# Preparing Solutions as Molar Equivalents

It is common to use a solubility aid such as 1 molar equivalent (1eq.) of sodium hydroxide (NaOH) in the preparation of aqueous solutions of some amino acids. We generally recommend that a 100 mM sodium hydroxide solution is used to dissolve the active compound.

### Protocol

#### Step 1.

Using the batch specific molecular weight (M.W.) of the compound, calculate the amount in grams that is required to prepare a 100 mM solution when 1L of solvent is added: (M.W. /10) = amount in grams (X)

#### Step 2.

From this, calculate the amount in grams required to prepare a 100 mM solution when 1 ml of solvent is added: (X /1000) = amount in grams (Y)

#### Step 3.

1 ml of the NaOH stock solution (100mM concentration) can now be added to this weight (Y) to dissolve the compound. In some cases warming of the solution or sonication may aid solubilization.

### Working example

Glutamic acid (Cat. No. 0217) has a batch M.W = 147.13

For a 100 mM solution: M.W./10 = 14.7 g in 1L

The amount required to prepare 1 ml of a 100 mM solution:
14.7/1000 = 14.7 x 10-3 g in 1 ml
= 14.7 mg in 1 ml

Weigh 14.7 mg of glutamic acid

Add 1 ml NaOH (100 mM)

= 1 ml of a 100 mM solution of glutamic acid in 1eq. NaOH

This solution can then be further diluted (with water) to the required concentration.