Table 1.
Half-lives of ortho-quinone products from catecholamine metabolites (1–4) and HPLC conditions used to follow the oxidation.
| Ortho-Quinone Derived from | Half-Life (t1/2, min) | HPLC Conditions 1 | |||
|---|---|---|---|---|---|
| with NaBH4 | with Ascorbic Acid | ||||
| pH 6.8 | pH 5.3 | pH 6.8 | pH 5.3 | ||
| DOPE (1) | 14.6 | 128 | 15.2 | 114 | 80:20, 35 °C |
| DOPEG (2) | 30.9 | 187 | 30.0 | 154 | 90:10, 35 °C |
| DHBAlc (6) from DOPAC (3) | 9.1 | 46.8 | 9.5 | 47.8 | 85:15, 50 °C |
| DHBAld (7) from DOMA (4) | 3.0 2 | 3.3 2 | 3.0 2 | 3.3 2 | 85:15, 50 °C |
1 The mobile phase of 0.4 M formic acid:methanol, v/v (%), and the column temperature; 2 These values were subject to experimental errors because of the rapid degradation of DHBAld (7)—quinone. DHBAlc, 3,4-dihydroxybenzylalcohol; DHBAld, 3,4-dihydroxybenzaldehyde.