marcnol - Buffers

Temperature Dependence of the pH for Commonly Used Buffers

Buffer System pK_a/20°C [Delta]pK_a/10°C

MES 6.15 -0.110

ADA 6.60 -0.110

PIPES 6.80 -0.085

ACES 6.90 -0.200

BES 7.15 -0.160

MOPS 7.20 -0.013

TES 7.50 -0.200

HEPES 7.55 -0.140

TRICINE 8.15 -0.210

TRIS 8.30 -0.310

BICINE 8.35 -0.180

GLYCYLGLYCINE 8.40 -0.280

Reference

Good, N.E., Hydrogen ion buffers for biological research, Biochemistry 5, 467-476, 1986.

Temperature Dependence of the pH of 50mM Tris-HCl Solutions

4°C 25°C 37°C

8.1 7.5 7.2

8.2 7.6 7.3

8.3 7.7 7.4

8.4 7.8 7.5

8.5 7.9 7.6

8.6 8.0 7.7

8.7 8.1 7.8

8.8 8.2 7.9

8.9 8.3 8.0

9.0 8.4 8.1

9.1 8.5 8.2

9.2 8.6 8.3

9.3 8.7 8.4

9.4 8.8 8.5

Concentrations of Acids and Bases

Substance Formula MW Moles/liter* Grams/liter % by weight Specific gravity ml/liter to prepare 1M solution

Acetic acid, glacial CH₃COOH 60.05 17.4 1045 99.5 1.05 57.5

Acetic acid CH₃COOH 60.05 6.27 376 36 1.045 159.5

Formic acid HCOOH 46.02 23.4 1080 90 1.20 42.7

Hydrochloric acid HCl 36.5 11.6 424 36 1.18 86.2

Nitric acid HNO₃ 63.02 15.99 1008 71 1.42 62.5

Perchloric acid HClO₄ 100.5 11.65 1172 70 1.67 85.8

Phosphoric acid H₃PO₄ 97.9 14.8 1445 85 1.70 67.7

Sulfuric acid H₂SO₄ 98.1 18.0 1766 96 1.84 55.6

Ammonium hydroxide NH₄OH 35.0 14.8 251 28 0.898 67.6

Potassium hydroxide KOH 56.1 13.5 757 50 1.52 74.1

Sodium hydroxide NaOH 40.0 19.1 763 50 1.53 52.4

`Buffer System`	`pK_a/20°C`	`[Delta]pK_a/10°C`
MES	6.15	-0.110
ADA	6.60	-0.110
PIPES	6.80	-0.085
ACES	6.90	-0.200
BES	7.15	-0.160
MOPS	7.20	-0.013
TES	7.50	-0.200
HEPES	7.55	-0.140
TRICINE	8.15	-0.210
TRIS	8.30	-0.310
BICINE	8.35	-0.180
GLYCYLGLYCINE	8.40	-0.280

`4°C`	`25°C`	`37°C`
8.1	7.5	7.2
8.2	7.6	7.3
8.3	7.7	7.4
8.4	7.8	7.5
8.5	7.9	7.6
8.6	8.0	7.7
8.7	8.1	7.8
8.8	8.2	7.9
8.9	8.3	8.0
9.0	8.4	8.1
9.1	8.5	8.2
9.2	8.6	8.3
9.3	8.7	8.4
9.4	8.8	8.5

Substance	Formula	MW	Moles/liter*	Grams/liter	% by weight	Specific gravity	ml/liter to prepare 1M solution
Acetic acid, glacial	CH₃COOH	60.05	17.4	1045	99.5	1.05	57.5
Acetic acid	CH₃COOH	60.05	6.27	376	36	1.045	159.5
Formic acid	HCOOH	46.02	23.4	1080	90	1.20	42.7
Hydrochloric acid	HCl	36.5	11.6	424	36	1.18	86.2
Nitric acid	HNO₃	63.02	15.99	1008	71	1.42	62.5
Perchloric acid	HClO₄	100.5	11.65	1172	70	1.67	85.8
Phosphoric acid	H₃PO₄	97.9	14.8	1445	85	1.70	67.7
Sulfuric acid	H₂SO₄	98.1	18.0	1766	96	1.84	55.6
Ammonium hydroxide	NH₄OH	35.0	14.8	251	28	0.898	67.6
Potassium hydroxide	KOH	56.1	13.5	757	50	1.52	74.1
Sodium hydroxide	NaOH	40.0	19.1	763	50	1.53	52.4