Lecture 3 + 4 Volumetric Calculations

% w/w solution formula

g solute / 100 g solution

% w/v solution formula

g solute / 100 ml solution

(in calculations, remember this is mL not L)

% v/v solution formula

ml solute / 100 ml solution

(in calculations, remember this is mL not L)

parts of dilution (overall)

- sample (aka stock)

- diluent (usually water)

what does 1:10 dilution mean?

1 stock for every 10 solution. aka. 1 stock every 9 diluent

what does 1:10 ratio mean?

1 stock for every 10 diluents.

how to get "true value" after diluting?

After you get the instrument reading, multiply it by the dilution factor, which is just the reciprocal of the dilution.

true value = diluted value * DF

In serial dilutions, how do you get to a value of a tube?

keep dividing by the DF until you get the tube you want.

what is a titer?

the last/lowest positive reaction in a serial dilution. It's the inverse of the dilution, or the DF.

so if the last positive value is from a 1/640 dilution, then the pt's titer is 640.