Highlighted articles (November 12, 2014)

We recommend the following articles that deal with different aspects related to sample preparation.

1. Development of combined salt- and air-assisted liquid–liquid microextraction as a novel sample preparation technique. Air assisted liquid-liquid microextraction is an interesting technique that uses air to assist the dispersion of the extractant solvent into the sample. It is usually performed by adding a small volume of extractant to the sample, the resulting mixture being sucked several times by a glass syringe. The process generates an efficient dispersion of the solvent and a final centrifugation is required to recover the acceptor phase for its final analysis. In this article, the authors face up the phases separation using a gas stream to break the emulsion and to recover a low volume of organic solvent (typically 10 µL). This proposal has been evaluated for the determination of β-naphtol, naphthalene and anthracene in water and wastewater. This article merits attention and you can read it freely for the next few weeks at this link.

2. Aptamer functionalized SPME–LC- tamdem MS for selective enrichment and determination of thrombin. Aptamers, which are nucleic acids or peptides that can bind target molecules with high affinity and specificity, are promising materials in Analytical Chemistry in general and in the microextraction filed in particular. Prof. Pawliszyn group has already proposed the use of aptamers as selective receptors in solid phase microextraction, using the determination of thrombin in serum as proof-of-concept. A stainless steel wire is coated by electrospinning with a polymeric mat of poly(acrylonitrile-co-maleic acid). The monomer composition and ratio defines the stability of the coating and its hydrophilicity, the latter aspect being essential for the immobilization of the aptamer. The resulting fiber demonstrated high selectivity towards the analyte when it is compared with other potential interferents like prothrombin, hemoglobin, cytochrome C and human serum albumin. Although the extraction capacity of the fiber resulted to be low in plasma samples, this problem can be avoided diluting the sample. This article presents a powerful combination and you can read it at this link.

3. A needle extraction utilizing a molecularly imprinted-sol–gel xerogel for on-line microextraction of the lung cancer biomarker bilirubin from plasma and urine samples. Dr. M. Abdel-Rehim and collaborators have already presented an interesting extraction unit for the selective extraction of bilirubin from plasma and urine samples. The unit consists of a needle whose inner surface is coated with a thin film of molecularly imprinted xerogel synthesized by sol-gel reaction of 3-(propylmethacrylate) trimethoxysilane. The new coating presents recognition potential when it is compared with the non-imprinted polymer. In addition, it can be reused up to 100 times with a negligible effect on the extraction performance. Read this article at this link.