New Raman Instrumentation and Applications for QAQC and PAT

1
New Raman Instrumentation and Applications for
QA/QC and PAT
2
History of Raman Spectroscopy

• In 1928, Sir C.V. Raman discovered that radiation
  scattered by materials had an inelastic
  component.
• Only 1 in 1,000,000 (0.0001) photons are
  scattered inelastically.
• By the 1930s, Raman had become the principal
  means of non-destructive chemical analysis.
• After WWII, advances in electronics and detectors
  allowed IR to surpass Raman in this role.
• Advent of lasers in the 1960s revived interest in
  Raman to some extent.

3
History of Raman Spectroscopy

• In 1986, the first commercial FT-Raman instrument
  became available.
• In the late 1980s, notch filters improved the
  viability of Raman spectra.
• 1980s and 1990s, dispersive Raman technology
  improved including the development of holographic
  instruments, refinement of triple spectrographs,
  etc.

4
History of Raman Spectroscopy

• In 1992, the first holographic transmission
  grating is introduced.
• In 1993, the first 532-nm Raman spectrometer
  based on volume holographics is introduced.
• First KOSI on-line system is introduced in 1994.
• In 1996, the first non-contact fiber optic probe
  is introduced.

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What is the Raman Effect?
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What is Raman Spectroscopy?
Raman is a scattering technique
LASER
Rayleigh scattering Elastic scatter
1400
1200
1000
Raman Stokes Anti-Stokes Inelastic
scatter
800
Raman Intensity
600
400
200
-400
-200
0
200
400
Raman Shift (cm-1)
7
Polarizability...
...is a measure of the ease with which an an
electron cloud can be induced to slosh up and
down a molecule under the influence of an applied
field
Therefore, application of an Electric Field can
induce a Dipole
P ? E
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Stokes Scattering

• Stokes scattering is, by convention,
  positive-shifted Raman scatter. Most Analytical
  work is done in this region.
• Represents inelastic scattering to a region of
  lower energy. This means that the energy of the
  detected radiation is higher in wavelength
  relative to the laser.
• The scattered spectrum appears similar to an IR
  spectrum and is interpreted similarly.
• The Principle of Mutual Exclusion often makes
  Raman spectrum complementary to the IR spectrum.

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Rayleigh and Anti-Stokes Scattering

• Rayleigh scatter is the elastic scatter, i.e.
  same wavelength, as the incident laser. It is
  filtered and is excluded from the spectrum.
• Anti-Stokes scattering is inelastic scattering to
  a region of higher energy. This means that the
  energy of the detected radiation is lower in
  wavelength relative to the laser (therefore,
  higher frequency). By convention, it represents a
  negative Raman shift.
• The scattered spectrum is the mirror image to the
  spectrum from the Stokes scatter but is less
  intense. Therefore, only the more intense Raman
  bands are seen in the Anti-Stokes spectrum.

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Scattering Intensities

• Scattering in general is dependent on the
  frequency of the excitation radiation to the
  fourth power
• Rayleigh scattering is considerably stronger than
  Raman scattering
• Stokes and Anti-Stokes scattering are related to
  the population in the ground state and the first
  excited vibrational level
• It may take as many as 108 excitation photons to
  give rise to one Raman photon

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The Paradigm Factor

• The reason we dont use newer technologies is
  that we fear that FDA wont accept them because
  of the agencys unfamiliarity with them. But the
  reason FDA is unfamiliar with newer technologies
  is that companies dont submit themWe owe it to
  our customers to use the best and fastest
  techniques to analyze our products
• Emil Ciurczak, Pharm Tech, Analytical
• Validation Issue 1999

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The Purpose of PAT

• To understand processes (manage variability)
• To improve processes (time, automation, etc.)
• To correct processes
• To identify where routine monitoring is needed
• Facilitate continuous processing
• Facilitate mechanistic-based regulatory
  specifications
• Real-time release (?)
• To save money by eliminating non-optimal
  practices which lead, in worst-case scenarios, to
  product rejection

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Why is Spectroscopy of interest for PAT?

• Spectroscopy can be used for real-time
  quantification.
• Spectroscopy can be used to understand the
  chemistry of each process.
• Spectroscopy can be used to optimize the timing
  of the process stages and the endpoint.
• Spectroscopy can be used for routine monitoring
  by non-experts.
• Spectroscopy can be used for remote monitoring.
• Safety advantages
• Also implies non-contact monitoring in the case
  of Raman. Process is undisturbed which is
  advantageous because of minimal impact on process

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Why is Raman being used for PAT?
improvements in instrumentation have allowed
users to focus on their applications rather than
on the operation and limitations of the
instrument
M. Pelletier, Quantitative Analysis Using Raman
Spectrometry, Appl. Spectrosc., 57 (1), 2003
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Why is Raman being used for PAT?

• Raman is a specific and selective technique
  providing well resolved information leading
  toBETTER PROCESS UNDERSTANDING
• Flexible sampling (remote sampling)
• Confocal optics
• Sampling through containers
• Measurement of various types of samples (liquids,
  slurries, pastes, solids, powders, etc.)
• Ease of use no longer requires an expert

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PAT Uses of Raman

• To detect quantitative trends
• To understand the chemistry of the process
• Crystallinity
• Particle characteristics
• Reaction intermediates
• Reaction equilibria
• Optimization of timing
• To detect end-points, i.e., desired product status

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Fiber Optic Coupling Remote Process Monitoring
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Reaction Monitoring Hydrogenation of Cyclohexene
to Cyclohexane
H2
Process Understanding and Optimization
19
Experimental Setup
Instrument Kaiser RamanRxn1 Analyzer Spectral
Range 100 to 3500 cm-1 Laser 785
nm Sampling Immersion probe Collection Time 10
x 6 seconds
20
Spectra from 200 1800 cm-1
0 min
6000
17 min
28 min
39 min
59 min
5000
70 min
80 min
91 min
491 min
4000
1122 min
Raman Inensitty
3000
2000
1000
400
600
800
1000
1200
1400
1600
1800
Raman shift (cm-1)
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Expansion of CH2 Deformation Ring Mode Bands
0 min
17 min
5.0
28 min
Cyclohexene 823 cm-1
Cyclohexane 802 cm-1
39 min
59 min
70 min
4.0
80 min
91 min
491 min
1122 min
3.0
Raman Intensity
2.0
1.0
0.0
790
800
810
820
830
840
850
Raman shift (cm-1)
22
CC Stretch Also Shows Appropriate Trend
0 min
3.5
17 min
28 min
39 min
59 min
3.3
70 min
80 min
91 min
3.1
491 min
1122 min
Raman Intensity
2.9
2.7
2.5
2.3
1635
1640
1645
1650
1655
1660
1665
1670
Raman shift (cm-1)
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Trend Using Baseline Integrated Bands in 800
850 cm-1 Region
1.2
Cyclohexane
1
0.8
0.6
Relative Intensity
0.4
0.2
Cyclohexene
0
-0.2
0
0.5
1
1.5
2
2.5
3
3.5
Time (hours)
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MCR (Multivariate Curve Resolution) Shows Some
Interesting Results
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Cyclohexene Pd/C
0.6
y -0.3102x 0.5026
0.5
2
R
0.9748
0.4
0.3
Cyclohexene Molarity
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Time (hrs)
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Cyclohexene Pt/C
0.5
y -0.9466x 0.4296
0.45
2
R
0.9865
0.4
0.35
0.3
0.25
Cyclohexene Molarity
0.2
0.15
0.1
0.05
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Time after 2nd H2 addition (hrs.)
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Cyclohexene Rh Profile
0.6
y -0.5043x 0.4965
0.5
2
R
0.995
0.4
0.3
Cyclohexene Molarity
0.2
0.1
0
0
0.2
0.4
0.6
0.8
1
1.2
Time (hrs.)
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Kinetics Data for Cyclohexene
Catalyst Zero-Order Constant Pd/C 0.310 Pt/C
0.947 Rh 0.504
Understand and Optimize the Process!
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Hydrogenation of Carvone
Process Understanding and Optimization
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Carvone Peak Disappearance
Complex Spectral Changes
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Kinetic Profile for Full Data Set
500
Dihydrocarvone
400
Carvone
300
Tetrahydrocarvone
200
arb. units
100
0
-100
0
2
4
6
8
10
12
14
16
18
Time (hours)
Note Analysis uses 452 cm-1 498 cm-1 region,
MCR 3 factor data reduction used for trend
plotting
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Catalytic Hydrogenation Reaction

• Intermediate (hydroxylamine) is a potential
  thermal safety hazard
• Preferred pathway excludes the intermediate
  species

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Catalytic Hydrogenation Reaction
Reactant Intermediate Product
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Catalytic Hydrogenation Reaction
Reactant Intermediate Product
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Analytical Raman Spectroscopy
IlsLCI Il Raman intensity s Raman
cross section L Pathlength C Concentration I
Instrument parameters
Sample
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Univariate Quantitative Analysis

• Sometimes univariate techniques will do
• Peak heights or areas if isolated peaks are
  available
• Peak positions
• Peak ratios (internal standard or total area)
• These techniques better fit the mold for a
  traditional validation approach

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Example of Peak Intensity - Clotrimazole Films
PEO Only
Clotrimazole E - 7.5
Clotrimazole A - 1
Clotrimazole F - 10
20000
Clotrimazole B - 2
Clotrimazole G - 12.5
Clotrimazole C - 4
Clotrimazole H - 15
Clotrimazole D - 5
Clotrimazole I - 20
Pure Clotrimazole
10000
2nd Derivative
0
-10000
2nd Derivative Spectra
-20000
1550
1560
1570
1580
1590
1600
Raman shift (cm-1)
38
Calibration Results for Clotrimazole
r2 0.9969 SEC 0.493 SECV 0.722 MLR using
band at 1585 cm-1
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Raman Spectra of Progesterone
Crystal Forms I and II

• For this Study the CO Stretching Vibration was
  used to Quantitate Form I and Form II Polymorphs.
  Form I _at_ 1662 cm-1. Form II _at_ 1667 cm-1.

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Calibration Form I in Slurry
90
70
50
Form I Conc. (wt)
30
10
1661
1663
1665
1667
CO Peak Position (cm-1)
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Polymorphic Transformation at 45?C

Form I
Form II
_at_1662
_at_1667

• Crystallizations were monitored over the
  temperature range from 5 to 45? C .
• Slurry 2 grams Progesterone (25ml Organic Sol.)
  added to 500ml H2O .
• Temperature control and stirring were provided by
  a LabMax automated lab reactor.
• Polymorph concentration was determined from the
  CO stretch band center position.
• Raman measurements were made in-situ with the
  RamanRxn1.

1680
1660
1670
Raman Shift (cm 1)
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Transformation Thermodynamics
Crystal Form II to I
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The Analysis of Extruded Films by Raman
Spectroscopy
Process Understanding, Optimization and Monitoring
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Hot-Melt Extrusions
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Raman Spectra for Extruded Films Containing
Clotrimazole
PEO Only
3.0
Clotrimazole A - 1
Clotrimazole E - 7.5
Clotrimazole I - 20
2.6
Pure Clotrimazole
2.2
1.8
Intensity (x10-5)
1.4
1.0
0.6
0.2
500
1000
1500
2000
2500
3000
Raman shift (cm-1)
46
2nd Derivative Spectra
10000
0
2nd Derivative
-5000
-15000
-25000
PEO Only
Clotrimazole A - 1
Clotrimazole E - 7.5
Clotrimazole I - 20
-35000
Pure Clotrimazole
800
1000
1200
1400
1600
Raman shift (cm-1)
47
2nd Derivative in Area of Interest
PEO Only
Clotrimazole E - 7.5
Clotrimazole A - 1
Clotrimazole F - 10
20000
Clotrimazole B - 2
Clotrimazole G - 12.5
Clotrimazole C - 4
Clotrimazole H - 15
Clotrimazole D - 5
Clotrimazole I - 20
Pure Clotrimazole
10000
2nd Derivative
0
-10000
-20000
1550
1560
1570
1580
1590
1600
Raman shift (cm-1)
48
Calibration Results
r2 0.9969 SEC 0.493 SECV 0.722 MLR using
band at 1585 cm-1
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Ketoprofen Films
5.0
4.5
4.0
PEO
ketoD-5
ketoG-15
3.5
Pure ketoprofen
3.0
Raman Intensity (x10-5)
2.5
2.0
1.5
1.0
0.5
500
1000
1500
2000
2500
3000
Raman shift (cm-1)
50
2nd Derivative
0.8
0.4
0.0
-0.4
2nd Derivative
-0.8
PEO
-1.2
ketoD-5
ketoG-15
Pure ketoprofen
-1.6
-2.0
200
400
600
800
1000
1200
1400
1600
1800
Raman shift (cm-1)
51
2nd Derivative in Area of Interest
PEO
ketoD-5
ketoA-1
ketoE-7.5
0.8
ketoB-2
ketoF-10
ketoC-4
ketoG-15
Pure ketoprofen
0.4
2nd Derivative
0.0
-0.4
-0.8
985
990
995
1000
1005
1010
1015
1020
Raman shift (cm-1)
52
Calibration Results
r2 0.9979 SEC 0.307 SECV 0.657 MLR using
band at 998/886 cm-1
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SAMPLING LARGER SPOT
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Representative Measurement - Area
PhAT System 6 mm Diameter
Traditional Dispersive and FT-Raman lt100 microns
55
Relationship between MCC thickness and API
Intensity (675cm-1)

• API signal is observed when 1.88mm of MCC present
• No API signal is observed when 2.42mm of MCC
  Present

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Quantification of Furosemide Degradation
57
Furosemide Tablet Spectra
1.60
1.50
1.40
1.30
Intensity
Degradant
1.20
1.10
1.00
0.90
0.80
Degradant
6
10
200
400
600
800
1000
1200
1400
1600
1800
Raman shift (cm-1)
58
2nd Derivative Expansion
0.03
0.01
-0.01
Intensity
-0.03
-0.05
-0.07
-0.09
1540
1560
1580
1600
1620
1640
1660
Raman shift (cm-1)
59
Averaged Data Five Replicates
Note Cross Validation suggests extremes (T0 and
T9) introduce non-linearity
60
For Process Too!!!
61
Nitrofurantoin Granulation- Small Spot Size
100
-6
y x - 410
2
0.9732
R
80
60
Observed
40
Linearity OK but not Outstanding
20
0
0
20
40
60
80
100
Predicted
62
Nitrofurantoin Granulation- Large Spot Size
100
-6
y x - 210
2
R
0.9992
80
60
Observed
40
Much Improved Results Linearity excellent
20
0
0
20
40
60
80
100
Predicted
63
Conclusions

• Raman is compatible with PAT goals
• Raman facilitates process understanding
• Raman facilitates process monitoring
• Raman can facilitate risk mitigation
• Raman can facilitate the development of
  mechanistic-based (rational) regulatory
  specifications

64
Everybody Loves Raman!!
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Acknowledgements

• Pfizer
• Steve Arrivo
• Fred LaPlant
• Joep Timmermans
• Purdue University
• Lynne Taylor
• Solvias
• Arne Zillian
• Michigan State Univ.
• Kris Berglund

• FDA
• Robbe Lyon
• Ajaz Hussein
• Chris Ellison
• Everett Jefferson
• University of Mississippi
• Bonnie Avery
• Mitch Avery
• Mike Repka
• Venkat Tumuluri
• Suneela Prodduturi