Chromatography Forum

Hello everyone,

Are there any detergents or methods for cleaning the deposite around

the bottom of glass vessel after dry ashing for As determination ?

Will the deposite be MgCl2 or Cl compounds since NaCl solution and ashing aids of MgO and Mg(NO3)2 were used ?


Thank you all for the reply.

Dear kingsemma,

MgCl2 is soluble in water and acids, so if you suspect on this compound you should be able to clean it by now. If you have other "unknown deposits" on the glassware but you know that they are mainly inorganic you could try to clean the glassware with chromic-sulfuric acid and then completely wash them with conventional detergents.
Immerse the glassware in the chromic-sulfuric acid solution or put the acid solution in to the glassware and let them to stay overnight. Next day dispose the acid solution and wash the cleaned glassware with detergents and hot water.

Hope this helps

Thanks zokitano

can nitric-sulfuric acid clean the glassware ?
My supervisor may not allow me to use chromic acid.

Thank you

You can purchase prepared solutions of chromic-sulfuric acids and it is very useful for cleaning inorganic deposits. With thorough cleaning after using cromic-sulfuric acid you'll be able to remove it completely.

can nitric-sulfuric acid clean the glassware ?

I don't know about that combination of acids, but you could also try (for very insoluble and inert inorganic compounds):

- concentrated (25% w/w) HCl in combination with 3% H2O2
- for very persistent heavy/precious metal compounds (Ag, Au, Pt...) - royal water (conc HNO3:conc HCl = 1:3 v/v)

Regards

Thanks zokitano

can nitric-sulfuric acid clean the glassware ?
My supervisor may not allow me to use chromic acid.

Thank you

We've had good luck with Nochromix, you mix it with sulfuric acid and it cleans about as well as chromic acid without the waste disposal issues.

Thank you for all your kind replies

My colleague had used royal water and boiled, but still no effect.

Can conc. HCl+H2O2 or Nochromix work ?


Thank you

You could try IPA saturated with KOH.

Sooner or later the cleaning costs more than new glassware.

Peter