## How do you find the minimum Weightable quantity?

Terms in this set (10)

- single ingredient or a mixture which does not contain any active drug.
- must be done last (can only be done last)
- LWQ = (100% x sensitivity requirement (SR)) / (acceptable error %)
- variation on percent of error equation:
- mass of the drug that is weighed.
- – use MWQ/LWQ method to find LWQ (mg)

**What is minimum Weighable amount?**

Explanation: The minimum weighable quantity in an electronic balance is 1 mg. This may vary from place to place. For example this is for the electronic balance that is used in the groceries shop.

**How do you compute for the smallest quantity of a substance that can be weighed on a balance with the desired precision?**

Calculate the smallest quantity of a substance that can be weighed on the balance with the desired precision. The equation used: 100% X Sensitivity Requirement (mg) /Acceptable Error (%) = Smallest Quantity (mg)

### How do you calculate balance of sensitivity?

Count the number of graph squares that cause the smallest detectable motion. Multiply that number of squares times the calculated mass of a single square to determine the balance’s sensitivity.

**How do you calculate Trituration?**

If your dilution is to be 250 g trituration, then, from the above, 1:1000:x:250, x = 250/1000 = 0.25. Therefore the trituration is 0.25:250, but the ratio of the T-3 (“solute”) to the diluent (“solvent”) is 0.25 in 250-0.25, or 249.75.

**What is the minimum Weighable amount for powders?**

The minimum weighable quantity of a drug powder, usually taken to be 50 mg or 100mg, is mixed with an inert substance to produce a 1:10 or 1:100 dilution. In practice, when making individual powders it is recommended to make in excess to allow for losses.

#### How much is an aliquot?

That is, an aliquot is the fractional part of an entire whole sample. For example, let’s say we have a 20ml solution of salt water (NaCl) and decide that we only want to work smaller 5ml samples.

**What is the minimum Weighable quantity on torsion balance?**

120 milligrams

The least weighable quantity would be 120 milligrams. The amount of drug substance to be weighed, therefore, must be equal to or greater than 120 milligrams.

**What is the minimum amount that can be weighed on a Class A prescription balance with a potential error of not more than 10 %?**

The minimum quantity that can be weighed accurately on the Class III (Class A) prescription balance with an error of not more than 5% is 120 mg (assuming a SR of 6 mg).