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Science: Equipment update for ETE’s analytical laboratory

Gepubliceerd op
19 november 2016

‘This is one of our newest hypermodern gas chromatograph or GC’, says Hans Beijleveld, Laboratory Coordinator at ETE, while he points to an impressive looking piece of machinery. ‘This single instrument replaces two older machines that were mainly used to analyze volatile fatty acids and short-chained alcohols.’ Volatile fatty acids, briefly VFA’s, are formed by bacteria during anaerobic breakdown processes.

The VFA composition gives important information about the presence of different bacteria species as well as the rate and routes of the metabolic conversions.

Outdated system
The analytical procedure to analyze VFA’s using the older GC was robust but kind of inefficient; separation was achieved by a so-called packed column. This outdated system often required two distinct runs to achieve good separation and quantification of the VFA’s and alcohols present. In the new GC, a capillary column takes care of separation, resulting in way more efficient analyses: excellent separation can now be achieved in just one system and one single run.

But the new machine is also needed because more substances are relevant in today’s environmental research. Beijleveld: ‘With our new system we are able to separate many more different VFA’s and other components than previously.’ And there is another important reason for the GC update. The old system was over 25 years old. Spare parts were increasingly difficult to get, while repair time became a real issue.  

Flexible GC
Flexible GC
GC auto sampler
GC auto sampler

Analytical flexibility
A second new GC was purchased aiming at increased analytical flexibility in just one system. ‘We are running many types of analyses during a year’, Beijleveld explains. ‘This machine can run a range of different analyses and replaces four older GC’s!’

Capillary column in the new GC
Capillary column in the new GC
Detail of a capillary column
Detail of a capillary column

At the same time, analyses time is diminished; run time may be reduced by more than 50%. The new multi-purpose machine will be used by many different researchers in the near future.

For example, methane (CH4), an important component formed during anaerobic conversions, can be analyzed with high sensitivity. But also different toxic solvents can be analyzed, including benzene, toluene, ethylbenzene and different xylenes. These so called BTEX analyses are indispensable in soil surveys. Another group of compounds that can be measured are the mineral oils, important for oil spill research. The versatility of the system is among others due to the presence of two different injection positions. Each position leads to a different detector with specific analytical qualities. The first one is the electron capture detector, ECD. This detector is very sensitive to halogenated compounds, for example some groups of pesticides.

The second detector, the flame ionization detector, or FID, measures organic compounds without halogens, for example oil components. ‘All in all this GC is extremely flexible and will be used in many different projects’, Beijleveld says.

GC sample injector
GC sample injector
Two different injection positions
Two different injection positions

Basic analyses The third new machine doesn’t replace older systems, but adds to the analytical capacity of ETE’s laboratory. This so called TOC analyzer is still being installed, but it will be up and running very soon. The TOC analyser is an advanced instrument using infrared light for detection of next to Total Organic Carbon (TOC). It is also able to measure Total Inorganic Carbon (TIC), like dissolved carbon dioxide and total nitrogen (TN). In the recent past, ETE used to outsource these analyses, but now they can be carried out in house. The TOC-related analyses are considered basic in the environmental sciences, resulting in extensive use by many projects. An important project where the TICTOC will play an important role is Water Nexus. This project is aimed at the use of salt water wherever possible, to limit the use of precious and scarce fresh water.

For example, salt water may be used as cooling water in different industrial processes instead of fresh water. To prevent algae growth, a biocide is often added. This results in a new type of waste water: salt water with a biocide. ‘To find out if anaerobic cleaning using microorganisms is possible, we need to measure Chemical Oxygen Demand, briefly COD, an indication of total oxidizable organic contaminants present’, Beijleveld explains. ‘Unfortunately, salt influences the traditional COD analyses.’ The new TICTOC can analyze organic compounds, like the biocide, also in salt water without any interference with the final outcome. ‘These three new machines have dramatically increased our analytical capacity’, Beijleveld says. ‘The laboratory team has done a great job in making these new systems up and running in so little time in addition to their regular daily lab support!’