Ward Labs vs. LaMotte Basic kit

[eps2103]

I recently picked up the LaMotte brew lab basic kit, and I used it for the first time last week. Since I have never had any experience with these tests before, I decided I'd take a water sample at the same time as my LaMotte testing, and send it off to Ward Labs to see if agrees with the brew lab kit...and mostly it does agree with the exception of Chloride and Sodium.

Ward Labs
Sodium 49
Calcium 54
Magnesium 19
Total Hardness 214
Sulfate 33
Chloride 129
Total Alkalinity 93

LaMotte
Sodium 127 (calculated per instructions)
Calcium 52
Magnesium 17
Total Hardness 200
Sulfate 30 (rough guess at the grayscale shade between 0 and 50)
Chloride 225
Total Alkalinity 125

I'd be ok with "in the ballpark" but those two numbers are not even close to what Ward tells me. According to LaMotte I have so much sodium that I'd be looking to dilute with distilled for my next batch.

Am I missing something? I ran the Chloride test three times and I got the same results each time.

Thanks for any input...

Eric

 

[EJay]

I don't know squat about water chemistry, but the AJ Delang water primer says "Ward Labs reports as sulfur so multiply the SO4 number by 3 to get as sulfate".

I don't know about Chloride, but maybe something similar is going on.

 

[ajdelange]

Looks as if the attention needs to focus on the chloride test given that everything else except the sodium checks and the sodium is, therefore, essentially determined by the chloride measurement. You need to check the chloride test against a standard and you can certainly buy chloride standardized solutions but probably don't want to. I did find and error in the instructions for this kit when it first came out but they corrected that as soon as it was called to their attention. Perhaps there is an error in the chloride instructions still standing. I'd suggest you go to the grocery store and buy some bottled water which has the analysis on the label and run the chloride test against that. And, of course, ask if any one else here has noticed a problem with chloride values with this kit.

 

[eps2103]

Thanks AJ.

I'd suggest you go to the grocery store and buy some bottled water which has the analysis on the label and run the chloride test against that.

I will try that today hopefully and report back with findings.

And, of course, ask if any one else here has noticed a problem with chloride values with this kit.

Has anyone else noticed any issue with the chloride test?

 

[Staestc]

You may want to ask Ward Labs. They have a customer service number on their web site, and they are the experts. They may just blow you off with "we can't address results from other test products performed by other people" or they may be helpful. I have never contacted them, so I don't know what to expect. Just a thought.

 

[Staestc]

As AJ said, in the LaMotte kits, Sodium is a calculated value that is dependent on your Chloride measurement. Just for kicks, try putting the Ward chloride number into the LaMotte equations for sodium, leaving the Sulphate, Alkalinity, and Total Hardness numbers at the values measured with your kit. If the Sodium result is in the ballpark, then your Chloride measurement is likely the only issue.

I can't find anything that says Chloride is reported in multiple ways from different test methods, but it may be.

 

[eps2103]

try putting the Ward chloride number into the LaMotte equations for sodium

Yeah I had already done that, and the result is within 20 ppm sodium (64 calculated vs 49 measured). I also took the Ward numbers and put them into the Lamotte sodium formula, and the result of that was within 5 ppm. As discussed the primary item of interest is the chloride reading.

I will see if I can get something from the supermarket that has a relatively current analysis available.

 

[eps2103]

Update: As AJ suggested, I picked up a bottle of water (Evian natural spring water) and on the label it listed the analysis with "Chlorides" 6.8 mg/L (that's the same as ppm?). That was the highest level I could find on any of the brands in the cooler.

I let the bottle warm to room temperature. I used a 25 ml sample size and went through the test. 5 drops Chloride Reagent A, then counting the drops of Silver Nitrate 0.171N until the sample turns completely orange-brown. Each drop represents 10 ppm chloride. I would have expected one drop to do the trick since the chloride level is so low, but it took two drops to get it the sample to turn color, and it was not what I would call orange-brown, but definitely not yellow. Three drops gave it an orange-brown hue.

I did contact LaMotte, and their reply was polite but not very helpful. "I’m not sure why there would be such a large difference, unless they [Ward Lab] were reporting the number in different increments then our test. We have had that test around for a long time and its always had good results."

As far as I can tell the reporting increments is the same with both LaMotte and Ward -- ppm.

Either I am an idiot or something is out of whack with their test.

 

[huckbof]

could it be, oh no it can't be the reagent, could it? j/k

I looked at the instructions on-line and it looks like the number of indicator drops [chloride reagentA 4069] is the same for both 10 mL and 25 mL samples, so if you need 5 drops to indicate in 10 mLs why wouldn't you need more than 5 for 25 mLs [of course, I haven't bothered to look at the chemistry], I was just teeing off on your statement that the sample didn't show any color prior to adding the silver.

"I would have expected one drop to do the trick since the chloride level is so low, but it took two drops to get it the sample to turn color"

If the sample wasn't yellow after adding the 5 drops of indicator, maybe that could explain why it took 2 to 3 drops of silver for the sample to indicate? the instructions I read say that the sample will turn yellow with the 5 drops of indicator....here...

http://www.manualsdir.com/manuals/596860/lamotte-water-analysis-kit-for-home-brewers.html?page=6

so try a 10 mL test or use more indicator drops in a 25 mL test to get it yellow before adding the silver

 

[eps2103]

Yeah, I believe five drops is fine in either case since the multiplier is different (higher, less precise with a smaller sample).

The sample was definitely a very light yellow after adding the reagent, but it didn't turn to the orange-brown as expected when I crossed the chloride threshold with the first drop.

I'm not a chemist, and I'm not looking for exact numbers...just trying to get "in the ballpark" as Palmer says.

 

[huckbof]

ok, so it was slightly yellow after the 5 drops of indicator

this sounds like the mohr test from way back in 1856

check this out...

http://www.titrations.info/precipitation-titration-argentometry-chlorides-Mohr

"Intense yellow color of chromate may make detection of first signs of formation of red silver chromate precipitation difficult. As some excess of silver must be added before precipitate starts to form, if concentration of titrant is below 0.1M, we may expect singificant [sic] positive error. To correct for this error we can determine a blank, titrating a solution of the indicator potassium chromate with standard silver nitrate solution. To make result more realistic we can add small amount of chloride free calcium carbonate to the solution to imitate the white silver precipitate."

Reading this, I would guess that the silver nitrate solution [0.171N which is the same as 0.171M for this reaction] is likely to be the issue. It only has a 2 yr shelf life and 0.171M is close to the 0.1M limit where you can get "singificant [sic] positive error".

 

[eps2103]

I was able to get a standard solution from one of the members in my brew club. I will run the test again with that standard.

Also I don't have it in front of me now but I'll check if there is a date on the silver nitrate when I get home.

Thanks to all for the input on this. Much appreciated.

 

[Staestc]

I was able to get a standard solution from one of the members in my brew club. I will run the test again with that standard.

Also I don't have it in front of me now but I'll check if there is a date on the silver nitrate when I get home.

Thanks to all for the input on this. Much appreciated.

Well I, for one, am anxious for this to be resolved. I want to get the kit.

Off the topic of the suspicious chloride reading, I see you got the basic kit. Are you doing anything to measure pH?

 

[eps2103]

Yes I have the Milwaukee MW102 to measure the pH.

 

[PlinyTheMiddleAged]

...You need to check the chloride test against a standard and you can certainly buy chloride standardized solutions but probably don't want to...

AJ,

Could the OP mix up his own "known" sample? Perhaps use distilled water and canning salt (NaCl with no anti-caking agents or iodine)? The OP can create a solution that is comparable to what Wards reports and then check with the test kit. That way, they're not working down in the low resolution area of the test kit - if I read eps2103's post correctly, he had to use somewhat more than one drop to get a change out of the Evian sample.

If eps2103 starts with a "known", then he could adjust for the old reagents - if the known sample (canning salt and distilled water) has 50 ppm sodium and the test kit says it has 75 ppm, then he knows that the test kit reads 50% too high. Would this work?

Just an idea.

 

[ajdelange]

Yes, that's the idea behind calibration with standards. Preparing a standard is the problem. To make a good chloride standard one, obviously, needs a very pure chloride salt which can be conveniently weighed or otherwise measured and most people don't have that around the house. But OP says he was able to obtain a standard solution so he is OK.

A possible way to make up a fair standard might be to take some calcium chloride, dissolve it in DI water and measure the SG as described at https://www.homebrewtalk.com/f128/measuring-calcium-chloride-501377/

 

[PlinyTheMiddleAged]

Yes. I see that the OP got his hands on a standard (I started the post and got interrupted several times prior to posting so I was late to the game). Anyway, that problem is solved.

Thanks!

 

[eps2103]

Yep. I should be able to pick up the standard solution over the weekend and test it. I'll report those findings as soon as I can.

Thanks

 

[eps2103]

Oh boy. I received the standard solution yesterday evening. 200 ppm chloride. I ran the test with a 10 ml sample, so one drop of silver nitrate equals 25 ppm. I counted 7 drops before it *just* started turning color, and with 8 drops it turned the expected orange-brown. That equates to apx 200 ppm, and so the LaMotte test looks to be pretty accurate.

So I ran the test on my own water yet again, and the result was consistent with previous results - 9 drops = apx 225 ppm. I took some pics along the way...

The attached photos show (sorry I could not get it to show a linked flickr photo so I had to upload them)

Instruction sheet
Initial sample
The Lamotte kit drops
After 5 drops of reagent
After 7 drops of silver nitrate
After 9 drops of silver nitrate
...and 30 seconds later

It seems pretty unlikely to me, but this does point to the Ward report being incorrect, or at least misunderstood. Unless someone notices something wrong with the way I am testing, I will contact Ward on Monday.

 

[Staestc]

Interesting. I wonder if Ward Labs will retest for you for free?

 

[ajdelange]

I don't think you have much of a case with Ward Labs unless they are in an expansive mood and I have seen reported here many times that where you can show that they goofed they will provide a free test. But were I them I'd say to myself "We run a chloride test and a sodium test in addition to all the other tests and when we are finished we add all the anions and cations and if they balance we know we didn't goof up. If we goofed this guy's chloride we'd have to goof some other test by exactly the same amount (mEq) in order to get balance and we got balance. He's probably got some cheap kit and doesn't know how to use it." Now if you were polite and explained what you did including checking against the standard I might soften and say "OK, it isn't going to bankrupt the company." and agree to a makeup test.

Of course this doesn't answer the question as to why there is a discrepancy. The only explanation I can come up with is a bookkeeping error e.g. your chloride number didn't get from the testing device to the report. But as I noted that would require some other ion to be in error by an equal amount with opposite sign. Actually, do you have the balance numbers for your report? That might shed some light.

 

[eps2103]

Thanks AJ. Of course Ward does this all day long every day, so that's why I find it very unlikely that their numbers are wrong. And if I didn't get the standard to test against, I'd just record a fraction of the actual result from the chloride test and be done with it.

Anyway here is the full report, I am not sure what to look for other than the cation/anion ratio which seems to balanced.

Thanks.

 

[ajdelange]

Not only do they balance but they agree with the reported ion concentrations.

 

[brick_haus]

Sounds like your kit is accurate at 200ppm. Go with your results.

 

[eps2103]

Sounds like your kit is accurate at 200ppm. Go with your results.

Yes, I thought the same, and in fact I used the Lamotte results for an IPA over the weekend. Time and taste will tell...

Thanks to everyone for the input on this one.

 

[Staestc]

My Lamotte Brewlab arrived today. I want to test before and after filtering, and after chloramines removal. Those alone almost pay for the kit if I was to send 3 samples in to Ward. And based on this thread and others I trust the results from this kit as much as those from Ward labs. Seemed like money well spent. I looked everywhere possible on the net and contacted my water supplier twice via email and can't get anything beyond the contaminates they are legally required to report. So time to measure it myself!

I really wanted the plus kit to get the pH meter, but could not justify the extra money. Will have to figure out some other way to measure pH.

 

[mabrungard]

Filtering and chloramines removal will not alter the ionic content of water.

By the way, a Total Chlorine test kit for swimming pool use can be an effective way to assess if your chloramines removal process was effective.

 

[Staestc]

I thought activated charcoal filters remove chloride. Does that not alter the ionic content of the water?

I had already thought of using my pool kit to measure total combined chlorine before and after chloramine removal

 

[ajdelange]

When chlorine is bubbled into water the following reaction takes place:

Cl2 + H2O --> H+ + OCl- + Cl-

If ammonia is subsequently bubbled through the mix the following reaction takes place:

H+ + OCl- + NH3 --> NH2Cl + H2O

A carbon filter will remove the OCl- (hypochlorite) and NH2Cl (monochloramine) but will not touch the chloride (Cl-) from the chlorine addition or any other chloride which was already in the water.

 

[Staestc]

I should remember that. I minored in chemistry, about 100 years ago! lol Thanks!

 

[jmf143]

What about sending a water sample to a third lab?