Magdalena Biesaga

Porphyrins in analytical chemistry. A review

The porphyrins, naturally occurring macrocyclic compounds, have, in the last 10 years, gained increasing interest in analytical chemistry. This review based on 123 original literature references, mostly published in the 1990s, presents catalytic applications of metalloporphyrins in electroanalysis as electroactive agents in ion selective membranes, as unique reagents in spectrophotometry and as new stationary phases offering unusual resolution in HPLC. The collected data are also presented in four tables.

Solid-phase extraction procedure for determination of phenolic acids and some flavonols in honey

The solid-phase extraction procedure (SPE) for isolation and preconcentration of phenolic acids (gallic, p-HBA, p-coumaric, vanillic, caffeic and syringic acid) and some flavonols (rutin, quercetin and kaempferol) from honey samples prior to their determination by HPLC is reported. Different solid sorbents such as Bond Elut octadecyl C(18), Oasis HLB, Strata-X and Amberlite XAD-2 were tested for this purpose. The best results were obtain when aqueous solution of honey (100 mL) was adjusted to pH 2 and passed through the microcolumn containing 2.5 g of Oasis HB followed by washing the sorbent with 50 mL of acidified water (pH 2). The analytes were then eluted with methanol. The proposed method permits the quantification of the studied compounds with the limit of detections ranged from 25 ng kg(-1) to 0.75 microg kg(-1) for p-HBA and quercetin, respectively. The precision of the overall analytical procedure was estimated by measuring the within-day repeatability and the relative standard deviations of the parallel (n=3) results were in the range of 1.9-10.1%. The method was tested for real honey samples from different botanical origins.

Liquid chromatography/tandem mass spectrometry studies of the phenolic compounds in honey ☆

An improved and simplified analytical method which offers rapid, accurate determination and identification of phenolic compounds in honey samples is reported. The honey samples were diluted by acidified water (pH 2), and analyzed by HPLC-ESI-MS/MS. Simultaneously determination of phenolic acids and flavonoids was carried out by a liquid chromatography-mass spectrometry. Comparison between atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) was performed by analysis of standards. Fragmentation of analytes for subsequent selective Multiple Reaction Monitoring (MRM) analysis was investigated in negative mode. Sample preparation without separation of sugars and clean-up procedure, followed by fast chromatographic separation using a narrow-bore column C18 (50 mm x 2.1 mm, 3 microm) allowed the analysis to be completed in a short run time. LODs were ranged between 1 and 15 ng L(-1) for p-coumaric acid and naringenin, respectively. The method was applied for determination of phenolic acids and flavonoids in honey samples from different botanical origin.

Stability of bioactive polyphenols from honey during different extraction methods.

The LC-MS/MS technique was applied to the stability study of several flavonoids and phenolic acids in honey samples during the ultrasonic extraction (USE) and microwave-assisted extraction (MAE). Phenolic compounds from the standard mixture were stable under ultrasounds action with the mean recovery of (90.4%±7.1%), but during microwave-assisted extraction the benzoic acid derivatives and aglycones of flavonoids showed lower recovery (70-80%). In honey matrix, the phenolic acids and the glycosides exhibited the high stability for MAE and USE treatments. However, the recoveries of tested aglycones were below 10%. In the presence of an artificial sugar matrix, flavonols were almost completely degraded after successive treatment under MAE and USE conditions. The obtained results indicated that standard addition method for flavonoids quantification in honey samples should not be recommended. Application of the USE conditions provided higher and/or similar extraction yields for phenolic acids than usually applied shaking with solvent. It also allowed shortening the time required for the whole sample preparation procedure. Phenolic acids and glycosides such as quercetrin, rutin and hesperidin appeared to be stable under such conditions.

Separation of chlorine-containing anions by ion chromatography and capillary electrophoresis

Chlorine is still commonly used as disinfectant in water and waste treatment and as bleaching agents in the paper industry. In these processes, numerous chlorine-containing anions are formed with different oxidation states, such as chloride, chlorite, chlorate and perchlorate. The present study is focused on the development of a single-column ion chromatography (SCIC) method and the use of capillary electrophoresis (CE) for the determination of chlorine anions in water at a concentration level up to 25 mg/l for IC and 20 mg/l for CE in the presence of nitrate and sulphate.

Characterisation of honeys according to their content of phenolic compounds using high performance liquid chromatography/tandem mass spectrometry

A simple, fast and specific high performance liquid chromatography separation with an electro-spray ionisation tandem mass spectrometry detection in a negative single reaction ion monitoring scan mode was developed and used for the characterization of Polish honeys according to the content of phenolic acids, including caffeic, chlorogenic, p-coumaric, ferulic, homogentisic, p-hydroxybenzoic and vanillic acids, and flavonoids, i.e., apigenin, genistein, hesperetin, kaempferol, luteolin, rhamnetin, rutin, tricetin and quercetin. Target compounds were isolated and pre-concentrated from the honey matrix by means of the solid phase extraction using Strata X (500mg) cartridges. Analysed honeys did not contain tricetin and genistein. Hesperetin was determined for the first time in heather and linden honeys while rutin in rape honey.

Identification of Natural Dyestuff in Archeological Coptic Textiles by HPLC with Fluorescence Detection

Abstract High performance liquid chromatography with UV–Vis detection and post-column derivatization with fluorimetric detection was used for analysis of dyes used in Coptic textiles. To obtain the best separation of analyzed compounds composition of mobile phase was optimized. The best results were obtained for 25 mM phosphoric buffer at pH 2.5 with gradient change of methanol concentration (Table 1). As post-column reagents used to enhance fluorescence signal of analyzed compounds, solutions of Al(III), Ga(III), In(III), and Zn(II) were used. The highest increase of fluorescence signal was observed for Ga(III) and 10 mM solution of this ion was used for investigation of plant extracts and extracts from Coptic textiles.

Historical and archaeological textiles: an insight on degradation products of wool and silk yarns.

The characterisation of micro-samples from works of art and archaeological residues is a particularly complex task, due to the fact that only a relatively low amount of material is available for sampling, and compounds both derived from the target analytes and the matrix can be simultaneously present. Thus, sensitive, selective and reliable analytical procedures need to be developed. This paper presents the optimisation of an instrumental procedure based on liquid chromatography with mass spectrometric detection, which allows for determining selected analytes (anthraquinones, tannins, flavonoids), along with their known degradation products: phenolic acids. The instrumental parameters were optimised in terms of selecting the best ionisation source (APCI and ESI were compared), choosing the compound-dependant MS parameters and enhancing selectivity and sensitivity (SIM and MRM analyses were compared). The proposed procedure proved to be sensitive and selective, with limits of detection (0.4-20 ng/mL). The analytical procedure was validated by characterising reference materials, i.e. dyed and undyed woollen and silk yarns, both freshly prepared and artificially aged. Particularly, the study focused on the determination of 4-hydroxybenzoic acid, and on the correlation between its relative amounts with respect to ageing time. The optimised procedure was also applied to historical samples and proved fundamental in unravelling the complex composition of black dyed yarns collected from a medieval tapestry. The much degraded yarns were dyed with a tannin based dye, extracted from gallnuts, alder bark or sumac; the less degraded ones were coloured by superimposing colours with cochineal, madder, weld and indigo dye baths, and eventually by adding gallo-tannins as well.

Suitability of three-dimensional synchronous fluorescence spectroscopy for fingerprint analysis of honey samples with reference to their phenolic profiles.

The suitability of a right-angle geometry three-dimensional synchronous fluorescence spectroscopy (3D-SFS) for the differentiation and classification of different honey types, including acacia, buckwheat, heather, linden, multiflower and rape honeys, was evaluated with reference to their phenolic profiles. The fraction of phenolic compounds was initially isolated and pre-concentrated from analyzed samples by means of polymeric reversed phase Strata X solid phase extraction (SPE) cartridges. A thoughtful analysis of 3D-SF spectra of resulting methanolic extracts of honey samples containing the separated fraction of phenolics and standards of phenolic acids and flavonoids revealed that the proposed methodology based on SPE and 3D-SFS is capable of discriminating honey samples due to different floral sources in a fast and straightforward way.

Analytical Procedures for Determination of Quercetin and its Glycosides in Plant Material

Quercetin and its glycosides are widely distributed in the plant kingdom and belong to the most abundant of the flavonoid molecules. Besides their important biological roles in plant pigmentation, these flavonols possess anti-cancer and anti-inflammatory properties, which are the consequence of their affinity for proteins and their anti-oxidant properties. The content of quercetin and its glycosides in different plants have been summarized in various papers, although quantitative data are not so reliable due to the wide diversity of extraction and determination procedures. The general analytical strategy involves the isolation from a sample matrix followed by separation, identification and measurement. The recovery step usually involves solvent extraction using a range of solvents. Separation is commonly achieved by high-performance liquid chromatography (HPLC) and capillary electrophoresis. This paper intends to present and discuss the analytical procedures for determination of quercetin—aglycone as well as its conjugates—in different plant materials by means of routine and more recently developed separation techniques. Selected applications are included to illustrate the scope and limitations of the various approaches.