Hanna Phosphorus checker

[Fudsey]

1. Same except I use 2 cuvettes
2. Same
3. Fill both with 10ml tank water
4. Zero with one and add reagent to other
5. Shake for 2 min while other is zeroing
6. Remove cuvette with tank water and replace it with sample
7. Press button and wait for results
8. Repeat Zero and test again with sample
9. Repeat #8...

I tried to hold button on mine and it resets asking for c1 again

 

[sghera64]

1. Same except I use 2 cuvettes
2. Same
3. Fill both with 10ml tank water
4. Zero with one and add reagent to other
5. Shake for 2 min while other is zeroing
6. Remove cuvette with tank water and replace it with sample
7. Press button and wait for results
8. Repeat Zero and test again with sample
9. Repeat #8...

I tried to hold button on mine and it resets asking for c1 again

So, how long do you think it is between the time your two minute shake is over and the time you take your readings?

Since you are getting multiple readings, what is the range on those (high/low)?

 

[rtparty]

How are others using the Hanna ULR conducting their test?

My procedure:
1. Wipe cuvette clear inside and out with micro fiber cloth.
2. Tap reagent packet until reagent is gathered in one corner of packet, cut the packet open on right angle sides, fold half of the packet into a triangle pour spout and set aside.
3. Fill cuvette with 10ml tank water.
4. Zero the checker with the same cuvette.
5. Take cuvette out, unscrew the lid and pour/tap reagent into sample water.
6. Recap and shake for 2 minutes (timed on smartphone).
7. Place cuvette back in checker in exactly the same orientation as before.
8. Press and hold down the button until 3 minute countdown counter appears.
9. Sip a cold one until final number appears.

From the way I do it, the reagent is in solution for 5 minutes (give or take a few seconds) until final reading. Should I be waiting longer to take a reading?

I always use the same cuvette. Never both because now you've introduced a variable that can skew results.

My biggest complaint is I have to really rush to get the cuvette out, fill it with the reagent, shake for 2 minutes and put it back in the checker before it turns off. I have to be super quick and ready

 

[Fudsey]

@rtparty Why would it change if your using another cuvette? I have checked them against each other with just tank water and they always come out at zero. No matter which order I do them in.

@sghera64 probably about 2-3 minutes. The zero only takes a couple seconds and by that time I am starting to mix the sample but, my 1st test is always higher. That is primarily why I test a couple times. This time was the 1st time that the initial was 10ppb more than the 2nd. This is also why I tested an additional 3 times. The last 3 were more in line with the 2nd. A week ago I did the test and the initial was only 3 more than the 2nd and 5 more than the 3rd. This is why I asked the question in the OP. You can see the test results in the OP for the latest test.

 

[sghera64]

@sghera64 probably about 2-3 minutes. The zero only takes a couple seconds and by that time I am starting to mix the sample but, my 1st test is always higher. That is primarily why I test a couple times. This time was the 1st time that the initial was 10ppb more than the 2nd. This is also why I tested an additional 3 times. The last 3 were more in line with the 2nd. A week ago I did the test and the initial was only 3 more than the 2nd and 5 more than the 3rd. This is why I asked the question in the OP. You can see the test results in the OP for the latest test.[/QUOTE]

Ah yes. This initial high reading followed by lower and more consistent subsequent readings is consistent with what I experience too.

Randy shared in an earlier post that the Hach test requires about 8 minutes to develop for low range readings. At <50 ppB, we are in that low range - - BUT we are using Hanna reagents. I’ve repeated my reading for up to 20 minutes and got consistent readings from about 6-7 minutes all they way up to 20.

 

[rtparty]

@rtparty Why would it change if your using another cuvette? I have checked them against each other with just tank water and they always come out at zero. No matter which order I do them in.

@sghera64 probably about 2-3 minutes. The zero only takes a couple seconds and by that time I am starting to mix the sample but, my 1st test is always higher. That is primarily why I test a couple times. This time was the 1st time that the initial was 10ppb more than the 2nd. This is also why I tested an additional 3 times. The last 3 were more in line with the 2nd. A week ago I did the test and the initial was only 3 more than the 2nd and 5 more than the 3rd. This is why I asked the question in the OP. You can see the test results in the OP for the latest test.

I'm not a chemist or scientist so I can't tell you why. But Hanna states what to do in the instructions so I follow them.

To me, the least amount of variables the better. One cuvette could be a different "color" even if our eyes don't see it. Not all glass is equal

 

[MnFish1]

If the reaction is time sensitive, only the first reading would be valid. I wouldn't run that test more than once without knowing the answer to that.

Exactly - you can only run it once - and pick the first one - if you want to do it again - great - but you can't just keep running it....

 

[MnFish1]

Here is an experiment to try:
Clean two different cuvettes and fill them with tank water. “Zero” the meter with one of the cuvettes. Then insert the other cuvette and do a reading. You should get zero (no error, no positive reading). Repeat those steps, but switch the cuvettes (use the second one as the calibration cuvette). Again, you should get zero. Repeat this several times orienting the cuvettes (based on the “10 mL” mark) to different positions.

I have done this several times with different Hanna checkers and I always get zero each time.

For grins, one time I took a cuvette from a phosphate test when it gave me a 5ppm reading and used it to zero the meter. Then I tried to take a reading of a cuvette with RO/DI water in it. I got an error “- - “.


What this tells me is that we can zero the instrument with one cuvette and measure the other (i.e. we don’t have to calibrate and measure the exact same cuvette with the same orientation).

The manual says not to let the sample stay in the vial for “too long” or accuracy will be lost. How long is too long? Is the three minute timer for consistency? What about the mix for “up to two minutes”? If that is not kept consistent, then accuracy will (and does as I’ve proven) suffer.

If one can get a repeatable (and reproducible) reading after a total of 7 minutes, then maybe that is how the instrument should be used. It is possible that this introduces a repeatable bias/error, but the value is that the user can more accurately see shifts in phosphate readings (even if the readings are all low/high by a consistent amount).

The reason I wait 7 minutes is because I see micro bubbles in the vial after 5 minutes.

Isn't it just common sense to follow the directions on the test? Anything else is 'not valid'. Thats standard science - not a criticism.

 

[MnFish1]

@rtparty Why would it change if your using another cuvette? I have checked them against each other with just tank water and they always come out at zero. No matter which order I do them in.

@sghera64 probably about 2-3 minutes. The zero only takes a couple seconds and by that time I am starting to mix the sample but, my 1st test is always higher. That is primarily why I test a couple times. This time was the 1st time that the initial was 10ppb more than the 2nd. This is also why I tested an additional 3 times. The last 3 were more in line with the 2nd. A week ago I did the test and the initial was only 3 more than the 2nd and 5 more than the 3rd. This is why I asked the question in the OP. You can see the test results in the OP for the latest test.

The test is designed to use 2 cuvettes. As long as both are clean - thats how it works. EDITED - see below - this is not correct

 

[terri_ann]

Hanna says you use the same give the to run the test. Zero it and THEN add reagent. Hanna also says to mark an area on the give the to place it the same for testing. I took a permanent marker and placed a tiny mark on both the cuvette and meter. Each test i line the 2 marks up. This makes sense as the cuvette could have a microscopic scratch/es.

I also use a tiny funnel to pour the reagent into the cuvette. This prevents spillage and ensures I get all the reagent out of the packets. Any questions, give Hanna Instruments a call.

 

[Victoria M]

How are others using the Hanna ULR conducting their test?

My procedure:
1. Wipe cuvette clear inside and out with micro fiber cloth.
2. Tap reagent packet until reagent is gathered in one corner of packet, cut the packet open on right angle sides, fold half of the packet into a triangle pour spout and set aside.
3. Fill cuvette with 10ml tank water.
4. Zero the checker with the same cuvette.
5. Take cuvette out, unscrew the lid and pour/tap reagent into sample water.
6. Recap and shake for 2 minutes (timed on smartphone).
7. Place cuvette back in checker in exactly the same orientation as before.
8. Press and hold down the button until 3 minute countdown counter appears.
9. Sip a cold one until final number appears.

From the way I do it, the reagent is in solution for 5 minutes (give or take a few seconds) until final reading. Should I be waiting longer to take a reading?

I think this is the method I used. But the first time I used the checker it timed out on me. The stoopid thing has too small of an inactivity window to be slow and steady with ones process. I am sure I will get faster but geesh. I also experimented with using two vials. One to zereo and one to read. Probably not the best idea but I was curious.

 

[XNavyDiver]

I think this is the method I used. But the first time I used the checker it timed out on me. The stoopid thing has too small of an inactivity window to be slow and steady with ones process. I am sure I will get faster but geesh. I also experimented with using two vials. One to zereo and one to read. Probably not the best idea but I was curious.

I find that if you pre cut the packet and have that ready to pour before hand, it makes it easy to pour the reagent and shake for 2 minutes well before the timeout.

 

[MnFish1]

The test is designed to use 2 cuvettes. As long as both are clean - thats how it works.

In retrospect, this is not the 'recommended' way to do it - but - testing my system - I did it with one vial (according to instructions) and then again with 1 vial as the 'control' and the other vial with the 'test reagant'. Then I reversed the vials (using the other one as the control and the other one with the test reagent. All 3 tests gave the identical result. At least with my cuvettes it seems to work - and it makes doing the test much quicker/simpler.

 

[MnFish1]

I have a question about running the Hanna Checker Phosphorus test:

How many times do you run the test with the same sample?

I ran the test and the 1st result was 17, then I decided to run it a couple more time just to see. I have 2 vials(one with sample and one with tank water) and just kept rerunning the test for a few times.

Here are the results

1. 17
2. 7
3. 5
4. 4
5. 7

Which number should I use? Or do a avg of them all?

I misread a couple posts - and i also re-read the Hanna recommendations. You can ONLY use the measurement that comes out the first time. As time goes on, the test is not accurate. Additionally, according to Hanna, the cuvette can be stained by reagent the longer the testing reagent is in the cuvette - so it should be rinsed immediately after testing.

This potential staining is probably also a good reason to only use one cuvette as the control - and then put the testing reagent in that same bottle because its likely that over time there will be some variance in the 2 cuvettes even if they test out the same 'in the beginning'. Sorry for my seemingly contradictory posts

 

[Diazcm]

I dont know how you all are able to use the SAME cuvette for this test. When i perform my test i use both cuvettes one with tank water and other with reagent cause in my experience using one cuvette and mixing it for two minutes as the instructions states will cause the device to time out and shut off leaving you with a cuvette full of reagent and a not zeroed out device forcing you to start over and waste a test. IMO that's why hanna includes two cuvettes so you can zero with one and sample with the other.

 

[XNavyDiver]

I dont know how you all are able to use the SAME cuvette for this test. When i perform my test i use both cuvettes one with tank water and other with reagent cause in my experience using one cuvette and mixing it for two minutes as the instructions states will cause the device to time out and shut off leaving you with a cuvette full of reagent and a not zeroed out device forcing you to start over and waste a test. IMO that's why hanna includes two cuvettes so you can zero with one and sample with the other.

Easy. I find that if you pre cut the packet and have that ready to pour before hand, it makes it easy to pour the reagent and shake for 2 minutes well before the timeout.

*posted just a couple of replies above.

 

[MnFish1]

Although its interesting - Using the Hanna calibration set - they supply 2 cuvettes 1 to use as 'control' and the other with 'reagent'. So differences in at least that test in the cuvettes apparently is not a variable..... But I am going to start using one cuvette.

 

[rtparty]

People can "feel" however they want in here. Hanna CLEARLY states to use the SAME cuvette for zeroing and testing. Using both can easily skew results.

You MUST prepare before hand. Cut the packet open, get it all setup and then start the testing. That way you waste no time from the zeroing to adding reagent. If you setup before, you won't run out of time.

However, Hanna's shut off happens way too early. It needs to be at least 5 minutes IMO. Things happen and wasting a test is BS because of their oversight.

 

[sghera64]

I doubt the staining claim unless you leave a very dark blue sample sit in the vial for a very long time (e.g. forgot to take it out and discovered it was in there for a few days). Most of us have very low Phosphate/Phosphorous readings so there is very little blue color. Leaving that in the vial for 5-10 minutes is harmless. Also, you can simply soak your cuvette in diluted muriatic (HCl) acid to remove the staining. I do this periodically as a matter of habit.

One final note, a number of us have demonstrated that using 1 or 2 vials gives similar results (within sample/assay variation). Randy (RHF) has shared that the Hach test requires about 8 minutes to develop for low range phosphate. From my observation withe the Hanna I see a consistent "decrecendo" when I mix the reagent for 2 minutes and then try to make it do readings at minutes 2, 3, 4, 5, 6, 7. After that the reading holds fairly steady (repeatible) for minutes 8-20. I had to use two vials to do this. I switch vials filled with untested/unreacted tank water to verify that there was a zero difference in readings independent of the order of using the vials or their orientation in the checker. I just don't think these checker are that sensitive. They are not like the analytical lab grade UV-VIS spectraphotomers.

 

[Diazcm]

Easy. I find that if you pre cut the packet and have that ready to pour before hand, it makes it easy to pour the reagent and shake for 2 minutes well before the timeout.

*posted just a couple of replies above.

thats great if it works for you all but when i test i my checker times out on me and thats with everything cut, folded, ready to pour, and cloth right there. I guess i'm just to slow for the device lol .