I recommend to the users of this Q/A in analytical chemistry to be more precise in their questions; For example here the "liquid" H2O is OK, but is there any matrix (biological, environmental...)? Do you look for anions and cations? What are the expected concentrations or detection limits (LOD, LOQ)?  AAS was mentionned (for metals). Atomic emission spectrophotometry (AES) is also possible for some metals: flame emission for alkali and alkali-earth metals, and ICP-OES (= optical emission) or ICP-MS (ppb and lower detection limits) for most metals.

The method used in clinical chemistry are the ion-selective electrodes, which are transducers that converts the activity of a specific ion dissolved in a solution into an electrical potential, which can be measured by a voltmeter or pH meter. The composition of the outer (glass, mostly) surface of the meter, allows for selective passage of ions onto the transducers. Since departments of clinical chemistry measure ions routinely, they may be the ones to contact for your research question.

http://en.wikipedia.org/wiki/Ion_selective_electrode

This sounds like an experiment I did as a first year undergrad. You can get an overview of the experiment by following the link below.

There are several other ways of doing the analysis (Ion-selective electrodes and ion chromatography, for example), but this is the least expensive.

http://justonly.com/chemistry/chem201/students/labs/qualitative_analysis.pdf

Another method in use is liquid ion exchange chromatography which can use a universal detector like mass spec. It has the resolution to separate and quantitate the anions, and it can be configured for cations also. It won't speciate the polyvalent  anions ( i.e  Phosphate is only analyzed as PO4(-3) ) The pH will give H+ and help speciate these anions.

Ionized organics may be a bit more difficult, and if one is looking at dd H2O, the limits of detection may need to be the major factor in pursuing methods. ICP for cations will give good sensitivity, and spectroscopic methods for the oxyanions. The halides may have to be analyzed by gravimetric concentration and ion exchange chromatography.

If you are going to use ISEs to analyze your sample, you better have some knowledge of the sample first. So ion chromatography and atomic absorption spectroscopy (AAS) would help to see what are inside.

Dear Researcher,

Hi,

If you can afford, Ion Chromatography, is the best multi-ion technique, to individually finger print ions, like Fluoride, chloride, bromide, bromate, chlorate, nitrate, nitrite,sulfate and phosphate. We are routinely using this technique in our labs, If not then individual wet tests can give u all ions separately, using different techniques. Silver nitrate titration for chloride, turbidimetric method, using barium chloride for sulfate, Cd reduction method for nitrate, ammonium molybdate for P, and so on.

Best wishes,

Tahir zaidi-Center for Env. & Water-Research Institute- KFUPM-Dhahran

I recommend to the users of this Q/A in analytical chemistry to be more precise in their questions; For example here the "liquid" H2O is OK, but is there any matrix (biological, environmental...)? Do you look for anions and cations? What are the expected concentrations or detection limits (LOD, LOQ)?  AAS was mentionned (for metals). Atomic emission spectrophotometry (AES) is also possible for some metals: flame emission for alkali and alkali-earth metals, and ICP-OES (= optical emission) or ICP-MS (ppb and lower detection limits) for most metals.