Phosphate-citrate buffer

The phosphate-citrate buffer (synonymous McIlvaine buffer ) is a buffer used in biochemistry , which consists of phosphate and citrate , among other things .

properties

The phosphate-citrate buffer is generated from two aqueous stock solutions A (basic, 0.2 M disodium phosphate ) and B (acidic, 0.1 M citric acid ). By changing the proportions of the two stock solutions, pH values of 2.2 to 8 can be set in the phosphate citrate buffer .

It is used, among other things, in the staining solution for horseradish peroxidase in the course of immunostaining , e.g. B. in ELISA . In a 1: 1 mixture with glycerol , it is also used as a mounting medium in microscopy . It is also used in microscopy for washing and staining specimens. The phosphate-citrate buffer with a pH value between 3.8 and 4 is used for RNase digestion. The phosphate-citrate buffer was published in 1921 by Theodore Clinton McIlvaine .

Mixing table for 20 mL McIlvaine buffer

pH	0.2 M Na 2 HPO 4 (mL)	0.1 M citric acid (mL)
2.2	00.40	19.60
2.4	01.24	18.76
2.6	02.18	17.82
2.8	03.17	16.83
3.0	04.11	15.89
3.2	04.94	15.06
3.4	05.70	14.30
3.6	06.44	13.56
3.8	07.10	12.90
4.0	07.71	12.29
4.2	08.28	11.72
4.4	08.82	11.18
4.6	09.35	10.65
4.8	09.86	10.14
5.0	10.30	09.70
5.2	10.72	09.28
5.4	11.15	08.85
5.6	11.60	8.40
5.8	12.09	07.91
6.0	12.63	07.37
6.2	13.22	06.78
6.4	13.85	06.15
6.6	14.55	05.45
6.8	15.45	04.55
7.0	16.47	03.53
7.2	17.39	02.61
7.4	18.17	01.83
7.6	18.73	01.27
7.8	19.15	00.85
8.0	19.45	00.55

Individual evidence

1. ↑ Arun Kumar Sharma: Chromosome Techniques. Butterworth-Heinemann, 2014, ISBN 978-1-4831-0084-5 .
2. ↑ Karl Maramorosch: Methods in Virology. Academic Press, 2014, ISBN 978-1-4832-6226-0 , p. 508.
3. ^ ^{A b} McIlvaine TC: A buffer solution for colorimetric comparison . (PDF) In: J. Biol. Chem. . 49, No. 1, 1921, pp. 183-186.