Articles & Tech Notes
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The Latest from Our sp & Articles & Tech Notes
Increasing Metabolite Recoveries in ADMET Studies of Animal Models Using a Centrifugal Evaporator
The effectiveness of ADME/Toxicology studies is, now more than ever, critical to the
shortening the time-to-market of novel drugs. An ability to obtain rapidly accurate and
reliable data from animal models in order to track the metabolic fate of a novel
chemical entity in vivo is now a key skill in the drug discovery industry.
Development of an Enhanced Methodology & Technology for Safe, Rapid Freeze Drying of High Performance Liquid Chromatography Purification Fractions
Drying high performance liquid chromatography (HPLC) purification fractions,
principally comprising water and acetonitrile, is a routine yet essential task in many
laboratories. The requirement is to dry the samples to a powder form, such that
samples can be accurately weighed, easily sub-sampled and redissolved. Freeze
drying is therefore the preferred technology, however, large scale traditional freeze
driers may have difficulty processing the organic solvents which can boil out of the
samples and damage the vacuum pump. Actelion Pharmaceuticals adopted the fast
lyophilisation (LyoSpeed™) methodology developed by Genevac1, and implemented
this using the Genevac HT-12 centrifugal evaporation systems. The LyoSpeed
method concentrates the organic solvent with the centrifuge controlling boiling
preventing sample loss. The system then drains the organic solvent from the
condenser and then lyophilises the remaining water. This works well for hydrophilic
samples but problems may arise where the sample cannot dissolve in only water –
when the organic solvent is removed - the sample then crashes out and/or forms an
oil. Such samples require further processing to achieve the desired dry powder form.
An Improved Evaporative Sample Preparation Methodology for Determining Nitrofuran Antibiotic Residues in Foodstuffs
Introduction
Nitrofuran antibiotics were banned from use in the European Union [EU] in 1995 due to
concerns that their residues were carcinogenic. In 2002/3 the EU introduced a stringent testing
regimen which calls for the use of highly sensitive methods to test food stuffs, principally meat,
fish & shellfish, for the presence of this class of antibiotics. The Minimum Required
Performance Limit [MRPL] laid down by the EU directive is 1g per kg for edible tissues, and is
enforced on all products whether produced locally or imported into the EU. Many papers detail
methods and identify metabolites and derivatives of the drugs concerned and are listed by Vass,
Hruska & Franek (2008). The analytical method calls for good upstream sample preparation to
eliminate the effects of the matrix, and can be manual and time consuming, particularly where
evaporation is concerned. This article describes operational benefits including workflow
improvements gained by the official food control authority of the canton of Zurich (Kantonales
Labor Zurich) or KLZH during improvement of their upstream sample preparation methodology.
Evaluation of an Improved Sample Preparation Method for Quantative Analysis of Very Low Levels of Airborne Polycyclic Aromatic Hydrocarbons for Worker Protection and Health Screening
Introduction
Polycyclic Aromatic Hydrocarbons (PAHs) are large class of compounds comprising
two or more fused aromatic rings. PAHs are naturally occurring in fossil fuels and
their derived products and can be formed during incomplete combustion of carbon
based fuels. As such they are a by-product of many industrial processes. PAHs vary
greatly in size, nature and hazard to human health, some are not classified as toxic,
where as others are known carcinogens. The IARC specified 16 as being of particular
interest, others have subsequently added this list. In all, over 100 PAHs have been
described.
Given the risks and potential risks to human health presented by PAHs, many high
risk organisations, such as Foundries, Bitumen Works & Smoke Houses routinely
monitor workers and their environment for PAH levels. Typically PAHs are trapped
using filters (particulate forms) or resins such as XAD2 (gaseous forms) through
which work place environmental air is drawn. Filters may be situated in a small
device attached to the workers overalls, or from larger units measuring the air in a
wider area. Potential problems exist when recovering the PAHs from the filters and
preparing the samples for analysis, principally, losses due to PAH volatility are
reported for bi- and tri-cyclic PAHs (ISO11338-2:2003). Therefore, ITGA undertook
a study to improve sample recovery and therefore PAH determination when working
with low and very low levels of analytes.
Evaluation of Evaporative Sample Preparation Techniques for the Extraction of Drugs of Abuse from Urine Samples by Forensic Science Ireland.
Introduction
A method for the extraction of drugs of abuse from urine samples pertaining to drug facilitated sexual assault
cases has been developed in house by Forensic Science Ireland (FSI). The method involves the use of solid
phase extraction techniques prior to screening analysis by LCMSMS. As part of the solid phase extraction
process, the extracted sample eluent is evaporated to dryness. FSI evaluated the use of a Genevac EZ‐2
personal evaporator (Figure 1) as an alternative method of evaporation as part of their validation process.
The EZ‐2 was chosen due the fact that it eliminated the need for gases such as nitrogen, required for the
conventional blow down evaporation method, and also reduced sample handling and reformatting stages.