Modern flow analysis

A brief overview of articles published in this Special Issue of Molecules titled “Modern Flow Analysis” is provided. In addition to cross-sectional and methodological works, there are some reports on new technical and instrumental achievements. It has been shown that all these papers create a good picture of contemporary flow analysis, revealing the most current trends and problems in this branch of flow chemistry

Analytical evaluation of the iron transfer from cigarette tobacco to human body

It was analytically examined how great amount of total iron can be absorbed during cigarette smoking. For this purpose, tobacco taken from cigarettes of selected brands (Marlboro, L&M, and Popular) was carefully analyzed before and after smoking. In addition, the cigarette filters were checked in terms of iron content. In all samples iron was determined by means of spectrophotometric method with sulfosalicylic acid. The method was realized with the aid of an original flow system allowing the analytical calibration to be performed with high reliability. As a result iron present in a sample in trace amount was able to be found with very good accuracy and with precision not exceeding 1.5% (in RSD). It was stated that typical amount of iron in a single cigarette is ranged between 0.3 and 0.4 mg. When smoking the risk should be taken into account that even 99% of this amount is transferred to human body without any chance to be limited by the cigarette filter

Determination of selenium as a biomarker of thyroid cancer by HG-AFS method

A simple and versatile procedure has been developed for the determination of selenium in biological samples for clinical purposes. The procedure consists of microwave sample digestion and the determination of selenium using atomic fluorescence spectrometry with a hydride generation system (HG-AFS). The method allows the determination of selenium in a range of 0.5–100.0 μg L–1 with a detection limit not higher than 0.2 μg L–1 and with good repeatability not exceeding 1%. It was applied for determination of selenium in women’s plasma samples (n = 90) with a suspicion of a thyroid cancer and the control group of women (n = 87). Most of the obtained results were in the range 30.0–60.0 μg L–1 and either did not match the physiological level of selenium in human plasma or indicate moderate selenium deficiency. In the further examinations the thyroid tissues taken from 30 patients were analyzed. In most of the cases the selenium concentration was found to be lower (0.14–1.67 μg g–1 wet weight) than its physiological level in a healthy tissue. On this basis the hypothesis has been drawn that selenium can be considered as an additional marker of the thyroid cancer disease

Capillary coating as an important factor in optimization of the off-line and on-line MEKC assays of the highly hydrophobic enzyme chlorophyllase

The choice between bare and coated capillaries is a key decision in the development and use of any methods based on capillary electrophoresis. In this work several permanently and dynamically coated capillaries were successfully implemented in a previously developed micellar electrokinetic chromatography (MEKC) assay of the plant membrane enzyme chlorophyllase. The results obtained demonstrate the rationale behind the use of capillary coating, which is crucial for successful optimization of both the off-line mode and the on-line/electrophoretically mediated microanalysis assay mode. The application of an amine permanently coated capillary (eCAP) is a simple way to significantly increase the repeatability of migration times and peak areas, and to ensure a strong electroosmotic flow that considerably decreases the overall analysis time. A dynamic coating (CEofix) allows one to apply an on-line incubation to control the reaction progress inside the capillary, and to increase the signal-to-noise ratio and peak efficiency. The dynamic coating is possible with use of both the normally applied uncoated silica capillary and the precoated amine capillary, which ensures more repeatable migration times. The strong points of the uncoated silica capillary are its attractive price and wide range of pH that can be applied. The characteristics presented may simplify the choice of capillary modification, especially in the case of hydrophobic analytes, MEKC-based separations, and other enzymatic assays. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00216-016-0097-5) contains supplementary material, which is available to authorized users