Table 2. Compositions of... | Rockefeller University Press

Table 2.

Compositions of phosphate-buffered solutions (in millimolars)

Solution	150 K	50 K	20 K	20 K	10 K	50 K/100 Na	50 K/100 Na	20 K/130 Na	20 K/100 Na	10 K/100 Na	150 Na
Figures^{^a}	Figs. 1 B, 2, 3, 4, and 5	Figs. 3, 4, and 5	Figs. 3 and 5	Fig. 4	Figs. 3 and 5	Figs. 3 and 4	Fig. 5	Figs. 3 and 4	Fig. 5	Fig. 5	Fig. 2
KCl	120	20		10		50	20	20
K₂EDTA^{^b}	4	4	2	1	1		4		2	1
K₂HPO₄	7.2	7.2	7.2	3.6	3.6		7.2		7.2	3.6
KH₂PO₄	2.8	2.8	2.8	1.4	1.4		2.8		2.8	1.4
KOH^{^c}	∼3.9	∼3.2	∼1.1	∼0.7	∼0.5		∼3.2		∼1.1	∼0.5
NaCl						70	100	100	100	100	120
Na₂EDTA						4		4			4
Na₂HPO₄						6.8		6.8			6.8
NaH₂PO₄						3.2		3.2			3.2
NaOH^{^c}						∼3		∼3			∼2.6
Total [K⁺]	149.1	48.4	22.3	21.3	11.1	50.0	48.4	20.0	22.3	11.1	0
Ionic strength (M)	0.168	0.067	0.036	0.028	0.018	0.167	0.167	0.167	0.136	0.118
Activity coefficient (dimensionless)	0.75	0.80	0.84	0.85	0.88	0.75	0.75	0.75	0.76	0.77
[K⁺] activity	112.5	38.9	18.7	17.8	9.7	37.7	36.5	15.1	17.0	8.6

Solution	150 K	50 K	20 K	20 K	10 K	50 K/100 Na	50 K/100 Na	20 K/130 Na	20 K/100 Na	10 K/100 Na	150 Na
Figures^{^a}	Figs. 1 B, 2, 3, 4, and 5	Figs. 3, 4, and 5	Figs. 3 and 5	Fig. 4	Figs. 3 and 5	Figs. 3 and 4	Fig. 5	Figs. 3 and 4	Fig. 5	Fig. 5	Fig. 2
KCl	120	20		10		50	20	20
K₂EDTA^{^b}	4	4	2	1	1		4		2	1
K₂HPO₄	7.2	7.2	7.2	3.6	3.6		7.2		7.2	3.6
KH₂PO₄	2.8	2.8	2.8	1.4	1.4		2.8		2.8	1.4
KOH^{^c}	∼3.9	∼3.2	∼1.1	∼0.7	∼0.5		∼3.2		∼1.1	∼0.5
NaCl						70	100	100	100	100	120
Na₂EDTA						4		4			4
Na₂HPO₄						6.8		6.8			6.8
NaH₂PO₄						3.2		3.2			3.2
NaOH^{^c}						∼3		∼3			∼2.6
Total [K⁺]	149.1	48.4	22.3	21.3	11.1	50.0	48.4	20.0	22.3	11.1	0
Ionic strength (M)	0.168	0.067	0.036	0.028	0.018	0.167	0.167	0.167	0.136	0.118
Activity coefficient (dimensionless)	0.75	0.80	0.84	0.85	0.88	0.75	0.75	0.75	0.76	0.77
[K⁺] activity	112.5	38.9	18.7	17.8	9.7	37.7	36.5	15.1	17.0	8.6

Figures showing the experiment in which the solution was used.

For calculating ionic strength, fractions of HEDTA³⁻ and H₂EDTA²⁻ at pH 7.2 were assumed to be 0.915 and 0.08 of the total EDTA, respectively.

pH was adjusted to 7.2 with KOH or NaOH.