Enantioselective analysis of chiral pharmaceuticals in environment

Edmond Sanganyado and Jay Gan

Department of Environmental Science

University of California Riverside

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Chiral center

Thalidomide Tragedy

Chiral Pharmaceuticals in the Environment

U.S. Geological Survey, http://toxics.usgs.gov/regional/emc/transport_fate.html 3

Purpose of Study•Develop method for enantioseparation of chiral pharmaceuticals

•Determine the enantiomeric composition of chiral pharmaceuticals in the environment

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Enantioseparation achieved in normal phase HPLC

Rs 1.10

Rs 1.66

Rs 7.95

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Enantioseparation on Vancomycin based column

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A: 80 % 20 mM ammonium acetateB: 20 % organic modifier

Enantioseparation on Vancomycin based column

• Effect of amount and type of inorganic salts

• van’t Hoff plots

• Mechanism of chiral recognition7

Mobile Phase: •Methanol + 0.1% acetic acid + 0.1% triethylamine•1.0ml/min flow rate

Effect of type and amount of ammonium salt on Rs and α

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Effect of pH on enantioseparation

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Effect of temperature on Rs and α in PIM

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Temperature dependence of retention and selectivity factors

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Mobile phase Atenolol Fluoxetine

Additive Conc.,

mM

-ΔH˚i

kJ/mol

ΔSi*

J/mol

r2i -ΔΔH˚

kJ/mol

-ΔΔS r2 -ΔH˚i

kJ/

mol

ΔSi*

J/mol

r2i -ΔΔH˚ -ΔΔS r2

Ammonium

acetate

20 3.50

4.11

-5.61

-6.86

0.989

0.993

0.61 1.25

0.999 4.05

4.99

-9.33

-11.82

0.996

0.996

0.94 2.49 0.998

15 3.11

3.70

-3.07

-4.20

0.998

0.999

0.59 1.14 0.999 3.78

4.68

-6.64

-9.00

0.999

0.999

0.90 2.36 0.999

10 2.37

2.99

1.26

0.0005

0.997

0.998

0.62 1.20 1 3.09

4.02

-2.00

-4.44

0.999

0.999

0.93 2.45 0.998

4 1.13

1.67

9.47

8.54

0.992

0.996

0.54 0.93 0.997 1.82

2.79

6.96

4.41

0.999

0.999

0.97 2.55 0.999

Ammonium

nitrate

10 0.63

0.47

-2.00

-1.25

0.682

0.997

1.11 2.72 0.877 1.21

2.45

-6.56

-9.73

0.809

0.942

1.24 3.16 0.999

Factors affecting separation of enantiomers: Summary

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Multiresidue separation and extraction in water

• 1mg/ml racemic standard spiked in 500 ml water• Extraction by SPE using HLB cartridge 13

Work in Progress

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Conclusion• Analysis of drugs at trace levels in environmental

matrices poses a significant analytical challenge.

• Development of methods for the enantioseparation

of chiral drugs is vital in the understanding of

their occurrence, fate and toxicity in the

environment.

• Chiral separation is important for preparing

enantiopure compounds required in

biodegradation and toxicity experiments.

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Acknowledgements

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