Question

6. Accurate calculation of reagents is a key aspect that will determine your success or failure during the development of immunological assays. Clearly describe the steps and calculation to prepare the following reagents. (Please show work, i need to understand)

6a. 100 ml of a 0.9M solution of sodium chloride (molecular weight of NaCl = 58.4)

6b. 150ml of 1xPBS/3% BSA using a stock of 10X PBS and BSA that comes in a powder.

Answer 1

6a. Molarity= Gram molecular mass of solute per 1 litre of solution

So our gram molecular mass of NaCl 58.4, therefore Molarity is 58.4 divided by1L(1000ml)= 0.0584

For 100 ml of 0.9M NaCl would= 0.0584*100

= 5.84g(So, dissolving 5.84g of NaCl in 100ml of distilled water will give you 0.9M Nacl Solution)

6b. 10X PBS mean there is 10 times dilution of PBS meaning there is 10ml PBS and 990 water.

to make1X pbs from 10x pbs ypu have to follow the C1V1=C2V2

C1 is the concentration of the working solution =1X

C2 is the concentration of the stock solution= 10X

V1 is the volume of the working solution =150ml

V2 is the volume of the stock solution =?

putting all these togather 1X*150ml=10X* V2

therefore V2= 150/10

= 15ml

So, to make 1X PBS from 10X stock solution you have to add 15ml of 10X PBS and 100ml of distilled water to make up the volume.

3% BSA means 3g BSA in 100ml solution

so, for 150ml 3% would be 3/100*150=4.5g

add 4.5 g of BSA into 150ml of solution.