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Analysis of Zn-Ni plating & trivalent chrome

(-----) 2007

Q. We are doing alkaline non-cyanide zinc - nickel alloy electroplating to meet one of our specific customer requirements. At present we do analyse by Atomic Absorption Spectrometric method. Due to some un avoidable circumstances, we could not continue our bath analysis (Zinc, Nickel in plating bath & Trivalent Chrome in passivation bath).

We also have ED-XRF and UV Visible spectrometer. We like to standardise this for our analysis purpose. Is it possible to analyse as mentioned above quantitatively? If so, request to mention the international standards to carryout our analysis.


Narasimhun Parthasarathy
Process Development Engineer - Chennai, Tamilnadu, India


A. AA is best for zinc nickel solution analysis. You should consider getting it going again. I do not personally like XRF for solution analysis, but you can analyze your %Ni in the plate if you can get good standards. Your spectrophotometer could work if you spend some time validating your method. You should buy Aubrey Knowles' book "Colorimetric Analysis of Metal Finishing & Metal Working Solutions & Effluents" [affil. link to book on Amazon], which will give you various methods to try out.

Jon Barrows
Jon Barrows, MSF, EHSSC
GOAD Company
supporting advertiser
Independence, Missouri

January 2, 2008


Why you don't like the XRF method?
Could I know your reasons please?

Jose Castellanos
- Minneapolis, Minnesota, USA

January 23, 2008

A. Jose-
It's just my opinion here. Every technology has ideal applications as well as applications that are possible, but not ideal. For Zinc/Nickel plating, XRF is ideally suited for determining the %Ni and %Zn in the final plate as well as the plating thickness. XRF can be outfitted to analyse solutions accurately, but it's just not what they are good at. There are too many other options, like AA, that will give a more reliable result for the wet chemistry. If you have an XRF already with all of the necessary upgrades for solution analysis, then by all means use it. Just run standards to make sure that you are getting a good and repeatable result. Be prepared to be disappointed with the accuracy and precision. My opinion is that you need both the XRF and the AA for a reliable Zn-Ni process.

Jon Barrows
Jon Barrows, MSF, EHSSC
GOAD Company
supporting advertiser
Independence, Missouri

February 27, 2008

thumbs up sign JON,

Thank you so much with your response. I agree totally with you. AAS is the best technique. It only need an expert.

Jose Castellanos [returning]
- Minneapolis, Minnesota, USA

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