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Dekati® BOLAR™
Bipolar Charge Analyzer
Jonna Kannosto
Technical Marketing Specialist, PhD
Sales & Marketing
Jonna Kannosto
Content
• BOLAR construction
• Background of charge measurement in inhaler studies– Why charge is important?
– Net charge measurement results
• BOLAR – Operating principle
– How to do measurement
© Dekati Ltd.
BOLAR™ Construction
USP Port connection
Flow divider
Bipolar detector
• Stand alone unit
• Fully automated self check
• Automated test sequence
• Result calculation
• Analysis of collected particles
– Charge per mass
– Chemical analysis
Why particle charge is measured?
Particle charge affects:
- Lung deposition
- Dispersion / agglomeration of
particles
- Particle losses inside the device
- Powder processing and handling
© Dekati Ltd.
Charge can cause problems but can also be useful !!!
Jonna Kannosto
Particles and lung deposition
• Inertial impaction
• Diffusion
• Electrostatic attraction
• Gravitational sedimentation
• Interception
© Dekati Ltd. Jonna Kannosto
Effect of particle charge on lung deposition
Electrostatic charge enhances deposition by increasing
attractive forces towards airway surfaces.• Melandri et al 1987, 1975:
Electrostatic charge affects deposition in two ways
• space charge: – predominant in upper airways
• image charge:– predominant in lower airways
© Dekati Ltd.C
harg
e
Lung
depositio
n
+
+ +
+
+
+++
++
- - - - -
Jonna Kannosto
Particle separation
• Significant for effective aerosol generation
• Main interaction between particles
1. Mechanical interlocking
2. Capillary forces (in the presence of water)
3. Intermolecular interactions
4. Electrostatic forces
© Dekati Ltd. Jonna Kannosto
Contact charging
© Dekati Ltd.
- - - - -
+++++
Drug
_
“Both drugs were found to
profoundly alter the charging
properties of lactose” Elaijnaf et al. J. of Pharm. Sci., 2006
“It is common knowledge that
lactose powders become positively
charged in contact with glass” Karner et al. J. of Aerosol Sci., 2011
“Liquids can also be charged
by flowing against a solid
surface” Philip Kwok, Doctoral Thesis, 2007
Jonna Kannosto
Particle charging: influencing variables
© Dekati Ltd.
Particle size
Particle shapeSurface roughness
Particle material
Surface material
Impurities Amorphicity
Relative humidity
Energy of contact
Nature and work functions(triboelectric series)
+ +
+ + -
-
-
-
Surface of particle
Crystallinity
Jonna Kannosto
++
© Dekati Ltd.
Particle charge measurements
Net charge measurement Bipolar charge measurement
Total net charge
- - - - ++0
3
+
4
-4
-
3
+
1
-
+-
-
5
-
3
+
2
-
vs. size dependent bipolar charge
4
-
3
++-5
-
3
+
1
-Result
vs. size dependent net charge
Jonna Kannosto
© Dekati Ltd.
NET charge size measurements:
ELPI+™ (Electrical Low Pressure Impactor)
• Real-time particle number concentration and size distribution
• Real-time particle net charge distribution
• 14 size fractions
• 6nm – 10µm
Jonna Kannosto
Powder: reliability of production and storage
© Dekati Ltd.
Martin Jan Telko, Investigation of electrostatic charging phenomena in dry powder
inhalers and the effect on deposition, PhD Thesis, 2009
Jonna Kannosto
Net charge/particle
© Dekati Ltd.
Martin Jan Telko, Investigation of
electrostatic charging phenomena in dry
powder inhalers and the effect on
deposition, PhD Thesis, 2009
Based on simulations and
in vivo studies:
• micron-size particles
Effect of drug and excipient
© Dekati Ltd.
Martin Jan Telko, Investigation of electrostatic charging
phenomena in dry powder inhalers and the effect on
deposition, PhD Thesis, 2009
Alb
ute
rol
Budesonid
e
Jonna Kannosto
BOLAR™
Calibration
Jonna Kannosto
© Dekati Ltd.
Operating Principle
USP Port
Flow divider
Impactor stage
Bipolar detector
tube x 5
Flow divider
• Devides flow
• Pre-separator
Impactor
• Size classification
Bipolar detector
tubes
• Detects and collects
• Positively charged particles
• Negatively charged particles
Electrometers measure current
carried by the charged particles
Jonna Kannosto
© Dekati Ltd.
Operating Principle
Bipolar detector
tube x 5
Flow divider
• Devides flow
• Pre-separator
Impactor
• Size classification
Bipolar detector
tubes
• Detects and collects
• Positively charged particles
• Negatively charged particles
ImpactorImpactorImpactorImpactorFilter
Bipolar detector
tubes
Bipolar detector
tubes
Bipolar detector
tubes
Bipolar detector
tubes
Flow divider
Flow divider
Flow divider
Flow divider
Flow divider
Electrometers measure current
carried by the charged particles
Jonna Kannosto
Bipolar detector: operation and construction
© Dekati Ltd.
• Five bipolar detectors:
• five particle size classes
• pre-separator impactors and bipolar
detector tube
• Each bipolar detector tube consists of two
concentric cylinders
• Electrical field (1kV) to separate and collect
positively and negatively charged particles to
inner and outer tubes
• Electrometers connected to tubes measuring
charge carried by particles
• Back-up filters Bipolar Detector Tube
Size range (µm)
1 0 - 0.95
2 0 - 2.60
3 0 - 4.17
4 0 – 7.29
5 0 – 11.57Jonna Kannosto
Calibration paperBipolar Charge Analyzer (BOLAR™): A new aerosol
instrument for bipolar charge measurementsJaakko Yli-Ojanperä, Ari Ukkonen, Anssi Järvinen, Stve M. Layzell, Ville
Niemelä and Jorma Keskinen
Jonna Kannosto
Bipolar Charge size distribution
© Dekati Ltd.
J Kannosto, H Isherwood, V Niemelä, A Ukkonen, High Bipolar
Electrical Charge Levels of Lactose Particles Measured from DPI, RDD
Europe 2013 (2013), Vol. 2, pp. 285-290
Capsule based DPI, Lactose particles, 60L/min flow rate, T=20Cº, RH=50%
Lactose particles present much higher positive and lower negative charge
values than measured net charge values
→ More precise information about charge state of particles
Jonna Kannosto
© Dekati Ltd.
Bipolar Charge/Mass size distribution
After the charge measurements, mass of particles were analyzed
• Small lactose particles have larger absolute charge/mass ratio
• Charge/mass ratio decreases when particle size increases
J Kannosto, H Isherwood, V Niemelä, A Ukkonen, High Bipolar
Electrical Charge Levels of Lactose Particles Measured from DPI, RDD
Europe 2013 (2013), Vol. 2, pp. 285-290
Jonna Kannosto
Conclusions
• Electrical charge of particle has effect on– Lung deposition
– Particle separation
– Particle losses inside the device
• Results from NET charge measurements– Drug and carrier
– Inhaler
– Storage
– Relative humidity
– …
→ All these have effect on particle charge
• Based on BIPOLAR charge measurements– Particles can have much high positive and negative values even net charge is zero
– Unique information about charge state of particles
© Dekati Ltd. Jonna Kannosto
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