Articles & Tech Notes

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.

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.

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 1g 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.

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.

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.