CH
3
OH, pH7.5, 40 ºC
CH
3
OH, pH6.0, 22 ºC
Sunniest C18
0 2
4 6 8 10 12 14 16
Retention time/min
Column A C18
Column B C18
N(4) =11,000
TF
(4)
=1.06
N(4) =8,950
TF(4)
=1.76
N(4) =10,000
TF(4)
=1.50
1
1
1
2
1
2
2
2
３
３
３
３
４
４
４
４
N(4) =10,500
TF(4)
=1.07
Sunniest RP-AQUA
Column size: 150 x 4.6 mm
Particle size: 5
μ
m
Mobile phase:
CH
3
OH/20mM Phosphate buffer pH7.5 or 6.0 =80/20
CH
3
CN/20mM Phosphate buffer pH7.0 =60/40
Flow rate: 1.0 mL/min
Temperature: 40 ºC or 22 ºC
Sample: 1 = Uracil
2 = Propranolol
3 = Nortriptyline
4 = Amitriptyline
O
OH
NH CH
3
CH
3
NH
CH
3
N
CH
3
CH
3
0 2 4 6 8 10 12 14
Retention time/min
Column A C18
Column B C18
N(4) =8,000
TF
(4)
=1.10
1
1
1
2
2
2
2
３
３
３
３
４
４
４
４
N(4) =5,800
TF
(4)
=2.86
N(4) =3,900
TF
(4)
=2.92
1
Sunniest C18
Sunniest RP-AQUA
N(4) =9,000
TF(4)
=1.09
CH
3
CN, pH7.0, 40 ºC
1
1
1
2
2
2
2
３
1
Sunniest C18
Sunniest RP-AQUA
Column A C18
Column B C18
N(4) =14,000
TF(4)
=1.16
N(4) =13,800
TF
(4)
=1.20
３
３
３
４
４
４
４
N(4) =4,300
TF
(4)
=5.24
N(4) =4,000
TF
(4)
=4.33
0 2 4 6 8 10 12 14 16 18 20 22 24
Retention time/min
Sunniest C8
N(4) =12,000
TF
(4)
=1.09
４
３
2
1
Sunniest C18
Sunniest RP-AQUA
Sunniest C8
◆
Evaluation of End-capping
Comparison of plates number (N) and USP tailing factor (TF) of amitriptyline
Amitriptyline is widely used to evaluate residual silanol groups on the C18 stationary phase.
Peak shape of amitriptyline was compared under 3 kinds of conditions such as
methanol/phosphate buffer/40 ºC, methanol/phosphate buffer/22 ºC and
acetonitrile/phosphate buffer/40 ºC. Under methanol/phosphate buffer/40 ºC conditions
which is the most common among HPLC manufacturers, good peak shape was obtained
for all columns. There were little difference of a peak shape. Under
acetonitrile/phosphate buffer/40 ºC, however, Sunniest columns showed a symmetrical
peak, while column A and B C18 showed a terribly tailing peak.
Sunniest C18, RP-AQUA and C8
columns allow to use a wide range of mobile phase
without peak tailing because of extremely low content of residual silanol groups on the
stationary phase.
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