Maize Stalk Material for On-Site Treatment of Highly Polluted Leachate and Mine Wastewater

New research applications involving the use of cellulosic material derived from maize stalk for on-site treatment of leachate were evaluated for specific removal of Cu(II) and Fe(III) from real, highly polluted tailing pond and mine wastewater samples. Two major issues generated by anthropic mining activities were also tackled: wastewater metal content decrease to improve water quality and subsequently metal specific recovery, increasing the economic efficiency of metal production by using a green technology for residual management. Rapid saturation of the maize stalk mass determined in batch studies and the mine pilot experiment led to diminished metal concentrations in the second pilot experiment, where Cu(II) and Pb(II) from synthetic solutions were monitored in order to test biomaterial performances. In addition, in the second pilot experiment, maize stalk removed Pb(II) in the first 36 h, below the determination limit of the analytical method. The biomaterial bed in the column was saturated after 252 h of inflow solution. FTIR-ATR, TG and SEM techniques probed the interaction between maize stalk polar groups C=O, –OH, C–O and tailing water metallic ions by large FTIR band displacements, intensity decrease and shape changes, modification of thermal stability and by changes in the appearance of adsorbent microstructure images owing mainly to ion exchange mechanism.

Integral assessment of food products contamination with priority polyaromatic hydrocarbons

Polyaromatic hydrocarbons (PAH) occur in the environment as complex mixtures and each congener has different carcinogenic and mutagenic activity. Our research goal was to accomplish an integral assessment of food products contamination with priority PAH basing on their determination with high precision procedures. We validated a procedure for determining the said substances and hygienically assessed contamination of certain food products with benzpyrene, as well as with different carcinogenic and mutagenic PAH equivalents taking into account samples with low contamination. Quantitative determination limit for benz(a)anthracene and benzpyrene was fixed at 0.01 μg/kg; benz(b)fluoranthene and chrysene, 0.1 μg/kg. Detection limit for benz(a)anthracene and benzpyrene amounted to 0.003 μg/kg in our research; for benz(b)fluoranthene and chrysene, 0.03 μg/kg. A procedure for integral assessment of contamination with the examined compounds allowed us to calculate benz(a)anthracene, benzpyrene, benz(b)fluoranthene, and chrysene contents in certain food products taking into account mixture of the examined substances, their individual contributions into aggregated contamination, and their different toxic and mutagenic activity. Median food products contamination with benzpyrene amounted to 0.0065–0.42 μg/kg; PAH taking into account carcinogenic equivalents, 0.03–0.55 μg/kg; PAH based on mutagenic equivalents, 0.04–0.81 μg/kg. Maximum concentrations of benzpyrene and PAH based on carcinogenic and mutagenic equivalents are due to a combination of subsequent technological processes that make for occurrence of the examined substances and also due to physical and chemical properties of the examined food products.

Integral assessment of food products contamination with priority polyaromatic hydrocarbons

Polyaromatic hydrocarbons (PAH) occur in the environment as complex mixtures and each congener has different carcinogenic and mutagenic activity. Our research goal was to accomplish an integral assessment of food products contamination with priority PAH basing on their determination with high precision procedures. We validated a procedure for determining the said substances and hygienically assessed contamination of certain food products with benzpyrene, as well as with different carcinogenic and mutagenic PAH equivalents taking into account samples with low contamination. Quantitative determination limit for benz(a)anthracene and benzpyrene was fixed at 0.01 μg/kg; benz(b)fluoranthene and chrysene, 0.1 μg/kg. Detection limit for benz(a)anthracene and benzpyrene amounted to 0.003 μg/kg in our research; for benz(b)fluoranthene and chrysene, 0.03 μg/kg. A procedure for integral assessment of contamination with the examined compounds allowed us to calculate benz(a)anthracene, benzpyrene, benz(b)fluoranthene, and chrysene contents in certain food products taking into account mixture of the examined substances, their individual contributions into aggregated contamination, and their different toxic and mutagenic activity. Median food products contamination with benzpyrene amounted to 0.0065–0.42 μg/kg; PAH taking into account carcinogenic equivalents, 0.03–0.55 μg/kg; PAH based on mutagenic equivalents, 0.04–0.81 μg/kg. Maximum concentrations of benzpyrene and PAH based on carcinogenic and mutagenic equivalents are due to a combination of subsequent technological processes that make for occurrence of the examined substances and also due to physical and chemical properties of the examined food products.

Rapid Determination of Catechin Content in Black Tea by Fluorescence Spectroscopy

Catechin can effectively prevent the occurrence of cancers due to its strong antioxidant capacity. In this study, the catechin contents of black teas from 12 different regions of south China were investigated using fluorescence spectroscopy. Herein, the catechin contents of various black teas with constant concentration were determined at the optimal excitation and emission wavelength combining the standard addition method and fluorescence spectroscopy. The results indicated that there was a linear relationship between the obtained concentration and fluorescence intensity, where the R values were all greater than 0.99 and the limit of quantification (LOQ) was 0.02 μg/mL. Furthermore, the content of catechin monomer in the chlorophyll environment was measured under the same experimental conditions to demonstrate the correctness of the above experimental methods. It revealed that the experimental error was about 1.14% compared with the actual content. The current work was proved to be an efficient way to detect fluorescence spectrum through diluting the concentration of tea samples, thereby increasing the determination limit of catechin.

Simultaneous Determination of Ternary Mixture of Carboxin, Chlorpyrifos, and Tebuconazole Residues in Cabbage Samples Using Three Spectrophotometric Methods

Three simple precise and accurate spectrophotometric methods are developed for simultaneous determination of ternary mixtures of carboxin, chlorpyrifos, and tebuconazole residues in cabbage grown in the experimental field. The first method is a double divisor-ratio spectra derivative that relies on the derivative of ratio spectra and attained through dividing the absorption spectra of the ternary mixture by the sum of standard spectrum of a mixture of two from three components, using methanol as a solvent and measuring CAR at 242 nm, CHL at 236 nm, 276 nm, and 300 nm, and TEB at 226 nm. The second method is a successive derivative of ratio spectra which determined CAR at 256 nm and 258 nm, CHL at 290 nm and 292 nm, and TEB at 226 nm and 228 nm. The third method is a mean centering of ratio spectra where CAR, CHL, and TEB were measured at 306 nm, 280 nm, and 240 nm, respectively. These procedures do not involve any previous separation. The extraction of analytes was carried out by using acetonitrile, and the procedure of purification was fulfilled by dispersive solid-phase extraction with a primary-secondary amine (PSA). The proposed methods showed excellent linearity range for three spectrophotometric methods over the concentration ranges of 1–30 μg/mL, 1–50 μg/mL, and 1–45 μg/mL for carboxin, chlorpyrifos, and tebuconazole, respectively. The analytical characteristics such as detection limit, determination limit, relative standard deviation, and accuracy of the three methods were performed. The limits of detection were in the range of 0.153–0.260 μg/mL for carboxin, 0.137–0.272 μg/mL for chlorpyrifos, and 0.109–0.205 μg/mL for tebuconazole with limits of quantification lower than 0.790, 0.824, and 0.621 μg/mL for CAR, CHL, and TEB, respectively. The recoveries ranged from 87.02% to 94.53% for carboxin, 92.32% to 108.53% for chlorpyrifos, and 87.19% to 98.00% for tebuconazole with relative standard deviations less than 5.91%, 5.99%, and 5.53% in all instances for carboxin, chlorpyrifos, and tebuconazole, respectively. The results obtained from the proposed methods were compared statistically by using one-way ANOVA, and the results revealed that there were no significant differences between three different spectrophotometric methods. The suggested methods can be applied with great success to the simultaneous estimation of carboxin, chlorpyrifos, and tebuconazole residues in cabbage samples.

Quick Detection of Aldehydes and Ketones in Automotive Textiles

This study was aimed to develop a quick detection method to test aldehydes and ketones in textiles in order to control the quality of automotive textiles in the development process from fabric production to end-use in vehicles. In this study, a pretreatment of samples was applied to simulate the actual environment of textiles used in vehicles. Collected volatiles were reacted with 2,4-dinitrophenylhydrazine and then eluted with acetonitrile tetrahydrofuran. The eluent was analyzed with high-performance liquid chromatography. Findings showed more than 90% volatiles could be detected in the established method; the lowest determination limit was 0.0297 mg/mL; and the lowest quantification limit was 0.0991 mg/mL, which meant sensitivity and capability of the method were high. Regression coefficients of linear models between volatile concentrations and chromatographic peak characteristics were >0.995, indicating that the method could effectively and efficiently determine the contents of volatiles in automotive textiles.

A Case Study: The Effect of Flooring Renovation with Adsorptive Cloth on the Residual Emissions of 2-ethyl-1-hexanol and C9-C10 Alcohols

This paper presents a renovation case study of a multi-storey building with initially elevated indoor air concentrations of 2-ethyl-1-hexanol and C9-C10 alcohols originating from PVC flooring. The main aim of the study was to determine the effectivity of renovation that included the use of a novel renovation material, cTrap adsorption cloth, in reducing the surface emissions and indoor air concentrations of the named compounds. Indoor air concentrations and surface emission rates of volatile organic compounds (VOC) were measured in the case building before and after renovation according to ISO16000-6 and NT Build 484 standards. The results show that the measured indoor air concentrations of the alcohols decreased to ca. 1/10 of the original concentration, and the surface emission rates dropped below the determination limit after the renovation.

Residual behaviour of imidacloprid in the country bean growing soil

The assessment of residual behavior of imidacloprid (Admire 20SL) in the soil of country bean agroecosystem and its risk assessment for consumption was studied. QuEChERS method was used for the extraction and clean-up of samples and the residues of imidacloprid was estimated using Gas Chromatography. The dissipation studies in the soil system were carried out by application of imidacloprid at five different dosages i.e. 100, 200, 300, 400, and 500 g a.i. ha-1. Average initial deposits of imidacloprid were found to be 0.99, 1.33, 1.62, 1.83 and 2.20 mg.kg-1. The residues reached below determination limit (BDL) of 0.01 mg kg-1 in 9 days for recommended dose and 12 days for remaining higher dosages. Half-life (T1/2)) of imidacloprid in the soil was observed to be 1.88, 1.74, 1.73, 1.56 and 1.52 days for 100, 200, 300, 400, and 500 g a.i. ha-1, respectively. The chemodynamics study of imidacloprid spray indicated that only 27.20 -28.40% sprays were deposited to the target site (plant canopy) and 71.60-72.80% were lost to non-target site such as soil and air. The drift of imidacloprid to soil (39.47-40.20%) was higher than the air (32.13-32.60%). Based on degradation pattern and maximum, the recommended preharvest interval (PHI) might be eight 9 days and a waiting period of two days might be suggested for reapplication of the imidacloprid in country bean agroecosystem. Bangladesh J. Agril. Res. 44(1): 89-101, March 2019

L-lysine determination in animal feed using microbiological microtiter plate assay

Chromatographic methods are most commonly used for the analysis of amino acids; however, there is growing need for faster, simpler and more price-effective assays. In this paper, the applicability of a rapid microbiological assay for quantification of the total content of L-lysine in feed samples was evaluated. The assay relies on the dependency of bacterial growth of Pediococcus acidilactici on the presence of L-lysine. Microbiological microtiter plate assay method for the quantitative determination of total (added and natural) L-lysine in feed samples has been verified, and parameters such as accuracy, precision, limit of detection, and limit of determination were evaluated. Results of total L-lysine determination in different feed samples have been compared with results of validated HPLC method. The microbiological microtiter plate assay method can be employed as a qualitative and quantification method for total L-lysine determination with detection and determination limit of 0.040 % and 0.085 %, respectively. However, further research on the influence of sample matrix on the determination of low lysine levels is required.

PHYSICO-CHEMICAL STUDIES OF APITOXIN AND PRODUCTS ON ITS BASIS

Introduction.Nowadays, it is vitally important to develop a method for quantifying melittin not only in apitoxin samples, but also in the products of its processing.The aim of our studyis to investigate physical and chemical characteristics of melittin, the main component of apitoxin, as well as the development of methods for the quantitative determination of melittin in the samples of apitoxin and in the pharmaceutical products derived from apitoxin: “Sophia with apitoxin” cream and “Apizartron” ointment.Materials and methods.The objects of the research were apitoxin and melittin, as well as the samples of “Sophia with apitoxin” cream and “Apizartron” ointment satisfying the requirements of regulatory documentation, produced in lots by domestic and foreign manufacturers. The UV spectra of melittin and apitoxin were registered on SF 103 spectrophotometer in quartz cuvettes with 1 cm thickness. The IR spectra were investigated on the IR-instrument of Fourier – FSM-1201 spectrophotometer, LLC “Infraspek”. The determination of melittin purity was carried out by chromatography.Results and discussion. The basic physical and chemical characteristics were established for melittin as a reference sample and the main component of apitoxin. The melting temperature was: (Tmelt.)=190ºС. In the UV-spectrum there could be watched the absorption maxima corresponding to 2 peaks: λ max = 225±2 nm and 285±2 nm were observed. As an analytical wavelength, it is necessary to choose the peak λ =285 nm, since the peak with λ =225 nm is associated with the absorption of light by the internal (shielded) benzene ring of the tryptophan molecule. The nature of the curve and the position of the maxima of the spectra of melittin and the apitoxin solution coincide, which makes it possible to use melittin as a standard for spectrometric quantitative determination of the active substances in apitoxin and preparations based on apitoxin.Conclusion. The worked out spectrophotometric methods for the quantitative determination of melittin in apitoxin has been validated by the indices of specificity, accuracy, detection limit, quantitative determination limit, linearity.