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The generation of A/Ci curves is one of the most common experiments that is currently being performed for assessing the effects of increasing atmospheric carbon dioxide concentrations on plant growth. Current ambient air carbon dioxide concentration is about 389ppm. Many scientifically generated models predict that the imbalance between carbon emissions and carbon sinks, such as oceans and forests, will mean a doubling in ambient carbon dioxide concentrations in the next 40 years. There is therefore significant concern regarding how such predictions could alter global plant growth and crop production. The A/Ci experiment involves measuring photosynthesis rate and related parameters at a range of above current ambient carbon dioxide concentrations. From this data it is possible to assess the efficiency of a plant to take in and utilise carbon dioxide at these potential higher ambient concentrations. All data and experimental programs are stored on easily exchangeable SD cards providing unlimited data storage.

Figure 2. LCA2 "The first portable system".

One such gas exchange instrument that truly reflects these trends is the new LCpro-SDmanufactured by ADC BioScientific Ltd. The LCpro-SD, introduced in 2011, consists of only a small console weighing 4kg and a plant leaf chamber. Miniaturisation of the IRGA has now developed to such an extent that the analysis cell is now housed in the leaf chamber directly next to the leaf. The response time, therefore, from when the plant undergoes gas exchange to when the analyser is able to measure these changes is greatly reduced. It is now possible to accurately and automatically control the environmental conditions within the chamber. Carbon dioxide, water vapour, temperature and light levels can all be programmed at single concentrations or at multiple steps, above or below ambient conditions. This is a key requirement for many contemporary environmental research projects.

Environmental Analysis Increased versatility


The development of new types of chambers means that more types of crop species can be more easily investigated including grasses, conifers and even whole plants. Gas exchange chambers can now be combined with optical fluorometers providing researchers with even more information and data on a plant’s ability to utilise sunlight; a comparatively new technique developed for analysing environmental stress on a plant. Many portable gas exchange systems can also be

easily adapted to measure soil respiration (CO2 emissions from soil), an increasingly important parameter in the investigation of rising ambient carbon dioxide concentrations.

The future Predicting the future is very difficult, but it is apparent that the driving forces for agronomic research for the foreseeable future will continue to be issues relating to global climatic change. It is difficult to believe that the trend for evermore portable, sophisticated and easy to use equipment will not continue. It is possible that increased collaboration between different research disciplines will occur. Plant physiologists and molecular biologists are already working together to apply cellular research findings on species such as Arabidopsis to whole plant activity in field conditions.

As in most scientific subjects, future experimentation will only be restricted by the researcher’s imagination and the instrumentation available to them. It will be up to the manufacturers to continue to respond to the new and changing challenges placed on them by researchers driven by international political concerns.

Figure 3. "Portable analysis today: the LCpro-SD in the field".

Operation and Performance of the Parallel Evaporator Syncore Analyst for Environmental Analysis

The Syncore® Analyst from Buchi

(Switzerland) allows for efficient, fast and parallel concentration of liquid samples and minimises the environmental impact by solvent recovery. This automated parallel evaporation system is designed for gentle concentration of 4, 6 or 12 samples with working volumes of 10 to 500 ml down to pre-defined residual volumes of 0.3, 1.0 or 3.0 ml by means of heating under vacuum.

The key feature of the Syncore® is an integrated cooling zone which


stores the concentrated sample in a cooled environment. Programmable conditions (vacuum, temperature, orbital movement) allow for a reproducible concentration without supervision and with high precision. The system can be places outside the fume hood due to the fact that the solvent is recovered by a condenser with a receiving flask. An efficient concentration from most solvents is performed in 30-60 minutes. Best results are achieved with a moderate evaporation rate generated by a vacuum gradient. Highly volatile analytes (e.g. naphthalene), in particular, require a rather slow but smooth evaporation, since a fast evaporation rate tends to carry along volatile analytes. However, this is not the case for non-volatiles (e.g. benzo[a]pyrene).

The orbital movement has a considerable effect on the evaporation rate and the final volume. Although concentration is accelerated, a high orbital movement is not only beneficial in environmental analysis. An increase of the movement implements an extension of the glass surface being in contact with the sample. Particularly oily and greasy substances tend to stick on the glass wall. Due to the sophisticated design of the vacuum cover, the individual sealing system of each sample glass and the possibility to clean the glass vessels in dish washers, the risk of cross-contamination is mostly insignificant. At a naphthalene sample concentration of up

to 800 µg the detected level of naphthalene in blank positions is below 0.1% of the sample concentration. High recovery rates are achieved with the ultimate Flushback Module that gentle rinses the glass walls during operation with the solvent being evaporated. These numerous advantages make the Syncore® trace and ultra-trace analysis.

Analyst the system of choice for concentration in Reader Reply Card No. 85 Reader Reply Card No. 86 AET October / November 2011



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© Agilent Technologies, Inc. 2011

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