HydroCarbon
Hazard to Self
Posts: 77
Registered: 7-7-2008
Location: Anytown, USA
Member Is Offline
Mood: No Mood
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Isolating Stearate from a Detergent
Hello, I want to know if this is likely to work.
I want to determine if a lab detergent contains stearate or not. The detergent is Fisherbrand Sparkleen 1 MSDS . The MSDS shows some of the ingredients, but it doesn't show them all it leaves off about 40% of the contents as "non-hazardous
ingredients" I believe this is where the stearate is hiding as either the potassium or sodium salt.
My plan is to make a concentrated solution of Sparkleen in DI water, then add a concentrated solution of calcium chloride. I'm hoping this will
precipitate out the stearate as calcium stearate, which I can then confirm by IR spec.
Will this work? And is it possible that the calcium chloride will cause some of the other ingredients to precipitate out (Sodium
dodecylbenzenesulfonate, and/or sodium carbonate)?
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ScienceSquirrel
International Hazard
Posts: 1863
Registered: 18-6-2008
Location: Brittany
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Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
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The sodium carbonate is going to precipitate out loads of calcium carbonate when you add the calcium chloride solution.
I doubt your detergent contains any stearate at all. I think the two detergents contained in it are Ethylene oxide-nonylphenol polymer and Sodium
dodecylbenzenesulfonate.
Stearic acid is only poorly soluble in water and the presence of a strong acid makes it even more insoluble. Try adding dilute sulphuric acid to a
strong soap solution and you will obtain an immediate waxy precipitate.
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