[kaitai]

I've a problem with analysis of a sample of wastewater. this sample derives from a train wash plant. What sort of  compounds could be an interference in a cationic determinations? I used a Merck kit, who used extraction with disulfineblue, Rodie method who used alizarine.

The glycol family could make interfernce with non ionic analisys?

[kevins]

Which cation(s) do you want to determine?

[kaitai]

I will determine cations surface active agent.

[kevins]

I got two methods for cationic detergent determination on hand
1. BS 2690:Part 11:1971 (very old method)
the range is up to 50ug and the max sample size is 90mL.
Interferences: Cl up to 4.5gm and NO3 up to 1.5gm in the test solution does not cause significiant interference.
Reagent: methylene blue and chloroform extraction.
spectrophotometer: 625nm and 10mm cell.

2. By Ion-chromatography
Column: Alltech Surfactant/R
Mobile Phase: A: 2mM Nonafluoropentanoic Acid
                     B: 100% Acetonitrile
Gradient mode.
flowrate: 1.0mL/min
Detector: Suppressed Conductivity.

for the glycol interference, you may try to add some glycol to the pure water and add the same amount of testing reagents for non ionic analysis to see any signal given out from the instrument.