The direct titration of silver in the presence of halide ion. the sliver, in an alkaline solution as the thiosulphate complex, is titrated potentiometrically with thioacetamide solution using sliver sulfide-calomel electrode pair.

reference, D. G. BUSH, C, W ZUEHLKE, and A.E. BALLARD.

Volumetric Determination of silver using thioacetamide.

Hi Namrata,

Saeed Ayaz Khan is correct, precipitation of the poorly soluble compounds AgCl (white) and Ag2S (black) are very sensitive detections for silver ions. Both methods can be performed qualitatively or quantitatively. There are very numerous working instructions for this in the literature. You should note that AgCl dissolves in ammonia as [Ag(NH3)2]+ and in hydrochloric acid as [AgCl2]-, so the determination is best done in neutral solution. Ag2S is also poorly soluble in strongly acidic solutions.

I wish you much success in your research.

Saeed Ayaz Khan Florian Morsbach Thank you for your suggestions. Appreciate it.

Hi! You are wrong to resign from measuring techniques such as AA spectrometry or ICP-AES spectrometry (ICP-OES) as being too expensive and requiring outstanding knowledge and skills from the spectrometer user. The cost of purchasing a spectrometer can be high, but the operating costs can be small. Although you have not given further details on your solutions, the ideal measurement technique for you and, especially for silver, will be Flame Atomic Absorption Spectrometry (FAAS). Concentrations from several dozen micrograms / L to several dozen mg / L can be measured using this technique with an accuracy similar to that of classic titrations. Measurements with an AA flame spectrometer in the case of silver are extremely simple and do not require the exceptional skills of the user. To say jokingly, the operator of the spectrometer does not have to be familiar with the physics of atoms or even believe in their existence. The possible difficulties in making measurements consist rather in the accurate selection of chemical conditions in the measured solutions (both in sample solutions and in calibration solutions) in order to maintain the stability of silver concentrations in them for the time needed to perform the measurements. For higher concentrations of silver, it is best to use solutions with a high percentage of hydrochloric acid, which is a good solvent for silver chloride and prevents memory effects occurring in the spectrometer (in and on the burner head) when measuring high concentrations of Ag, alternating with low concentrations.

So, rather, try to access and learn to use the FAAS spectrometer, rather than wasting time on classic analytical methodologies. Anyway, the FAAS technique is itself a classic technique, so it's high time that it was the obvious first choice.

ZJ

Dear Namrata Dhakal,

Have you ever tried ion-selective electrodes? Potentiometry is the least expensive technique in terms of the cost of the instrument.

You need an adequate potentiometer. You also need a silver selective electrode - it can even be a simple silver wire of high purity - and a double junction Ag/AgCl reference electrode with an external solution without chloride. Or you can use the same silver selective electrode together with a single junction Ag/AgCl electrode that is not immersed in your sample/standard but is immersed in an adequate solution that is linked to your sample or standard through a salt bridge without chloride. You will have to prepare standards for your calibration curve that are buffered with the same high ionic strength.

There are some considerations before measuring your sample. And do not forget that your calibration curve should use - log [concentration] in the x-axis.

You can dilute the sample 1000x or more with the same ionic buffer with high ionic strength that you used to prepare your standards. And you can just measure the diluted sample and compare the voltage with your experimental calibration curve. The calculated concentration must be corrected to the original concentration before dilution. This is the simplest method but sometimes your sample is already too diluted to add so much dilution to it.

When you cannot dilute your sample so much you need to use the standard addition method. However, standard addition in potentiometry does not follow the same rules as in spectrophotometry. In operational terms is even simpler, although the calculations are a lot more complicated. Nothing that a spreadsheet app like Excel cannot help but you need to know the theory behind it to make the correct calculations.

I won't explain it here because it would be too long and you may solve it through direct measurement if your sample has enough concentration. Or you may choose another technique. As Zbigniew Jońca mentioned, if you already have the equipment, FAAS is fast and easy to use and the cost of the analysis is quite cheap if you dismiss the price of the instrument. However, good FAAS instruments are extremely robust, have very cheap maintenance and can last for decades as I know by my own experience. Nevertheless, for a few analyses, I would try potentiometry.

Good luck!

Appreciate the suggestions by Zbigniew Jońca and Ademario Junior

I haven't tried ion-selective electrodes yet. I tried to develop method with calorimetric assay but it didn't work as expected( it had long incubation time between silver and the reagent). But I need to measure silver for release assay. FAAS seems to be the way to go based on overall recommendations. Thank you.