Related Information
The Glossary below is provided to supply a simple explanation of specialist terminology used within this web site.
If you cannot find what you are looking for here, then please email your question to questions@avaloninst.com.
21 CFR 11: A sub-section of the American Code of Federal Regulations corresponding to tracking and tampering of digital information (spectra and collection settings), this regulation is broadly adopted by the worldwide pharmaceutical industry. All Avalon files are acquired and stored in a 21-CFR-11 compliant fashion.
Assay Plate: See Microtiter Plate
ASTM: American Society for Testing and Materials, a global forum for the development and publication of voluntary consensus standards for various materials, products, systems, services and calibration standards.
Back Illuminated CCD: The Back Illuminated CCD is very like a front Illuminated CCD (FI-CCD) but the CCD chip is mounted backwards, this has an advantage and a disadvantage. The advantage is that as the back of the CCD has no electrodes on it, the surface is clear of obstruction, and is therefore more sensitive. The disadvantage is that Back Illuminated technology is not suitable for use with 785nm or other nearIR lasers. Back Illuminated CCDs are sometimes called Back Thinned CCDs.
CCD: Charge Coupled Device Detector, the "camera" used to detect the Raman spectrum. A CCD detector is a two dimensional array of very low noise Silicon detectors. These detectors are like the Chips used in modern digital cameras, but are of a hugh huch higher specification and sensitivity. High performance CCD detectors should be cooled for optimum performance. Avalon's CCD detectors are operated between -100°C to -50°C depending on the application and type of CCD. A regular CCD detector is known as a Front Illuminated CCD. But there are other more sensititive variants:
the Open Electrode CCD OE-CCD
the Back Illuminated CCD BI-CCD
the Deep Depletion CCD DD-CCD
& and the Electron Multiplying EM-CCD
CDRH: Center for Devices and Radiological Health, a division of the FDA, who among many other things, classify the safety of laser based instruments.
Chemical Imaging: A technique whereby Raman Spectra are acquired in a grid pattern (or map). Using software each spectrum can be analysed to determine a property, this can be peak intensity, peak area, peak wavelength, % concentration or even properties like % crystallinity. If a colour is assigned to this property, then an XY Colour image can be generted. Where the X & Y coordinates are representitative of the X & Y coordinates on the sample, and the colour is representitative of the property of interest, typically considered to be chemical composition, hence the name Chemical Imaging.
Chemometrics: A software based statistical analysis technique, in which software can be trained using a series of spectra of known properties, thereafter this chemometric 'model', can be used to calibrate the spectrometer and allow prediction of these properties in unknown samples. chemometrics allows for prediction of concentration (even on multiple components in mixtures), prediction of crystallinity, melting point, degree of crosslinking.
Class 1 laser system: A safe to use laser system, class 1 systems contain lasers which them selves are considered hazardous, but these systems are constructed in such a way that there is very little or on accessible laser emission, examples are CD players and laser printers.
Class 3 laser system: A laser system where laser light is emitted at levels where it could be damaging to individuals using the system or those nearby.
DCS: Distributed Control System, a master control station used to control instruments and reactors, typically found in pharmaceutical, chemical and polymer production facilities.
Deep Depletion CCD: CCD detectors (Also see CCD) become somewhat insensitive to light in the infrared end of the spectrum. because of this some 785nm based Raman Instruments have weak signals in the CH region (above 2800cm-1). All Avalon 785nm instruments are designed to address this drop off in sensitivity and all offer excellent performance in this region. But is extra high sensitivity is required in the CH region of a 785nm Raman instrument a Deep Depletion CCD can be used. The Deep Depletion CCD is just like a Back Illuminated CCD(BI-CCD) but has a deeper photoactive region, allowing it to measure photons which might have otherwise passed right through the CCD chip and not been detected. The photoactive region is known as the depleted region.
Echelle: A (spectrograph) detector system which disperses light in 2 dimensions allowing for high resolution data acquisition over the entire Raman range. Typical 1 dimensional spectrographs offer a choice of the entire Raman range and low resolution, or low range and high resolution. The only way to achieve echelle like performance from a standard 1D spectrograph is to add motorized components and then to stitch the spectral information together, this relies on motorizing critical optical components which can lead to unreliable calibration.
EMCCD or Electron Multiplying CCD: A type of CCD detector (also see CCD) which can aplify signal levels allowing for detection of very low light levels or very fast acquisition. EMCCDs are more expensive than regular CCD detectors, but are unsurpassed when it comes to detection of weak signals, monitoring fast reactions and for ultra fast chemical imaging.
Fiber Optic Probe: A flexible fiber optic cable which allows for the collection of Raman spectra at long distances from the spectrometer, (up to approx 0.5 miles) and in extreme environments inside reaction vessels, at elevated temperatures and pressures.
FWHM: (aka FWHH ):Full Width Half Maximum (Full Width Half Height) a measurement of a spectral feature where the width of the feature at the position of half its height is measured. This is a universally accepted technique for the measurement of resolution.
HT: High Throughput, see HTE and HTS
HTE: High Throughput Experimentation, the ability to automatically perform experiments in automated parallel or serial experiments, these can take the form of automates sample deposition through to automated large scale parallel reactions.
HTS: High Throughput Screening, the ability to automatically analyze and process information from large batches of Samples. For HTS analysis samples are typically loaded into instruments in the form of a Multi Will plate.
IQ: Installation Qualification, a documented record that the instrument is installed in the correct fashion. IQ is required when instrumentation is used in FDA or GMP environments.
OQ: Operational Qualification , a documented record that the instrument is operating correctly. OQ is required when instrumentation is used in FDA or GMP environments.
Open Electrode CCD: The Open Electrode CCD is very like a front Illuminated CCD (FI-CCD) but is more sensitive, this is achieved by modifying the electrode structure on the surface of the CCD so as to make it more open to photons, thereby allowing more photons to be detected.
Process Control: The control (direct or through human intervention) of a chemical process, typically a reaction.
Microtiter plate / Multiwell plate: A standard "plate" for chemical storage / analysis, which has a grid of wells where samples can be placed. All plates have the same footprint and typically have 96 wells, although 6, 12, 24, 48, 384 and 1536 are also available.
NIST: The National Institute of Standards and Technology, a US government body who regulate weights, measurements and instrument calibrations.
Resolution: The ability to resolve spectral features which are very closely spaced. The correct way to measure resolution is to measure the FWHM of spectral features. When it comes to Raman 2cm-1 is considered to be very high resolution, 4cm-1 resolution is considered High Resolution, larger than 8 cm-1 is considered low resolution.
SERS: Surface Enhanced Raman Spectrum, a technique allowing very low concentration of many species. For additional information click here.
Video in Window: Video output which is displayed as a window on the main computer monitor.
Click here to check out the cutting edge in Raman Instrumentation
This page is always being reviewed and added to, if there are any other terms which you would like explained please contact us.
