Pawel Pohl

Quality of the Trace Element Analysis: Sample Preparation Steps

Current status of elemental analysis performed using atomic spectroscopy techniques is to reach the best results in the shortest time and with minimal contamination and reagent consumption. Various spectroscopic methods such as flameand graphite furnace atomic absorption spectrometry (Fand GF-AAS), inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) have been used for many years for determination of elements, since they met needs required in analytical applications. Constant progress in detector technology can still been observed, e.g. in terms of lowering quantification limits. Despite these advantages, quality of results does not follow the same tendency and sample preparation is recognized to be a critical point and the most important error source in modern analytical method development. This is especially true for solid samples that have to be brought into solution before measurements. It is dictated by instrumentation requirements dedicated to analysis of liquid samples. Determination of analyte concentrations in solid materials is not an easy task and several factors should be considered in order to minimize uncertainty in sample preparation and to achieve real objectives of analysis. It includes sample type and its matrix composition responsible mainly for the degree of difficulties during sample preparation and analyte determination. Therefore, the good choice of sample treatment and confidence of its application become a key ensuring to obtain reliable results.

Rapid eradication of bacterial phytopathogens by atmospheric pressure glow discharge generated in contact with a flowing liquid cathode

Diseases caused by phytopathogenic bacteria are responsible for significant economic losses, and these bacteria spread through diverse pathways including waterways and industrial wastes. It is therefore of high interest to develop potent methods for their eradication. Here, antibacterial properties of direct current atmospheric pressure glow discharge (dc‐APGD) generated in contact with flowing bacterial suspensions were examined against five species of phytopathogens. Complete eradication of Clavibacter michiganensis subsp. sepedonicus, Dickeya solani, and Xanthomonas campestris pv. campestris from suspensions of OD600u2009≈u20090.1 was observed, while there was at least 3.43 logarithmic reduction in population densities of Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum. Analysis of plasma‐chemical parameters of the dc‐APGD system revealed its high rotational temperatures of 2,300u2009±u2009100u2009K and 4,200u2009±u2009200u2009K, as measured from N2 and OH molecular bands, respectively, electron temperature of 6,050u2009±u2009400u2009K, vibrational temperature of 4000u2009±u2009300u2009K, and high electron number density of 1.1u2009×u20091015u2009cm−1. In addition, plasma treatment led to formation of numerous reactive species and states in the treated liquid, including reactive nitrogen and oxygen species such as NOx, NH, H2O2, O2, O, and OH. Further examination revealed that bactericidal activity of dc‐APGD was primarily due to presence of these reactive species as well as to UVA, UVB, and UVC irradiation generated by the dc‐APGD source. Plasma treatment also resulted in an increase in temperature (from 24.2 to 40.2u2009°C) and pH (from 6.0 to 10.8) of bacterial suspensions, although these changes had minor effects on cell viability. All results suggest that the newly developed dc‐APGD‐based system can be successfully implemented as a simple, rapid, efficient, and cost‐effective disinfection method for liquids originating from different industrial and agricultural settings.

Development and optimization of simplified method of fast sequential HR-CS-FAAS analysis of apple juices on the content of Ca, Fe, K, Mg, Mn and Na with the aid of response surface methodology

A new method for fast sequential measurements of concentrations of Ca, Fe, K, Mg, Mn and Na in apple juices by high resolution-continuum source-flame atomic absorption spectrometry (HR-CS-FAAS) was developed using response surface methodology (RSM). By combination of Box-Behnken response surface design and desirability functions, compromise conditions of simplified sample preparation of apple juices, including 2-fold dilution with water and acidification with HNO3 to 0.8u202fmolu202fL-1, were established and verified that provided reliable results. The method was applied for analysis of 20 different samples of commercially sold apple juices. Precision (as relative standard deviation for 3 parallel samples, RSD) and accuracy (as relative error in relation to reference values obtained with prior wet digestion of samples) were very good, i.e. from 0.5% to 6% and from -5 to +u202f6%, respectively.

Understanding element composition of medicinal plants used in herbalism—A case study by analytical atomic spectrometry

HighlightsSources of elements in medicinal plants and herbs outlined.Sample treatment for element analysis of herbal decoctions and infusions surveyed.Spectrochemical element analysis of herbal decoctions and infusions reviewed.Ways of calibration and quality assurance of results discussed. ABSTRACT This review article is focused on element composition of medicinal plants and herbs as well as their decoctions and infusions determined by atomic spectrometry methods. Considering quality and safety of these herbal beverages, widely practiced in herbalism for medicinal and supplementing purposes, element analysis is important, and quality of its results should not raise any doubts about reliability. Hence, original researches devoted to element analysis of decoctions and infusions of medicinal plants and herbs, published after 2000, have been surveyed in details, particularly focusing on sources of elements in medicinal plants, their availability for the intake during preparation of infusions and decoctions as well as different methodological aspects related to element analysis by atomic spectrometry, including sample pretreatment and preparation before measurements, calibration methods used, and verification of reliability of results.

Influence of pH and low-molecular weight organic compounds in solution on selected spectroscopic and analytical parameters of flowing liquid anode atmospheric pressure glow discharge (FLA-APGD) for the optical emission spectrometric (OES) determination of Ag, Cd, and Pb

Atmospheric pressure glow discharge operated in contact with a flowing liquid anode (FLA-APGD), with the solution pH adjusted to pH 6.0 or pH 1.0, was performed to elucidate plasma-chemical processes and reactions occurring in the discharge and the liquid phase. The morphologies in the emission spectra of both FLA-APGD systems in reference to molecular (NO, OH, N2, and N2+) and atomic (H and O) excited species in addition to selected spectroscopic parameters, including the rotational, vibrational, and excitation temperatures and electron number density, were assessed for both discharge systems and compared with those evaluated for APGD operated in contact with a flowing liquid cathode (FLC-APGD). The effect of low-molecular weight (LMW) alcohols (methanol and ethanol) and carboxylic acids (formic acid and acetic acid) added to the FLA solution on the morphology of the spectra and spectroscopic parameters of both discharge systems was studied as well. The analytical performance of both FLA-APGD systems, compliant with the intensities of the atomic lines of Ag, Cd, and Pb, the signal-to-background ratios of these lines, and the detection limits of Ag, Cd, and Pb, under conditions of the absence and presence of the aforementioned LMW organic compounds was determined and compared. It was established that APGD operated in contact with FLA solutions acidified to pH 1.0 or buffered to pH 6.0 conferred a unique set of advantages as compared to the case of the FLC-APGD system. Both FLA-APGD systems were characterized by a large population of high energy electrons and molecular and atomic excited states not quenched by H2O vapor, as in the case of FLC-APGD. Particularly, for the FLA-APGD (pH 1.0) system, the addition of LMW organic compounds resulted in an improvement in its analytical performance for the detection and determination of Ag, Cd, and Pb.

Simple ICP-OES based method for determination of selected elements in brewed ground and soluble coffees prior to evaluation of their intake and chemical fractionation

A simple method of simultaneous determination of aluminum (Al), barium (Ba), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), strontium (Sr) and zinc (Zn) in brews of ground and soluble coffees was proposed. It relied on acidification of brews with HNO3 to 1.3u202fmolu202fL-1 and their analysis by inductively coupled plasma optical emission spectrometry. Precision of 0.1-9% and detection limits from 0.07u202fngu202fmL-1 (Sr) to 3u202fngu202fmL-1 (Ni) were achieved. Trueness of the method was verified by comparison of results with those achieved with wet digestion and by the recovery study, and was better than 5%. Additionally, chemical fractionation by tandem solid phase extraction with reverse-phase and strong cation-exchange extraction tubes was carried out. Differences in chemical fractionation patterns, particularly the residual fraction, was useful for differentiation of ground and soluble coffees by analysis of variance, principle component analysis and hierarchical clustering analysis.