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Photoreactor ICH-2
LUZCHEM has designed a photoreactor that fully complies with ICH guidelines for drug photostability testing under ICH option-2 exposure. The instrument is certified for ICH compliance and includes UVA and visible lamps, power meter, turntable and carousel (to equalize exposure), digital timer, temperature control and a recessed magnetic stirrer for stress tests.
 Specifications for the ICH-2 can be found in the Download Area.
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Technical release
This unit is equipped with sixteen T5-8Watt fluorescent lamps providing an illuminated area of about 144 square inches, of which an active area of about 96 square inches (8 x 12 inches) have fluctuations of under 8% in the incident power.
A number of tools provided as standard in the ICH-2 unit allow control of the irradiation conditions and greatly facilitate photostability work.
- A magnetic stirrer, bulkhead gas connectors, a shut-down digital timer, a carousel for liquid samples, a turntable for solid samples, a cut off filter at 400 nm, a power meter,and a temperature control module are provided (further details in Standard Features).
- Four separate switches allow different sets of lamps to be selected for illumination.
- While not required under ICH guidelines, the excellent exhaust design of LUZCHEM photoreactors allows the easy exhaust of ozone for users employing UVC lamps at 254 nm.
- The brushed aluminum interior of LUZCHEM photoreactors allows quasi-spectrally neutral reflections, thus ensuring that reflected light has essentially the same spectral composition as direct light.
- Complete sets of sixteen UVA and visible lamps are provided with ICH-2 photoreactors. UVB and UVC lamps are optionally available from LUZCHEM
- Easily changeable lamps allow users to switch UVA and visible lamps in minutes, or to expose with a preferred combination of lamps. For those choosing to have two separate photoreactors for visible and UVA irradiations, LUZCHEM will advice on how to avoid duplications of options where this is unnecessary, and will provide appropriate credit.
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Illumination conditions
The lamp arrangement of the ICH-2 unit is shown in Figure 1, where the numbers indicate sets of lamps operated with separate control switches. For most homogeneous exposure sets 1, 2 and 3 (10 lamps) are used, while all lamps are utilized for stress tests.
Typical intensities achievable in the UVA region are between 25 and 30 watt/square meter, requiring around 10 hours to achieve the ICH recommended 200 watt.hour/square meter. The emission spectrum of Luzchem's UVA lamps is shown in Figure 2.
(Note: Any figure below can be enlarged by clicking on it) |
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| For visible light illumination,
Luzchem uses and recommends Sylvania's cool white lamps (model F8T5/CW).
The ICH-2 unit has its lamp configuration optimized for best homogeneity
of exposure. Figure 3 shows the relative power across the photoreactor,
as determined at the half-depth of the chamber, i.e., 6 inches from
the front access area. The measurements where made on the 'floor' of the chamber, about 9 inches from the lamps. Measurements were performed
with lamp set 4 off but installed.
The interior of the chamber is constructed
of aluminum. Its surface has been designed to avoid specular reflectance
of the light, thus providing a mechanism for diffusive reflectance
and helping achieve illumination homogeneity. The diffuse reflectance
spectrum of the chamber walls is shown in Figure 4. The relative small
variations and the fact that reflections only contribute to ~ 20 %
of the light incident on samples minimizes spectral variations across
the chamber surface.
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| Power distrubution
is excellent across the chamber, as shown in Figure 3. This ensures
that any group of samples placed across the chamber at constant depth
will receive essentially identical doses.
However, there is some unavoidable drop in power towards the back
of the chamber, and near the front, where the door access is located.
Samples at these positions are below the electrode region of the lamps,
and thus the 2-inch strip nearest the back and front show significant
variations, as shown in Figures 5 and 6, where the numeric axia labels
correspond to a 2-inch grid at the floor of the photoreactor.
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Standard features
The ICH-2 includes a number of features which make it ideal for applications
in drug phototesting. A brief description follows:
- Digital timer: An easy-to-use timer allows unattended
exposure times from a few seconds to 99 hours.
- Magneric stirrer: A hidden recessed stirrer does not
interfere with work requiring full use of the photoreactor illuminated
surface, but is readily available for stress tests that may require
the exposure of relatively large samples for product characterization.
- Carousel and turntable: While the illumination characteristics
of the ICH-2 (see above) already provide for excellent homogeneity
of illumination, this can be further improved by slow rotation
of samples supported in a carousel or turntable which ensures
that a set of samples will receive identical doses. The turntable
is suitable for solid samples held in closed or open containers,
such as Petry dishes or small trays, as well as film-like materials
such as paper. The carousel is designed for liquid sample contained
in test tubes of up to 16 mm in diameter. For special needs, Luzchem
provides blank carousel disks that can be modified to accommodate
special sample containers. Since equalization of exposure requires
several rotations, these units are only recommended for exposure
times exceeding 30 seconds. The carousel or turntable are easily
installed or removed by inserting their shaft through a small
orifice in the chamber floor, under which the locking drive is
located. The units are controlled from the front panel which also
includes an indicator LED.
- Temperature control: The ICH-2 model includes a digital
temperature control module. Operating temperatures can be selected
from 3 ºC above room temperature to about 46 ºC. Temperature regulation
is achieved by controlling exhaust fan operation. A second small
fan provides enough air movement to ensure temperature homogeneity
in the chamber even when the main fan is shut off by the controller.
All units are individually tested for accurate operation at 25
ºC and 37 ºC, although other temperatures are also controllable.
- Power meter: A power meter, pre-calibrated in the UVA
and visible regions allows light intensity determinations in both
regions with about 10% accuracy. In order to meet more stringent
requirements Luzchem also manufactures spectroradiometers. A sharp cut off filter at 400 nm (provided)
can be used to estimate and correct for the fraction of visible
light emitted by lamps of other (e.g., UVA) specifications.
- Gas inlet: The ICH-2 unit includes a rear mounted bulkhead
connector for gases, which readily allows the introduction of
oxygen, nitrogen or carbon dioxide to meet special needs. This
convenient feature is not recommended for use with flammable or
toxic gases.
- Safety goggles: One set of yellow goggles with cut-off
around 420 nm ensure safe operation even if the door is open to
remove samples or to verify lamp operation.
- Certification: Each ICH-2 photoreactor is individually
tested and cerified to meet ICH guidelines under option 2, as
well as to meet LUZCHEM
standards for illumination, as shown in Figures 3, 5 and 6.
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5509 Canotek RD, Unit 12, Ottawa Ontario, Canada, K1J9J9
sales@luzchem.com
Copyright © 2006 Luzchem Research Inc.
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