Download read the full Application Note (M-2-123)

as presented by Ian Fletcher
AstraZeneca
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at Lasentec Users’ Forum 2001 - Barcelona
Preliminary trials with multiple suspensions of titanium dioxide (TiO2) in
water show a very good linear relationship between the log10 of solid
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concentration (expressed as % w/w) and number of FBRM counts per
second. TiO2 was chosen because it yields a stable suspension with a
regular particle size distribution.
When the log10 of concentration is calculated and plotted against total
counts, it comes out to the straight line shown in Figure 1, with an R2 of
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0.9944. Calculating the equation of the line with Microsoft Excel provides
a formula that allows prediction of TiO2 concentration solely from the total
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number of FBRM counts.
R2=0.9944
Particle counts per second (0 to 100,000)
Application Notes
Measure concentration suspensions
using Lasentec® FBRM®
Log10 concentration TiO2 , % (-3 to 0)
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Figure 1: FBRM data correlates well with log10 results
Mean particle size, microns (0 to 30)
Mean size
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FBRM counts (0 to 50,000)
Application Notes
In a more complex pharmaceutical suspension, where the particle size
distribution changes during production, the log10 of concentration was
found to be directly proportional to the mean particle size as calculated by
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FBRM multiplied by the number of particles detected per second. When
only one suspension was used and concentration was slowly increased,
mean size initially jumped before gradually decreasing - possibly as a
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result of agglomerate breakdown due to stirring. FBRM counts per second
initially dipped and then increased again (see Figure 2).
Total counts
Figure 2:
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Nonlinear FBRM
data indicates
agglomerate
breakdown as an
effect of stirring
Drug concentration, % w/w (0.000 to 0.450)
By calculating the log10 of concentration and comparing that to counts per
second multiplied by mean size, a straight line - again with exremely good
correlation - was obtained (see Figure 3). The equation for this straight line
yields a formula by which the drug concentration can be predicted solely
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from FBRM counts and mean particle size.
2
Counts x mean size, microns (0 to 700,000)
R =0.991
Log10 drug concentration, % w/w (-2 to -0.4)
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Figure 3: When mean particle size is multiplied by total FBRM counts per second, the
line returns to a logarithmic relationship
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M-2-123 Rev E (03/2006) Printed in USA
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