Nitrite determination in domestic wastewater

[peterjakab]

Dear Community,

The goal anion (F, Cl, NO2, NO3, SO4, PO4) analysis in domestic wastewater (particules, hydrophobic matrices)

We have to reach LOD 50 ug/L for nitrite, for the others the LODs are higher. 

I'm thinking about the following, with some question:

1. sample preparation - C18 SPE or OnGuard II RP + 0,45 um filtering

Is the SPE require or enough just do the cleaning protocol for the guard+analytical column (suppressor?) occasionally?

2. Aquion system -  50 uL injection, AS22 column, carbonate eluent,  ADRS 600 suppressor, CD 

I dont want to inject too much because of the matrix but need to reach the 50 ug/L LOD with the Aquion system, in this reason i hope enough 50 uL injection.

The UV detection could increase the sensitivity?

Should to be use Integrion system with KOH EGC for that application for lower LOD?

We will have 30 samples per day, so I try to set up the best IC configuration.

If somebody have experience in wastewater analysis i would appreciate some good advice in this area!

Thank you!

Best regards

Peter

[Molly_I2]

@peterjakab Welcome back and thanks for your question. I will work with the team to sort an answer for you and look forward to when we can connect you with others doing wastewater analysis! We have a few articles on wastewater, just don't see a match to what you are searching for. I will follow up. @The_Ion_Lady and @chris-shevlin - see Peter's question!

[The_Ion_Lady · Accepted solution]

Hello @peterjakab ,

Welcome back!

Here attached is application update on anions wastewater determination: AU197: Anion Determinations in Municipal Wastewater Samples Using EPA Method 300.1 (A) on an Integra...

This uses similar to what you have mentioned that you have above.

If you use standard-bore (4mm) columns, this should give you enough capacity to for the other anions and nitrite.

If you worry about organics and humic acids, you can use C18 SPE or OnGuard II RP + 0,45 µm filtering as you mentioned. If you have an AS-DV autosampler then you can use the Dionex Guardcap HRP Vial Caps and no need to use the 0.45 µm filters. No need to do offline prep.

Other autosamplers, you might consider adding a 4 mm Dionex IonPac NG1 guard in front of your normal guard column to get rid of organics & humic acids.

Also, yes adding a UV can enhance the nitrite sensitivity. It is usually added after the CD:

This set up can be use for carbonate eluent or hydroxide eluent. Yes, Integrion with KOH will give you a lower background to carbonate as KOH is suppressed to water with almost zero conductivity.

I hope this is helpful to you.

[peterjakab]

Dear @The_Ion_Lady 

Thank you again your detailed quick answer 🙂

It helps a lot!