you know how a lab might go about determining what was in such a sample?
     
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  7. Trippy ALEA IACTA EST Staff Member

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    Any lab worth considering uses the APHA standard methods. They're a group of well tested standardized tests that are universally applicable. The specifics of an individual test depend on the analyte being tested. If I recall correctly, total metals use acid digestion followed by some form of spectroscopy. Caffiene is a flourescence test, BOD[sub]5[/sub] involves locking a flask away in a warm dark cupboard for five days, Ammoniacal Nitrogen uses a chromometric technique where nitrate/nitrite use flame spectroscopy (I think).

    For what it's worth, your best bet would be to first decide on what source you want to test, then have a chat with your local lab about what contaminants it would be best to test for.

    Addendum:
    More information on the APHA Standarf Methods is available here: http://www.standardmethods.org/
     
  8. arauca Banned Banned

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    4,564
    When you say source , River . lake , underground ( wheal ), bottled water, then pollutant Chloride, cadmium , barium, radon, chromium. ete ete. Now there is a whole range of organic pollutants were you might detect them , after drying you can attempt IR and not dry, you can attempt use Raman . Then you have bacterial pollutants , that is a different animal.
     
  9. fionn Registered Member

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    3
    Thanks for the suggestions. I would be mainly interested in organic pollutants. If I wanted to look at bacterial, I guess I could culture samples and then attempt to identify?
     
  10. exchemist Valued Senior Member

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    6,618
    Sounds like a trick question. Distil it?
     
  11. exchemist Valued Senior Member

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    6,618
    I second Trippy's advice. In general you cannot test for unspecified contaminants in anything. You need to specify what it is you suspect may be present and then apply a test for that. Also, since you are testing for "pollutants", you are probably concerned with detecting species that are known, or alleged, to be harmful at very low levels, so you will need sensitive tests. As I recall, though IR is good in principle for many organic compounds (e.g. comparing a pure specimen with the one of interest and looking for differences in the IR trace), it is not great with aqueous systems, due to the wide absorption band of the water itself. Also it is not that sensitive.

    There's a whole industry that tests for pollutants of various types, e.g pesticides, PCBs and so on, so if you can be more specific there will be be plenty of help available.
     
  12. Trooper Secular Sanity Valued Senior Member

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    I liked this.

    [video=youtube;XrvUDkwGpSA]https://www.youtube.com/watch?v=XrvUDkwGpSA[/video]
     
  13. arauca Banned Banned

    Messages:
    4,564
    Take a wooden barrel in the bottom put opening , place into the barrel some small pebbles the to the middle fill it with bigger stone to 3/4 of the barrel and fill it with water then let it stand for few hours then open then get your clean water in the bottom
     
  14. ankit7540 Registered Member

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    No. Only using IR will not help you out. Maybe you need to collect a detailed list of contaminants you wanna test and find their allowed levels. Then start for testing each one and find the situation with your water samples. As far as the methods involved you may need chromatography, HPLC, UHPLC and then further identification by IR and NMR. It is a long tedious work.
     
  15. ankit7540 Registered Member

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    6
    also , you cannot use water as the solvent for IR testing. Water itself gives bands and may prove harmful for your device/ instrument. You will need to evaporate the water by rotatory evaporator and then use some other solvent and go for IR.
     
  16. arauca Banned Banned

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    4,564
    There are some special windows which water will not dissolve them , so if you put water as a reference which will be subtracted then you might see some organic picks .
     
  17. Peregrine Registered Member

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    90
    At home water sampling kits are available. You can test for basics like phosphates and fecal coliform.

    They are relatively cheap.

    You may also try checking with your state's environmental or parks agency.

    In my state, they will give you a kit to test water and send them results. Saves money!!

    -Peregrine
     
  18. kumar11 Registered Member

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    7
    I don't think that IR is your answer here. If you are looking for organic pollutants (carbon based), there are two classes to consider...volatile organics and non-volatile. If you are seeking volatile organics, then one approach to obtain these would be to distill your sample at a temperature below that of water, and collect any substances in a dry ice chilled receiving flask. Thees could be analyzed by GC or GC/MS for better characterizations.

    The non-volatile organics could be better analyzed by extracting the water sample with an organic solvent, such as Ethyl Acetate, Hexane, Methylene chloride, and analyzing the extracts by GC or GC/MS. Extraction is a nice way to avoid pulling out any ionic components of the water sample, thus complicating your analysis.
     

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