Sorption technology for pharmaceutical applications

Nachal Subramanian

Surface Measurement Systems

• Surface Measurement Systems - Introduction

• Dynamic Vapour Sorption (DVS)

• Inverse gas chromatography (iGC)

Overview

Surface Measurement Systems

Surface Measurement Systems develops and engineers techniques and instrumentation for

physico-chemical characterisation of complex solids. We are the world leaders in Dynamic Vapor

Sorption technology and Inverse Gas chromatography instrumentation, providing professional world-

class scientific and technical support for our international customers.

Our range of characterization instruments continues to help solve difficult problems in the

pharmaceuticals, biomaterials, polymers, catalysts, chemical, cosmetics, building materials and food

industries, and are used by hundreds of leading laboratories and universities throughout the world.

• Surface Measurement Systems - Introduction

• Dynamic Vapour Sorption (DVS)

• Inverse gas chromatography (iGC)

Overview

Dynamic Vapour Sorption

DVS is a gravimetric technique that measures how quickly and how

much of a solvent is absorbed by a sample.

- Sample is exposed to a series of step changes in relative humidity

and the mass change is measured as a function of time.

What is DVS?

Time

Rela

tive H

um

idit

y

Weig

ht

What can the DVS do for me?1. How does my material interact with moisture or solvents and temperature in the vapour phase?

2. Stability, Performance and Processing issues: Reversible and Irreversible effects of moisture

3. Create Moisture Isotherms – i.e. Equilibrium moisture content as a function of %RH

4. Heterogeneity? – Identify the Heterogeneity of a sample batch

5. Homogeneity? – Identify variance within one sample

6. Kinetics – Moisture transport properties, how fast or slow?

7. Energy – How strongly is the moisture bound to the material, surface or bulk?

8. Identify & Characterise Phase Transition/Changes, e.g. polymorphs, amorphous stoichiometry

9. Hydration and Solvate Formation

10.Drying Analysis

11.Diffusion and Activation Energy

12.Heat of Sorption

13.Moisture Uptake/Content? i.e. how much moisture/vapour is taken up or release

• Static system - Very slow achievement of equilibrium• Longer experiment time• Large amounts of sample required (1 to 10 g) • Risk of contamination or sample loss due to manual

weighing

Jar Method (static sorption)

Comparison to traditional jar method

• Dynamic Flowing Gas System - Faster Equilibrium

• High sensitivity Ultra-Microbalance (0.1 µg resolution)

• Allows small sample to be used (1 to 10 mg)

• No risk of contamination or sample loss

• Both sorption and desorption measured

DVS (dynamic sorption)

Typical DVS data

DVS Change In Mass (dry) Plot

-5

0

5

10

15

20

25

0 2000 4000 6000 8000 10000 12000 14000

Time/mins

Ch

an

ge In

Mass (

%)

- D

ry

0

10

20

30

40

50

60

70

80

90

100

Targ

et

RH

(%

)

dm - dry Target RH

© Surface Measurement Systems Ltd UK 1996-2001DVS - The Sorption Solution

Date: 07 Dec 2001

Time: 4:14 pm

File: ricestarch071201_reduced.XLS

Sample: rice starch

Temp: 24.8 °C

Meth: duncan.sao

M(0): 40.5303

Drying

Sorption SorptionDesorption Desorption

First cycle Second cycle

Phase transitions - Amorphous Lactose

DVS Data

DVS Sorption Data - LACTOSE

20.5

21

21.5

22

22.5

23

23.5

0 500 1000 1500 2000 2500

Time/mins

Ma

ss

/mg

0

10

20

30

40

50

60

70

80

90

100

Ta

rge

t %

P/P

o

Mass

Target % P/Po

© Surface Measurement Systems Ltd 2008DVS - The Sorption Solution

Amorphous State Crystalline State

60% RH

Amorphous State Crystalline State

Video

Images

Raman Data

Absorption Cycle 1

0

200

400

600

800

1000

1200

1400

1600

0 500 1000 1500 2000 2500 3000 3500 4000

Raman shifts (cm-1

)

Co

un

ts

Amorphous State

Crystalline State

0% RH

40% RH

60% RH

95% RH

Applications of DVS - Examples

Glass Transition and Crystallisation

Applications of DVS - Examples

Time /mins

Ch

an

ge I

n M

as

s (

%)

-d

ry

Ta

rge

t R

H (

%)

Tg RHSurface adsorption

Glass transition

Bulk absorption & surface adsorption

Recrystallisation

Pure Sucrose Images

❑ 0% RH ❑ 32.7% RH Glass Transition

❑ 80.9% RH Crystallized ❑ 92.6% RH Deliquesced

Properties measured by DVS

DVS is a tool for thermodynamic and kinetic studies of surface and bulk properties

• Sorption Isotherms

• BET Specific Surface Area

• Phase Transitions

• Permeability and Diffusion

• Competitive (Multicomponent) Adsorption

• Kinetics information

• Heat of Sorption

• Tg RH determination

• Amorphous content determination

• Camera and Raman capability

DVS Family of Products

DVSADVENTURE

Water vapor only

20-40 °C Small footprint

10-6 Torr to Atmospheric

20-70 °C

Water + Organic Vapors

& Gases

Competitive sorption Sample preheat to 400 °C

Water only

5-85 °C

Temp stability +/-

0.1°C

Camera and Raman

Sample preheat up to

300 °C

Water + Organic Vapors &

Gases

5–85 °C

Speed of Sound Sensor

Temp stability +/- 0.1°C

Camera and Raman

Sample preheat up to 300°C

Has 2 configurations:

Standard and Advanced

5 experiments in

parallel

DVSENDEAVOUR

DVSRESOLUTION

DVSVACUUM

DVSINTRINSIC PLUS

• Surface Measurement Systems - Introduction

• Dynamic Vapour Sorption (DVS)

• Inverse gas chromatography (iGC)

Overview

Inverse Gas Chromatography

• Gas phase sorption technique.

• Focus on physicochemical studies - kinetic information and

thermodynamic quantities from sorption equilibria.

• Earlier work on catalytic materials, e.g. activated carbon,

alumina and silica.

• Powerful physico-chemical characterization tool for

powders, fibres, films, particulates, semi-solids.

• Surface Energy is the most common measured property by

iGC.** Schultz, J., Lavielle, L., and Martin, C., The role of the interface in carbon fibre epoxy composites. J. of Adhesion, 1987. 23(1): p45-60.

IGC Principles

Animation by L. Teng, Surface Measurement Systems

iGC-SEA Introduction• Gas phase injection (like Headspace) - 12 vapor

reservoirs (50 ml)

• Carrier gas is helium/nitrogen

• 2 column position oven design: 20 to 150 °C

• Background Humidity Controller

• Flame Ionization Detector (FID)

• User Friendly Control and Analysis Software

Safety Features:Hydrogen Leak & Organic Vapor

Leak Detectors

medicalmetalimplants

Carbonfiber

cotton hair granules powder

Properties measured by IGC-SEA

The IGC-SEA provides unique access to the following physico-chemical properties of a wide range of solid

materials in a controlled humidity environment:

• Dispersive and Polar Surface Energies

• Heats and Entropies of Adsorption

• Acid/Base Interactions

• BET Specific Surface Area

• Phase Transitions

• Sorption Isotherms

• Permeability, Solubility and Diffusion

• Competitive (Multicomponent) Adsorption

• Thermodynamic Work of Cohesion and Adhesion

• Surface Energy heterogeneity mapping

• Constantly extend the applications – future applications e.g. Chemisorption

Thank you!

Head Office:

Surface Measurement Systems, Ltd.

5 Wharfside, Rosemont Road

London HA0 4PE, UK

Tel: +44 (0)20 8795 9400

Fax: +44 (0)20 8795 9401

Email: info@surfacemeasurementsystems.com

United States Office:

Surface Measurement Systems, Ltd, NA

2125 28th Street SW, Suite 1

Allentown PA, 18103

Tel: +1 610 798 8299

Fax: +1 610 798 0334