Sorption of amitriptyline and amphetamine to mixed-mode solid-phase microextraction in different test conditions

Environmental Sorption Behavior of Ionic and Ionizable Organic Chemicals

Traditionally our tools for environmental risk assessment of organic chemicals have been developed for neutral chemicals. However, many commercial chemicals are ionic or ionizable and require different tools and approaches for their assessment. In recent years this task starts to obtain increasing attention but our understanding for their environmental fate is still far behind that for neutral chemicals. This review first gives an overview on the principles that govern ionic partitioning in environmental systems which are more complex than the simple partition processes of neutral chemicals. Second, a summary of our current knowledge on various topics such as bioaccumulation, sorption in soils, and nonspecific-toxicity reveals that ionic species can actually be quite hydrophobic contrary to commonly held beliefs. Eventually, we discuss existing models for the quantitative prediction of organic ions' sorption in soils and biota. We have to assert that the available model tools are quite restricted in their application range compared to neutral chemicals which is due to the higher complexity of the various ionic sorption processes. In order to further advance our understanding more high-quality sorption data are needed with a focus on multivalent and zwitterionic ions in all partition systems as well as cations in biological matrices.

Recent advances in microextraction procedures for determination of amphetamines in biological samples

Amphetamine and its related derivatives have stimulant and hallucinogenic properties. Illegal use of these drugs is an increasing global problem resulting in significant public health and legal problems. Deaths have been reported after intake of these drugs due to overdose. It is important to determine the type and concentration of illicit drugs in biological samples. These compounds are found in complex matrices at low concentration levels. The microextraction techniques are dominant sample preparation procedure and they are widely accepted as the most labor-intensive part of the bioanalytical process. For this purpose, a survey of recent published advances in microextraction procedures for quantification of amphetamines in biological samples found in the different databases from 2008 to date will be conducted.

Mixed-mode chromatography in pharmaceutical and biopharmaceutical applications

Mixed-mode chromatography (MMC) is a fast growing area in recent years, thanks to the new generation of mixed-mode stationary phases and better understanding of multimode interactions. MMC has superior applications in the separation of compounds that are not retained or not well resolved by typical reversed-phase LC methods, especially for polar and charged molecules. Due to the multiple retention modes that a single MMC column can offer, often MMC provides additional dimension to a separation method by adjusting the mobile phase conditions. Mixed-mode media is also an effective way to clean up complex sample matrices for purification purposes or for sensitive detection of trace amounts of analytes. In this article, we discuss mixed-mode stationary phases and separation mechanisms and review recent advances in pharmaceutical and biopharmaceutical applications including the analysis and/or purification of counterions, small molecule drugs, impurities, formulation excipients, peptides and proteins.