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Re: Dosing and quantitation



Diane Brown wrote:
>
> Just dilute your stock solutions (via serial dilutions, like 
> in  chemistry class) so your're dosing easily measured 
> amounts. make  the solutions so your usual dose is 1 teaspoon, 
> or 5 cc, and  your measurements become simple and quick and 
> you don't need to  bother with little tiny syringes. And by 
> the way, the diabetic  syringes I've prescribed for my 
> patients are marked in 0.02 cc  increments--but they're only 
> available by prescription, as far  as I know (they come with 
> needles attached, after all). They do  exist but aren't very 
> available. Diluting your solutions is  easier--and most of the 
> chemicals we'd be working with should be  quite stable in 
> dilute solutions.  
> 
> Diane Brown, MD, PhD Fellow in Pediatric Rheumatology and  
> Immunology St. Louis Children's Hospital  
> 314-454-6124/brown_d at kids_wustl.edu  
> ________________________________  

How do you measure your stock solutions then? The higher the
concentration of the solution you are working with, the higher the
errors: a 0.2mL error measuring a 10,000 mg/L solution gives a larger
dosage error than a 0.2mL error measuring a 0.01 mg/L solution.

Serial dilution is amplifying measurement errors also. That's why
measuring out 100cc in a proper vessel is more accurate than measuring 6
Tbsp and 2 tsp.

I'm not saying that it is all terribly important to be that accurate,
just that I like to be. My personality is just that way. I set my
watches to the NIST atomic clock regularly (to keep within 1 second), I
measure things with calipers and/or a micrometer instead of a ruler. I
can't help it ;-)

-- 
Jerry Baker