Current Analytical Chemistry - Volume 4, Issue 2, 2008

Anthocyanins are a class of polyphenols responsible for the orange, red, purple and blue colors of many fruits, vegetables, grains, flowers and other plants. Consumption of anthocyanins has been linked as protective agents against many chronic diseases and possesses strong antioxidant properties leading to a variety of health benefits. In this review, we examine the advances in the chemical profiling of natural anthocyanins in plant and biological matrices using various chromatographic separations (HPLC and CE) coupled with different detection systems (UV, MS and NMR). An overview of anthocyanin chemistry, prevalence in plants, biosynthesis and metabolism, bioactivities and health properties, sample preparation and phytochemical investigations are discussed while the major focus examines the comparative advantages and disadvantages of each analytical technique.

Accelerator mass spectrometry (AMS) has emerged as an important analytical tool in biomedical and pharmaceutical research. Its sensitivity (up to attomole, 10-18 levels), precision, low sample requirements and the ability to trace a biomarker over a prolonged period of time are valuable attributes. Metabolomic, kinetic, toxicokinetic and dosimetric studies of various chemical molecules, at environmental exposure levels and physiologically relevant doses, using radioisotopes (e.g. 14C, 3H, 26Al and 41Ca) are possible. AMS has contributed significantly to the understanding of DNA-adduct formation in carcinogenesis and is finding new uses in the changing drug development paradigm where more researchers are turning to biomarkers to predict functional and clinical outcomes in patients. Microdosing and first-in-human studies are also breakthroughs spearheaded by the innovative use of AMS. Recent advances see AMS driven into fields of phytochemical and nutritional research as well as clinical diagnosis and disease state monitoring. As a result of the high initial costs and forbidding size, developments in equipment miniaturization and enhanced sample throughput seek to overcome these barriers. AMS is expected to present new and exciting opportunities in biomedical research as its breadth of applications continues to expand. This article provides an insight into the pharmaceutical and biomedical applications of AMS.

Hydromorphone, a semi-synthetic derivative of morphine, is being used in the treatment of moderate to severe cancer-related and post-operative pain. It is also one of the most commonly prescribed drug that is often abused. Hence, its detection in biological samples and tissues is important for legal and therapeutic reasons. The purpose of this review is to give a brief description of the various non-chromatographic and chromatographic analytical techniques, namely immunoassays, thin layer chromatography, high performance liquid chromatography, liquid chromatography/mass spectrometry, gas chromatography/mass spectrometry and capillary electrochromatography, that have been used by analysts to assay hydromorphone from the early 1970s to present. This review aims to help the analytical community make efficient choices between various analytical methodologies based on concrete parameters of reliability, sensitivity, specificity, precision, accuracy, cost and potential for automation.

Immobilised metal affinity chromatography (IMAC) has become an established purification procedure for the selective isolation of proteins, peptides and post-translationally modified peptides, using a wide range of metal ions, including Cu(II), Fe(III) and Ga(III). Recently, the potential of interfacing capillary IMAC with mass spectrometry has been explored. This article reviews the development and use of IMAC in protein/peptide analysis, highlighting the benefits of capillary columns and their application to IMAC based enrichment.

The electrochemical reduction of 4-{[(1E)-(2-hydroxynaphthyl)methylidene]amino}-1,5-dimethyl-2-phenyl- 2,3-dihydro-1H-pyrazol-3-one (NAP) was studied by using cyclic voltammetry in acetonitrile media at a glassy carbon (GC) and modified GC electrodes. The GC electrodes were grafted by electrochemical reduction of diazonium salts of various organic molecules. GC surfaces modified with anthraquinone, p-nitrophenyl, p-aminophenyl, p-amino-N,Ndimethylphenyl and p-methoxyphenyl radicals were used to investigate the reduction behaviors of NAP. The effect of the modified glassy carbon electrodes on the reduction of NAP was studied as being related to the role of the electron donor or the electron acceptor groups on the phenyl ring attached to the surface. The compound NAP shows two reduction peaks in a cyclic voltammogram. These peaks were observed at -2.1 V and -2.7 V on the GC electrode surface. Also, the reduction peaks of NAP were obtained for all the modified electrodes studied. The p-methoxyphenyl modified GC electrode showed a significant increase in the rate of electron transfer at the reduction of NAP. The kinetics and the mechanism of the electrode process were simulated and some parameters were calculated using BAS Digi-Sim® software.

A review is presented on recent applications of experimental design and optimization techniques for the analysis of compounds of food, biomedical, toxicological and environmental concern. The main features and the significant advantages of chemometric approaches are discussed. Examples related to the determination of substances like xenobiotics, naturally occurring compounds and metals using different analytical techniques like inductively coupled plasma (ICP) sources, voltammetry and other techniques are provided in this Part. The use of experimental design techniques for optimization of extraction techniques is also emphasized. This survey will attempt to cover the state-of-the-art from 2004 to 2006.

A new method was developed for the determination of lomefloxacin by using flow-injection chemiluminescence( CL) based on the reaction of Ce(IV)-sodium thiosulfate-lomefloxacin-sulfuric acid system. The CL conditions were investigated and optimized. The CL intensity was correlated linearly with concentration of lomefloxacin in the range of 1.0x10-5∼6.0x10-2 g L-1. The determination limit (3σ) is 3x10-6 g L-1. The relative standard deviation is 1.9% for 11 measurements of 2.0x10-4 g L-1 lomefloxacin. The method has been applied satisfactorily to determine lomefloxacin in drugs, serum and urine with the recovery of 97.0%∼104.5%. The CL mechanism of the system was proposed.

This review updates knowledge on pressurized liquid extraction (PLE), a sample preparation technique that is increasingly used to extract moderately volatile and non-volatile organic pollutants from solid and semi-solid environmental matrices. In environmental analyses, therefore, it is mainly been used to analyse soils and sewage sludge, though it has also been used, albeit to a lesser extent, to analyse air samples. As interest in analysing contaminants in environmental solid samples has increased in recent years, more extraction methods are being developed. This review is divided into two parts. In the first part we discuss the main parameters affecting extraction, such as solvent, extraction time, temperature, pressure, number of cycles, flush volume and purge time. In the second part we review recent applications of PLE in environmental analysis and discuss the advantages of PLE over other extraction techniques such as ultrasonic solvent extraction and microwave assisted extraction.