Question

a torsion prescription balance has a SR of 8 mg. To weigh 6 mg of atropine sulfate with an accuracy of +/- 5%, using lactose as the diluent, I calculated the minimum quantity of the drug to weigh on this balance, which was ______ mg. Then I weighed 200 mg of atropine sulfate and diluted with 5800 mg of lactose. In order to get my desired 6mg of atropine sulfate, what is the aliquot amount (mg) that I should take from the mixture?

Answer 1

Solution,

Given that

SR=8mg

Amount of atropine sulfate to be weigh=6mg

Accuracy=+/-5%

The smallest amount to be weighed on this balance= (S÷error)×100

= (8÷5)×100

= 160mg

Amount of drug required=6mg which is too small to weighed

So, 160mg is the total amount of mixture= drug+diluents

Diluent= 160(total mix.)-6(drug)

= 154mg

So,aliquot amount of 154mg that should taken from the mixture