# Hanna Photometers



## SuRje1976 (Mar 3, 2006)

Well, I got a bit tired of fussing with the LaMotte kits, and was in an impulsive mood the other night. So I ordered these:

Hanna Nitrate Photometer

Hanna Low Range Phosphate Photometer

I also picked up 2 of these, because I'm goofy:

Shockproof Boot

They came today! I'm not going to bother posting pictures, they don't look any different from the ones in the links above.

The Nitrate Photometer reads Nitrate-Nitrogen (not the same as Nitrate). It has a range of 0.0 to 30.0 mg/L. This equates to about 0-130 mg/L Nitrate. It reads in increments of 0.1 mg/L and is accurate to 0.5 mg/L, or +-10% (probably due to the fact that the reagents come in unit-dose packets, and an a somewhat unpredictable amout adheres to the inside of the packet itself). This is probably still more accurate than my interpretation of the colorimetric test results I get with the LaMotte kits. Conversion of the Nitrate-Nitrogen result reported by the device itself to Nitrate is done by multiplying the result by 4.43. Not too difficult.

The LR Phosphate Photometer has a range of 0.00 to 2.50 mg/L of Phosphate. It reports results with a resolution of 0.01 mg/L, and is accurate to 0.04mg/L, or +- 4%. No conversion is necessary.

They are simple to operate. A sample is added to the vial and is used to "zero" the device. The reagent (content of one single-dose packet) is added, shaken for a minute and put back into the machine. There is a "Read Timed" button that can be pressed and the machine will count down the appropriate amount of time before it takes the reading (analagous to "wait 5 minutes, compare to colorimeter" with traditional kits). The alternative is to wait the appropriate amount of time "manually," and use the "Read Direct" button. I'll probably never use that, because if I'm not impatient and read the result prematurely, I'll forget about it, and leave it much too long. Both are considered to make the result less accurate.

I used them both today, to test the water on the 120P. I got 12.7ppm NO3 and 1.17ppm PO4. A little more NO3 than I would have liked, so I'll change some water tonight!


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## Freemann (Mar 19, 2004)

Hi SuRje1976
I have the Hanna turbidometer for K and the composite instrument that measures 32 different chemicals for a year and a half now. I must say that the nitrate tests made in Hungary (the ones made prior in Italy were accurate) have great problems of accuracy, you could confirm this by doing multiple tests of the same sample of water and see if you have repeated results which I doubt. I am at the process of "bothering" them on this problem but I haven't had any response as yet. I have already used 3 different lots of tests all having the same inaccuracies, but different behavior (some will deteriorate some months after arrival other lots are inaccurate from the beginning). I had problems with the phosphate tests as well which in some cases top the scale and then the next test will show a value below 2.7 which is the higher limit on the low range kit. I am at loss with Hanna (and very frustrated) on this one it has been so long since I first realized this problems and still no remedy. So be warned. Please let me know if you have consistent results with your NO3 tests (do a number of test one after the other or test distilled water and tell me if the test reads 0 nitrates, here it doesn't) and tell me the lot number if you do.


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## SuRje1976 (Mar 3, 2006)

Freemann, thanks for the input! I'm experiencing somewhat similar issues.

A couple of preliminary observations. The cuvets that the sample is to be placed into are marked at 10mL. This is OK(ish) for the PO4 test, but the NO3 test requires a 6mL sample (cuvette is not marked at 6mL) SO, you'd need a means of measuring this out. I am using 10mL Class A Mohr Pipettes for this. The 10mL mark on the cuvette appears to be slightly mis-marked as well. Sample would probably be 10.2mL if filled to the mark. 

Another issue is - variability in readings. I know the "test kits are no good" crew is going to jump on this, but I really think I know where it's coming from. It's a bit difficult to tell when you've completely emptied the pre-filled unit-of-use reagent packets into the sample cuvet. If you aren't extremely careful, you'll leave quite a bit of reagent in the corners of the packet itself, but it will appear that you've emptied the packet completely. I've emailed Hanna regarding this and asked them if they could provide the actual WEIGHT of reagent that I should be able to produce from each packet. I also intend to ask if the reagents can be purchased in a bottle, as opposed to the packets, but I'll wait for a response on the initial inquiry first.


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## Freemann (Mar 19, 2004)

Pipettes is my approach as well, what I do with the packets of reagents is this:
I bend a piece of small square paper in half open the packet with scissors open the top edges by bending them in opposite directions and empty the contents (hitting with my finger the packet at the process) in the paper then empty the paper in the vial hitting it again this way I make sure all contents is emptied I use a timer called bigtime (http://www.hahntech.com/) (it can countdown showing different colors for time spans and voice the time passed) in NO3 measurement (initial fast mixing 10 Sec and 50 seconds after slow mixing), as you said vial is wrongly marked so I always use pipette. What Hanna Greece suggested is to contact by fax the American offices(they seem to be in control) and refer the fax to the president of Hanna there addressing the problems I have. Maybe we could do this at the same time with 2 different letters to them (or maybe you could hurry and exchange this unit for another brand  ). It sounds like a joke to pay all this money for a "useless" instrument that is supposed to be used in labs.
Please work with me on this one. I am at you disposal for any questions, suggestions.


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## SuRje1976 (Mar 3, 2006)

I appreciate it Freemann. I'm a bit discouraged that you never received a response from them. If I don't get one by the end of the week, I'll call. I have access to a scale that can weigh mg (0.001g) very accurately. I'll weigh out the reagents before running the tests. I'll certainly keep you posted!


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## Freemann (Mar 19, 2004)

As I said keep me posted, PM me whenever you have any news


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## Laith (Sep 4, 2004)

This is interesting. I was actually thinking of one day purchasing a photometer precisely because the normal test kits can be so unreliable.

I'm surprised the photometers can also be unreliable, and for such a higher cost!  

Perhaps the LaMotte photometers are better?


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## Freemann (Mar 19, 2004)

Laith as I said it is not the photometer (it can actually be calibrated per se with some special test) it is the reagents produced in Hungary that have caused the problem the Italian produced reagents were fine (at least they gave consistent results). I guess I will have to try to resolve the problem by correspondence with them. We will see. LaMotte could be another serious possibility but in my case I had no choice.


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## SuRje1976 (Mar 3, 2006)

Ok, this is where I'm at. (Freeman, my Nitrate reagents came from Italy  ). I did receive a response (a couple actually) from Hanna. They asked that I looked over the manual to ensure that none of the interfering substances are present in my water. I unforunately do not have a means to PROVE that my water contains none of them, it likely does actually. BUT, I would expect that it contains a fairly consistent amount of them from one sample to the next, so logically I would presume the results should be consistent as well.

What I intend to do is to run multiple tests on a sample made with RO/DI water and enough KNO3 to result in 15mg/L NO3-N and see if I can get consistent results with a consistent amount of reagent. This will rule out pretty much anything other than a defective machine/design. I MAY even be able to calculate how much reagent I SHOULD be using to produce an accurate result (assuming that I actually GET consistent results).

I haven't been GIVEN the weight of reagent that I should be getting (yet), but I have a dialogue going with a representative that seems to be helpful. He actually asked me to keep him posted with results, but I don't really think he wants to divulge any proprietary information to me.

All of my test samples are taken right before lights-on. SO, today I began weighing the reagents before the tests. I got:

212mg (0.212g) of Nitrate reagent out of its packet. This gave me a test result of 2.4mg/L NO3-N (10.6mg/L NO3) I will not add NO3 today, I hope it is less tomorrow, I have a light fish load!

170mg (0.170g) of Phosphate reagent from its packet. This gave 1.89mg/L PO4. I will also not add anything today, and retest tomorrow. This kit SEEMS to be a bit more accurate so far. The results I've been getting from it make sense.

I will report my results here (reagent weight & test result) daily (ideally). I will also report any useful info I get from Hanna as well.


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## SuRje1976 (Mar 3, 2006)

A bit useful info was brought to my attention, and confirmed via email from Hanna. There is no need to weigh the reagent, because there is sufficient reagent in the packet to react with all of the NO3 present in a sample on the high end of the range of the photometer (30ppm NO3-N). The unreacted reagent basically just "sits there" in solution. My samples will NEVER be that high (equivalent to >130ppm NO3) , so there is always going to be MUCH more reagent available to completely react with my tank's nitrate levels (1.2 to 2.2ppm NO3-N, or 5-10ppm NO3).

The new question I need to answer is this: Is the accuracy of the machine consistent across the ENTIRE range of testing?


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## Freemann (Mar 19, 2004)

> What I intend to do is to run multiple tests on a sample made with RO/DI water and enough KNO3 to result in 15mg/L NO3-N and see if I can get consistent results with a consistent amount of reagent. This will rule out pretty much anything other than a defective machine/design. I MAY even be able to calculate how much reagent I SHOULD be using to produce an accurate result (assuming that I actually GET consistent results).


Yes do this first. Did you do repeated tests on the same sample to check consistency of results?
Did you try testing distiled water? Why do you get the Italians reagents and they tell me that US gets the Hungarian as well, while we get the Hungarian stuff I really wonder?



> A bit useful info was brought to my attention, and confirmed via email from Hanna. There is no need to weigh the reagent, because there is sufficient reagent in the packet to react with all of the NO3 present in a sample on the high end of the range of the photometer (30ppm NO3-N). The unreacted reagent basically just "sits there" in solution. My samples will NEVER be that high (equivalent to >130ppm NO3) , so there is always going to be MUCH more reagent available to completely react with my tank's nitrate levels (1.2 to 2.2ppm NO3-N, or 5-10ppm NO3).


Interesting bit of info



> The new question I need to answer is this: Is the accuracy of the machine consistent across the ENTIRE range of testing?


That would be nice to know aswell.
Also if you get consistent results can you tell me the lot number of the tests?


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## SuRje1976 (Mar 3, 2006)

Freemann - I did run several tests using a prepared standard solution of 3ppm NO3-N. I ran 2 sets of tests, zeroing the machine with the same cuvette as the actual sample each time. The first time I got results from 2.1 to 4.3. The second time, from 1.0 to 2.4. All with the same prepared sample. I also ran tests with the LaMotte Nitrate kit I was using up until last week, and it gave accurate and repeatable results - right on 3.0 (well, right between 2.0 & 4.0) each time. I'm convinced that the Nitrate photometer is not accurate enough for my application. It certainly isn't as accurate at the low end of its range as stated in the specifications. I got a variability of 3.2ppm NO3-N. This is a swing of more than 14ppm NO3! I'm trying to keep my NO3 below 10ppm, so clearly this level of accuracy in not sufficient. I will be returning the photometers as soon as I can get a RA#.

I have started looking at the LaMotte colorimeter as a potential alternative.


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## Freemann (Mar 19, 2004)

I talked with the representatives here in Greece today and this is what they told me.
They spoke with the chemist responsible for the reagents, it all probably has to do with the Chinese company that prepares the mixtures. He is going to prepare NO3 reagents and make sure this are calibrated himself they will send them here next week. He also wants to test the previous lots I have plus someone else's here that complained as well. They also told me and this is positive not some commercial thing that the other brands have similar problems with the NO3 reagents. So I will have to wait and see. The guys here have been really helpful I must admit.


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## dennis (Mar 1, 2004)

Have you considered making your own reagents. It sounds like you, Sergio, have access to a lab so maybe you can order the chemicals you need and mix your own? I don't know how to do it but I do know it is common practice to make your own photometer reagents in labs. The cost savings should be significant.


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## Freemann (Mar 19, 2004)

I have considered it .
All I know is that the NO3 test is using the cadmium reduction method, and I bet you they all use the same chemical (probably from PermaChem) all that remains is getting this powder. Maybe someone here can help.


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