Red stock standard TS

Procedure. To 40.5 mL of cobalt colour TS, add 6.1 mL of copper colour TS, 6.3 mL of dichromate colour TS, 12.0 mL of iron colour TS, dilute to 100.0 mL with sulfuric acid (~10 g/L) TS and mix.

Resazurin sodium (1 g/L) TS

A solution of resazurin sodium R containing about 1 g/L of C₁₂H₆NNaO₄.

Note: Resazurin sodium (1 g/L) TS must be freshly prepared.

Resazurin sodium R

C₁₂H₆NNaO₄ (SRIP, 1963, p. 170).

Resorcinol (20 g/L) TS

A solution of resorcinol R containing 20 g/L of C₆H₆O₂.

Resorcinol R

1,3-Dihydroxybenzene, C₆H₆O₂ (SRIP, 1963, p. 171).

Resorcinol/toluene TS

Procedure. Shake 0.2 g of resorcinol R with 100 mL of toluene R until saturated and decant.

Note: Resorcinol/toluene TS should be prepared immediately before use.

Rhodamine B R

C₂₈H₃₁ClN₂O₃.

Description. Green crystals or reddish-violet powder.

A commercially available reagent of suitable grade.

Solubility. Soluble in water and in alcohol.