Solutions Containing More Than One Solute SM Buffer TE Buffer NOTE: To successfully accomplish this section you must be familiar and comfortable with all information, manipulation and definition from previous lectures. This section will allow you to use every thing you have learned in this unit. Congratulations!!

SOLUTION WITH KNOWN ELEMENTS When given a solution with multiple known solute weights and final solution volume the procedure is like a recipe. This is the easiest way to make a solution with multiple solutes. Ex) You are asked to make 2 liters of syrup water by weighing out 2 grams of sugar, 1 gram of salt and dissolving it in water. You simply weigh out 2 grams of sugar, 1 gram of salt and dissolve it in water then bring it to volume to 2 liters. Much like sugar, some solutes require that they are heated on a heating plate to be able to dissolve. Always check your reagent information sheet (MSDS)

INDIVIDUAL SOLUTION PREPARATION PRIOR TO THE FINAL SOLUTION Final solutions maybe composed of a specific combination of small amounts of other solutions that you must also prepare. Ex) You are asked to make a media for a cell line by adding 100mL of IMDM 50mL of FBS 10µL Penicillin You would make each of the three solutions according to their recipes and then add 100mL of IMDM, 50mL of FBS and 10µL of penicillin in a sterile bottle. You would not bring it to volume since specific amounts of each one are required and this maybe due to a desired percent concentration.

SOLUTION PREPARED FROM ONLY FINAL CONCENTRATIONS There is no final volume or weight of each solute given in this type of solution. The only information provided is the concentration of each one solute. This is so one can make this solution at any volume desired. To do this you would have to calculate the amounts of each solute needed to produce the desired concentration in your preferred final volume. There are two very popular solutions used in laboratories: SM Buffer and TE Buffer

SM BUFFER SM Buffer is made by combining: 0.2M Tris, pH mM MgSO M NaCl 0.01 % gelatin Neither the amounts of each nor the final volume is given, thus there are no stock solutions. Follow these steps: 1. Decide a final volume to prepare. This volume depends on how often and how much will be used. 2. Weigh out the Tris. Solve using equations in Topic 8 One Solute Solutions Bring the Tris to desired pH 3. Weigh out the NaCl. Add into the Tris 4. Weigh out MgSO 4, add to buffer 5. Weigh out and add gelatin after calculating how much gelatin is required to make 1% in 1 liter.

TE BUFFER TE Buffer is made by combining: 10 mM Tris, pH mM Na 2 -EDTA 1. Decide how much you would like to prepare. We will prepare 100mL in this example 2. Determine how much Tris and Na 2 -EDTA is required to properly dissolve by referring to the product label and the proper stock solution of each one. In this case Na 2 -EDTA is dissolved at 0.5M stock solution; tris 0.1M stock solution. 3. Calculate how much Tris is required using C 1 V 1 =C 2 V 2 (0.1M)(x)=(0.010M)(100mL); x= 10mL Calculate how much Na 2 -EDTA is required using C 1 V 1 =C 2 V 2 (0.5 M)(x)=(0.001M)(100mL); x=0.2mL= 200µL 4. Combine 10mL trist stock, 200uL Na 2 -EDTA stock and bring to final volume 100mL with water. 5. Check pH