Cleaning Quartz Cuvettes

[billing at vetsci.microvet.arizona.edu]

I have inherited a pair of quartz cuvettes that are partially coated 
with a slightly opaque film.  I have tried soaking them in detergent 
(Alconox) for several hours - the film is still there.  I will soak them 
overnight as well, but I am not hopeful.  Does anyone know what I can 
soak the cuvettes in that will a) clean them and b) not damage them.  
How about acetone?

Steve