Table 1. Phosphate analysis: determination of RNA extinction coefficient.

[Na+]a (mM)	OD260 nmb	[P]c (µΜ)	[RNA]d (mΜ)	ɛe (cm–1 mM–1)
10	8.94	26.8	0.05826	153.45
20	7.59	25.9	0.05630	134.80
40	6.54	18.8	0.04870	134.29
80	6.18	19.1	0.04152	148.84
160	6.02	18.6	0.04044	144.88
320	6.22	18.3	0.03978	156.35

^aBackground [Na⁺] concentration.

^bOD at 260 nm.

^cConcentration of phosphorus determined by ICP-MS.

^dConcentration of RNA determined by ICP-MS, assuming a molecular weight for RNA of 7105.

^eThe extinction coefficient determined from the data in columns 2 and 4.