The RX.2000 Rapid Mix accessory from Applied Photophysics
is a stop flow accessory that allows you to start measuring
reagents as soon as they have been mixed. This is an
obvious advantage for reactions which are short-lived.
The syringes are mounted on a rigid drive platform ensuring
that the flow is stopped precisely and instantaneously. This
platform and the syringe mounting blocks are extremely resistant
to chemical attack.
Reagents travel in this inert sample circuit through an umbilical
cord to the flow cell where they are mixed by a high efficiency
T-format mixer.
Varian offers both the RX.2000accessory from Applied Photophysics
and the SFA-20
from Hi-Tech Scientific.
Key Features
of the RX.2000
Short Dead Time The
dead time of the RX.2000is only 6ms, as determined by the
protocol of Tonomura et al (Anal. Biochem84,
p370-383, 1978). This enables first order reaction rates
over 200s-1 to be measured.
Total Thermostatting.
Uniquely, the entire flow circuit of the RX.2000is thermostated
(including drive syringes). In addition to providing reliable
temperature equilibration, this also has the added benefit
of aiding in the rigorous exclusion of oxygen from the entire
sample when undertaking anaerobic work.
Chemical resistant materials.
Carefully selected materials are used throughout to protect
the instrument from aggressive chemical spillage.
Wide temperature range.
High performance syringes with canted seals are used exclusively,
providing reliable operation over a wide temperature range.
Large ratio mixing capability.
The drive syringes can be readily substituted to allow mixing
ratios from 1:1 to 1:25.
Universal compatibility.
The RX.2000cell can be fitted in seconds without tools to
ANY spectrometer that can accommodate a standard 1cm rectangular
cell.
Exceptional Sample Economy.
The prime volume of the RX.2000is only 260 µl per reagent
(with the standard umbilical length of 60cm) and the subsequent
volume per shot is only 100 µl. Other lengths of umbilical
can be supplied on request.
No Birefringence. The
advanced micro-cell is configured optically for both absorption,
fluorescence and circular dichroism. Crucially for circular
dichroism (CD) and anisotropy experiments the cell is triple-annealed
during manufacture to eliminate birefringence artefacts.
Adjustable Drive Volume.
The volume required per determination can be altered by
adjusting the position of the stopping block/trigger mechanism.
This flexibility is of particular importance when performing
large ratio asymmetric mixing experiments, and when eliminating
air bubbles from the flow circuit.
Armoured Umbilical.
The 60cm umbilical is armoured to prevent damage.The observation
cell can therefore be positioned through tight turns without
constricting the flow of the thermostatt fluid.
Triggering. The RX.2000is
provided with the following popular triggering configurations,
TTL, open collector and switch contact. The trigger output
is accessed by a standard 5 pin DIN socket.
Digital Temperature Display.This
integral feature, fitted as standard, indicates the sample
temperature in the cell to within 0.10C. It also
features programmable high and low temperature alarms.
