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topic 8976

Sodium hydroxide analysis of alkaline zinc

A discussion started in 2001 but continuing through 2019


Q. What indicator do you suggest I use for analysis of sodium hydroxide in alkaline non cyanide zincs? The one used at present is BDH 11-13 but this is no longer available.

Philip Gormley
plating services - Irvine ,Ayrshire, Scotland


A. Try using Sulfo-orange or phenolpthalein. I use the sulfo-orange for cyanide based solutions. It might work. I use the phenolpthalein for alkaline cleaners.

I'm not at work until Tuesday, at which time, if you want I can try a couple of experiments and get back to you.

K. Gendron
- Trenton, ON, Canada


A. 1. 5 ml. sample into a 250 ml. flask.

2. Add 25 ml. 20 % barium carbonate.

3. Add 3 drops phenolphthalein indicator.

4. Titrate with 0.1 N hydrochloric acid, color change is pink to white.

5. mls. titrated x 1.06 = oz/gal.

Bill Hemp
tech svc. w/ chemical supplier - Grand Rapids, Michigan


A. In response to the NaOH Titration procedure of Alkaline Zinc At our shop we use 5 ml sample 20 ml water A few specks of Indigo Carmine Indicator Titrate with 1.0N HCl from yellow to blue mls titrated * 0.95 = OZ/GAL * 7.5 = gms/lt

Lee Moss
- Calgary, Alberta, CANADA


A. We gave up on indicators and now use a pH meter and stirrer this gives more repeatable results. End point pH 11.2

Martin Trigg-Hogarth
Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England

April 7, 2019

A. BDH 11-13 indicator is actually pretty easy to make yourself ... only 2 reagents needed
I have been making my own for years

Nigel Gill
Aerospace - Glasgow, Scotland

July 17, 2019

Q. And how can I make the BDH 11-13 indicator by myself?
Which reagents are needed?

Benjamin Buettner
- Newhouse, Thuringia, Germany

August 5, 2019

Q. Good morning,
I would like to know the recipe for the preparation of the BDH 11-13 that I used but, at the end of the product, I was no longer able to obtain it from my supplier who did it in his laboratory.
Paul from Torino Italia

Paolo Scialuga
Surfaces treatment - Torino Piemonte Italia

October 30, 2019

A. Hi Paolo,
The compound used in BDH 1113 indicator is 4-(4-Nitrophenylazo)resorcinol.
So, dissolve ~1% m/v in ethanol.
You can get 4-(4-Nitrophenylazo)resorcinol from Fisher Scientific.
Best Regards,

Mark Lees
aerospace - A not so warm rock in the irish sea

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