PBS vs. Sodium Phosphate Buffer

Yup they are an abbreviation.

When you dissolve a PBS tablet in the quantity of distilled water specified by the manufacturer, what molarity is it? Or if not molarity, is it 10x? (http://wiki.answers.com/Q/PBS_buffer_composition)

PBS does not contain just one solute, so the only way to answer your question is to address the molarities of the individual components, which are usually NaCl, KCl, Sodium Phosphate, and maybe Potassium Phosphate. Didn't the manufacturer give you this information? For most experiments, such as for washes, you would use a 0.01 M (in other words, 10 mM) 1X PBS solution which contains the following:

137 mM NaCl
2.7  mM KCl
10  mM Na2HPO4
2     mM KH2PO4

10X PBS STOCK solution would be:

1.37 M NaCl
27  mM KCl
100  mM Na2HPO4
20     mM KH2PO4

You calculate this in the following manner:

For example, 10X PBS:

Given: MW NaCl 58.44, that is 58.44 g in 1 L = 1 M (58.44 g/L), your desired molarity 1.37 M in 1 L
58.44 g/L x 1.37 M =  80 g in 1 L

Given: MW KCl 74.55, desired molarity 27 mM (or in other words 0.027 M) in 1 L
74.55 g/l x 0.027 M =2 g in 1 L

Thanks for your reply Duddy! So if the tablet has the following ingredients, the solution would be 0.01 M and I can adjust the concentration by varying the quantity of the water used Cheers!

137 mM NaCl
2.7  mM KCl
10  mM Na2HPO4
2     mM KH2PO4

NP man, good luck with it.