Sodium phosphate buffer

[waite07 at angis.su.oz.au]

	When reference is made to sodium phosphate buffer of a particular pH,
what is meant, is a specific ratio of the mono- and di-sodium salts which gives
a correspondingly specific pH value. The ratios can be obtained from;

	Dawson, R. M. C., Elliot, D. C., Elliot, W. H. and Jones, K. M.,
	(1986). Data for biochemical research. 3rd ed. 432. Clarendon
	Press, Oxford.

	In case this reference can not be found, I include the relevant table;

	pH, 25 deg. C	x ml 0.2M Di-sodium	y ml 0.2M mono-sodium
	--------------------------------------------------------------
	5.8		4.0			46.0
	6.0		6.15			43.85
	6.2		9.25			40.75
	6.4		13.25			36.75
	6.6		18.75			31.25
	6.8		24.5			25.5
	7.0		30.5			19.5
	7.2		36.0			14.0
	7.4		40.5			9.5
	7.6		43.5			6.5
	7.8		45.75			4.25
	8.0		47.35			2.65
	--------------------------------------------------------------
	Original reference;
	 Gomori, after Sorensen, Meth. Enzymol. 1, 143 (1955)

	I usually assume that any dilution of a 0.2M solution will not change
the pH provided that nanopure, or equivalent, water is used.
	I hope this is of some help.

						Alex Jeffries


-------------------------------------------------------------------------------
Alex Jeffries
Plant Virology Lab.
Department of Plant Sciences		waite07 at angis.su.oz.au (129.78.25.38)
Waite Agricultural Research Institute
The University of Adelaide		Tel.;  61  8  372 2392
South Australia
Australia
===============================================================================