Sciencemadness Discussion Board

Purity of store bought distilled water

prole - 16-3-2006 at 11:34

Recently, I purchased a nice 4L amber glass jar, and decided that it needed to store pure water. I rinsed the jar with dH2O and distilled acetone to remove any dusty residues, then dried it. Then I distilled 4L of store-bought distilled water (now twice distilled). What remained in the distilling flask after all this was about 25 mL of milky, translucent residue, not unlike watery skim milk. I figured that this may happen, and it's probably no surprise to you, the estimable mad scientists, but I felt compelled to post this here. This new, purer water is now to be used whenever dH2O is called for in a reaction. It is reasonably safe to assume that no foreign matter is present to offset a reaction.

This is posted for informational purposes only. Distillation of water should only be performed by a qualified, competent professional (which I am not). :D

neutrino - 16-3-2006 at 11:51

Really? I've always used my water straight from the jug and never had any problems. It will dissolve AgNO<sub>3</sub> without a trace of cloudiness, so I figure it's clean.

What brand of water are you using? Mine is Richfood (yes, the cheapest one).

prole - 16-3-2006 at 12:56

I'm using Absopure. It's supposed to be 'absolutely pure'. Although I've never had problems with using it straight from the jug, I doubted it's purity, whatever the brand. After distilling 4 litres, I finally proved to myself that it was indeed impure. It's probably a negligible amount of crap (plastic particles, dust, processing contamination), but for purity nuts, distilling may be the way to go.

It may be important to note that the cloudy residue was the result of 4L distilled without ever changing the distilling flask. More water was added as the level dropped. This was a leap of faith on my part, I wasn't sure if there were impurities. I was happy and sad to find I was right. Knowing this makes me sleep that much better at night (and some Saturday afternoons).

It should also be noted that I used 'distilled water', and not 'spring water'. Both are offered by Absopure.

[Edited on 3/16/2006 by prole]

[Edited on 3/16/2006 by prole]

BromicAcid - 16-3-2006 at 14:02

My regular brand of distilled water was used to dillute the nitric acid that I used to make my silver nitrate. After dissolution there was not a hint of cloudiness and despite me boiling it to dryness there was no decomposition that can be associated with less then pure ingredients.

But then again different jugs of distilled water have different tasts so there has to be something in there, expecially in some of the brands that I can hardly even stomac. I mean, it's distilled water, they should all be the same! The components either arise through leeching of the jug they come in, or they are simply things that distill over with the water. It is afterall only distilled water, not carbon filtered distilled water.

Water Quality

lordmagnus - 16-3-2006 at 14:39

Hummm, that is curious...

It maybe elements that leached from the cheap plastic in the bottles, I've been using R.O (reverse Osmosis) water that is treated with OZONE to preserve it's sterility. I may run a test soon on the last half galon I have, run it thorugh the 1000ml flask with a liebig condneser, and see what remains when all is said and done

Glass

MadHatter - 16-3-2006 at 16:44

I like to distill my own water using glass. 1st, its absolutely tasteless and, 2nd, it keeps most of
the metal cations out. IIRC, commercially, and all the home water distillers from Sears, JC Penny,
etc., use stainless-steel vessels to boil the water. Now, the cations aren't a problem unless it's
for hydrazine using the ammonia/bleach combination. The cations can catalyze the intermediate
chloramine into ammonium chloride and I like to use my gelatin solution sparingly because of
it's cost.

Otherwise, cheapass distilled water that is nearly tasteless is great for fractional crystallization.

jack-sparrow - 17-3-2006 at 08:21

Maybe Absopure distilled water is a hoax. Did you try to acidify the residue? If it bubbles it is contains probably carbonates which means that the Absopure distilled water is partially purified Absocrap spring water !

prole - 17-3-2006 at 09:01

studur - I didn't save the residue, but that might have been a fun experiment. I was just glad to be rid of it. My money's on plastic leachate as the primary contaminate. I've read that we all get a fair amount of plastic in our diet, which may or may not lead to health issues down the road, and this is why I decided to undertake this project, to see if it might be true. I suppose I'll have to distill another 4L to find out, but not today.:D

vulture - 17-3-2006 at 12:30

I was shocked to find that a mixture of 50% pure isopropanol and 50% distilled water left a distinct spot on glass when it evaporated.

I'll have to put my water under more scrutiny it seems. :(

unionised - 19-3-2006 at 02:48

I guess the stuff left behind was extracted from the plastic so there's a fair chance that it's phthalate or one of the bisphenol derivatives that the press love to call "genderbending".
Anyway, an amber glass container will almost certainly leach alkali into your pure water. Even if it doesn't the water will still pick up CO2 from the air. That's the probem with pure water- it doesn't like to stay that way.

lacrima97 - 19-3-2006 at 09:19

So you are saying that the amber glass bottle can contaminate the water???

12AX7 - 19-3-2006 at 09:30

I suppose there isn't anything that won't contaminate, well maybe a bottle made of HgS, that's pretty damned insoluble stuff, but yeah, the sodium and calcium ions on the surface can be leached, even the silica tetrahedra can dissolve. Not to mention everything adsorbed on the surface. But geez, this is all ppm if not ppb level, ain't it? Detectable, but insignificant outside of rinsing in-process silicon wafers..or something.

Tim

woelen - 19-3-2006 at 11:38

I agree with 12AX7. Although distilled water, as purchased from hardware stores, may have some impurities (e.g. from the plastic bottle), I've never had problems with it. Solutions of silver nitrate remain perfectly clear and even the exceedingly sensitive basic vanadate (IV) solutions remain clear in that water, while the latter give a thick flocculent precipitate with our tap-water (which is not bad at all).

So, in practice, I have no problems with the distilled water I have. The only time, when it might give problems for me is if I have to isolate a few grams of dissolved matter from liters of water, but I do not have that kind of experiments at home.

Btw, I also tested my distilled water and it leaves very faint stains, when a large drop is allowed to dry on a clean piece of glass. But, I have to say, this may also be due to invisible impurities on the glass, which dissolve in the water and then settle at the glass in another pattern than on the other parts of the glass. I observe the same effect with all other solvents I have (e.g. 99.9% methanol, diethylether, acetone).

prole - 19-3-2006 at 13:37

Like everyone else here, I've never had problems with the various brands of dH2O I've used. But perhaps unlike some here, I'm a bit particular (understatement here) about stuff that doesn't belong to a particular molecule ending up in one (read: purity nut). Besides, I like to grow crystals for fun, and I don't want gender-bending dust/particles/residues/foreign matter influencing the ultimate shape of it. (No bias towards transgender people, only chemistry). I'm sure only a Scanning Electron Microscope or other fancy-schmancy high-tech gizmo would be able to detect the minute amounts of crap in my crystals, but the more I can eliminate, the better I feel. Plus, I wanted to see what distilled water residue looked like. Now I know.

[Edited on 3/19/2006 by prole]

Yeah yeah, I know, you can't grow crystals of molecules.

[Edited on 3/19/2006 by prole]

neutrino - 19-3-2006 at 13:51

What makes you say that? Sucrose is a molecule and plenty of people have seen sugar crystals. :)

[Edited on 19-3-2006 by neutrino]

prole - 19-3-2006 at 15:56

Ever try growing megacrystals of sugar? Can't do it. Large crystals can only be grown from ionic substances.

One of these days, when I become technically proficient, I will upload my photos of my crystal collection, that is, if anyone's innerested.:D

[Edited on 3/19/2006 by prole]

[Edited on 3/19/2006 by prole]

12AX7 - 19-3-2006 at 20:06

Hum, I don't see why not, long-range order in a molecular substance is probably going to be worse than an ionic, but nonetheless, if molecules can be arranged on a small scale, they can always be added to the crystal faces, if not necessarily evenly.

Personally I'd love to see some crystals :)

Pure enough !

jack-sparrow - 20-3-2006 at 06:04

I am working in a deuterated chemical factory. We make deuterated solvents for NMR. We store all our solvents in amber glass bottles with teflon caps. If anybody is concerned about any contamination/leeching please don't. I use oven dried flasks blown with nitrogen (to remove humidity and dust) straight from the box and I have never had any problem storing NMR solvents at 99.96% deuterium content. I really think that the water you use is pure enough for ANY chemical reactions you want to do. We make our own deionized heavy water (D2O) at 0.00±1 mS conductivity and we store it in cheap polyethylene barrels. Hydro-Ontario told us that it was perfectly pure. So if it is pure enough for a nuclear reactor, it must be OK for anybody on this planet dont you think so ? So the container is not your contamination source. It is most probably 1) the chemist or 2) the purification. If you have 10 mg of residue in 4 kg of water we are talking about 2.5 ppm which is practicaly nothing. It wont screw up your reactions. You are a most probable source of experimental failure than 2.5 ppm of crap in your water.

Sorry if it sounds rude but I do the same mistake sometimes. We have to stop and think about what is significant and what is not.

prole - 20-3-2006 at 07:30

No sweat, studur. I new I might catch some flack for my pickiness. As stated above, no one has problems with their water. But what I saw in my flask was like skim milk, and that screamed 'IMPURE!'. It was an experiment, you know. The water I distilled is only going to be used for certain experiments for special reactions and/or crystal growing, as further experiments. For the rest, good ol' dirty distilled water will suffice.:P

I would have liked to post a photo of it here, but 1) I only have black 'n white film, 2)no digital camera, 3)don't know how to post photos yet 4) too cheap to buy colour film (a bias agains films of colour). But I'm working on it.

12AX7 - 20-3-2006 at 10:23

Quote:
Originally posted by studur
We make our own deionized heavy water (D2O) at 0.00±1 mS conductivity and we store it in cheap polyethylene barrels. Hydro-Ontario told us that it was perfectly pure. So if it is pure enough for a nuclear reactor, it must be OK for anybody on this planet dont you think so ?


Conductivity of... 1 cm cube? 1km rectangle? Where are the probes? I'm totally pissed at hearing of "16.7Mohm" pure water, megohms of WHAT!!! (Nothing personal.)

The other thing, a nuclear reactor isn't exactly clean, that fuel makes a lot of trash after all! I highly doubt they really care about ppm's of anything, although if they do you'd know better than me. The deuterium content would be a concern, though.

Tim

[Edited on 3-20-2006 by 12AX7]

Measure unit definitions

jack-sparrow - 20-3-2006 at 10:32

mS means milli - Siemens. The Siemens (S) is the measure unit for electrical conductivity. Ohm is the unit for electrical resistance. The lower the measure in mS is, the lower is the conductivity. You need ions to conduct electrical current. If the conductivity is low, then the water is low in ions (I am not talking about H+ and OH- ions of course ut electrolytes likes metal cations and anions like chlorides, sulfates, phosphates, etc.).

12AX7 - 20-3-2006 at 12:59

Ya I know. Siemens work for the conduction of objects. You kind of have to define the geometry. Resistivity (or conductivity) is in units of ohms times length per area!!

Tim

jack-sparrow - 20-3-2006 at 13:34

V=RI

Volt=Ampere*Ohm

Ohm=Volt/Ampere

conductivity = 1/resistivity

Siemens = 1/ohm = ampere/volt

ampere = 1 coulomb/sec
1 coulomb = 6.2*10^18 electrons
volt = (kg*m^2)/(s^2 * coulomb) or (kg*m^2)/(s^3*A)

You should have all what you need

12AX7 - 20-3-2006 at 14:22

So, no matter the seperation or area of the electrodes, my ohmmeter will ***ALWAYS*** read 1 megohm in this stuff?

Tim

neutrino - 20-3-2006 at 14:45

Resistance is still based on geometry. All things being equal, a homogeneous block of graphite 2 cm thick will have twice the resistance of a block 1 cm thick. You cannot calculate the resistivity from resistance without geometry.

For those who are unfamiliar with the subject, see this page.

unionised - 21-3-2006 at 13:02

My 1963 copy of the British pharmacopoea gives details of testing glass vessels for alkalinity by extracting with hot water for half an hour then measuring the base colourimetricly. The limit for acceptability is equivalent to extracting about 0.2 mg of NaOH. Since the containers they are concerned with are about 10 ml in volume that's about 20ppm.

"Detectable, but insignificant outside of rinsing in-process silicon wafers..or something."
Detectable by the colour change of an indicator (hardly the most obscure test) and enough to destroy base sensitive drugs (that's why the BP is interested).
I agree that the water stored in a glass bottle will almost certainly be pure enough for most things but a plastic milk bottle will often do better.

The nuclear industry uses tons of D2O for things and, for a lot of those things, they recirculate it through a purifier. They do that precisely because they know that water doesn't stay pure for long.
That could explain why they can tolerate levels of contamination that would be unacceptable for pharmacology. It's also fair to say that, for NMR the presence of disolved Na compounds won't usually make a difference. For HPLC/MS the sodium adducts are sometimes a royal pain in the neck- even using lab grade (borosilicate) glassware and methanol or acetonitrile as the solvent.

"We have to stop and think about what is significant and what is not. "
OK, let's do that.
The isotopic purity of a deuterated solvent is no measure of the presence of ionic impurities. Also, we weren't talking about other solvents, just water.

The cheap polyethylene barrels used for D2O are not going to leach alkalies into the water. That makes no possible difference to whether or not Prole's glass jar will.
The plastic jugs in which water is sold are usually clear plastic (so people can see the water is clear I guess) therefore they are not made from polythene which is slightly cloudy.
They may well be made from polyester or polycarbonate. That's a fairly reasonable source of of the chemicals I mentioned.

And, you don't know the difference between restistance and resistivity.

While we are at it, I have seen crystals (and quite good ones too) of sugar an inch or so across. They took years to grow

If you don't like sugar as a molecule, I'm sure we have all seen gemstones which are molecular solids (There's no way diamond is ionic).
If you really want nice crystals, ask the semiconductor industry- they grow silicon to huge sizes in single crystals

jack-sparrow - 21-3-2006 at 13:41

Quote:
Originally posted by unionised
The isotopic purity of a deuterated solvent is no measure of the presence of ionic impurities. Also, we weren't talking about other solvents, just water. The cheap polyethylene barrels used for D2O are not going to leach alkalies into the water. That makes no possible difference to whether or not Prole's glass jar will. The plastic jugs in which water is sold are usually clear plastic (so people can see the water is clear I guess) therefore they are not made from polythene which is slightly cloudy.


If you have significant monomer/polymer leeching in 99.96%D D2O you will see it in NMR. At this enrichment level, you can see contamination level at the ppm level. I have no problem storing 100 000 $ worth of heavy water in a plastic barrel. Our quality standard is that no impurity is visible in the base line when the spectrum is normalized on the C13 satellites of the main solvent peak (this is ppm level). Obviously in D2O you dont have C13 satellites but you need a flat baseline anyway and D2O is always the most enriched solvent we have because all others are derived from D2O. When I spend 50 hours on purifying NMR solvents to remove the last impurities, I want to keep it that way and glass jugs for organic solvents and plastic jugs for water are enough for my purpose. Sorry I don't deal with semi-conductor grade crystals or USP grade pharmeceuticals but you are right, in these case water purity might be a major issue.

prole - 21-3-2006 at 14:36

Hmmmm, ah yes, perhaps 'molecule' was a poor choice of words. Sorry. I forget that I'm not talking to my ape-ish coworkers, but very knowledgable folks. Ionic substances are easier to grow as crystals, but, most any crystalline substance may be grown given ample time and proper conditions. Given the fact that I just read a whole book about synthetic diamonds...

Distiled water purity

lordmagnus - 31-3-2006 at 15:00

Well, just as a test, I distille dthe last liter of a gallon of R.O. water I had in the fridge. I ran it with a 2000ml boiling flask connected to a liebig condensor, I don't have a conductivity meter, but when the boiling water reach about 100ml, I took a good look at it, and it appeared clean. It is possible that if you were using R.O. water like I was, the plant that made it might have had a torn membrane or something like that, which caused the contamination.

prole - 31-3-2006 at 15:49

Lordmagnus,
The water I used was 'steam distilled' (from the label), and I distilled 4.0-ish litres of it. I didn't remove the distilling flask from the oil bath to check it until I was finished with the project, but peering into it periodically revealed that it was probably clean until the 3rd litre was run through.

lordmagnus - 28-4-2006 at 13:39

On the subject of water purity, check E-BAY, you can get a T.D.S. (Total Dissolved Solids) meter for 20$ or so, it measure the resistance across a couple of platinum electrodes in the tip of the pen style meters, the higher the resistance, the purer the water. Distilled water should be the purest, you can get pretty close with R.O. water, as long as after the R.O. element, it doesn't pass through any other filters, carbon after the R.O. would degrade the purity a little, and really wouldn't make any since, since they usuall use 2 or 3 .5 micron carbon filters before the r.o. membrane to keep the membrane clean and long lasting.