Environmental Laboratory 27 Processing with up to 4 Bar Pressure
“This is, because the FREESTYLE system operates under a pressure of up to 4 bar. Only when this relatively high value, or another pressure value previously defi ned in the method, is exceeded, the device will interrupt sample processing. The interrupted sample is marked in the sample list, the system will clean itself, and then continues processing with the next sample,” explains Wierer. The sequence as such is not terminated, and the unprocessed sample is clearly recognizable. With two special features, namely the plungers and the positive pressure of up to 4 bar, many samples, which may lead to blockages on other systems, can be reliably passed through the columns. Thus, unlike other robotic systems, the FREESTYLE is also particularly suitable for diffi cult matrices containing suspended particles or fi laments. For example, in addition to urine, this system can also be used for river water with sediments.
LCTech expanded the software of the robotic system, enabling the automated processing of two solid phase extractions in succession using two different column formats within one method. Method set-up for the so-called “Dual SPE” is easy just by clicking on the required parameters.
Source: LCTech GmbH
By clicking on various on-screen buttons, processing steps are selected, parameters such as fl ow rate and pressure can be entered, thus defi ning the method,” says Wierer. As soon as the method is saved, it can be called up and utilised by any employee for their laboratory routine at any time.
Effective and Fast Clean-up by Combining Columns and Plungers
As SPE columns, the CVUA-MEL uses MACHEREY-NAGEL’s CHROMABOND models to effectively and quickly purify the samples. “The columns can be used for both the systematic method development in sample preparation or the standard routine clean-up of a more regular volume of samples using the FREESTYLE,” explains Dr. Hans Rainer Wollseifen, application specialist at MACHEREY-NAGEL GmbH & Co. KG. The base materials ensure an effi cient enrichment and ideal fl ow behaviour. The optimised pore structure and the highly specifi c surface area are, amongst other things, responsible for a low solvent consumption. “In order to increase the fl ow rates and minimize dead volumes in the columns, we have developed special plungers that are inserted into the CHROMABOND columns,” says Wierer. “Without the plungers and at higher fl ow rates, one would often have to wait until the column bed supernatant has drained off. Now, however, all conditioning, washing and elution solutions can be passed over the column at a constant pressure”.
More Consistent Measuring Signals with Less Effort
For automated sample preparation, the already hydrolysed samples and the plunger-equipped SPE columns as well as two elution vials are simply put into the device. The fi rst elution vial receives the sample after the fi rst solid phase extraction. The container into which the sample is eluted after the second solid phase extraction is shaped in such a way that it can then be placed into the TurboVap for evaporation.
Then the sequence is started. “The device carries out the two clean-up steps automatically in the manner described earlier, after which the samples will only need evaporating and re-dissolving in another solvent,” explains Dr. Bernsmann. For example, 18 samples can be processed in one run, while the respective staff have the freedom to carry out other tasks.
The automated clean-up of sample extracts signifi cantly saves time: “Loading the FREESTYLE and starting the sequence takes only a fraction of the time required for manual processing of the samples,” says Dr. Bernsmann. “The sensitivity of the process is just as good as that of the manual preparation”. The consistency of the measuring signals has even improved since all solutions are passed over the column at a constant pressure. In contrast to manual processing, the standard deviation in the results has decreased signifi cantly, which means that the system works far more reproducible and more stable than manual processing. In addition, the different viscosities of the samples hardly play a role anymore.
In addition to the constant pressure, which leads to reproducible results, the switch to automated sample preparation has also other advantages. “As with the manual method, the LCTech
The CVUA-MEL uses for clean-up the MACHEREY-NAGEL CHROMABOND columns, which are particularly suitable for the fast and effective sample clean-up in the robotic device. In order to minimize dead volumes in the columns and to increase the fl ow rates, LCTech has developed special plungers that are inserted into the columns.
robotic system will process approximately 50 samples per week. However, the use of the FREESTYLE system signifi cantly reduces man hours,” explains Dr. Bernsmann. “In fact, the robotic system actually increases our effi ciency, as the CVUA-MEL staff can carry out other important tasks that cannot be automated during the sample clean-up. Even the previously manually performed, time-consuming SPE method development can now be carried out automatically overnight. Unattended sample processing is also possible over the weekend, so that the system can be used very effi ciently. In addition, the results show that the system processes absolutely cross-
contamination free,” sums up the scientist.
The urine samples together with the SPE columns and two elution vials are simply placed into the FREESTYLE, and then the sequence can be started. The fi rst clean-up of the sample extract is carried out with a C18- SPE column. Washing is done with a 5 % methanol solution and pure methanol is used for elution. The second clean-up is carried out using an NH2-SPE column. These clean-up steps are performed automatically, and then the samples only need evaporating and re-dissolving in another solvent before the measurement can take place.
“The FREESTYLE system operates with a pressure of up to 4 bar. As a result, many samples, which lead to blockages on other systems, reliably pass through the columns. This makes the FREESTYLE particularly suitable for diffi cult matrices with suspended particles or fi laments – apart from urine, also river water with sediments could be tested,” explains Sebastian Wierer, process developer at LCTech.
The Chemical and Veterinary Investigation Offi ce Münsterland – Emscher – Lippe (CVUA-MEL) with two sites in Münster and Recklinghausen is a public institution. Institutional authority lies with the counties and cities of the administra- tive district of Münster and the state of North-Rhine-Westphalia. Their duties include the maintenance of animal health and welfare, and the protection of consumers against fraud, deception and exposure to health hazards.
MACHEREY-NAGEL GmbH & Co. KG was founded in 1911 in Düren as a manufacturer of special fi ltration papers. In 1952, the company launched the fi rst products for paper chromatography and, from the end of the 1950s, developed into a special- ist in analytical chemistry and pioneer in thin-layer chromatography. In 1970, the product area chromatography was expanded by column chromatography. Today, MACHEREY-NAGEL is Europe’s leading manufacturer of SPE products. The DIN EN ISO 9001 certifi ed company places high value on the quality and purity of the sorbents and plastics used, and is as a manufac- turer of sorbents, particularly attentive to high reproducibility, freedom from blank values and ideal fl ow characteristics of the cartridges. The family business has branches in Switzerland, France and the USA, and supplies customers in over 150 countries worldwide.
The LCTech GmbH has headquarters in the Bavarian Obertaufkirchen, where products and methods for the preparation and analysis of food, feed, forensic and environmental samples have been developed and distributed since 1998. The product range includes semi- and fully automated sample preparation systems and consumables for the analysis of contaminants and residues. The company, which has over 40 employees, is represented through an extensive distributor network worldwide and acts as exclusive distributor for PICKERING Laboratories in Europe, Africa and the Arab countries. Numerous public and private laboratories in food and feed analysis, pharmaceuticals and research are among the customers of LCTech.
Author Contact Details Sebastian Wierer, LCTech GmbH • Daimlerstr. 4, D-84419 Obertaufkirchen • Tel: +49 8082 2717-0 • Email:
info@LCTech.de • Web:
www.LCTech.de Dr. Hans Rainer Wollseifen, MACHEREY-NAGEL GmbH • Neumann-Neander Str. 6-8, D-52355 Düren • Tel: +49 2421 969-0 • Email:
sales@mn-net.com • Web:
www.mn-net.com
www.envirotech-online.com IET May / June 2017
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