Sample Preparation & Processing


Benchtop Concentrator Enhances Forensic Sample Preparation


Genevac report on a paper by UK researchers describing use of its miVac DNA concentrator to provide reliable and efficient sample preparation in the development of a novel forensic method to detect diclofenac residues in vultures and livestock animals.


Traditionally, livestock carcasses on the Indian subcontinent and in Africa have been left out by the millions for scavengers, particularly vultures. Over the last decade several species of the vultures that were the primary consumers of these carcasses face extinction, with diclofenac residues in the livestock carcasses implicated in the cause.


To address the difficulty in collecting samples from long dead livestock and vultures, a new GC-MS method, which could detect diclofenac residues in long-lived keratinous matrices, was developed to enable long-term monitoring and conservation work. The method comprised extracting samples of hair, nails and feathers in methanol overnight, drying down the extracts and derivatising with N,O-Bis(trimethylsilyl)trifluoroacetamide with 1.0% trimethylchlorosilane (BSTFA 1.0% TMCS) and ethyl acetate prior to GC-MS analysis.


Initially extracted samples were evaporated to dryness at 40ºC under a steady stream of nitrogen in a block heater. However, this method was time-consuming, inconvenient and results lacked uniformity.


Due to the problems the researchers developed a sample concentration methodology using a miVac DNA concentrator. The researchers report in the paper that using the miVac DNA concentrator they were able to dry 44 samples in approximately 15 minutes, a great improvement on the nitrogen blow down system. There were no incidents of partial or incomplete drying, eliminating anomalous results due to poor or incomplete derivatisation. In addition, as the miVac runs free from operator attention and requires no consumables, it is a much more suitable laboratory tool for use in areas were the supply chain of scientific materials may be weak.


The miVac DNA concentrator from Genevac is capable of safely and efficiently removing water and organic solvents from biological samples in a variety of formats including tubes, microplates and vials. The miVac DNA system is very simple to use. The ‘select & set’ single control knob control enables even new users to obtain excellent results first time and every time. To improve performance there are built-in stored methods for concentration of water and water/alcohol based samples, which optimise concentration time.


To download a copy of the ‘Wildlife Forensics’ paper please visit http://www.evaporatorinfo.com/info10.html 41146pr@reply-direct.com


New Grinder Quickly Pulverises Large Sample Volumes


No grinder can beat the speed of a Vibratory Disc Mill when it comes to preparing samples, e.g. for XRF analyses. In addition to the well-proven Vibratory Disc Mill RS 200 Retsch now offers the RS 300 XL for sample volumes of up to 2000 ml.


This new model allows for simultaneous processing of up to 4 samples. Thanks to the robust universal drive shaft, which sets the grinding jar into a 3-D motion, it accepts grinding sets weighing up to 30 kg. The RS 300 XL very effectively grinds hard, brittle and fibrous samples like cement, coal, minerals or electronic components by impact and friction. Grind sizes below 50 microns are typically obtained in a matter of seconds. For safe operation the grinding set is firmly attached to the vibration plate with a pneumatic clamping device.


A selection of grinding jar materials and sizes makes this mill versatile and suitable for grinding a variety of sample materials without affecting analysis results. Due to the high final fineness and speed both Retsch Vibratory Disc Mills are the perfect choice when it comes to preparing samples for spectral analysis.


Benefits of the RS 300 XL include: reproducible results and homogeneous samples; short grinding times; programmable interval function; optional Autolifter for ergonomic handling of heavy grinding sets.


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Flexible Vacuum Mixing Dispersion System


A new Vacuum Dispersion and Mixing System which offers users’ outstanding flexibility, is now available from laboratory instrumentation specialists Fullbrook Systems. The range of Dispermat CHS Vacuum Systems, manufactured by VMA-Getzmann GmbH, is ideal for small batches and sample production where vacuum is required.


The Dispermat CHS vacuum system offers users exceptional versatility because it’s designed to accept single wall pails, buckets, non-standard and most importantly even users own containers. Users place the container on the mobile system trolley then a top-mounted fixing ring is screwed into place which securely holds the container in place. The vacuum cylinder is then placed over the container whilst the assembled vacuum system is positioned underneath the powerful Dispermat AE pilot plant vacuum dissolver, ready for the dispersion process to begin.


The dissolver disc is height adjustable even with the cover in place which allows the blade to be positioned at the perfect height to ensure that addition of powders can be made to the batch under optimum conditions. The complete process and the product under vacuum are able to be observed by the operator through a large viewing glass in the vacuum cover.


The solid scraper arm within the vacuum container effectively removes any product residue which is sticking on the container wall and folds it back into the dispersion process. For temperature sensitive applications, an optional PT100 probe enables operators to control temperature as required.


At the end of the dispersion process the container is simply released and removed, the finished de-aerated and dispersed product is held in its own container, so no transfer to another container, which often adds air back in, or cleaning is required.


The Dispermat CHS30 accepts 30 litre containers but is also available for container volumes up to 60 litres and also for other specific container sizes if required. An explosion-proof ATEX certified version is also available.


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