Hanna Phosphate meter question

[Niclas]

Hi everybody, I received ´my Hanna meter today and I have one question regarding the reagents. It seems to be difficult to get the reagents to solve completely, I always have some grains at the bottom of the test cuvet. Is it a problem? will I get false readings?
Thanks in advance for your answers!
Regards
Niclas

[fkadir]

you have to stir the cuvet gently and all will dissolve in a short period of time. That is my experience so far.

[CAReefer]

I have found that any remaining "grains" of regeant will cause high readings. My procedure is to swirl/shake the cuvette until 90% or so is dissolved, about 2 minutes. I will then put the cuvette into the meter and run the timed test. At about 1 min 30 seconds I will take the cuvette out and give it a gentle swirl and replace into the meter. This, for me, gives me the most repeatable procedure.

HTH
CAReefer

[Niclas]

Ok! thanks for your answers, I will try it CAReefer´s way right now and se if there are any different readings than thoose I just got (0.18).

[fkadir]

yeah, I will try Careefer's way and see if there is a difference in read-outs too.

[Aged Salt]

I have found that any remaining "grains" of regeant will cause high readings. CAReefer

Before I run my "read-time" all the reagent should be dissolved completely, which is easily accomplished after shaking the curvette for 2-3 min Bob

[fkadir]

Before I run my "read-time" all the reagent should be dissolved completely, which is easily accomplished after shaking the curvette for 2-3 min Bob

Bob , after shaking it for 2-3 min, do u run the read delayed and wait for another 3 mins or you do an immediate read?

[GTR]

IMO, the reason to allow the test to sit for three mins before reading is two-fold.

First it allows the reagent to react and the color change to occur. Extending the time we shake will increase the time for the color change. (It does'nt know it should wait until we stop shaking.)

Second it allows any undissolved reagent to settle so it won't interfere with the light source reading. Not allowing it to settle may cause a cloudiness and a false high reading I'd think.

When I talked to Hanna last year via email and they told me vigorous shaking for 30 seconds or so would allow enough reagent to dissolved to give accurate results.
If all reagent is not dissolved I don't see how that's any different than not getting every last grain out of the packet. The only part of this test I don't like is trying to pour the reagent from the packet into the small neck of the vial.

From the Hanna EM...

The reagent for this meter does not have to completly dissolve. The 3-minute hold time gives the reagent time to react so that you will get your reading result correctly.

SteveU

[Niclas]

Hi again, I got this mail from Hanna today:
It’s really not a big deal but you should get as much of it dissolved as possible. Maybe if you shake the cuvet a little longer than suggested. I hope this helps you.



Regards,
Jo-Anne Hebert
Hanna Instruments Inc.
Inside Sales Representative
Tel: 800-426-6287 ext 45

[GTR]

Niclas... Same Jo-Anne Herbert sent the email I quote above.

SteveU

[Aquatic Image]

I agree. As long as there are no particles suspended inside the vial it should read accurate. I shake mine until its almost all dissolved then do the timed read to let the particles settle to the bottom.