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PiStar Kinetic Circular Dichroism Spectrometer Accessories
Accessories
A comprehensive range of options considerably expands the number and type of application that can be addressed using the PiStar. All are available for both new and existing systems, allowing expansion of the PiStar capabilities as one's research interests evolve.
| Group 1: Sample handling and conditioning |
This option provides the PiStar spectrometer with sequential stopped-flow in addition to standard stopped-flow operation. Two reagents ("A" and "B"), are mixed together and allowed to incubate in an ageing loop. After a programmable delay, the contents of the age loop are mixed with a third reagent "C".
PC.2 Peltier temperature controller
Square and circular cell blocks incorporating rapid and precise peltier temperature control over the range -20°C* and +110°C.
*Requires chiller. Temperatures down to -5° can be achieved by running tap water through the peltier heat exchanger.
The TT.2 is a fully automated dual syringe titration accessory. Priming and experimental protocols are provided in the Pistar software.
STM.2 Stirrer/temperature module
This provides multiple temperature probe inputs for monitoring the sample and its immediate environment and magnetic stirrer support for the 1cm cell holder in the equilibrium sample handling unit.
A recently developed system with proven anaerobic performance will ensure that the reaction kinetics of even the most sensitive of samples can be successfully analysed. Ultimate performance is obtained when the AN.2 is used in conjunction with a glove box but excellent results can be achieved even when only rudimentary precautions are taken to exclude air.
Removes contaminants from the purge gas supply.
A 5µl cell in a removable cartridge.
The quench-flow adaptor allows the PiStar (with option SQ.1) to be configured in minutes to enable quench-flow capability.
| Group 2: Detection modes |
SK.2E provides the user with an emission scanning capability (includes a second programmable monochromator) thereby providing comprehensive steady-state and time resolved fluorescence excitation/emission detection.
With the PDA.2 accessory, the PiStar can be reconfigured in seconds to provide high performance, rapid scanning capability in absorbance mode. It features up to 1600 UV/Vis spectra per acquisition, wide dynamic range, high sensitivity, logarithmic time-base and rapid sampling frequency. Data can be immediately transferred into Pro/K global analysis package. PDA.2 is available in two versions - a 256-element array with a minimum scan time of approximately 1.28ms and a high resolution 512-element version. Both arrays are able to cover a range of wavelengths from 200nm to >1100nm. No optical alignment or calibration is required, and configuration to and from photomultiplier detection takes a few seconds.
The TF.2 comprises a dedicated amplified fluorescence detector with filters. The addition of the unit MC.2 (multi-channel data acquisition) will allow simultaneous collection of fluorescence and Circular Dichroism data.
FP.2 Fluorescence polarisation/anisotropy
Fluorescence anisotropy is used to study the change in rotational motion of fluorescent molecules on binding or in response to a change in their environment. With the FP.2, data can be collected in polarisation or anisotropy units. Total emission data is also recorded with each measurement.
ORD.2 Optical rotatory dispersion
The ORD.2 accessory enables the measurement of optical rotation on the PiStar, allowing detection of optical activity in regions away from absorption bands. Measurement is based on PEM modulation of the input light, and transformation of the resulting AC and DC signals to produce measurements directly in millidegrees. The accessory consists of an analyser rotation housing (with course and fine null adjustments), a specialised detector, and lock-in board upgrade (if required).
| Group 3: Source enhancements |
The UV.2 is a powerful deuterium light source. The profile of the lamp spectrum is such that the UV output is much enhanced with respect to the visible output; this leads to a reduction in stray light contamination of the far-UV, making this an ideal source for use with the UV version of the PDA.2 photodiode-array detector. With the combination of the UV.2 and the UV PDA.2, photometric accuracy down to 200nm is assured.
| Group 4: Software and data acquisition |
This is a unique stand-alone software package providing global analysis of time resolved spectral data accompanied by a comprehensive data simulation capability. It features singular value decomposition (a type of factor analysis) allowing spectral component prediction and data reduction. Global fitting to an arbitrary reaction schemes is available through the use of fast numerical integration techniques coupled to a symbolic reaction scheme editor. True intermediate spectra of all coloured species are calculated together with their associated concentration profiles. Data obtained from SK.1/SK.1E and PDA.1 are ideally suited for analysis with Pro-K.
Pro-K II 2ndOrder Global analysis for PC
This offers all that its predecessor Pro-K offers but adds second order globalisation to the analysis, whereby separately acquired concentration dependant data sets can be combined for simultaneous analysis. This feature enormously increases the ability to define rates and spectra in more complex models. In addition rapid equilibria can be included in the model facilitating the modelling of pH dependent systems by inclusion of rapid protonation equilibria. For more information on Pro-K II click here.
MC.2 Multi-channel acquisition module
With this module, up to five different data-channels can be collected simultaneously. It could be used, for example, to simultaneously monitor Circular Dichroism and fluorescence behaviour. The information thus collected can be used to provide a more robust understanding of the behaviour of the sample from a single experiment.
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