Question

In a research lab, you will not always be given a protocol with the solutions you will need explicitly described. Often researchers have to adapt to the information that is provided in a published paper in order to make a solution. For the following questions assume you have been given the following information:

4X TGB (tris-glycine buffer) pH 8.3
Tris: 25mM
Glycine: 250mM
SDS: 0.1%

Part A: How many milligrams of SDS will you add when making 500mL of 4X TGB? (Formula Weight for SDS is 288.38)?

Part B: If you were making 1X working solution of TGB, at what concentration will each component be? (Tris, Glycine, and SDS)

Part C: Using your previous 500mL solution of 4X TGB, show your calculations for making 25mL of 1X TGB.

Please help! Also, please provide your best explaination because I am lost on part C. Parts A and B I've found different answers on the internet so I'm not sure if I'm right or not. Thank you so much in advance <3

Answer 1

here the composition of 4X TGB is given as

Tris: 25mM
Glycine: 250mM
SDS: 0.1%

A) for SDS 0.1% indicate that per 100ml of solution will contain 0.1gm of SDS in order to make 4x TGB solution

so for 500ml 4X TGB solution you will have to add =5x0.1= 0.5gm of SDS

B) we know the concentration of component in 4X solution so, in order to find the concentration of component in 1X solution just divide the component concentration by 4

therefore, the concentration of the component in 1X TGB solution will be

Tris: (25/4) = 6.25mM
Glycine: (250/4)=62.5mM
SDS: (0.1/4)= 0.025%

C) in onrder to make 25ml of 1X TGB solution you can do calculation as follow.

V1S1=V2S2

V1 and V2 is the volume of 4x and 1x solution

V1 x 4 = 25 x 1   V1 = 6.25ml

that means you will have to draw 6.25ml solution from previously made 4x TGB solution and will have to add into 18.75ml of water.