Development of Chiral Separation Phases for CNT

Deping XUE

The Design of the New Ion-exchange Resins

Ion-exchange Stationary Phase

PS/DVBHydrophilic layer

Functional group layer

Development

1. Select the right type of IEX functional groups

2. Impact of the length of ion-exchange polymer chain

3. Hydrophobicity vs. hydrophilicity

Initiation

I+M +M Pm

Chain transfer

S

S

Pm

+M

S

S

Pm

SS

Pm

S

Reinitiation

S+M +M

S Pn

Chain equilibration

S PnS

Pm

S

S PnS S

Pm S PnS S

Initiation

I+M +M Pm

Chain transfer

S

S

Pm

+M

S

S

Pm

SS

Pm

S

Reinitiation

S+M +M

S Pn

Chain equilibration

S PnS

Pm

S

S PnS S

Pm S PnS S

Mechanism of surface RAFT for synthesizing controlled polymers on PS/DVB resin.

O

O

N C

S H

O

N

O

n

1

O

O

N C

S H

O

N

O

n

++ ++

++ +

Weak anion exchange (WAX)

Strong anion exchange (SAX)

2

O

O

N C

S H

O

N

O

n

O

O

N C

S H

O

N

O

n

++ ++

++ +

++ +

++ +

Ion-exchange stationary phase structures of WAX and SAX

Impact of the Ion-exchanger: SAX vs. WAX column

SAX

WAX

[M]/[I] = 20

[M]/[I] = 20

[M]/[I]

402010

[M]/[I]

402010

52.51.51.00.5

Ion-exchange Capacity

min0 1 2 3 4 5 6 7 8 9

0 10 20 30 404.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Ret

entio

n Tim

e(m

in)

[M]/[I]

[M]/[I]

0.51.01.52.55.0102040

HPLC ConditionsMobile phase:20 mM Tris buffer, pH 8.0Sample: NaNO2

Chain Length Optimization (WAX)

[M]/[I] = 0.5

[M]/[I] = 1.0

[M]/[I] = 2.5

Hydrophilic (-OH)/WAX

WAX / -OH

[M]/[I] = 1

0

100

200

300

400

500

mAU

0.0 10.0 20.0 30.0 40.0 min

0 5 10 15 20 25 30 35 40 45 50 55 60 65

0.99

1.00

1.01

1.02

1.03

1.04

1.05

1.06

1.07

1.08

BSA R

ete

ntio

n tim

e(m

in)

B%

Hydrophilic (-OH) / WAX

1/1

1.5/1

5/1HPLC ConditionsMobile phase:A. 20 mM Tris buffer, pH 8B. A+0.5 M NaCl

WAX / C8

[M]/[I] = 1

Hydrophobic (-C8)/WAX

0 10 20 30 40 50 60

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

Hydrophobic (C8) / WAX

BSA rete

ntio

n tim

e(m

in)

B%

1.5/1

1/1

HPLC ConditionsMobile phase:A. 20 mM Tris buffer, pH 8B. A+0.5 M NaCl

Future Work

• Systematically study the impact of the hydrophobicity on the chiral separation resolution

• We believe this is the right direction to solve the challenge of CNT chiral separation

Acknowledgement

• Dr.Anand Jagota (Lehigh University)• Dr.Ming Zheng (DuPont CR&D)• Dr.Xueying Huang (Sepax-tech. Inc.)• Dr.Chuping Luo (Sepax-tech. Inc.)• Dr.Sean Huang (Sepax-tech. Inc.)• Dr.Shenyi Wang, Dr.Mathew George,• Dr.Xiaotao Zhou, Ryan Pringle • Dr.Jianxing Zhou