Characterization of natural organic colorants in historical and art objects by high‐performance liquid chromatography

High‐performance liquid chromatography plays an important role in analysis of historical organic colorants. A number of papers have been published in this field over the last 30 years. Classification of the most commonly used natural dyes and an overview of high‐performance liquid chromatography methods with main focus on recent works (2008 to the beginning of 2014) are provided. The review deals with an entire analytical protocol covering sample preparation, chromatographic separation, and suitable detection (UV/visible and fluorescent spectroscopy and mass spectrometric techniques). High‐performance liquid chromatography has been successfully used in the complete characterization of some organic dyestuffs present in historical and art objects. The possibilities and difficulties for identification of natural sources of historical colorants are also discussed.     

CIEF separation,UV detection,and quantification of ampholytic antibiotics and bacteria from different matrices

The effect of antibiotics on the microbial cells and concentration of antibiotics in the human body is essential for the effective use of antimicrobial therapy. The capillary isoelectric focusing is a suitable technique for the separation and the detection of bacteria, and amphoteric substances from nature. However, the determination of isoelectric points of ampholytic antibiotics by conventional techniques is time consuming. For this reason, capillary isoelectric focusing seems to be appropriate as a simple and reliable way for establishing them. The separation conditions for the capillary isoelectric focusing of selected ampholytic antibiotics with known isoelectric points and pK _as, ampicillin (pI 4.9), ciprofloxacin (pI 7.4), ofloxacin (pI 7.1), tetracycline (pI 5.4), tigecycline (pI 9.7), and vancomycin (pI 8.1), were found and optimized in the suitable pH ranges pH 2.0–5.3, 2.0–9.6, and 9.0–10.4. The established values of isoelectric points correspond with those found in the literature except tigecycline. Its pI was not found in the literature. As an example of a possible procedure for direct detection of both ampholytic antibiotics and bacteria, Staphylococcus epidermidis, in the presence of culture media or whole human blood, was found. The changes of the bacterial cells after their treatment with tetracycline were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Capillary isoelectric focusing allows the fast and simple determination of isoelectric points of relevant antibiotics, their quantification from the environment, as well as studying their effectiveness on microorganisms in biological samples. Graphical Abstract

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Lead Film Electrode Prepared with the Use of a Reversibly Deposited Mediator Metal in Adsorptive Stripping Voltammetry of Nickel

The paper presents the first report on application of a “hybrid” lead film electrode for the adsorptive stripping voltammetric determination of Ni(II) in the presence of nioxime as a complexing agent. The strategy to create a “hybrid” electrode is based on the combination of ex situ and in situ plating methods and the use of a reversibly deposited mediator metal (Zn) for the lead film formation. The surface morphology of a new sensor was characterized by atomic force microscopy. The detection limit for Ni(II) obtained at 120 s of accumulation time was 3.9×10^?11 mol L^?1. The proposed method was validated for the determination of nickel in water certified reference materials with good results.     

Stability of poly(l‐lactic acid) in textile applications

The present paper is focused on the use of promising bio‐based thermoplastic—poly(l ‐lactic acid)—in textile applications and with possible limits related to its enhanced sensitivity to (bio)degradation. Linear and planar fabrics made of staple were exposed to standard washing cycles imitating the maintenance of textile materials. The effect of temperature and pH of the washing bath on the degradation rate of poly(l ‐lactic acid) was monitored by the abiotic hydrolysis test. The properties of the fabrics after carrying out the tests were evaluated from the changes of mass per areal weight, strength, and morphology of the fabrics. The changes of the structure of the polymer chains were assessed by differential scanning calorimetry, by the decrease of molar masses (determined using size exclusion chromatography) and of the viscosity of the polymer solutions, and by infrared spectroscopy. Poly(l ‐lactic acid) fabric finds application for various kinds of garments, and untreated fabric reliably tolerates 60 standard washing cycles. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of Racemic Ketorolac,Ketorolac Enantiomers and Their Metabolites in Human Plasma and Urine by LC–UV,Applied in Clinical Study During and After Pregnancy

In order to enhance the sensitivity and to develop a faster direct method for plasma and urine quantification of racemic ketorolac, its metabolites (p-hydroxy-ketorolac and ketorolac glucuronides) and ketorolac enantiomers, we developed an extraction procedure based on solid-phase extraction combined with specific and fast chromatographic separation. Extraction and chromatography resulted in cleaner chromatograms without interfering compounds. In both plasma and urine, linearity of the standard curves for racemic ketorolac and p-hydroxy-ketorolac was validated in the concentration range 0.025–10 mg L⁻¹, while for ketorolac enantiomers in the concentration range 0.025–5 mg L⁻¹. The lower limit of quantification was two times lower than in earlier described methods. The developed method was suitable for direct quantification of racemic ketorolac, p-hydroxy-ketorolac and ketorolac enantiomers in plasma and urine samples in women at delivery and in postpartum, enabling us to document significant intra-individual differences in pharmacokinetics between these physiological states.

     

Terminology Related to the Phenomenon ‘Self‐Disproportionation of Enantiomers’ (SDE)

Terms related to the phenomenon self‐disproportion of enantiomers (SDE) are discussed, particularly with respect to recently suggested alternative terms. Of the numerous terms proffered to describe this phenomenon, it is recommended that the acronym SDE be retained based on its qualities and the fact that its perceived shortcomings are invalid. The term can be readily applied to any process that exhibits the phenomenon of transforming a scalemic sample into fractions containing different enantiomeric compositions in comparison to the enantiomeric composition of the starting sample, and is not restricted solely to chromatographic occurrences. Chromatographic observations, though, can be specifically described by the term enantiomer self‐disproportionation over achiral chromatography (ESDAC). Use of the term homochiral in concert with its intended original meaning is also advocated.     

Electrolyte system for fast preparative focusing in wide pH range based on bidirectional isotachophoresis

In this paper, we suggest new electrolyte system for fast preparative electrofocusing in wide pH range. It is based on bidirectional ITP with multiple counterions and spacers created by commercially available defined simple buffers. The migration course of proposed focusing model can be simulated in advance by using separation conditions and electrolyte components that are consequently applied during the experiments. The suggested electrolyte system allows high current densities at the initial stages of focusing without danger of local overheating, which strongly reduces the time needed for analysis completion. The performance of the electrolyte system is demonstrated by the focusing of synthetic colored low molecular weight indicators and proteins in the arrangements with both linear narrow strip and nonwoven fabric sheet with continuous flow.