Spectrophotometer Water Testing

[Markushka]

I posted this in my tank thread, but I'll post here too...

 

In chem lab we are going to be conducting water tests with a spectrophotometer, so I'm going to put my tap water to the test since I currently use it in all my tanks. I need a list of what to test for. I really can test for anything I want, the only limiting factor is time, and I have about three hours the first day, and another three the next. (plus I could get another three at the end of the semestre, but that I want to use for testing my tank specs )

 

So here's what i've got so far:

Phosphates

Alkalinity

Calcium

Magnesium

Boron

Iodine/Iodide

Sodium

Chloride

 

and ofcourse i'll be doing pH, trates, trites and amm (plus the copper and iron we actually have to do for the lab)

 

Any more suggestions?

 

Oh did I mention these should be super accurate and hopefully I will be able to test my tank water the second day.

[Drew220]

Will you be preparing blanks for these samples, or running standards with known quantities?

[Markushka]

I'll be using reagents to be measuring samples as well as calibrating the SPM for each test. I'll have access to very accurate equipment. Not sure whether I'll be running blanks or standards, the prof didn't mention either yet. however I know that the water quantity will be standard, and the SPM will be zeroed using the sample in question prior to running the test.

 

To clarify a bit, I'm a bio student that has to take 100 level chem classes to fulfill requirements. Might be going further since I'm really liking my chem classes tho.

[cptbjorn]

If you talk to the professor and say what you are doing there is a pretty good chance he/she will give you all the lab time you want if you wash some glassware or w/e.

 

I'm with you on the chemistry courses, I'm going for engineering but I went through all of G and O chem for my elective credits

[Markushka]

If you talk to the professor and say what you are doing there is a pretty good chance he/she will give you all the lab time you want if you wash some glassware or w/e.

 

I'm with you on the chemistry courses, I'm going for engineering but I went through all of G and O chem for my elective credits

 

Probably could get as much time as I wanted, but my class runs from 6:30pm - 9:10 and I have a class before it and another that same day at 8am so i'm usually pretty wiped out by then. Maybe other days tho, my prof is cool so I doubt he'd mind much.

 

I'm sorta dreading orgo since all I hear are horrorstories about it, but thats coming from people who don't particularly like chem sorta wish I wasn't transferring next semestre cause my chem prof also teaches orgo and i'd love to take another class with him

[lakshwadeep]

I'm not sure how a spectrometer will be useful for many of the ions you listed since they (AFAIK) won't absorb or transmit light. However, spectrometry is used by hobbyists to measure phosphates. Do some research on any conflicting compounds in your water since saltwater is so complex and potentially giving misleading information. Here's some possibilities (the second page has a link to a book called "methods of seawater analysis"):

http://www.google.com/search?hl=en&cli...mp;aql=&oq=

 

Organic is not so bad (although I'm a biochem major), but it is a lot of new things coming at you at once. It depends a lot on the professor; I had a bad one for I but a very good one for II who also explained more about I.

[Lab-Rat]

Markushka - I gave a little info on the NCRA forums that I hope will help. One thing that I will mention that I didn't over there - in my personal experience, colleges tend to not always follow approved methods for testing. I have seen where the importance of multiple point calibrations, duplicates, and matrix spiking has been downplayed or ignored. As I said this is my experience in going form a college setting to a real world laboratory setting - it might or might not be the case for you. Make sure to check out that post for some of the QC I discuss (I could also repost here if anyone is interested). In that post, I mostly gave a brief summary of some important issues that I hope will be included in what your professor teaches. If further information is needed, let me know.

 

I'm not sure how a spectrometer will be useful for many of the ions you listed since they (AFAIK) won't absorb or transmit light. However, spectrometry is used by hobbyists to measure phosphates. Do some research on any conflicting compounds in your water since saltwater is so complex and potentially giving misleading information. Here's some possibilities (the second page has a link to a book called "methods of seawater analysis"):

http://www.google.com/search?hl=en&cli...mp;aql=&oq=

 

Actually specs have come a long way in recent years and can analyze for a lot of things. Although they are not nearly as accurate as other methods, they do pretty well. More and more spec methods are becoming EPA approved. Also, your point about conflicting compounds is a good one. I do not have much experience with saltwater, but high levels of calcium, sodium, etc are known to interfere with other methods. I'm not sure about the interferences when using a spec though. A good way to check to see if there are any interferences is to analyze a matrix spike - that is a known concentration of standard added to the sample. Good recoveries of the spike would indicate that the matrix (i.e. saltwater) are not interfering. Thanks for mentioning this though, I added some information on my original post on the other forum.

 

(hooray! my first post on nanoreef (been lurking and learning for a while though)

[Amphiprion1]

Yeah, they've come a long way. The old Spec-20s I used to use in college weren't good for much, except more obvious pigments, etc., like chlorophyll. They were really limited on what kind of absorbances they could detect and the accuracy wasn't particularly great. As you said, though, I highly doubt they were calibrated regularly. I did always use matrix spikes and/or blanks as references, though.

[Markushka]

Thanks for all the great responses guys, maybe i'll have something more coherent to say after i get some sleep...

 

But anyone want to suggest what to test for in my tap water first?

[violinist]

I feel assaulted by the last few posts.

[faub63]

If you have access to one, and atomic absorption spectrophotometer would be better suited for determining different metal concentrations in your water. With standard spectrophotometers you have so set up standard curves with known values, and have to add reagents to change the color of the solution based on your concentrations. With AAS, none of that is needed. You just insert the correct filter (Ca2+, Na+, etc.), the machine atomizes it, and gives you a very, very accurate reading. I used it a lot to determine calcium levels during undergrad.

 

For your water, I would test more for the metal ions, as the test kits aren't as accurate for them as they are for the nitrogen containing compounds. Calcium, copper, magnesium, and iodine would be good. See if you can take in some of your tank water and test it out too. It would be cool to see how accurate the test solutions/strips really are.

[systemtool]

I think its a great idea to test your water, but simply having a spec to use is only half the battle. Most of the tests used to measure things in the aquarium hobby are based on colorimetric assays (ammonia, nitrate, nitrite). So you could use spectroscopy to assay the colour changes, but you need reagents to be able to measure the color change. You could conceivably use reagents from an API test kit to measure something like nitrates, but you would need to buy some standardized solution to make a standard curve. Even then, the relationship must be linear in order to provide an accurate reading.

 

There are tons of water quality tests than can be performed on a spec, checkout sites like Hach and La motte to see the different tests and reagents.

[lakshwadeep]

I apologize for writing spectrometer when I meant specifically a spectrophotometer, at least the UV/vis ones that are most common in undergraduate chemistry labs.

[Markushka]

I think its a great idea to test your water, but simply having a spec to use is only half the battle. Most of the tests used to measure things in the aquarium hobby are based on colorimetric assays (ammonia, nitrate, nitrite). So you could use spectroscopy to assay the colour changes, but you need reagents to be able to measure the color change. You could conceivably use reagents from an API test kit to measure something like nitrates, but you would need to buy some standardized solution to make a standard curve. Even then, the relationship must be linear in order to provide an accurate reading.

 

There are tons of water quality tests than can be performed on a spec, checkout sites like Hach and La motte to see the different tests and reagents.

 

 

I will be using the appropriate reagents for the machine, so I won't need to go ghetto and use API bottles

 

list's been updated:

Phosphates

Alkalinity

Calcium

Magnesium

Boron

Iodine/Iodide

Strontium

pH

Nitrate

Copper

Iron

Silica

-Sodium

-Chloride

-Ammonia

-Nitrite

Nickel

Lead

Cobalt

Aluminum

 

Thanks guys.

 

I will take some tank water too, but I want to get most of my fish out first (moving to campus next semestre) I'll do tests then, or during the last lab, which ever's first.

[systemtool]

I will be using the appropriate reagents for the machine, so I won't need to go ghetto and use API bottles

 

list's been updated:

Phosphates

Alkalinity

Calcium

Magnesium

Boron

Iodine/Iodide

Strontium

pH

Nitrate

Copper

Iron

Silica

-Sodium

-Chloride

-Ammonia

-Nitrite

Nickel

Lead

Cobalt

Aluminum

 

Thanks guys.

 

I will take some tank water too, but I want to get most of my fish out first (moving to campus next semestre) I'll do tests then, or during the last lab, which ever's first.

 

You can usually find a lot of the metals and other elemental analytes in an annual municipal water report. Just check online for your city/municipality's water treatment source. I think its law for them to publicize a report, so they are pretty easy to find. If they are really low, I wouldn't bother trying to test them ( less than 1.0 mg/L).

 

These you will be able to measure for sure, as they should all be in the 20-30 mg/L range:

Alkalinity (as calcium carbonate)

Chloride

Calcium

Sodium

Sulphate .

and maybe phosphate

 

You will also be able to measure chlorine too.

[Markushka]

You can usually find a lot of the metals and other elemental analytes in an annual municipal water report. Just check online for your city/municipality's water treatment source. I think its law for them to publicize a report, so they are pretty easy to find. If they are really low, I wouldn't bother trying to test them ( less than 1.0 mg/L).

 

These you will be able to measure for sure, as they should all be in the 20-30 mg/L range:

Alkalinity (as calcium carbonate)

Chloride

Calcium

Sodium

Sulphate .

and maybe phosphate

 

You will also be able to measure chlorine too.

 

My water comes from a private well, so my municipal water report wouldn't reflect my tap water accurately. And since it is from a well, I do not need to worry about chlorine or other water treatments since I know that we do not use any. None the less I will look up this report and compare my test values to their values. I'm not sure though if there is any grounds for comparison since I do not know the source for municipal water. Sulfate may very well be worth testing for, but I doubt I have in any significant quantity.

[systemtool]

Oh, if you are on a well, chances are you have pretty good quality water.

[Markushka]

I got to do some tests, and they don't have reagents for others. so here's and update:

 

Phosphates - 0.44ppm

Alkalinity

Calcium

Magnesium

Boron

Iodine/Iodide

Strontium

pH

Nitrate

Copper - 0.12ppm

Iron - 0.04 ppm

Silica

Sodium

Chloride

Ammonia

Nitrite

Nickel

Lead

Cobalt

Aluminum

Sulfate

 

some of the others i'll be getting a chance to test for on this coming thursday.

 

I was kind of surprised by the high? phosphate levels, I'm guessing that is due to high fertilizer use by my neighbors and others on the aquifer. It also sort of explains all the random algal blooms of my FW tank. I'm guessing the presence of copper isn't too good either.

[Lab-Rat]

How old is the plumbing in your house? Older houses have a good chance to leach copper and lead from the pipes. Consider letting the water run for a few minutes and collect another sample to analyze.

 

Also, depending on the meter and how it was calibrated, the accuracy of the meter might be off at the low levels you are looking at.