Julita Malejko

A study on the selection of chemiluminescence system for the flow injection determination of the total polyphenol index of plant-derived foods.

Different chemiluminescence systems based on luminol, permanganate, manganese(IV) and cerium(IV) reagents were compared regarding their sensitivity and selectivity to determine plant polyphenols. Among the seventeen systems tested, Mn(IV)-formaldehyde-hexametaphosphate was considered to be the most suitable for polyphenols detection. The developed flow injection method (FI-CL) based on enhancing effect of polyphenols on Mn(IV) chemiluminescence is characterised by low detection limit of gallic acid (0.02μgL(-1)) and high precision (RSD=1.7%). The calibration graph was linear from 0.1 to 100μgL(-1). The selectivity studies revealed that the FI-CL method ensures accurate determination of the total polyphenols content in food samples. The method was successfully applied to analysis of a variety of plant-derived foods (wine, tea, cereal coffee, fruit and vegetable juices, herbs and spices). The proposed method is superior to conventional spectrophotometric assays due to its higher sample throughput (195samplesh(-1)), simplicity, sensitivity and, above all, higher selectivity.

A novel flow-injection method for the determination of Pt(IV) in environmental samples based on chemiluminescence reaction of lucigenin and biosorption.

A new flow-injection chemiluminescence method (FI-CL) was developed for the determination of trace amounts of Pt(IV). The method is based on the quenching effect of the analyte on CL emission generated by lucigenin in alkaline solution. Application of a column filled with an algae Chlorella vulgaris immobilized on Cellex-T resin allowed to preconcentrate and separate the Pt(IV) ions from complex environmental samples, such as road dust. The developed method is simple and does not require sophisticated instrumentation. It is also characterized by a very low limit of detection (0.1ngmL(-1)), good sensitivity and precision (RSD<3%). The accuracy of the presented method was confirmed by analysis of a certified reference material of tunnel dust (BCR-723). The content of Pt in road dust samples collected in Białystok (Poland) in 2009 determined by the evaluated method was 351.8+/-54.6ngg(-1) and was higher than in samples collected in years 2000 and 2003.

Determination of the total polyphenolic content in Cirsium palustre (L.) leaves extracts with manganese(IV) chemiluminescence detection.

It was found that weak chemiluminescence of manganese(IV)-hexametaphosphate-formaldehyde system was greatly enhanced by plant polyphenolic compounds. Based on this finding, a new flow injection chemiluminescence method (FI-CL) was developed for the determination of the total content of polyphenols in plant extracts. The calibration graph obtained for standard solutions of 6-hydroxyluteolin 7-O-glucoside (6OHLG) was linear in the range 0.001-0.8 μg mL(-1). The method was simple, rapid (203 samples h(-1)) and sensitive with a detection limit of 0.25 ng mL(-1). The FI-CL method was successfully applied to the determination of the total polyphenols content (as 6OHLG equivalents) in methanolic, ethyl acetate and aqueous extracts from leaves of Cirsium palustre (L.). Two types of solvent extraction methods (reflux and ultrasound assisted extraction) were used and compared in terms of extraction efficiency. A positive, significant linear correlation between the results obtained by FI-CL method and spectrophotometric methods was observed.

Determination of polyphenolic compounds in Cirsium palustre (L.) extracts by high performance liquid chromatography with chemiluminescence detection

The first method for the simultaneous determination of polyphenolic antioxidants in extracts from leaves of Cirsium palustre based on high performance liquid chromatography combined with flow injection chemiluminescence detection (HPLC-FI-CL) has been developed. The extracts were prepared by using methanol as extraction medium and two types of extraction methods (reflux and ultrasound assisted extraction). The post-column CL determination of polyphenols was based on their enhancing effect on the chemiluminescence intensity generated in manganese(IV)-hexametaphosphate-formaldehyde system in a phosphoric acid medium. Main antioxidants determined in C. palustre leaves were eriodictyol-7-O-glucoside, luteolin-7-O-glucoside and 6-hydroxyluteolin-7-O-glucoside belonging to flavonoids, and chlorogenic acid belonging to phenolic acids. Chromatographic separation was carried out on a C18 column with gradient elution by using a mobile phase containing 0.25% (v/v) phosphoric acid in water (solvent A) and 100% methanol (solvent B). Under the optimized conditions of chromatographic separation and CL detection the validation of the method was performed. The calibration curves showed good linearity in the concentration range from 0.5 to 40 µg mL(-1). The HPLC-FI-CL method was successfully applied to the determination of four polyphenolic compounds in methanolic extracts from leaves of C. palustre. The accuracy of the developed method was confirmed by the comparison of the results with those obtained by an HPLC-PDA method. The relative error of determination does not exceed 6.1%. However, the HPLC-FI-CL method is characterized by 40-65 times higher sensitivity compared to the HPLC-PDA method.

On the effect of hydrogen peroxide on the flow-injection determination of platinum based on luminol chemiluminescent reaction

Abstract A flow‐injection chemiluminescent (CL) method for the determination of trace amounts of Pt(IV) based on the oxidation reaction of luminol in alkaline solution is proposed. The effect of Pt(IV) on the oxidation of luminol was studied in the absence and in the presence of hydrogen peroxide. The positive effect of hydrogen peroxide as well as chloride ions on the sensitivity of measurements was observed. The developed method is characterized by a low limit of detection of Pt (LOD=0.06 ng mL−1) and good reproducibility (RSD=2.2%). The addition of hydrogen peroxide to the reaction medium resulted in decreasing of platinum detection limit to 0.03 ng mL−1.

Post-column determination of polyphenolic antioxidants in Cirsium vulgare (Savi) Ten. extracts

Novel methods for the determination of polyphenolic antioxidants present in extracts from inflorescences of Cirsium vulgare (Savi) Ten. based on ultra-high performance liquid chromatography with photodiode array and chemiluminescence detection have been developed. Under the optimized conditions of chromatographic separation the analytical characteristic of the method was performed. The proposed method was successfully applied to the determination of ten polyphenols present in inflorescences of Cirsium vulgare. A comparison of the contents of analytes in extracts prepared by using various extraction media (methanol, ethanol, 70% methanol, 70% ethanol, and water) was carried out for the first time. For the postcolumn detection of scavenging activity of polyphenolic antioxidants against reactive oxygen species (H2 O2 , • OH, O2• - ) three systems based on chemiluminescence of luminol were used. A review of the current scientific literature shows that this is the first report on the application of luminol-based postcolumn detection for the on-line investigation of • OH scavenging activity. The main compound determined in extracts from inflorescences of Cirsium vulgare was apigenin 7-O-glucuronide, whereas the highest antioxidant activity was observed for chlorogenic acid, luteolin 7-O-glucoside, and apigenin.

Appraisal of Biosorption for Recovery, Separation and Determination of Platinum, Palladium and Rhodium in Environmental Samples

The potential of metal sorption by certain types of biomass provides the basis for the development of a new approach to remove heavy metals when they are present at low concentration. Seaweeds, fungi, yeast, bacteria and other native biomaterials, such as industrial and agricultural wastes and compounds derived from plant and animal tissues (e.g. lignin, tannin, chitin and chitosan), can be used as metal sorbents. The literature review shows that in the case of biomaterials of plant and animal origin mainly basic investigation on the biosorption mechanism, kinetics and thermodynamics of biosorption process using standard solutions of platinum group elements was described. For the recovery of these metals from real effluents and waste materials different types of microorganisms were applied. Due to good sorption performance and high selectivity, microorganisms were also used in analytical application for the separation and preconcentration of metals from interfering matrix before their determination by spectrometric techniques. In this book chapter the employment of biosorption processes for removal/recovery of platinum, palladium and rhodium from wastes and the procedures of their determination in environmental samples using biosorption process and different detection techniques are presented and discussed.