The Use of an Acylhydrazone-Based Metal-Organic Framework in Solid-Contact Potassium-Selective Electrode for Water Analysis

A solid-contact ion-selective electrode was developed for detecting potassium in environmental water. Two versions of a stable cadmium acylhydrazone-based metal organic framework, i.e., JUK-13 and JUK-13_H2O, were used for the construction of the mediation layer. The potentiometric and electrochemical characterizations of the proposed electrodes were carried out. The implementation of the JUK-13_H2O interlayer is shown to improve the potentiometric response and stability of measured potential. The electrode exhibits a good Nernstian slope (56.30 mV/decade) in the concentration range from 10−5 to 10−1 mol L−1 with a detection limit of 2.1 µmol L−1. The long-term potential stability shows a small drift of 0.32 mV h−1 over 67 h. The electrode displays a good selectivity comparable to ion-selective electrodes with the same membrane. The K-JUK-13_H2O-ISE was successfully applied for the determination of potassium in three certified reference materials of environmental water with great precision (RSD < 3.00%) and accuracy (RE < 3.00%).

The <i>μ</i>Dose system: determination of environmental dose rates by combined alpha and beta counting – performance tests and practical experiences

The μDose system is a recently developed analytical instrument applying a combined α- and β-sensitive scintillation technique for determining the radioactivity arising from the decay chains of 235U, 238U and 232Th as well as from the decay of 40K. The device was designed to meet the particular requirements of trapped charge dating methods and allows the assessment of environmental (i.e. low) levels of natural radionuclides. The μDose system was developed as a piece of low-cost laboratory equipment, but a systematic test of its performance is still pending. For the first time, we present results from a comprehensive performance test based on an inter-laboratory comparison. We compare the results obtained with μDose measurements with those from thick source alpha counting (TSAC), inductively coupled plasma optical emission spectrometry (ICP-OES) and low-level high-resolution gamma spectrometry (HRGS) applied in five participating laboratories. In addition, the reproducibility and accuracy of μDose measurements were tested on certified reference materials distributed by the International Atomic Energy Agency (IAEA; RGU-1, RGTh-1 and RGK-1) and on two loess standards (Nussy and Volkegem) frequently used in trapped charge dating studies. We compare μDose-based results for a total of 47 sediment samples with results previously obtained for these materials by well-established methods of dose rate determination. The investigated natural samples cover a great variety of environments, including fluvial, aeolian, littoral, colluvial and (geo-)archaeological sites originating from high and low mountain regions as well as from lowlands in tropical areas, drylands and mid-latitude zones of Europe, Africa, Australia, Central Asia and the Americas. Our results suggest the μDose system's capability of assessing low-level radionuclide contents with very good accuracy and precision comparable to well-established dosimetry methods. Based on the results of our comparative study and with respect to the practical experiences gained so far, the μDose system appears to be a promising tool for trapped charge dating studies.

Development of a new highly sensitive and selective spectrophotometric method for the determination of selenium at nano-trace levels in various complex matrices using salicylaldehyde-orthoaminophenol

A new spectrophotometric reagent, salicylaldehyde-orthoaminophenol (Sal-OAP) has been synthesized and characterized for the determination of selenium through novel reaction techniques. Also, a new highly selective, and sensitive spectrophotometric method for the nano-trace determination of selenium using salicylaldehyde-orthoaminophenol (Sal-OAP) has been developed. Sal-OAP undergoes reaction in a slightly acidic solution (0.0001-0.0002 M H2S04) with selenium (IV) to give an orange-red chelate, which has an absorption maximum at 379 nm. The reaction is instantaneous and absorbance remains stable for over 24 h. The average molar absorption co-efficient and Sandell’s sensitivity were found to be 6.4×105 L/mol.cm and 1.0 ng/cm2 of, respectively. Linear calibration graphs were obtained for 0.001-40.000 mg/Lof Se having detection limit of 0.1 µg/L and RSD 0-2 %. The stoichiometric composition of the chelate is 1:2 (Se:Sal-OAP). A large excess of over 60 cations, anions and some common complexing agents, such as chloride, azide, tartrate, EDTA, SCN¯etc., do not interfere in the determination. The developed method was successfully used in the determination of selenium in several Certified Reference Materials (Alloys, steels, human urine, bovine liver, drinking water, tea, milk, soil, and sediments) as well as in some environmental waters (Potable and polluted), biological fluids (Human blood, urine, hair, and milk), soil samples, food samples (Vegetables, rice, and wheat) and pharmaceutical samples (Tablet and syrup) and solutions containing both selenium (IV) and selenium (VI) as well as complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetables and soil samples were comparable with ICP-OES and AAS were found to be in excellent agreement. The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L).

Microwave-Assisted Solid Sampling Analysis Coupled to Flame Furnace Atomic Absorption Spectrometry for Cd and Pb Determination in Food-Contact Polymers

Microwave-assisted solid sampling analysis coupled to flame furnace atomic absorption spectrometry (MW-SS-FF-AAS) was used for Cd and Pb determination in food-contact polymer samples, with the aim of minimizing reagents and laboratory waste. Operational parameters, such as the FF tube design, the oxygen flow rate, the flame stoichiometry, the sample mass, among others, were evaluated and optimized. Calibration was performed using only reference solutions, and the limits of quantification were 1.7 and 4.6 μg g−1 for Cd and Pb, respectively. Accuracy was assessed by the analysis of certified reference materials (CRMs), and by comparison with the results obtained by inductively coupled plasma mass spectrometry after microwave-assisted wet digestion. The MW-SS-FF-AAS results for the CRMs showed no statistical difference with the certified values, and good agreement was observed with the results of the digestion method. The MW-SS-FF-AAS method was considered suitable for Cd and Pb determination in food-contact polymers. The concentrations of Cd and Pb in the analyzed samples varied from <1.7 to 628 μg g−1, and from <4.6 to 614 μg g−1, respectively. As sample digestion is not necessary, the use of concentrated acids can be avoided by using the proposed MW-SS-FF-AAS method, greatly reducing waste generation.

Development of Genistein Synthesis for Use as a Certified Reference Material

Introduction. The use of certified reference materials (CRMs) ensures metrological traceability and comparability of analysis results performed in different laboratories, by different analysts, at different times. Genistein is a promising substance with a wide spectrum of pharmacological action. genistein is widely used in dietary supplements. Development of regulatory documents for CRM of genistein will ensure the quality of drugs and dietary supplements.Aim. Aim of our study is to improve of the ways of synthesis and determination of spectrum characteristics of genistein for the certification of CRM.Materials and methods. We used synthetic genistein, (Ph.D. V. Yu. Kovtun SPC "Pharmzashchita") (sample № 1) and genistein synthesized and studied at the departments of pharmaceutical chemistry and chemical technology of medicinal substances SPCPU (sample № 2). Infrared spectra of genistein samples were collected on an FSM 1201 infrared Fourier spectrometer (OOO Infraspek, Russia) via KBr pellets technique. All the spectra were collected in the 4000–500 cm−1 range. The NMR (1H and 13C) measurements were performed with a BrukerAvance III NMR spectrometer (400 and 100 MHz) (Bruker, Germany) in DMSO-d6 solvent. Raman spectra were recorded by an ORTES-785TRS-2700 analytical Raman scattering system at a laser power of 100 mW (OPTEC JSC, Russia). Laser interaction time was 5, 10, 20 and 60 seconds. The results were processed using the software "BWSpec 4.10_4", USA. GC-MS was performed on an Agilent Technologies 7890A gas chromatograph (Agilent Technologies, USA) with a 7693 autoinjector and a Hewlett Packard 5975C mass selective detector.Results and discussion. The synthesis was carried out according to the developer's method. The stage "removal of the alkyl protection" has been improved. The spectra of the synthesis intermediate of genistein (biochanin A) correspond to the literature data. Samples of genistein were investigated by methods: MC and NMR 13С, 1Н. The structure of the investigated substance was confirmed; Raman and IR spectroscopy showed that the spectra of the samples do not differ from each other and there are no additional signals.Conclusion. The spectrum characteristics of samples of genistein were obtained by NMR, IR and Raman spectroscopy, which will be used in the regulatory documentation for CRM of genistein. All of this will make it possible to control the quality of medicines based on it and to identify substandard dietary supplements.

Chemical characterization methods for biodegradable organic wastes with relevance for the composting process. Case study

The study aimed to develop some methods for the compositional characterization of biodegradable waste with relevance to the composting process at the laboratory level. For testing, four waste fractions were selected, such as waste-based on dehydrated sludge, waste from parks (leaves, branches), market waste (mixture of vegetable and fruit), and cardboard waste. For metals and phosphorus, several microwave digestion methods were applied. The ammonium nitrogen content (NH4-N) was determined using a number of extraction procedures (water, CaCl2, and KCl). Three certified reference materials were used for testing the validity of the results. Recovery percentages higher than 90% were obtained. The developed and validated methods are suitable for biodegradable waste characterization used in composting processes.

Determination of Some Elements in Legumes Using ICP-MS and EDXRF Methodology Applications

The current study involves two analytical research techniques, inductively coupled plasma-mass spectrometry (ICP-MS) and energy dispersive X-ray fluorescence (EDXRF) spectroscopy, used to determine the elemental composition of different legumes usually produced and consumed in Slovenia. Results indicate that data obtained using these methods are in agreement with certified reference materials. In total, nineteen elements were determined from twenty legume samples. An intercomparison between four macro- (P, S, K, Ca) and three microelements (Fe, Zn, Mo) measured using ICP-MS and EDXRF methods showed a strong correlation. The EDXRF was found to be a cheaper, simpler and more environmentally friendly method for determination of elements P, S, Cl, K, Ca, Fe, Zn, Mo, Sr, Rb, Ti and Br in legumes, while for the identification and determination of Na, Mg, V, Cr, Mn, Co and Cu content ICP‐MS was the method of choice due to its excellent sensitivity and accuracy. Using principal component analysis (PCA), the samples of the studied legumes were classified into four groups according to their elemental composition.

ICP-MS Measurement of Trace and Rare Earth Elements in Beach Placer-Deposit Soils of Odisha, East Coast of India, to Estimate Natural Enhancement of Elements in the Environment

Inductively coupled plasma mass spectrometry (ICP-MS) has been used to measure the concentration of trace and rare earth elements (REEs) in soils. Geochemical certified reference materials such as JLk-1, JB-1, and JB-3 were used for the validation of the analytical method. The measured values were in good agreement with the certified values for all the elements and were within 10% analytical error. Beach placer deposits of soils mainly from Odisha, on the east coast of India, have been selected to study selected trace and rare earth elements (REEs), to estimate enrichment factor (EF) and geoaccumulation index (Igeo) in the natural environment. Enrichment factor (EF) and geoaccumulation index (Igeo) results showed that Cr, Mn, Fe, Co, Zn, Y, Zr, Cd and U were significantly enriched, and Th was extremely enriched. The total content of REEs (ƩREEs) ranged from 101.3 to 12,911.3 µg g−1, with an average 2431.1 µg g−1 which was higher than the average crustal value of ΣREEs. A high concentration of Th and light REEs were strongly correlated, which confirmed soil enrichment with monazite minerals. High ratios of light REEs (LREEs)/heavy REEs (HREEs) with a strong negative Eu anomaly revealed a felsic origin. The comparison of the chondrite normalized REE patterns of soil with hinterland rocks such as granite, charnockite, khondalite and migmatite suggested that enhancement of trace and REEs are of natural origin.

Determination of Rare Earth Elements in Plant Samples by ICP-MS with Microwave Digestion

Method of microwave digestion using HNO3, HCl and HF in MARS‑5 system followed by ICP-MS analysis is proposed for determination of rare earth elements (REE) in plant materials. Limits of detection are 0.0001–0.001 ppm and allow for determination of all REE in certified reference materials Tr‑1, LB‑1 and EK‑1 and new reference material NSP‑1, relative standard deviations are lower than 13 %.Influence of HF addition during microwave digestion in UltraWAVE system on the ICP-MS analysis of REE in plant materials depending on silica content is studied. Necessity of HF addition during microwave digestion for better REE recoveries is shown for plant materials with Si contents exceeding 0.1 %