Table 5 UV/VIS absorbance maxima of various PPD oxidation products

PPD

242, 307

8

[35]

200, 251, 320

CH₃CN, CH₂Cl₂

[37]

p-Benzoquinone diimine (BQDI)

257

8

[35]

255, 256

ether

[59]

460

8

[35]

247

7

[36]

240, 303

8

[36]

450

7

[46]

p-Benzoquinone monoamine (BQMI)

253

8

[35]

Semibenzoquinone diimine radical cation (SBQDIRC)

319, 420 (720)

CH₃CN, CH₂Cl₂

[37]

462, 469

20 % acetate buffer pH 4.6/80 % methanol

[41]

247, 350, 465

8

[36]

512

7

[46]

300, 460, 490, 560

7

[43]

Bandrowski’s Base (BB)

460

9.2

[29]

530–540

5.0

[29]

400

Citrate buffer pH 2.3

[59]