Anna Dzimitrowicz

Direct elemental analysis of honeys by atmospheric pressure glow discharge generated in contact with a flowing liquid cathode

Miniaturized atmospheric pressure glow discharge sustained in a compact discharge cell in contact with a flowing liquid cathode was used for the elemental analysis of honeys by optical emission spectrometry. A simplified sample preparation procedure was proposed and samples of honeys were only dissolved in water and acidified with HCl to a concentration of 0.10 mol L−1. The resulting 1.0% m/v in the case of K and Na and 5.0% m/v in the case of Ca, Cu, Fe, Li, Mg, Mn, Rb and Zn solutions of honeys were directly introduced into the discharge cell acting as the liquid cathode of the discharge. To eliminate matrix effects coming from fructose and glucose, a non-ionic surfactant (Triton X-405) was added to the solutions and this resulted in improved signals of studied elements. For calibration, simple (for K and Na) and matrix-matching (for other elements) standard solutions were used. The method was proved to give reliable results and applied in the analysis of 16 commercial white- to amber-colored honeys with limits of detection at levels of 1.0 (Ca), 0.7 (Cu), 2.5 (Fe), 0.5 (K), 0.02 (Li), 0.2 (Mg), 1.8 (Mn), 0.04 (Na), 0.1 (Rb) and 0.2 (Zn) μg g−1.

The determination of elements in herbal teas and medicinal plant formulations and their tisanes

Elemental analysis of herbal teas and their tisanes is aimed at assessing their quality and safety in reference to specific food safety regulations and evaluating their nutritional value. This survey is dedicated to atomic spectroscopy and mass spectrometry element detection methods and sample preparation procedures used in elemental analysis of herbal teas and medicinal plant formulations. Referring to original works from the last 15 years, particular attention has been paid to tisane preparation, sample matrix decomposition, calibration and quality assurance of results in elemental analysis of herbal teas by different atomic and mass spectrometry methods. In addition, possible sources of elements in herbal teas and medicinal plant formulations have been discussed.

Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles

A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO3 solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

Production of gold nanoparticles using atmospheric pressure glow microdischarge generated in contact with a flowing liquid cathode - a design of experiments study

Direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between a miniature flow Ar plasma microjet and a small-sized flowing liquid cathode (FLC) was characterized with respect to the effects of the selected operating factors on the particle size of the synthesized Au nanoparticles (AuNPs). The factors that were investigated were the discharge current, the flow rate of the solution of the FLC, and the flow rate of the Ar plasma microjet-supporting gas. The effects of the individual factors and their inter-factor dependencies on the size and size distribution of the synthesized AuNPs were evaluated by changing the operating conditions according to the Box–Behnken design (BBD) plan and monitoring the wavelength of the maximum (λmax) of the localized surface plasmon resonance (LSPR) absorption band. The response surface methodology (RSM) was used to fit the experimental data with an appropriate regression model and optimize the plasma-reactor system to produce spherical AuNPs having the lowest particle size and size dispersion. It was established that a high discharge current and a low flow rate of the solution of the FLC facilitated the production of spherical, uniform and the smallest in size AuNPs. The correctness of the model was validated by producing the AuNPs in optimal and non-optimal conditions and the analysis of the resultant nanofluids by UV-Vis absorption spectrophotometry, dynamic light scattering (DLS), and scanning electron microscopy (SEM).

Size-controlled synthesis of gold nanoparticles by a novel atmospheric pressure glow discharge system with a metallic pin electrode and a flowing liquid electrode

A direct current atmospheric pressure glow discharge (APGD) operated between a pin-type solid metallic electrode and the surface of a flowing solution (the liquid electrode), positively or negatively charged and serving as the flowing liquid anode (FLA) or cathode (FLC), was used for synthesizing gold nanoparticles (AuNPs). To the best of our knowledge, the synthesis of AuNPs in such a system, with no noble gas required to support the APGD, has never been reported. The effect of the selected operating parameters on the performance of the AuNPs synthesis in the plasma-reaction system with the FLA or FLC was examined. The design of the experiments (DOE) was conducted using the response surface regression (RSR) approach. The response of both systems was the wavelength of the maximum (λmax) of the localized surface plasmon resonance (LSPR) absorption band of the AuNPs. On the basis of the established full quadratic regression models, the optimal operating parameters for both plasma-reaction systems (with the FLA or the FLC) were selected, which allowed for the smallest in size spherical AuNPs to be obtained. Both regression models were validated, the AuNPs produced in both plasma-reaction systems under the optimal operating parameters were characterized by UV-Vis absorption spectrophotometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Application of Silver Nanostructures Synthesized by Cold Atmospheric Pressure Plasma for Inactivation of Bacterial Phytopathogens from the Genera Dickeya and Pectobacterium

Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized by pectins (PEC) or sodium dodecyl sulphate (SDS), using a direct current atmospheric pressure glow discharge (dc-APGD) generated in an open-to-air and continuous-flow reaction-discharge system. Characterization of the PEC-AgNPs and SDS-AgNPs with UV/Vis absorption spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed the production of spherical, well dispersed, and face cubic centered crystalline AgNPs, with average sizes of 9.33 ± 3.37 nm and 28.3 ± 11.7 nm, respectively. Attenuated total reflection-Fourier transformation infrared spectroscopy supported the functionalization of the nanostructures by PEC and SDS. Antibacterial activity of the AgNPs was tested against Dickeya spp. and Pectobacterium spp. strains. Both PEC-AgNPs and SDS-AgNPs displayed bactericidal activity against all of the tested isolates, with minimum inhibitory concentrations of 5.5 mg∙L−1 and 0.75–3 mg∙L−1, respectively. The collected results suggest that the dc-APGD reaction-discharge system can be applied for the production of defined AgNPs with strong antibacterial properties, which may be further applied in plant disease management.

Sensitive Determination of Cd in Small-Volume Samples by Miniaturized Liquid Drop Anode Atmospheric Pressure Glow Discharge Optical Emission Spectrometry

A novel liquid drop anode (LDA) direct current atmospheric pressure glow discharge (dc-APGD) system was applied for direct determination of Cd in liquid microsamples (50 μL) by optical emission spectrometry (OES). The microdischarge was generated in open-to-air atmosphere between a solid pin type tungsten cathode and a liquid drop placed on a graphite disk anode. The arrangement of the graphite disk placed on a PTFE chip platform as well as the solid pin type cathode was simple and robust. The limit of detection (LOD) of Cd for the developed LDA-APGD-OES method was 0.20-0.40 μg L-1, while precision (as the relative standard deviation for the repeated measurements) was within 2-5%. By using the liquid drop of 50 μL, the linearity range of 1-1000 μg L-1 was achieved. The effect of addition of the low-molecular weight (LMW) organic compounds, easily ionized elements (EIEs), i.e., Ca, K, Mg, and Na, as well as the foreign ions (Al, Cu, Fe, Mn, Zn) to the solution on the in situ atomization and excitation processes occurred during operation of the LDA-APGD system, and the response of Cd was studied. Validation of the proposed method was demonstrated by analysis of Lobster hepatopancreas (TORT-2), pig kidney (ERM-BB186), and groundwater (ERM-CA615) certified reference materials (CRMs) and recoveries of Cd from water samples spiked with 25 μg L-1 of Cd. Very good agreement between the found and certified values of Cd in the CRMs (the recoveries were within the range of 96.3-99.6%) indicated trueness of the method and its reliability for determination of traces of Cd. In the case of the spiked water samples, the recoveries obtained were in the range from 95.2 to 99.5%.

Pulse-Modulated Radio-Frequency Alternating-Current-Driven Atmospheric-Pressure Glow Discharge for Continuous-Flow Synthesis of Silver Nanoparticles and Evaluation of Their Cytotoxicity toward Human Melanoma Cells

An innovative and environmentally friendly method for the synthesis of size-controlled silver nanoparticles (AgNPs) is presented. Pectin-stabilized AgNPs were synthesized in a plasma-reaction system in which pulse-modulated radio-frequency atmospheric-pressure glow discharge (pm-rf-APGD) was operated in contact with a flowing liquid electrode. The use of pm-rf-APGD allows for better control of the size of AgNPs and their stability and monodispersity. AgNPs synthesized under defined operating conditions exhibited average sizes of 41.62 ± 12.08 nm and 10.38 ± 4.56 nm, as determined by dynamic light scattering and transmission electron microscopy (TEM), respectively. Energy-dispersive X-ray spectroscopy (EDS) confirmed that the nanoparticles were composed of metallic Ag. Furthermore, the ξ-potential of the AgNPs was shown to be −43.11 ± 0.96 mV, which will facilitate their application in biological systems. Between 70% and 90% of the cancerous cells of the human melanoma Hs 294T cell line underwent necrosis following treatment with the synthesized AgNPs. Furthermore, optical emission spectrometry (OES) identified reactive species, such as NO, NH, N2, O, and H, as pm-rf-APGD produced compounds that may be involved in the reduction of the Ag(I) ions.

Polymerization-Driven Immobilization of dc-APGD Synthesized Gold Nanoparticles into a Quaternary Ammonium-Based Hydrogel Resulting in a Polymeric Nanocomposite with Heat-Transfer Applications

A new method for the production of nanocomposites, composed of gold nanoparticles (AuNPs) and (vinylbenzyl)trimethylammonium chloride-co-N,N-methylene bisacrylamide (VBTAC-co-MBA) hydrogel, is described. Raw-AuNPs of defined optical and granulometric properties were synthesized using direct current atmospheric pressure glow discharge (dc-APGD) generated in contact with a solution of HAuCl4. Different approaches to the polymerization-driven synthesis of Au/VBTAC-co-MBA nanocomposites were tested. It was established that homogenous dispersion of AuNPs in this new nanomaterial with was achieved in the presence of NaOH in the reaction mixture. The new nanocomposite was found to have excellent heat-transfer properties.

Determination of Elements in Fruit Juices

Abstract This chapter deals with different aspects of elemental analysis of fruit juices by spectrometric methods. The most commonly applied analytical spectrometric methods, including flame and graphite furnace atomic absorption spectrometries, as well as inductively coupled plasma optical emission and mass spectrometries, are described. Different procedures of sample treatment of fruit juices prior to elemental analysis are presented with details. In addition, calibration methods and quality assurance procedures are surveyed.