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The following formulas can be used to calculate the volumes of solute (V solute) and solvent (V solvent) to be used: [1] = = where V total is the desired total volume, and F is the desired dilution factor number (the number in the position of F if expressed as "1/F dilution factor" or "xF dilution"). However, some solutions and mixtures take up ...
For example, if there are 10 grams of salt (the solute) dissolved in 1 litre of water (the solvent), this solution has a certain salt concentration . If one adds 1 litre of water to this solution, the salt concentration is reduced. The diluted solution still contains 10 grams of salt (0.171 moles of NaCl).
A tenfold dilution for each step is called a logarithmic dilution or log-dilution, a 3.16-fold (10 0.5-fold) dilution is called a half-logarithmic dilution or half-log dilution, and a 1.78-fold (10 0.25-fold) dilution is called a quarter-logarithmic dilution or quarter-log dilution.
If one begins with a solution of 1 mol/L of a substance, the dilution required to reduce the number of molecules to less than one per litre is 1 part in 1×10 24 (24X or 12C) since: 6.02×10 23 /1×10 24 = 0.6 molecules per litre
The titer corresponds to the highest dilution factor that still yields a positive reading. [2] For example, positive readings in the first 8 serial, twofold dilutions translate into a titer of 1:256 (i.e., 2 −8). Titres are sometimes expressed by the denominator only, for example 1:256 is written 256. [3]
Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. [1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase : [2]
In this method a measured sub-sample (perhaps 10 ml) is diluted with 100 ml of sterile growth medium and an aliquot of 10 ml is then decanted into each of ten tubes. The remaining 10 ml is then diluted again and the process repeated. At the end of 5 dilutions this produces 50 tubes covering the dilution range of 1:10 through to 1:10000.
The sectors are labelled with the dilutions. In each sector, 1 x 20 μl of the appropriate dilution is dropped onto the surface of the agar and the drop allowed to spread naturally. In the original description of the method a drop from a height of 2.5 cm spread over an area of 1.5-2.0 cm.