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Table 2 Influence of acids on chromatographic behaviors of kukoamines

From: Quality control of Lycium chinense and Lycium barbarum cortex (Digupi) by HPLC using kukoamines as markers

Aqueous phasea (v/v)

Analytes

Retention time (min)

Platesb

Rc

Td

Water

KA

15.3

126

0.8

2.30

KB

20.9

52

4.40

0.2% Formic acid (v:v) pH 2.5

KA

34.6

4557

1.0

3.02

KB

37.8

4632

3.06

0.1% Phosphate acid (v:v) pH 2.0

KA

35.1

3954

0.7

2.01

KB

37.9

3249

2.52

0.1% Trifluoroacetic acid (v:v) pH 2.0

KA

47.3

10,091

2.6

1.10

KB

37.1

10,887

1.12

  1. aThe exp eriment was conducted on an Agilent Zorbax C18 SB-AQ column (250 mm × 4.6 mm i.d., 5 μm) with fixed proportions of acetonitrile and aqueous phase (16:84). The aqueous phase was investigated with different acids
  2. bThe number of theoretical plates was calculated as N = 5.54 (tR/Wh/2)2, where tR is the retention time and Wh/2 is the peak width at half height
  3. cThe resolution R refers to the resolution between KA and KB. It was calculated as R = 2 (tA − tB)/(WA + WB), where tA and tB are the retention times and WA and WB are the peak widths
  4. dThe tailing factor T was calculated as T = W0.05h/2f, where W0.05h is the peak width at 5% peak height and f is the width start point at 5% peak height to the time of the maximum point