U.S. patent application number 11/302870 was filed with the patent office on 2006-05-11 for method and device for the quantitative analysis of solutions and dispersions by means of near infrared spectroscopy.
This patent application is currently assigned to Sanofi-aventis Deutschland. Invention is credited to Christian-Peter Christiansen, Richard Mertens, Hans-Joachim Ploss, Heino Prinz.
Application Number | 20060097173 11/302870 |
Document ID | / |
Family ID | 36315374 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060097173 |
Kind Code |
A1 |
Christiansen; Christian-Peter ;
et al. |
May 11, 2006 |
Method and device for the quantitative analysis of solutions and
dispersions by means of near infrared spectroscopy
Abstract
The present invention relates to a method for quantifying the
composition of a product, with the following steps: irradiating the
product with a radiation source in the near infrared range;
receiving radiation which is reflected by or transmitted through
the product, and providing an output signal corresponding to the
intensity of the radiation received at a number of different
wavelengths; determining whether or not the product lies within
predetermined integrity criteria on the basis of the output signal
using a mathematical method, wherein the product contains a
solution or homogeneous dispersion, and the content of at least one
substance contained in the dispersion or solution is quantitatively
determined on the basis of the output signal. The present invention
also relates to an apparatus for carrying out this method.
Inventors: |
Christiansen; Christian-Peter;
(Frankfurt, DE) ; Ploss; Hans-Joachim; (Kriftel,
DE) ; Mertens; Richard; (Laupheim, DE) ;
Prinz; Heino; (Laupheim, DE) |
Correspondence
Address: |
ROSS J. OEHLER;AVENTIS PHARMACEUTICALS INC.
1041 ROUTE 202-206
MAIL CODE: D303A
BRIDGEWATER
NJ
08807
US
|
Assignee: |
Sanofi-aventis Deutschland
Frankfurt
DE
|
Family ID: |
36315374 |
Appl. No.: |
11/302870 |
Filed: |
December 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10861675 |
Jun 4, 2004 |
|
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11302870 |
Dec 14, 2005 |
|
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60511207 |
Oct 15, 2003 |
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Current U.S.
Class: |
250/339.12 |
Current CPC
Class: |
G01J 3/433 20130101;
G01N 21/359 20130101; G01N 21/3563 20130101; G01J 3/42 20130101;
G01N 21/9027 20130101; G01N 2201/08 20130101; G01N 21/274 20130101;
G01N 21/90 20130101; G01J 3/28 20130101 |
Class at
Publication: |
250/339.12 |
International
Class: |
G01J 5/02 20060101
G01J005/02 |
Claims
1. A method for quantifying the composition of a product,
comprising the steps of: irradiating the product with a radiation
source in the near infrared range; receiving radiation which is
reflected by or transmitted through the product, and providing an
output signal corresponding to the intensity of the radiation
received at a number of different wavelengths; determining whether
or not the product lies within predetermined integrity criteria on
the basis of the output signal using a mathematical method, wherein
the product contains a solution or homogeneous dispersion, and the
content of at least one substance contained in the dispersion or
solution is quantitatively determined on the basis of the output
signal.
2. The method of claim 1, wherein the product is moving.
3. The method of claim 1, wherein the product contains a
dispersion, and the at least one substance is present in the
disperse and/or continuous phase of the dispersion.
4. The method of claim 1, wherein the radiation transmitted through
the product is received.
5. The method of claim 1, wherein calibration is carried out at
least once by quantitatively determining the content of the at
least one substance in the solution or dispersion by means of an
alternative method.
6. The method of claim 5, wherein the alternative method is
HPLC.
7. The method of claim 1, wherein the determination step uses
weighting factors.
8. The method of claim 7, wherein the product contains a
dispersion, and weighting factors which are found on the basis of a
solution are used in the determination step.
9. The method of claim 8, wherein the solution for finding the
weighting factors and the dispersion contain the same substance to
be quantitatively determined.
10. The method of claim 8, wherein this substance contained in the
dispersion is distributed between the continuous and disperse
phases.
11. The method of claim 1, wherein the product contains a
dispersion which contains crystalline and/or dissolved insulin.
12. The method of claim 2, wherein the moving product is a solution
or dispersion in primary packaging.
13. The method of claim 12, wherein the moving product is an
insulin vial or insulin cartridge.
14. An apparatus for determining the quantitative content of at
least one substance in a moving product, which comprises a solution
or homogeneous dispersion in a container, comprising a radiation
source, which emits radiation in the near infrared range, for
irradiating the product; a radiation reception device, which
receives the radiation reflected by or transmitted through the
product; a spectrometer for receiving the radiation from the
radiation reception device and for providing an output signal
corresponding to the intensity of the radiation received at a
number of different wavelengths; a device for quantitatively
determining the content of at least one substance contained in the
dispersion or solution on the basis of the output signal.
15. The apparatus of claim 14, wherein the spectrometer has a
device for splitting the received radiation into a number of
wavelengths for detection by a photodiode array.
16. The apparatus of claim 14, wherein the source radiation source
is a mercury halogen lamp.
17. The apparatus of claim 14, wherein the radiation reception
device also has an optical fiber which delivers the radiation
emitted by the radiation source to the location of the product.
18. The apparatus claim 17, wherein the radiation reception device
has a converging lens.
19. The apparatus of claim 14, wherein the determination device
uses weighting factors.
20. The apparatus of claim 19, wherein the weighting factors that
are used are found on the basis of a solution.
21. The apparatus claim 14, additionally comprising a calibration
device, with which the quantitative content of the at least one
substance can be determined by an alternative method.
22. The apparatus of claim 21, wherein the calibration device
comprises a high pressure liquid chromatograph.
23. The apparatus of claim 14, additionally comprising a sorting
device for rejecting the products which do not lie within the
predetermined integrity criteria.
24. The apparatus of claim 14, additionally comprising a device for
homogenizing dispersions to be quantified.
25. The apparatus of claim 14, additionally comprising a device for
detecting the product position.
26. A method for line control of product units in the production,
filling and/or packaging of solutions or dispersions for
pharmaceutical purposes comprising use of the apparatus of claim
14.
27. A method of filling solutions and dispersions, comprising use
of the apparatus of claim 14.
Description
[0001] The invention relates to a method and a device for the
quantitative analysis of solutions and dispersions, such as
solutions and dispersions for pharmaceutical purposes, by means of
near infrared spectroscopy.
[0002] In the field of medicament production, efforts are
constantly being made to improve the quality control of medicament
safety. Production is in this case carried out according to the
international standard of good (current) manufacturing practice
(cGMP), and which is stipulated by the pharmaceutical monitoring
authorities (for example the US American Food and Drug
Administration, FDA). Authorization to produce medicaments may be
withdrawn from a company in the event of serious infringements
against this manufacturing practice.
[0003] Physicochemical and microbiological testing and approval of
a product is an important part of good manufacturing practice. In
the course of this testing, a plurality of parameters describing
the quality of the product are tested and compared against
specifications. The specifications are found either in the
licensing documents or in the international pharmacopeas. The
product can be marketed as long as all the specifications are
complied with. One of these test parameters is the active agent
content, which needs to be quantitatively determined. The
quantitative determination is usually carried out by spot checks
and in the form of destructive testing. Liquid chromatographic or
gas chromatographic methods, or spectroscopy methods, which require
sample preparation, are preferably used as the analysis methods.
These methods are distinguished by relatively high precision,
although the analysis speed is very slow. These methods are
therefore unsuitable for providing a result inline, that is to say
directly during the manufacturing process. Furthermore, the
measurement cannot be carried out on products in primary
packaging.
[0004] The disadvantage of spot-check batch testing is that trends
or anomalous events cannot be identified during production, for
example when filling suspensions. There is a risk that products
will be approved as compliant with specification even though they
do not actually lie within the approval limits. These "out of
specification" (OOS) products may, for example, occur owing to
temporary production problems or product admixtures.
[0005] The requirements for complete, rather than spot-check,
testing of each produced unit on the running production line can be
satisfied only by nondestructively operating and sufficiently fast
analysis methods. Both requirements can in principle be satisfied
by spectroscopy methods. The majority of spectroscopy methods,
however, are unsuitable for providing quantitative analysis results
without prior sample preparation, for example by dissolving,
concentrating or diluting the samples. As a rule, these methods are
also unsuitable for producing quantitatively evaluable spectra
through the primary packaging (for example glass or plastic) and/or
from dispersive systems. Only the relatively narrow wavelength
range of near infrared radiation (NIR), which extends from 800 to
2500 nm, can be used to perform such tasks.
[0006] Methods in which objects conveyed on a belt are controlled,
that is to say in real time and essentially fully, are known in
connection with refuse sorting and the sorting of plastic parts.
Some of these methods use near infrared (NIR) spectroscopy.
[0007] EP-B 1 030 740 discloses a method for identifying and
sorting objects conveyed on a belt, especially for refuse sorting,
in which the material composition of the objects is
spectroscopically recorded by means of an NIR measuring instrument,
and the sorting is carried out as a function of the spectroscopy
result by removing objects from the conveyor belt.
[0008] EP-B 0 696 236 discloses a method for sorting plastic parts,
in which the plastic parts are transported past a material
detection system, which determines the substance class of each
material part by contactless sampling thereof in a measurement
field. The material detection system contains a contactlessly
operating material sensor, for example a microwave sensor, an x-ray
sensor or a spectroscopy sensor operating in the near infrared
range.
[0009] In the filling of suspensions for pharmaceutical purposes,
fluctuations may occur during filling owing to segregation
processes. These fluctuations can cause some of the filled units
(for example cartridges) to have content values for the active
substance (for example insulin) or auxiliaries (for example
protamine sulfate) which lie outside the requisite specification
(for example from 95.0 to 105.0% of the nominal value for
insulin).
[0010] European Patent Application EP-A 0 887 638 describes a
method and a device for analyzing the composition of a moving
sample, with a near infrared (NIR) radiation source being used and
the NIR light reflected by the sample being detected. Tablets or
capsules on a conveyor belt are analyzed as the samples.
[0011] In principle, high pressure (performance) liquid
chromatography (HPLC) is suitable for the quantitative analysis of
liquid samples. However, quality control by quantitative analysis
of samples by means of HPLC has the disadvantage that it is slow
and does not take place nondestructively. It is therefore only
suitable for spot-check quality control. This method is quite
unsuitable for line control, in which each of the filled product
units needs to be checked for whether its active agent content lies
within the requisite specifications.
[0012] Herkert (2001, Dissertation, Eberhard-Karls University,
Tubingen) has evaluated an NIR method for line control of
pharmaceuticals on a packaging line. The purpose of the work was,
in particular, to evaluate the VisioNIR.RTM. spectrometer (Uhlmann
Visio Tec GmbH, Laupheim). The evaluation was carried out, inter
alia, on insulin suspensions.
[0013] Herkert detected the re-emission in his work, that is to say
the diffuse reflection of the incident NIR light. Only qualitative
discrimination of three different insulin types was carried out in
this case, which differed in their composition of soluble and
crystalline insulin. The spectral differences in the raw spectra or
derivative spectra were used to assess whether it is possible to
identify the individual products with the aid of NIR spectra.
Pattern recognition could be carried out on the basis of these
differences with the aid of principal component analysis (PCA) or
the VisioNIR.RTM. evaluation statistics. Quantitative analysis was
not carried out. The measurement of liquids (insulin suspensions)
was not possible with the VisioNIR.RTM. spectrometer
instrumentation over the packaging line. Scattering effects from
the glass and in the air space above the suspension prevented valid
spectral recording (see the cited dissertation by Herkert, page 76,
2.sup.nd paragraph).
[0014] It is an object of the invention to provide a method for the
analysis of products which contain a solution or dispersion, for
example for pharmaceutical purposes, with which rapid quantitative
determination of substances contained in the solution or dispersion
is possible, and which is noninvasive and operates
nondestructively. In particular, the method should be suitable for
the analysis of a large number of product units per unit time, for
example in order to be used for line control of the composition of
solutions or dispersions when they are being filled in a filling
system or a packaging line during the production process. Line
control is in this case intended to mean realtime control, which
includes essentially all of the product units.
[0015] Surprisingly, it is now been found that it is possible to
employ a method for quantifying the composition of a product, in
particular a moving product, with the following steps:
[0016] irradiating the product with a radiation source in the near
infrared range;
[0017] receiving radiation which is reflected by or transmitted
through the product, and providing an output signal corresponding
to the intensity of the radiation received at a number of different
wavelengths;
[0018] determining whether or not the product lies within
predetermined integrity criteria on the basis of the output signal
using a mathematical method.
[0019] The method according to the invention is one wherein the
moving product contains a solution or homogeneous dispersion, and
the content of at least one substance contained in the dispersion
or solution is quantitatively determined on the basis of the output
signal.
[0020] In the context of the present invention, quantitatively
means that the content of at least one substance to be determined
in the solution or dispersion can be determined unequivocally and
correctly within a range of in general .+-.3%, preferably .+-.5%,
particularly preferably .+-.10% and in particular .+-.20% of the
setpoint value (for example defined by the pharmaceutical
formulation). Unequivocally means that the values determined by the
method according to the invention are reliable with a relative
standard deviation of no more than 1.5%, preferably no more than
1%, particularly preferably no more than 0.5%. Reference values
which have been determined by means of a tried and tested reference
method, for example a chromatographic method such as HPLC, are in
this case regarded as correct, with the reference value and the
value determined by the method according to the invention deviating
from each other by at most 5%, preferably at most 3%, particularly
preferably at most 1%.
[0021] The product may contain any solutions or dispersions,
usually in a container which is transparent for NIR radiation. If
the product contains a dispersions, this will in general be a
liquid dispersion such as an emulsion or suspension. The substance
contained in the dispersion, and whose content is intended to be
quantitatively determined by the method according to the invention,
may be present only in the continuous phase or only in the disperse
phase, or alternatively distributed in both phases. The dispersions
or solutions may be pharmaceutical products, which contain a
dissolved and/or dispersed active agent. The substance whose
content is intended to be quantitatively determined may, for
example, be a pharmaceutical active agent or an auxiliary. For
example, the solution may be an insulin solution or the dispersion
may be an insulin suspension, which contains suspended crystalline
or amorphous insulin optionally together with dissolved insulin,
for example insulins of the NPH type (neutral protamine Hagedorn
insulin preparations), mixtures of NPH insulins and dissolved
insulins or insulin zinc suspensions. The insulins may, for
example, be human insulin or its genetically or enzymatically
modified analogs.
[0022] The solutions or dispersions may be present in primary
packaging, for example cartridges, vials or bottles, for example
made of glass or plastic. These may be located on a conveyor belt
and studied by the method according to the invention during the
delivery process, for example from a filling system to a packaging
machine.
[0023] The method according to the invention may be carried out in
a reflection arrangement or in a transmission arrangement. In one
embodiment of the method, operation is carried out in a
transmission arrangement, that is to say the radiation transmitted
through the product is received.
[0024] The product whose composition is intended to be verified is
irradiated with a radiation source in the near infrared range. The
near infrared range conventionally comprises the wavelength range
of from 800 to 2500 nm. Suitable radiation sources are, for
example, mercury halogen lamps.
[0025] The radiation reflected or transmitted by the product is
received by a radiation reception device. An output signal
corresponding to the intensity of the radiation received at a
number of different wavelengths is obtained. This may be done by
splitting the received radiation into a number of wavelengths in a
spectrometer and detecting it with a photodiode array. The current
from each photodiode may be integrated over a preselected time and
subsequently converted into a digital signal by means of an
analog/digital (A/D) converter.
[0026] The integration time may be started by a trigger, for
example a photoelectric barrier, as a function of the position of
the moving object.
[0027] The content of the at least one substance contained in the
dispersion or solution is quantitatively determined using a
mathematical method on the basis of the output signal obtained at
the different wavelengths. Suitable mathematical methods are
multivariate data analysis methods. Suitable methods are, for
example, the PLS (partial least squares) method or principal
component analysis (PCA). Such methods are known to the person
skilled in the art.
[0028] The mathematical method may use weighting factors in order
to reduce the effect of spurious variabilities, not attributable to
the composition, in the recorded NIR spectra during evaluation, and
to emphasize spectral features which do not vary between samples of
the same product type.
[0029] Conventionally, calibration is carried out at least once by
quantitatively determining the content of the at least one
substance in the solution or dispersion by means of an alternative
method.
[0030] A preferred alternative method which is used for the
calibration is HPLC. The calibration may be repeated at regular
intervals while the method according to the invention is being
carried out.
[0031] In one embodiment of the method according to the invention,
the mathematical method described on page 5, line 47 to page 8,
line 12 of EP-B 0 887 638 is used. EP-B 0 887 638 is in this
respect fully included in the present description. Weighting
factors are used in the mathematical method described therein.
[0032] The data of the raw spectra, which reflect the radiation
intensities in intervals (for example 3.8 nm) are in this case
corrected, a standard value being obtained which is independent of
the characteristics of the spectrometer and of the radiation
reception device. The intensities calibrated in this way are
smoothed in order to minimize effects due to signal noise, with a
Gaussian smoothing function being used. The data may be autoscaled
order to minimize the systematic effects. To this end, the
individual intensities of the spectrum are normalized to a standard
deviation of zero and variance of one over the entire wavelength
range. The differences of the individual spectra with respect to
slope and spectral features of the individual product samples may
be emphasized by forming the 1.sup.st derivative. Instead of the
1.sup.st derivative, it is also possible to use the 2.sup.nd or
0.sup.th derivative.
[0033] The differences between a model spectrum and the spectrum of
the product sample (sample spectrum) are then calculated for each
measured wavelength. If the differences exceed a specified limit,
then the sample is identified as being significantly different from
the model.
[0034] The model (master model) is set up from the calibration data
records of a number of equivalent samples of the different product
types. An average spectrum is then calculated. If the variance of
the model per measurement point (wavelength) is considered, then
spectral ranges with significantly high standard deviations are
found. These regions reflect the variability of calibration samples
(equivalent in respect of their composition) with respect to
various extraneous factors, for example differences in the glass or
in the position of a cartridge. In order to minimize the effect of
these spurious variances, weighting factors are calculated. These
weighting factors weight spectral ranges with a smaller standard
deviation more highly than ranges with a high standard deviation.
The weighting factor is found from the standard deviation of the
difference between the intensity values and the intensity value of
the model at each wavelength.
[0035] The Euclidian distance of every data record within the
calibration sample data records is subsequently calculated by using
the weighting factors. The mean of this value corresponds to the
standard deviation of the model. The mean Euclidian distance of the
model is also calculated at the end of the modeling. This value is
given as a reference quantity in terms of model standard
deviations.
[0036] Where the method according to the invention is being carried
out, the spectrum obtained for each product sample is contrasted
against the model spectrum. To this end, the Euclidian distance
between the intensity at each wavelength and the corresponding
intensity for the model is calculated, with the weighting factor at
each wavelength being applied. The weighting factors which are used
were found in the modeling. The result is used to calculate the
Euclidian distance of the sample. This is given as a reference
quantity in terms of model standard deviations of the model.
[0037] The value of the Euclidian distance of the sample is
subsequently compared with a fixed limit value. The limit value is
derived from the mean Euclidian distance of the model and a
probability range.
[0038] The mathematical method described above makes it possible to
verify the composition of solutions and dispersions. If the
composition of dispersions is being verified, then, in a
particularly preferred embodiment of the invention, those weighting
factors which were found on the basis of a solution are used in the
determination step. The solution, on the basis of which the
weighting factors are found, in this case preferably contains the
same substance to be determined as the dispersion. In the
dispersion, the substance may be dispersed as well as dissolved
or--more generally--distributed between the continuous and disperse
phases.
[0039] For example, insulin suspensions contain a proportion of
dissolved insulin and a proportion of insulin suspended in
crystalline form. This proportion of crystalline insulin may vary
in wide ranges even if the insulin content is constant. In this
case, it may prove advantageous for the weighting factors which
were found on the basis of a pure insulin solution to be used in
the determination step. Using the weighting factors of the pure
solution eliminates the influence of scattering effects which are
caused by the suspended crystals.
[0040] With the described mathematical evaluation method,
evaluation of the product can be carried out at a high speed, for
example within a time window of only 5 ms. This makes it possible
to analyze a large number of products within a short time. The
method is furthermore noninvasive and can function without contact.
For example, it is therefore very suitable for the analysis of
products on a packaging line or in conjunction with a filling
system for cartridges or bottles. The analysis may be carried out
in realtime and include 100% of the products being transported on
the packaging line. At least 3, preferably at least 8 or even 50 or
more products can be successively analyzed per second by the method
according to the invention. For example, it is therefore suitable
for the line control of product units in the production, filling
and/or packaging of solutions or dispersions for pharmaceutical
purposes.
[0041] With the method according to the invention, for example, it
is possible to upgrade from spot-check control to 100% control when
filling solutions or dispersions for pharmaceutical purposes.
[0042] The present invention also relates to an apparatus for
determining the quantitative content of at least one substance in a
moving product, which comprises a solution or dispersion in a
container, comprising
[0043] a radiation source, which emits radiation in the near
infrared range, for irradiating the product;
[0044] a radiation reception device, which receives the radiation
reflected by or transmitted through the product;
[0045] a spectrometer for receiving the radiation from the
radiation reception device and for providing an output signal
corresponding to the intensity of the radiation received at a
number of different wavelengths;
[0046] a device for quantitatively determining the content of at
least one substance contained in the dispersion or solution on the
basis of the output signal.
[0047] The radiation reception device may have a converging lens
and an optical fiber. The radiation reception device may have a
photodiode array as its detector.
[0048] The apparatus preferably also has a calibration device, with
which the quantitative content of the at least one substance can be
determined by an alternative method, for example a high pressure
liquid chromatograph.
[0049] The apparatus may furthermore have a sorting device used to
reject those products not complying with specification which have
been found by the method according to the invention. Products not
complying with specification are those which do not lie within the
predetermined integrity criteria.
[0050] If the apparatus is (also) used for the quantitative
analysis of dispersions, then it preferably also comprises a device
for homogenizing the dispersions to be quantified, before the
dispersions are analyzed. The dispersions may, for example, be
homogenized in the containers by a shaking mechanism or by a
rotation mechanism. Homogenization may, however, also be achieved
directly by the filling process.
[0051] The apparatus may furthermore have a device for detecting
the product position, for example an imaging system or a
photoelectric barrier.
[0052] The apparatus may be used in conjunction with a filling
device, in which primary packaging is filled with the solutions or
dispersions. The apparatus may also be a component of such a
filling device.
[0053] In one embodiment of the invention, an apparatus which
operates in transmission is provided, the device having an optical
fiber which delivers the radiation emitted by the radiation source
to the location of the product.
[0054] The invention will be explained in more detail below with
reference to the figures.
[0055] FIG. 1 schematically shows a device according to the
invention, which operates in transmission. The device comprises a
radiation source (1), for example a tungsten halogen lamp. The near
infrared radiation emitted by the radiation source is collimated by
a converging lens (2) and delivered to the location of the product
(4) by means of an optical fiber (3). The product may, for example,
be a glass cartridge which contains an insulin suspension and,
coming for example from a filling device, is transported past the
end of the optical fiber (3) on a conveyor belt. The radiation
transmitted by the product (4) is collimated by a converging lens
(5) and delivered to the spectrometer (6) by means of an optical
fiber. In the spectrometer (6), the transmitted radiation which
contains the spectral information of the product (4) irradiated in
transmission, is split into radiation of different wavelengths by
means of a grating (7) and detected by a photodiode array (8). The
intensities detected by the photodiode array as a function of
wavelength are converted into digital signals by means of an A/D
converter (9) and evaluated in the determination device (10), for
example a PC.
EXAMPLE 1
[0056] The purpose of line-monitoring the insulin filling is
quantitative control of the insulin content in 100% of the filled
insulin vials. The insulin content of the filled insulin
suspensions should in this case only deviate from the nominal value
by at most +/-5%. Anomalies should be impeccably detectable.
[0057] In order to simulate monitoring of the insulin filling,
calibrations were carried out with a set of calibration samples,
which contained crystalline Insuman Basal.RTM. insulin in primary
packaging (glass cartridges), and production samples were
subsequently studied. Insulin packages with exactly known insulin
contents of from 90 to 120% of the setpoint content were used for
the calibration. The reference values were determined by HPLC. The
cartridges were thoroughly shaken before the measurements, so that
there was a homogeneous suspension.
[0058] The insulin spectra were recorded in transmission with a
photodiode array spectrometer (MCS 511 NIR 1.7). The wavelength
range of the measurement was from 960 to 1760 nm, the wavelength
range of from 960 to 1360 nm being evaluated. A 20 W halogen lamp
was used as the NIR radiation source. The spectrometer was
regularly compared against reference standards. A BG5 filter and a
BG9 filter were used for reference.
[0059] In order to preprocess the spectra, they were smoothed and
normalized. The spectra were used in 0.sup.th derivative. The
scattering properties of the insulin samples were thereby kept in
the spectra.
[0060] The spectra were subsequently evaluated by means of a
multivariate evaluation method. A PLS (partial least squares)
regression was used as the regression method, although it is also
possible to use other multivariate evaluation methods. A
mathematical relationship between the spectral information of the
insulin samples and the insulin content is obtained from the
regression. From the spectrum of an unknown sample, the insulin
content of this sample can later be calculated with the aid of this
relationship.
[0061] FIG. 2 shows the correlation between the values measured by
HPLC and the values found from the NIR transmission spectra for the
total insulin content of the Basal.RTM. insulin calibration samples
(respectively in % of the setpoint content). It is clear that there
is a good correlation between the values found from the NIR spectra
and the values found by means of HPLC.
[0062] Process samples from the insulin production process were
then studied. These are samples which were obtained in the regular
production process and had been discarded as unfit for use. The
total insulin content was found from the obtained NIR spectra with
the aid of the multivariate regression equation. The same vials
were subsequently studied by means of HPLC.
[0063] FIG. 3 shows the total insulin content of the studied
samples as determined by HPLC, and FIG. 4 shows their total insulin
content from the NIR spectra in the description as determined by
the evaluation method described (both in IU).
[0064] The values found from the NIR transmission spectra and the
values found by HPLC show a good match. It is clear that the
anomalies found by means of HPLC can be unequivocally detected with
the aid of the smoothed and normalized NIR transmission
spectra.
EXAMPLE 2
[0065] The purpose of line-monitoring the insulin filling is
quantitative control of the insulin content in 100% of the filled
insulin vials. The insulin content of the filled insulin
suspensions should in this case only deviate from the nominal value
by at most +/-5%. Anomalies should be impeccably detected. The
monitoring should take place either during the filling, on moving
insulin cartridges, or after the filling, on already filled
cartridges. In either case, the measurement takes place through the
primary packaging (glass cartridge) and in the moving contents.
[0066] To simulate the speeds involved in filling insulin
cartridges, an optical control machine of the 288 type from EISAI
Machinery was used. This machine can be equipped with insulin
cartridges (suspensions) and causes the cartridges to rotate, so
that a homogeneous suspension is formed by means of the metal balls
in the cartridges. The NIR measuring apparatus constructed
similarly to FIG. 1 was installed in this machine. The measurement
took place in the moving, rotating cartridge at a rate of 150
cartridges per minute. Care must be taken to ensure that a
homogeneous suspension is present at the time of measurement. The
installed measuring apparatus consists of a 50 watt halogen lamp
(Comar 12LL50), a holder for the lamp with integrated converging
lens (for example Comar 20LH00), which focuses the focus of the
radiation on the midpoint of the insulin cartridge, a second
converging lens (for example Comar 80TC50), which collimates the
transmitted radiation and transmits it via a coupling (for example
Zeiss, No. 772571-9020-000) and an optical fiber (for example
Zeiss, CZ-# 1050-724) to a photodiode array detector (Zeiss, MMS
NIR No. 301261). The analog signals at the detector are digitized
and read out into a text file. In total, the radiation is measured
at 128 photodiodes over a range from about 900 to 1670 nm. The time
of measurement was triggered via a light barrier (Wenglor UM55PA2
& 083-101-202) which has caused a spectrum to be recorded as
the cartridge passes through the optical path. The PDA detector was
initially compared against Spectralon at the day of each
measurement.
The apparatus described was used to measure insulin preparations
(suspensions) of the type Insuman Basal, Insuman Comb 25 and
Insuman Comb 50. Each spectrum took 8 milliseconds [ms] to
record.
[0067] The insulin spectra were judged against model spectra using
the method described in the description part. The model spectra and
their variability were obtained by measuring eight water-filled
cartridges. The model and insulin spectra were smoothed and
autoscaled. The Euclidian distance of each insulin spectrum from
the mean model spectrum was subsequently computed using
wavelength-specific weighting factors.
[0068] Samples of differing concentration were prepared and the
Euclidian distances from the model spectrum computed for each of
the Insuman Basal, Insuman Comb 25 and Insuman Comb 50
preparations. The dependence of the insulin content on the
Euclidian distance is shown in FIG. 5 for Insuman Comb 25 as an
example of the different types of preparations. The precision of
the method is likewise illustrated, since 4 repeat measurements are
depicted. A calibration function (2.sup.nd degree polynomial)
results for each type of preparation whereby the Euclidian distance
can be converted into insulin contents. After conversion of the
Euclidian distance into insulin contents, two correction factors
have to be taken into account. The insulin content has to be
corrected for the temperature of the measured material. In
addition, a preparation-specific factor has to be applied to
reflect the different crystal size distributions in the suspension.
As a result, the content can either be expressed as a percentage in
relation to the first 20 results. In that case, the content is
obtained in percent of the target value, based on the first
cartridges of a filling. On the other hand, the insulin content
found can also be corrected by a factor which results from the
ratio of the uncorrected value of a sample to the concurrently
measured insulin content. In FIG. 6, this correction factor has
been determined for sample 16 and a series of cartridges of unknown
content have been evaluated for Insuman Comb 25 by way of example
for other types of preparations. The samples in question had been
obtained in the regular production process and had been discarded
as unfit for use. The correction factor for the temperature was not
applied, since there were no differences in the course of the
measurement. Further samples were analyzed by HPLC in spot-check
fashion. It can be seen that the results using the method of the
present invention (black rectangles) agree well with the results
via the conventional method (HPLC, black crosses). It is
unambiguously and precisely possible to judge whether a value is
within the limits of 95 to 105% or outside.
* * * * *