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Preparation of Buffers for Use in Enzyme Studies
(by G. Gomori)
The buffers described in this section are suitable for use either in enzymatic or histochemical studies. The accuracy of the tables is within ± 0.05 pH at 23 ºC. In most cases the pH values will not be off by more than ± 0.02 pH even at 37 ºC and at molarities slightly different from those given (usually 0.05 M).
The methods of preparation described are not necessarily identical with those of the original authors. The titration curves of the majority of the buffers recommended have been redetermined by the writer. The buffers are arranged in the order of ascending pH range.
1. Hydrochloric Acid-Potassium Chloride Buffer.
Stocks solutions
A: 0.2 M solution of KCl (14.91 g in 1 …show more content…

Cacodylate Buffer.
Stocks solutions
A: 0.2 M solution of sodium cacodylate (42.8 g of Na(CH3)2AsO2.3H2O in 1 L)
B: 0.2 M HCl
50 mL of A + x mL of B, diluted to a total of 200 mL x 2.7
4.2
6.3
9.3
13.3
18.3
23.8

jun 14, 2004

pH
7.4
7.2
7.0
6.8
6.6
6.4
6.2

x
29.6
34.8
39.2
43.0
45.0
47.0

pH
6.0
5.8
5.6
5.4
5.2
5.0

Pag.5

12. Phosphate Buffer.
Stocks solutions
A: 0.2 M solution of monobasic sodium phospate (27.8 g in 1 L)
B: 0.2 M solution of dibasic sodium phosphate (53.65 g of Na2HPO4.7H2O or 71.7 g of Na2HPO4.12H2O in 1 L). x mL of A + y mL of B, diluted to a total of 200 mL x 93.5
92.0
90.0
87.7
85.0
81.5
77.5
73.5
68.5
62.5
56.5
51.0

y
6.5
8.0
10.0
12.3
15.0
18.5
22.5
26.5
31.5
37.5
43.5
49.0

pH
5.7
5.8
5.9
6.0
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8

x
45.0
39.0
33.0
28.0
23.0
19.0
16.0
13.0
10.5
8.5
7.0
5.3

y
55.0
61.0
67.0
72.0
77.0
81.0
84.0
87.0
90.5
91.5
93.0
94.7

pH
6.9
7.0
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
8.0

13. Tris(hydroxymethyl) aminomethane-maleate (Tris-maleate) Buffer.
Stocks solutions
A: 0.2 M solution of Tris acid maleate (24.2 g of tris(hydroxymethyl) aminomethane
+ 23.2 g of maleic acid or 19.6 g of maleic anhydride in 1 L)
B: 0.2 M NaOH
50 mL of A + x mL of B, diluted to a total of 200 mL x 7.0
10.8
15.5
20.5
26.0
31.5
37.0
42.5
45.0

jun 14, 2004

pH
5.2
5.4
5.6
5.8
6.0
6.2
6.4
6.6
6.8

x
48.0
51.0
54.0
58.0
63.5
69.0
75.0

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