YSI professional plus suitability for field measurements of nitrate and ammonium

[maxml...@gmail.com]

Hi Public lab, 

I have been offered a 2nd hand YSI pro plus at a reasonable price, and I was considering purchasing probes to measure surface water nitrate and ammonium concentrations at various points in the local catchment. Has anyone had experience with these devices, and can you advise me on the suitability of this device for for this application. I have around 20 sites to be measured fortnightly.

thanks in advance, 

Max

[Mathew Lippincott]

I can't say for sure, I've never used a YSI device with those sensors.

There are some YSI users in the public lab community.  Here is a project from the Stroud Center to connect YSI sensors to other devices. 

https://github.com/StroudCenter/Arduino-SDI-12

discussion (clearly some experienced YSI users here):

https://groups.google.com/forum/#!topic/publiclaboratory/b77RDqLuVME

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[Kevin M. Smith]

Hi Max,

Matt beat me to the punch about the Arduino SDI-12 library. 

I have personally used it with several YSI sondes in the past. It can take some work to figure out which of the pins coming out of the sonde is the SDI-12 control line, but after that it should be simple.

Note that the library only works with a few ATmega processors, most noteably the one used in the Arduino Uno. It does not provide support for boards with ARM processors (e.g. Arduino Due). 

If you have any questions about the library, feel free to get in touch - I am one of the authors.  

Regards,

Kevin

---

Kevin Smith

PhD. Student in Environmental and Water Resources Engineering &

NSF IGERT Fellow in Water and Diplomacy, Tufts University 

B.S. Earth & Environmental Engineering, Columbia University

B.A. Environmental Studies, Oberlin College

https://github.com/Kevin-M-Smith

[Jesse Robinson]

Hi Max, 

With respect to whether the sensors are a good choice for your work or not, I would point you to the advertised range (0 - 200 mg/L-N) and accuracy (+/- 10% or 2 mg/L-N, whichever is greater). If you expect significant differences in these concentrations within/between study sites, this might work for you. We have found these ISEs to be noisy when used in continuous monitoring, and although we have seen some pulses of ammonium, they are also prone to interference from other constituents (such as chloride, I believe) which may be present. 

I suspect that your catchment would have to be significantly impaired for you to see stratification in concentrations between sites using a YSI ISE.  

Jesse Robinson
502 - 320 - 1851

[maxml...@gmail.com]

Thanks for the response! I have been trawling for technical specifications for the accuracy of these probes, but having little success. Can you please let me know where you found those numbers?

I am taking samples for private customers to determine whether they are breaching local government water quality guidelines (and therefore liable for penalty or fines). The thresholds are 0.075 mg/L for nitrate and 0.1 mg/L for ammonium. It sounds like these probes are about an order of magnitude too coarse for this application. This is a real shame, as the landowners are very keen to consider any technology which can bring down the price of sampling - commercial labs currently cost about $100 per sample to determine the suite of 6 parameters specified by the local authority.

[Mathew Lippincott]

do you need to do real-time sampling?

there are test-strip based assays.  Most use a cobalt reagent which complicates disposal but these use an organic enzyme:
http://nitrate.com/store/

On Mon, Apr 20, 2015 at 5:15 PM, <maxml...@gmail.com> wrote:

Thanks for the response! I have been trawling for technical specifications for the accuracy of these probes, but having little success. Can you please let me know where you found those numbers?

I am taking samples for private customers to determine whether they are breaching local government water quality guidelines (and therefore liable for penalty or fines). The thresholds are 0.075 mg/L for nitrate and 0.1 mg/L for ammonium. It sounds like these probes are about an order of magnitude too coarse for this application. This is a real shame, as the landowners are very keen to consider any technology which can bring down the price of sampling - commercial labs currently cost about $100 per sample to determine the suite of 6 parameters specified by the local authority.

--

[Jesse Robinson]

Hi Max, 

You can find it on the pro plus product page (https://www.ysi.com/proplus). Just keep scrolling down, you'll see it under system specifications. 

If there is the potential for liability, you would want to know what sort of quality assurance is required for your data. Many agencies require approved EPA/standard methods for water analysis. Not sure where you are located.

On Mon, Apr 20, 2015 at 8:15 PM, <maxml...@gmail.com> wrote:

Thanks for the response! I have been trawling for technical specifications for the accuracy of these probes, but having little success. Can you please let me know where you found those numbers?

I am taking samples for private customers to determine whether they are breaching local government water quality guidelines (and therefore liable for penalty or fines). The thresholds are 0.075 mg/L for nitrate and 0.1 mg/L for ammonium. It sounds like these probes are about an order of magnitude too coarse for this application. This is a real shame, as the landowners are very keen to consider any technology which can bring down the price of sampling - commercial labs currently cost about $100 per sample to determine the suite of 6 parameters specified by the local authority.

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[maxml...@gmail.com]

Hi Jesse, thanks for the link - slightly embarrassing that I couldn't find that myself! I ended up getting a copy of the distributor.

You raise a good point, but I don't think liability is an issue here for a few reasons - primarily because we are in a 5 year lead-in period for the new compliance regime, so there will be no enforcement until then. Furthermore, if I go down this route I will make sure that my clients are aware of the difference in sensitivity and accuracy between field measurements and those carried out by a certified laboratory (and price accordingly). I am based in North Otago, New Zealand.

From the advice I have received from this group it seems that electrochemistry probes may not be the right tool for the job.  

[maxml...@gmail.com]

Hi Mathew, disregard my last post - while the test-strip based kits are not ideal, the spectrophotometry kits may be just the thing. Many thanks!

[punkno...@hotmail.com]

Hi, I am currently working with the nitrate sensor in question on drainage waters from arable land in Denmark.

I have been measuring nitrate in various locations with three different copies of the YSI sensor and also taken samples for laboratory analysis in order to assess the accuracy of this instruments

In some waters is does a very fine and is pretty much dead on the "true" nitrate concentration, however it seems to have trouble with some waters as it sometimes deviates around 10-80%, always more than the true value.

Do you have the similar experience with it, now that you have been working with for quite a while?

[Patrick Hixenbaugh]

Hi, and welcome!

This is a GREAT question! And I am also curious to know the answer. If I remember correctly, we had this model of sensor at my old office, but we weren't taking measurements with it while I was there.

I'm hoping someone with field experience has seen this. What have your experiences been -- when does it seem to work, and when does it fail? Have you taken a look at the manuals for the tolerance and operating conditions? Maybe sediment or some other characteristic can confound the measurements, and letting a water sample sit for 30 minutes to settle, prior to measuring nitrite, could help?

The 'specifications sheet' on the YSI page contains the following note for Ion Sensitive Electrodes: "*** ISE sensors for freshwater only; 17-meter maximum depth" but if you are using it within those conditions, I don't know why it would report outside of its 10% tolerance.

https://www.ysi.com/proplus (look for specifications sheet)

Good luck! Let us know what you find!

Patrick

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Patrick Hixenbaugh
University of Maryland, Baltimore County, 2014.

Chemistry / Environmental Science

+1-240-242-7449

https://publiclab.org/profile/pdhixenbaugh

[Jens Christensen]

Thanks for the response! I am currently still working on sorting out and try to understand the issures encountered with the YSI nitrate sensor. I'd also be very happy to hear other people's experience with this instrument.

So far there are indications that deviations are not attributed to suspended sediment in the water samples; I have measured water in both the inlet and outlet of a constructed wetland (surface flow) where i can see from the laboratory analysis and by looking at it that a great deal of sedimentation occurs. Deviations in these two follow the same pattern, so particles are probably not an issue.

My hypothesis is that either the deviations stems from the instrument having greater challenges measuring correctly at higher concentrations OR it could be due to dissolved ions interacting with the sensor.

Soon, I'll try to play with the sensivity, which could play a role in the challenges we have with it.

I'll be back when I continued the experiments.

---

Fra: plots-wat...@googlegroups.com <plots-wat...@googlegroups.com> på vegne af Patrick Hixenbaugh <patrick.h...@gmail.com>
Sendt: 2. marts 2017 12:47
Til: plots-waterquality
Emne: Re: [plots-waterquality] Re: YSI professional plus suitability for field measurements of nitrate and ammonium

 

Hi, and welcome!

This is a GREAT question! And I am also curious to know the answer. If I remember correctly, we had this model of sensor at my old office, but we weren't taking measurements with it while I was there.

I'm hoping someone with field experience has seen this. What have your experiences been -- when does it seem to work, and when does it fail? Have you taken a look at the manuals for the tolerance and operating conditions? Maybe sediment or some other characteristic can confound the measurements, and letting a water sample sit for 30 minutes to settle, prior to measuring nitrite, could help?

The 'specifications sheet' on the YSI page contains the following note for Ion Sensitive Electrodes: "*** ISE sensors for freshwater only; 17-meter maximum depth" but if you are using it within those conditions, I don't know why it would report outside of its 10% tolerance.

https://www.ysi.com/proplus (look for specifications sheet)

YSI Professional Plus handheld multiparameter meter ... www.ysi.com The YSI Professional Plus handheld multiparameter meter provides extreme flexibility for the measurement of a variety of combinations for dissolved oxygen ...

Good luck! Let us know what you find!

Patrick

On Thu, Mar 2, 2017 at 5:12 AM, <punkno...@hotmail.com> wrote:

Hi, I am currently working with the nitrate sensor in question on drainage waters from arable land in Denmark.

I have been measuring nitrate in various locations with three different copies of the YSI sensor and also taken samples for laboratory analysis in order to assess the accuracy of this instruments

In some waters is does a very fine and is pretty much dead on the "true" nitrate concentration, however it seems to have trouble with some waters as it sometimes deviates around 10-80%, always more than the true value.

Do you have the similar experience with it, now that you have been working with for quite a while?

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Patrick Hixenbaugh
University of Maryland, Baltimore County, 2014.

Chemistry / Environmental Science

+1-240-242-7449

https://publiclab.org/profile/pdhixenbaugh

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