Dear Anna,

The most accurate method is atomic absorption. You can use a specific electrode but there may be interference.

With my best regards

Prof. Bachir ACHOUR

Hello Anna:

Indeed, Prof. Achour's suggestion will provide the most sensitive result.  If you are willing to measure in the ppm range, then Hanna Instruments makes a HI96731 Zinc Portable Photometer.  They are around $200 or so.

Excellent! Thank you both.

think about Diffusive Gradients in Thin-films(DGT)

measuring Zn using Ion selective electrode will provide accurate result

Sahadeb Dey

Dear Ms Smith,

I agree with the colleagues who favour AAS. Specificity and reproducibility are excellent, and in case of a simple matrix and relatively high concentration you don't need a graphite furnace. In case of large sample numbers you csn use a autosampler as well.

I wish you much succes.

Kind regards,

Prof Frederik A de Wolff

Article Zinc in hair and urine of paediatric patients

Both AAS and Ion selective electrode are useful. It will depend on Zn concentration and access to the equipment/buying. Check for the range of concentrations you are working with and compare it to the linear response of both candidates. Do not dilute the sample in order to fit in the linear range of the technique, choose the technique that fits to your needs. Also AAS will require sampling and delivery: if the equipment is in your lab (or close to) do not no doubt. An ISE is a bench instrument, all you have to do is dip the electrode in your solution. Buying an AAS requires a lot of money, ISEs are cheaper than AAS (more expensive than a pH meter, but not too much).  Also pay attention to the lifetime of the electrode (some ISEs do not last long) and the spanning of your work.  Good luck and have fun!

Dear Ms Smith,

I would not recommend, Ion Selective Electrodes for a reason. They are extremely delicate, costly and come with limited shelf life. First of all, what are the range of concentrations you are looking at? If the range is higher (above 50 ppm) easiest one would be, relying on titration techniques. If you are looking at ranges around (5 to 15 ppm) go for AAS. I would stop at this point. However, if you can still afford, ICP AES gives trustworthy results at ppb range even. So, it all comes down to the range. Think and decide...

http://link.springer.com/article/10.1007/s10498-009-9074-3

http://www.metrohm.com/en/products/ion-chromatography/930-compact-ic-flex

Hello Anna...

Ion chromatography can also be a solution, depending upon the concentration you are dealing with and if you have to measure free, ionic Zinc... speciation is not a problem in zinc's case.

Regards.

AAS is definitely most sensitive and reliable but only measures total metal including all forms ( free ionic, complexes, suspended etc.) and speciations...

For the  approx determination  of Zinc in water, colour comparator / portable digital ionic meters are widely available, which are easy to operate, quick in determination and also economically viable.

I think AAS will be very useful ans you may tryHANNA instrument as suggested by Dr. Timothy.

Depending on organics colorimetric and iron selective electrodes may have issues over time and AA or ICP-MS cost/time and portability issues.

If assays are required quickly, in very low ppb range, even for salt or brackish waters, consider Atomic Striping Voltammetry (ASV) with medial cost much lower. It may be necessary to strip organics with a UV cell or denaturing, but results can be had within minutes. Test, assays generally 30sec. Units such as the PDV6000+ square wave formats, totally portable with battery operation yet reliable and comparable to AA/ICP for a range of metals. Furthermore ASV has wide applications, including portability for biological samples.