Gas-Phase Photosynthesis & Respiration Measurement
- Convenient, entry-level system for the study of photosynthesis & respiration measurements in gas-phase samples under illumination
- LD1/2 electrode unit suitable for leaf discs up to 10cm2 cut from whole leaves, algae or moss etc
- Oxygen electrode control & signal acquisition via Oxyview control unit
- LS2 intensity adjustable by insertion of neutral density filters
- Oxygen signal output from Oxyview to recording device via 0 – 5V analogue output
- Upper optical port allows illumination from LS2 high intensity white light source
Overview
Leafview 1 is an entry level system for studies of photosynthesis & respiration from gas-phase, solid-state samples under actinic illumination. The system is ideally suited to teaching environments for under & post-grad plant biology studies of the photosynthetic processes but is equally at home in research facilities where demands on equipment performance are high.
Samples typically consist of leaf discs which are either cut from a broad leaf or made up of a “mat” of smaller leaves to form a circular disc of 10cm2. These samples are cut using a supplied leaf disc cutter. Changes in oxygen content of the sealed sample chamber are determined by the integral oxygen electrode mounted in the base of the chamber.
The system comprises the Oxyview control unit, S1 Clark type electrode disc, LD1/2 gas-phase electrode chamber and LS2 high intensity light source with neutral density filters to modify light intensities. All necessary accessories and spares are also included (excluding circulating water bath and chart recorder).
Oxyview Control Unit
The OXYV1 Oxyview control unit has been designed as a convenient, low cost oxygen electrode control unit for teaching studies of photosynthesis and cellular respiration using the oxygen electrode measurement technique.
The Oxyview control unit is fully compatible with the range of oxygen electrode chambers produced by Hansatech Instruments thus allowing a wide range of different assays to be performed in both liquid and gas-phases.
The Oxyview is configured and controlled via a front mounted control panel featuring 4 touch-sensitive buttons. Configuration is achieved by navigating through a series of simple menu screens and following the displayed guidelines for each step of the setup process. These configuration steps include setting of the stirrer speed (for liquid-phase measurements) and back-off and gain settings. Once configured, the Oxyview control unit provides an accurate and stable reading of the oxygen content of the sample in question.
The Oxyview control unit has an integral magnetic stirrer for liquidphase applications allowing the overall footprint of the Oxyview 1 system to be minimal (90 x 135mm); convenient when multiple setups are required for teaching programmes in limited space.
The Oxyview control unit is powered by a 12V DC wall cube which connects directly to the rear of the unit. Also at the rear is a 0 – 5V analogue output. This allows the measured values from the control unit to be logged to an external recording device such as a chart recorder or similar datalogger accepting a 0 – 5V analogue input.
LD1/2
The LD1/2 leaf-disc electrode chamber is a simple device for measuring oxygen exchange from a 10cm2 leaf disc mounted within a sealed, gas-tight chamber. The LD1/2 is constructed from black acetal with a cast acrylic top window allowing the sample to be evenly illuminated for photosynthesis measurements using either the LH36/2R LED light source (when connected to the Oxylab electrode control unit) or the LS2 high intensity white light source. A prepared S1 oxygen electrode disc mounts into the base of the LD1/2 with the dome of the electrode forming the floor of the sample chamber.
S1 Electrode Disk
The S1 electrode was designed in the early 1970’s during a collaborative project between Prof. David Walker, Prof. Tom Delieu and Hansatech Instruments. Since the first S1 oxygen electrode disc went on sale in 1974, the design and manufacturing process has remained largely unchanged in nearly 40 years – a true testament to the popularity, quality and reliability of the sensor.
A range of complementary instruments have been continuously developed over the years in order to meet the needs of emerging trends in the scientific world. Modern oxygen measurement systems incorporate the S1 electrode to provide sensitive and reliable tools for a vast range of applications from the demonstration of oxygen evolution from photosynthetic organisms to the analysis of mitochondrial respiration rates.
When prepared and fitted into an electrode chamber, the dome of the electrode disc forms the floor of the electrode chamber reaction vessel providing a sensitive and rapid response to small changes in oxygen tension within the sample.
The electrode disc comprises a central platinum cathode and a concentric silver anode. Preparation of the electrode includes the addition of electrolyte and the application of a thin oxygen permeable P.T.F.E. membrane to the electrode dome.
Once prepared and positioned in the electrode chamber, the disc is connected to an electrode control unit which applies a small polarising voltage between the platinum and silver electrodes. In the presence of oxygen, a small current is generated proportional to oxygen activity in the sample.
With modifications and in conjunction with accessory equipment, the S1 oxygen electrode disc may be used to measure other gasses such as hydrogen and nitric oxide.
LS2 High Intensity White Light Source
The LS2 light source is a high intensity (100W) tungsten halogen light source which is powered from a stabilised power supply.
The lamp housing contains a cooling fan, infrared reducing “Hot-Mirror” and optics to provide light with minimum variation of intensity across the beam and little divergence from parallel. 2 slots are provided to accept 50mm square optical filters or a manual shutter plate.
A range of light intensity steps may be achieved by adding permutations of the 4 A5 neutral density filters supplied (0.1,0.3,0.6 and 1.0 O.D.) to attenuate the light intensity. Maximum sample illumination intensities vary depending on the type of electrode chamber in use.
The table below shows the maximum achievable sample illumination intensities for each electrode chamber.
| Electrode Chamber | Maximum Intensity |
| DW1 | 1800 µmols m-2 s-1 with LS2 mounted horizontally to chamber. |
| DW1/AD | 1800 µmols m-2 s-1 with LS2 mounted horizontally to chamber. |
| DW2/2 | 8000 µmols m-2 s-1 with LS2/FO and A8 accessories to interface with DW2/2 optical port. |
| DW3 | 1800 µmols m-2 s-1 with LS2 mounted on to locating ring of larger optical window.8000 µmols m-2 s-1 with LS2/FO and A8 accessories and 16mm dia. reducing adapter (supplied with DW3) inserted into smaller optical port. |
| LD1/2 | 1800 µmols m-2 s-1 with LS2 mounted vertically on to optical window of the chamber. |
| LD2/3 | 1800 µmols m-2 s-1 with LS2 mounted vertically on to optical window of the chamber.8000 µmols m-2 s-1 with LS2/FO and A8 accessories inserted into 16mm dia. optical port. |
Accessories & Spares Supplied
- A2 Membrane applicator
- A5 Set of 4 50 mm sq. neutral density filters 0.1, 0.3, 0.6 and 1.0. O.D.
- S4 30m roll of PTFE membrane
- S8B Spare O-rings for LD1/2 electrode chamber
- S14 Set of 3 stainless steel discs, capillary matting and foam spacer for Leafdisc electrode chambers
- S15 3-way gas taps and 1ml disposable syringe for Leafdisc electrode chambers (4 taps + 2 syringes)
- S16 Electrode cleaning kit
