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Ted Mooney, P.E. RET
Pine Beach, NJ

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Method for analysing Zn in rainwater

Q. Anyone know a simple method for analyzing for Zn and ammonia in rainwater runoff from a galvanizing plant site?
In the UK it might become necessary to collect runoff water and treat it to remove Zn and ammonia before it hits the storm water system.
Need to analyse the water to see what the current "contamination" level is.
Seeking a simple method for "bucket chemists" (titration?) as galvanizing plants typically don't have an AA, OES XRF etc.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

2007

"Colorimetric Analysis of Metal Finishing & Metal Working Solutions & Effluents"
by Aubrey Knowles
colormetric_analysis_knowles

on AbeBooks

or Amazon

(affil links)

You will not be able to titrate the zinc. You will be interested in concentrations that are far too dilute for that. In rainwater, they will likely require effluents to be less than 0.05 ppm. You really want an AA for this. If you already have a spectrophotometer, you should also have Aubrey Knowles book "Colorimetric Analysis of Metal Finishing & Metal Working Solutions and Effluents" ⇨
which lists two methods that you could try. If not, for your baseline you should just send samples (preserved) to a good lab in your area.

Jon Barrows, MSF, EHSSC
GOAD Company

Independence, Missouri

2007

Try Hach's "Zincon" method. I used to use it as a go/no go indicator for wastewater to be released.

You take a 25 ml sample, add a "ZincoVer" powder pillow, shake, then add one ml of cyclohexanone, and shake. No zinc at all is indicated by no change in color (orange) and the presence of Zn shows up as a blue color, the more intense, the more Zn.

Dave Wichern
Consultant - The Bronx, New York

Thanks for the advice.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

2007

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