Saline detector

Hi,

Attempting to make a device to measure salt concentration in water. There will be other ions disolved at the same time, namely Chlorates and Chlorites. Can anyone point me in the direction I need to go or any pointers on the web. I have goodled to no avail.

TIA

Cheers, Andy

Check out flame ionisation analysis and atomic absorbtion analysis - the sodium D-line is quite strong, quite specific and easy to detect in absorption or emission.

-- Bill Sloman, Nijmegen

Bill, the poster was asking for a quantitative device, not for a qualitative lab test. If he wants to distinguish chloride from chlorite and chlorate, I guess that's becoming complicated and expensive.

Rene

Flame ionisation detectors are quantitative devices, and have been since the 1950's, when my father bought one for the paper mill in Burnie, Tasmania to measure the sodium concetration in black liquor. Alan Walsh (whom I once met) invented atomic absorbtion spectrometry a little later, and Varian-Techtron have been selling systems ever since.

The devices are complicated and fairly expensive, but entriely suitable for routine analysis.

-- Bill Sloman, Nijmegen

Knowing expected concentrations and matrix would help. Also, saying 'salt concentration' means something different in chemistry talk than common language. There are sodium salts, lithium salts, potassiium salts, etc. In addition, any anion could have been joined to any cation (sodium chloride, lithium chloride, potassium chloride, etc,. etc), so it would not be possible with a single analysis to know what the starting compound was, and then only with much experience with your process system - best guess would come from known contaminant into pure water matrix. 'Routine' means nothing more than what an instrument is standardized for, and is accompanied by accuracy and precision requirements, and assisted by whether it's on-line or run for only a few analyses at a time. Ion chromatography seems to be one way to get both the anion and cation concentrations easily. My minimum detactables by one IC are: Fl/Cl/SO4 0.14 ppt(rillion), and Na 0.14 ppt in a 3 ppm organic matrix. Minimum detectable Na by flame atomic emmission is 0.2 ppm. Graphite furnace is another option. If you're talking 'environmental levels' , AA and IC can do it, with much sample prep. But then, if it's that high, can you use a salinometer or conductivity meter?

Ion chromatography

The devices are complicated and fairly expensive, but entriely suitable for routine analysis.

Correction-- slip of the units tongue My minimum detactables by one IC are: Fl/Cl/SO4 0.14 ppb, and Na 0.14 ppb in a 3 ppm organic matrix.