The Oxytherm oxygen electrode control unit comprises a robust yet lightweight enclosure containing the integrated electronics and magnetic stirrer. The electrode chamber consists of a similarly constructed enclosure containing the 10mm precision bore borosilicate glass reaction vessel which is well insulated in order to minimise heat loss through the casing and also provides the capability to perform both light and dark reaction measurements. An optical port is situated on the side of the casing to suit
FMS 1 and
FMS 2 chlorophyll fluorometer fibre-optic cables allowing simultaneous measurement of chlorophyll fluorescence
from photosynthetically active samples. There is also a viewing port in the front of the electrode unit with an illuminating white LED controlled by a push button on the side of the unit. Both control box and the electrode unit are powered from a single external 12V DC power supply.
An Oxytherm system may be configured as a single or multi-channel setup in order to make comparative measurements of oxygen from multiple samples. Simultaneous recording of an optional auxiliary input signal (e.g. temperature, pH, fluorescence, TPP+ or other specific ion electrodes etc) is also possible using the
OXY/PHA amplifier unit coupled via the auxiliary input on the rear of the Oxytherm oxygen electrode control unit.
A system comprises a minimum of one (maximum of eight) control units linked together in a chain to the serial port of a Windows® PC. Oxytherm control units may be freely interspersed with
Oxygraph oxygen electrode control units within a multi-channel system. The control unit connects to a PC via the serial port and uses bi- directional RS232 communications for instrument control from the PC and data acquisition to the PC. There is no requirement for separate loggers, internal PC interfaces or A/D cards. Laptop or notebook computers are therefore just as suitable as a desktop PC and provide a highly portable, compact system whenever bench space is limited.
A custom Windows® software package, Oxygraph Plus, is supplied with the Oxytherm electrode control unit. The software is designed to provide control of all hardware functions from simple dialogue based controls. Oxygraph Plus contains Wizard-type semi-automated calibration routines for liquid or gas-phase measurements allowing system calibration to be performed with ease by following a series of onscreen prompts in order to record the signal from the
S1/MINI oxygen electrode at 2 known oxygen concentrations. Signal gain and back-off controls are also included in Oxygraph Plus which may be used to amplify smaller signals from samples with lower oxygen concentrations.
Once calibrated, Oxygraph Plus records the signal from the S1/MINI electrode disc (and an optional auxiliary input signal) at a user-defined data acquisition rate and presents the values as a real-time chart recorder emulation. Recorded values are also presented in a digital panel meter in calibrated units along with a Live Rate measurement which is calculated in real-time over a user-defined number of recorded data points.
Once the recording is complete, Oxygraph Plus contains several tools for basic analysis of the recorded data. A rate measurement tool provides easy estimation of oxygen rates over user-defined intervals and spot measurement tool allows precise oxygen and time base values to be obtained for any given point on the recorded trace. Data files are saved in a Comma Separated Values (*.CSV) format which may be opened directly in external data analysis packages, such as Microsoft Excel®, for more detailed statistical and graphical analysis of recorded data.
