mL Of Methanol Research Articles

SPECTROPHOTOMETRIC DETERMINATION OF COPPER (II) AFTER DISPERSIVE LIQUID-LIQUID EXTRACTION OF ITS COMPLEX WITH 6,7-DIHYDROXY-4-METHYL-2-PHENYLBENZOPYRYLIUM CHLORIDE

The specificity of the dispersive liquid-liquid semi-microextraction of Copper (II) complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyryl chloride has been studied. It is noted that the transition to semi-microextraction technology can significantly reduce the toxic organic solvents consumption, and the use of dispersion solvent can intensify the complex extraction of Сopper (II) complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyryl chloride. Optimal conditions for spectrophotometric determination of Сopper (II) after dispersive liquid-liquid semi-microextraction of its complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrylium chloride were found to be: 1.5 mL of chloroform, 1.5 mL of methanol, pH 4.5, λmax = 535 nm, l = 1 cm. The main analytical characteristics of the developed dispersive liquid-liquid semi-microextraction-spectrophotometric method are calculated: the calibration graph is linear in the wide range of concentrations of 17-480 μg/L, and the limit of detection and limit of determination are 5 and 17 μg/L, respectively. The molar ratios Copper (II) : interferer, in which there is no effect on the quantitative determination of Copper(II) by the proposed dispersive liquid-liquid semi-microextraction-spectrophotometric method have been established. The proposed method for Copper (II) spectrophotometric quantification after preconcentration via dispersive liquid-liquid semi-microextraction as a complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrilium chloride was tested in the analysis of model solutions and water samples. The accuracy of the developed dispersive liquid-liquid semi-microextraction-spectrophotometric method was checked by the "spiked-found" method and the relative standard deviation does not exceed 3.9%. The proposed technique is simple, sensitive and environmentally friendly.

Lipid ratios in adriamycin-induced pre-eclamptic Wistar rats exposed to methanolic plant extracts

The study accessed the lipid ratios in preeclamptic Wistar rats exposed to methanolic leaf extracts of Jatropha cacus, Alchonnea cordifolia, and Secamone afzelii. Plant samples (leaves) were washed severally with distilled water, air-dried, and crushed to powder and were filtered, then soaked in 200ml of methanol for 12 hours. The LD50 was determined to ascertain the safety of the plant extracts for use. Female Wistar rats, aged 3 days apart, used in the study, were acclimatized for one week. Peeclampsia was induced used the Adriamycin Model. Results showed that there was elevation of blood pressure (bp) due to preeclampsia. At 3rd trimester, systolic bp (177 mmHg) was higher than at postpartum (160 mmHg). The administration of plant extracts caused a significant reduction in systolic (127 – 150 mmHg) and diastolic (86 – 103 mmHg) bp during the 3rd trimester. Proteinuria was reduced to trace levels when Alchonnea cordifolia was used. Total cholesterol levels were higher in the third trimester (71.6 mg/dl) and postpartum (74.3 mg/dl), respectively. Preeclampsia was linked to similar increases in triglycerides, and low density lipoprotein cholesterol; with a reduction in high density lipoprotein cholesterol. The treatment with the various plant extracts lowered the incidence of arteriosclerotic cardiovascular events during preeclampsia. Although the extracts had a negative effect on systolic blood pressure and proteinuria during the third trimester, indicating that they were beneficial in reducing preeclampsia outcomes, there was no effect on blood pressure or proteinuria during the postpartum period.

Evaluation of Antibacterial Activity of Methanolic Extract of Avicennia marina Leaf Extract against Staphylococcus aureus

Introduction: Mangrove are widespread in the tropical and subtropical regions of Indo-West-Pacific area. Avicennia marina possesses vast medicinal values. The pharmacological activity of the plant is attributed to the presence of several phytochemicals.
 Aim: To evaluate the antibacterial activity of Avicennia marina leaf extract against Staphylococcus aureus. 
 Methods and Materials: Plant extract prepared by adding 20g of dried powdered mangrove leaf sample to 100 ml of methanol. MDRSA, MRSA & VRSA were cultured in Muller –Hinton Broth for 24 hr at room temperature. From this prepared bacterial suspension, 1ml of was spread over Muller Hinton agar plate and incubated for 24hrs at ambient temperature. Antibacterial activity carried out through the disc diffusion method. Whatman filter paper discs (5mm) were impregnated with various concentrations (50, 100, 150, 200, 250 & 300 µg/ml) of leaf extract. After incubating the plates for 24hr at room temperature the zone of inhibition was measured. Minimum Inhibitory Concentration was determined in 5 concentrations (50 -300 µg/ml) with blank (extract in Muller Hinton broth). The inoculated bacteria in test tubes are incubated for 24hr in ambient temperature. The results are noted as well growth (+) and inhibited (-). Tetracycline (1µg/ml) was used as standard and DMSO as negative control.
 Results: The zone of inhibition was greater at 300µg/ml of the extract for MDRSA ( 13±1.2) , MRSA ( ( 13±1.4) )& VRSA ( 9±1.2). MIC for MDRSA, MRSA and VRSA was 250µg/ml, 200µg/ml 150µg/ml respectively.
 Conclusion: The present study showed effective antibacterial activity of Avicennia marina against MDRSA, MRSA, VRSA. Hence, this extract may be used for infections against resistant Staphylococcus aureus.

Determination of selected herbicides employed in sugarcane crops by disposable pipette tip (DPX) extraction followed by LC-MS/MS and GC-MS/MS

A disposable pipette tip extraction (DPX) method followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed and validated to determine eleven herbicides employed in sugarcane crops. After improving conditions, the DPX method consists of conditioning a C18 tip with 0.3 mL of methanol, followed by the same volume of water and 0.15 mL of the sample. After completing the sorption interaction, the sample was dispensed, and elution was made with 0.15 mL of methanol before collecting the extract for injection. The total extraction time was 4 min, and recoveries ranged from 59.1 to 76.5%. DPX method was compared to cartridge solid-phase extraction, which presented recoveries between 30.4 and 108.6%. SPE consumed four times more solvent, total extraction time is five times longer than DPX, and cartridges are more expensive than the DPX tips. DPX performance was also evaluated by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The recoveries were similar to LC-MS/MS. Furthermore, the DPX-C18-LC-MS/MS method was applied to analyze sugarcane-derived juice samples. Results indicate that the method can determine the herbicides in actual samples and other sugarcane matrices.

The Effect of Catalyst Amount & Reacters Comperative on Glycerol Conversion From Castrol Oil With Catalyst Of Pertamina Cracking Process Unit III Palembang

Transesterification of oil with alcohol produces glycerol and methyl esters (biodiesel). The reaction is influenced, among others, by the amount of catalyst and the ratio of oil and meth hanol reagents. This purpose of research to determine the effect of the amount of catalyst and the ratio of reagents on the conversion of glycerol. The experiment was carried out in a three-necked flask equipped with a stirrer and reverse cooling. In a three-necked flask, 150 ml of castor oil was added, 0.375 ml of H2SO4 was added, heated to a temperature of 650C. Then add 185 ml of methanol and stir for 30 minutes. Then let stand 24 hours to form two layers. The bottom layer is glycerol. The transesterification process was continued by adding 100 ml of glycerol in a mixture of methanol (variation 1:2, 1:3, 1:4) with RCC catalyst (variation 1.7gr;1.9gr;2.1gr;2.3gr ;2.5gr) The mixture was then stirred at 90 rpm for 75 minutes. Based on the results of research conducted, the highest glycerol conversion value was in the amount of catalyst 2.1 g with a ratio of reagents between castor oil and methanol of 1:3 of 55.33%.

Isolation and Partial Purification of Bioactive Compounds from Sponge Sigmadocia Fibulata (Schmidt) Collected from West Coast of Mumbai, India

The sponge Sigmadocia fibulata (Schmidt) was collected during low tides from West Coast of Mumbai. Crude extract was obtained by taking 10 gram of sponge samples in10 ml of methanol. The preparative TLC (Thin Layer Chromatography) was performed by using Toluene: Ethyl acetate: Diethylamine (7:2:1) (v/v). The isolated compounds were subjected to GC-MS and FTIR analysis. The structural properties of bio active compounds were determined.From the structural determination it was confirmed that S. fibulata contains bioactive compounds as Triacontanoic acid, methyl ester – (Skin irritant), Hexadecanoic acid, 2- hydroxyl- (hydroxymethyl) ethyl ester – (Fatty acid, Metabolite and Irritant) and 2-Nitro-1, 3-bis-oclyoxy-benzene, (A natural product found in Neolitsea daibuensis. It has a role as a plant metabolite and an algal metabolite). From their biological properties it was confirmed that S. fibulata contains bio active compound, which has biomedical and pharmaceutical properties.

Impact of Different Extraction Methods on Furanosesquiterpenoids Content and Antibacterial Activity of Commiphora myrrha Resin.

The oleo-gum-resin of Commiphora myrrha is one of the most known natural antimicrobial agents, mainly due to its furanosesquiterpenes. A validated method based on sample extraction by matrix solid-phase dispersion (MSPD) followed by high-performance column chromatography (HPLC) determination is applied to analyze two furanosesquiterpenoids, namely, 2-methoxyfuranodiene (CM-1) and 2-acetoxyfuranodiene (CM-2), existing in C. myrrha. The trial parameters that controlled the extraction prospective were studied and optimized. These include the nature of dispersant, mass ratio of sample to the dispersant, and the volume of elution solvent. A comparative antimicrobial study that used the Minimum Inhibitory Concentration Assay (MIC) method between MSPD, ultrasonic, and Soxhlet of myrrh extracts was also conducted. The optimal MSPD parameters used were (i) 15 mL of methanol applied as elution solvent; (ii) silica gel/sample mass at a 2 : 1 ratio; and (iii) a dispersing sorbent selected as silica gel. Technique retrievals were regulated from 96.87% to 100.54%, with relative standard deviations (RSDs) from 1.24% to 4.45%. Commiphora myrrha-MSPD (CM-MSPD) extract showed the highest antibacterial activity against gram-positive and gram-negative bacteria (156.25 μg/mL and 312.5 μg/mL, respectively) and antifungal activity (156.25 μg/mL). Yields acquired through the MSPD technique were larger than yields from other extraction techniques (sonication and traditional reflux extraction methods) with less consumption of time, sample, and solvent. The mode of antibacterial action of CM-1 and CM-2 was elucidated by performing molecular docking with bacterial DNA gyrase. Both the compounds interacted with key residues of DNA gyrase.

Potential health risk index of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in fish species from Oguta Lake, Nigeria

ABSTRACT Polyaromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides are among the ubiquitous and lipophilic persistent organic pollutants that pose environmental hazards to humans. In this study, four fish of different species; mochokidae, perpyroclanusalpha, cintharinidae and ciclidae, locally known as Okpo, Ubu, Ifuru and Egu, respectively, from Oguta Lake were analysed for poly aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and the data obtained were subjected to some chemometric assessments models. 10 g of each of the samples were subjected to soxhlet extraction using 100 mL of methanol for the extraction of the organic pollutants. The extracts were analysed for PAHs, PCBs and OCPs using Buck 530 Gas Chromatograph. PAHs, PCBs and OCPs were detected in all the samples, however, Ifuru had an equal level of PAHs followed by Ubu and Egu. The total mean for PAH were 18.367 mg/kg. The concentration of PCBs were in the order Okpo> ubu> ifuru > egu with a total mean of 0.0513 mg/kg. Ifuru recorded the highest level of OCPs while Ubu had the lowest with a total mean of 0.0666 mg/kg. Estimated dietary intake (EDI) showed higher in children than in adults for all the pollutants. Okpo showed equal EDI with Ifuru for PAHs followed by Ubu and Egu. EDI for PCBs were in the order Okpo> Ubu> Ifuru> Egu. EDI for OCPs were insignificant except for Ifuru. The health risk analysis showed that consumption of fish from Oguta Lake could pose a non-carcinogenic health hazard especially in children.

Original Article BIOACTIVE COMPOUNDS FROM SPONGE SUBERITES CARNOSUS (JOHNSTON) COLLECTED FROM WEST COAST OF MUMBAI, INDIA

Objective: Structural elucidation of bioactive compounds from marine Sponge Suberites Carnosus (Johnston) by using Thin Layer Chromatography (TLC), Gas Chromatography-Mass Spectrometry (GC-MS), Fourier Transform Infrared Spectrometer (FTIR) techniques with respect to its pharmacological and biomedical properties.
 Methods: The sponge Suberites carnosus (Johnston) was collected during low tides from West Coast of Mumbai. Crude extract was obtained by taking 10 gram of sponge sample in10 ml of methanol. The preparative TLC (Thin Layer Chromatography) was performed by using Toluene: Ethyl acetate: Diethylamine (7:2:1) (v/v). The isolated compounds were subjected to GC-MS and FTIR analysis.
 Results: From the GC-MS and FTIR analysis, total ten compounds were identified. The GC-MS spectra correlate to the mass spectra. The structures of those compounds are 6-Fluoro 2-trifluromethylbenzoic acid,2,3-dichlorophenyl ester, Eicosane 3-cyclohexyl, Phosphine imide, P,P,P,-tris (p-chlorophenyl)-N-phenyl-, Dimethylhyl hexavinyl octasilsesquioxane, Hexanoicacid, hexadecyl ester, Hexadecanoic acid,2-hydroxy1-(hydroxymethyl)ethyl ester, 9, 19-Cyclolanostan-3-ol, acetate, (3β), Tetracosane, 3-ethyl-, 11, 14-Eicosadienoic acid, methyl ester, Triacontane, 11,20-didecyl-respectively.
 Conclusion: The nature and biological properties of the said compounds were determined and it was found that some of them act as a skin irritant. Some of them have fatty, metabolite, and irritant property, whereas some are act as masking and perfuming agents. Some compounds are highly toxic property, whereas others have an effect on health and environmental hazard. Some are highly corrosive in nature, whereas others are Cholesterol and chemotaxonomic significance.

Enantiomeric methadone quantitation on real post-mortem dried matrix spots samples: Comparison of liquid chromatography and supercritical fluid chromatography coupled to mass spectrometry

This study describes two bioanalytical methods for the quantitation of the two methadone enantiomers in dried matrix spots using high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) and high performance supercritical chromatography tandem mass spectrometry (HPSFC-MS/MS). Dried matrix spots were obtained by spotting 10 µL of each sample fluid on a Whatman paper. Methadone and its main metabolite, EDDP, were extracted with 100 µL methanol and subsequently injected into the LC-MS/MS and SFC-MS/MS systems. Enantiomeric separation was achieved with AGP-column for the LC conditions and with Chiralpak IH-3 in SFC. The two methods were fully validated and 93 post-mortem samples were analysed with both analytical methods. Results from validation parameters and results obtained for all post-mortem samples were compared with a significant spearman correlation of rs = 0.9978 for R-methadone and rs = 0.9981 for S-methadone. The LC method provided better results in terms of uncertainty, retention factor and resolution, whereas SFC provides better sensitivity, with lower LOD. Median R-/S-methadone ratio in peripheral blood was found equal to 1.60 (N = 32), varying from 0.79 to 4.23. The reported values were in good agreement with previously published results.Based on the results obtained here, SFC-MS/MS can be considered a reliable alternative to the widely used LC-MS/MS for the quantitation of methadone enantiomers in bioanalysis and should be evaluated for other bioanalytical methods. Both methods can be easily and quickly used in toxicological routine analysis for the methadone quantitation in human fluids matrices, even if considering that the polysaccharide coated column IH-3 used in SFC does not allow the enantiomeric EDDP separation.

Precise Assembly and Supramolecular Catalysis of Tetragonal- and Trigonal-Elongated Octahedral Coordination Containers

The construction of distorted or irregular coordination polyhedrons with specific shapes and functionalities is highly challenging. Here, we demonstrate a viable strategy for attaining a severely d...

Effects of Chronic Secondhand Smoke (SHS) Exposure on Cognitive Performance and Metabolic Pathways in the Hippocampus of Wild-Type and Human Tau Mice.

Background:Exposure to secondhand smoke (SHS) is a risk factor for developing sporadic forms of sporadic dementia. A human tau (htau) mouse model is available that exhibits age-dependent tau dysregulation, neurofibrillary tangles, neuronal loss, neuroinflammation, and oxidative stress starting at an early age (3–4 months) and in which tau dysregulation and neuronal loss correlate with synaptic dysfunction and cognitive decline.Objective:The goal of this study was to assess the effects of chronic SHS exposure (10 months’ exposure to ) on behavioral and cognitive function, metabolism, and neuropathology in mice.Methods:Wild-type (WT) and htau female and male mice were exposed to SHS (90% side stream, 10% main stream) using the SCIREQ® inExpose™ system or air control for 168 min per day, for 312 d, 7 d per week. The exposures continued during the days of behavioral and cognitive testing. In addition to behavioral and cognitive performance and neuropathology, the lungs of mice were examined for pathology and alterations in gene expression.Results:Mice exposed to chronic SHS exposure showed the following genotype-dependent responses: a) lower body weights in WT, but not htau, mice; b) less spontaneous alternation in WT, but not htau, mice in the Y maze; c) faster swim speeds of WT, but not htau, mice in the water maze; d) lower activity levels of WT and htau mice in the open field; e) lower expression of brain PHF1, TTCM1, , and HSP90 protein levels in WT male, but not female, mice; and f) more profound effects on hippocampal metabolic pathways in WT male than female mice and more profound effects in WT than htau mice.Discussion:The brain of WT mice, in particular WT male mice, might be especially susceptible to the effects of chronic SHS exposure. In WT males, independent pathways involving ascorbate, flavin adenine dinucleotide, or palmitoleic acid might contribute to the hippocampal injury following chronic SHS exposure. https://doi.org/10.1289/EHP8428

Magnetic Solid-Phase Extraction Based on Amino-functionalized Magnetic Starch for Analysis of Organochlorine Pesticides.

A magnetic starch modified with 3,5-diaminobenzoic acid and 3-aminopropyltriethoxysilane (Fe-starch@DABA-APTES) was synthesized and applied as adsorbent for the extraction of organochlorine pesticides (OCPs). Magnetic solid-phase extraction was developed using 75 mg of the sorbent and 15 mL of a sample solution. Extraction was conducted on a vortex mixer for 40 s. The adsorbent was collected using an external magnet before eluting the analytes using 0.5 mL of methanol. Quantification of the analytes was performed using gas chromatography with a micro-electron capture detector. The linearity was obtained for the studied OCPs in the range between 0.01 - 2.00 μg L-1. The detection and quantification limits were obtained in ranges of 0.5 - 4.0 and 1.5 - 15.0 ng L-1, respectively, with enrichment factors of up to 39. The precision in terms of the intra- and inter-day relative standard deviations (RSDs) were below 4.75, and 9.25%, respectively. The developed method has been applied in natural water and agricultural product samples. The recoveries ranged between 59.83 - 132.67% (RSDs < 10.73%).

Organic Based Additives Impact on Thermal Behavior of Ammonium Perchlorate: Superior 4, 4′‐Bipyridine Versus Inferior Biphenyl

AbstractFor the first time, the thermal decomposition behavior of heterogeneous mixtures of ammonium perchlorate (AP) with two organic additives – 4, 4’‐Bipyridine, and biphenyl – were investigated. The heterogeneous mixtures of the additives and ammonium perchlorate were prepared by dissolving 1, 2, 3, 4, and 5 mg of the organic additives and 100 mg ammonium perchlorate in 2 ml of methanol as solvent. After that, the thermal decomposition behavior of prepared solid heterogeneous mixtures was monitored by thermogravimetry analysis, differential scanning calorimetry, and mass spectrometry analysis. The effect of the 4, 4’‐Bipyridine on thermal decomposition of AP enhanced the released heat from 479 to 1842 J g−1 and produced a decrease of decomposition temperature from 433 °C to 308 °C while the thermal decomposition of AP in the presence of biphenyl did not change as dramatically as it did with 4, 4’‐Bipyridine. With biphenyl, the decomposition temperature was found to be similar to that of pure AP and the evolved heat was about 718 J g−1. The gaseous products of decomposition of 4, 4’‐Bipyridine /ammonium perchlorate were monitored by mass spectrometric analysis. The main evolved decomposition gases of pure AP are N2O, O2, Cl2, ClO, ClO2, ClO3, HClO4, and HCl, while the major gaseous products of the 5:100 (w/w) mixture of 4, 4’‐Bipyridine with AP were detected as N2, NO, N2O, O2, Cl2, ClO, ClO2, ClO3, HClO4, HCl and 4, 4’‐Bipyridine. The change in the composition of volatile products indicates a change in the mechanism of AP decomposition from proton transfer to electron transfer in the presence of 4, 4’‐Bipyridine.

A simple and easy-to-perform liquid chromatography–mass spectrometry method for the quantification of tacrolimus and its metabolites in human whole blood. Application to the determination of metabolic ratios in kidney transplant patients

Tacrolimus is the cornerstone of immunosuppressive therapy in solid organ transplantation and its blood concentrations are routinely monitored. Tacrolimus is extensively metabolized into metabolites that are supposed to be nephrotoxic. Yet, few analytical methods have been described to simultaneously quantify tacrolimus and its main metabolites. We developed and validated a simple liquid chromatography-mass spectrometry method for the quantification of tacrolimus and its three desmethylated metabolites, 13-O, 15-O, and 31-O-desmethylated tacrolimus (M−I, M−III, and M−II respectively) in human whole blood. Protein precipitation of 50 µL of whole blood with 100 µL methanol and zinc sulfate was used as a single-extraction procedure. Tacrolimus and its metabolites were quantified using electrospray ionization-triple quadrupole mass spectrometry in combination with selected reaction monitoring detection in the positive ionization mode. The method was validated following FDA recommendations. This method was precise (intra- and inter-assay coefficients of variation: 2.88–7.81% and 3.96–12.10% for low and high levels of internal quality controls, respectively) and accurate (intra- and inter-assay biases: −1.67–10.30%, and −0.77–-9.36%, respectively).In adult kidney transplant patients who were treated with tacrolimus prolonged release formulation, the median (10th-90th percentiles) trough concentrations (n = 16) of tacrolimus, M−I, and M−III were 5.85 (3.37–7.09), 0.100 (0.037–0.168), 0.051 (0.03–0.104), respectively. M−II was measured in only 2 trough samples. The metabolic ratios M−I/tacrolimus and M−III/tacrolimus were 0.017 (0.009–0.027) and 0.009 (0.006–0.015) when measured on trough concentration and 0.022 (0.011–0.037) and 0.008 (0.006–0.015) when measured on area under the curves 0–24 h.This method is a suitable and easy-to-perform tool for future pharmacokinetic-pharmacodynamics studies investigating the importance of tacrolimus and its metabolites blood exposure for solid organ graft survival.

Effect of ethylene diamine tetra‐acetic acid and functional monomers on the structure and adsorption properties of copper (II) ion‐imprinted polymers

Novel copper (II) ion‐imprinted polymers (Cu‐IIPs) were synthesized by bulk polymerization using 1 mmol of copper (II) sulfate pentahydrate as the template ion, 1 mmol of ethylenediaminetetraacetic acid (EDTA) as the ligand, and 4 mmol of 4‐vinyl pyridine (4‐VP) or methacrylic acid (MAA) as the functional monomer dissolved in a porogen of 20 mL of methanol. Polymerization was performed with 20 mmol of pentaerythritol triacrylate (PETA) as the crosslinker and 1 mmol of benzoyl peroxide as the initiator. The effect of pH, time, initial concentration of Cu2+, and selectivity tests on the adsorption capacity were investigated using flame atomic absorption spectroscopy (FAAS). The prepared polymers were characterized by Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM) and X‐ray diffraction (XRD). Adsorption capacity of Cu‐IIPs prepared with MAA increased from 0.794 to 2.163 mg g−1 at pH 6 within 24 hours, while Cu‐IIPs from MAA had high recognition ability with better recognition of Cu2+ than other ions. Thus, these Cu‐IIPs demonstrated potential application as an adsorbent for efficient removal of Cu2+ from aqueous solutions.

Benzidine. Determination in workplace air

Benzidine is a white, crystalline solid. In the past, it was used mainly for the production of dyes, and nowadays in chemical analysis. Benzidine can cause bladder cancer to humans. The aim of this study was to develop a method for determining benzidine in workplace air, which will makes it possible to determine its concentrations at the lowest possible level. The method is based on the chemisorption of benzidine on a glass fiber filter treated with sulphuric acid(VI), extraction of benzidine disulphate with water and sodium hydroxide solution, and after extraction to the solid phase (SPE), benzidine is eluted from the SPE cartridge using 1 mL of methanol. The obtained solution is analyzed chromatographically. The tests were performed using a liquid chromatograph (HPLC) 1200 series of Agilent Technologies with a fluorescence detector (FLD). Determinations were performed using an Ultra C18 column (25 cm × 4.6 mm, dp = 5 µm). The procedure was validated according to Standard No. EN 482. The method can be used to determine benzidine in workplace air in the concentration range from 0.1 to 2 µg/m3. The limit of quantification (LOQ) is 0.25 ng/m3. The overall accuracy of the method was 5.36% and its relative total uncertainty was 23%. This method makes it possible to selectively determine benzidine in workplace air in the presence of most substances that do not show fluorescence, and in the presence of: biphenyl-4-amine, 1-naphthylamine and 2-naphthylamine, which show fluorescence. The method of determining benzidine has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Priority mono-aromatics measured in anthropogenic impacted soils from Delta, Nigeria: concentrations, origin, and human health risk

This study determined the background occurrence, origin, and human health risk of priority mono-aromatics in soil samples around diesel-powered electricity generators from selected land use environments in the Niger Delta, Nigeria. Soil samples were collected in a 20 ml vial containing 5 ml of methanol and caped with a crimp. The BTEX species were determined with a Headspace gas chromatography-mass spectrometer (HS-GCMS). The mean concentration of ƩBTEX ranged from 0.04 to 2.42 mg kg−1 and was considerably higher in 56% of the sites. The individual and ƩBTEX concentrations are within the Ministry Order (MO) intervention threshold and below the Department of Petroleum Resources-Environmental guidelines and standards for the petroleum industry in Nigeria (DPR-EGASPIN) intervention values. The source analysis indicates that BTEX compounds originated from a common source attributed to gasoline-diesel combustion exhaust, storage, other stationary sources, and fuel evaporative losses from fuel service stations around the gasoline/diesel combustion electricity generator. The hazard index for infants' in 66% of the sites was higher than 1, suggesting adverse non-carcinogenic health effects. The cancer ingestion and dermal exposure risk for infants were greater than that of adults. This study has shown that the diesel-powered electricity generator has impacted considerable concentrations of ƩBTEX in the land-use sites. The agency for power and energy should ensure regular public electricity supply, while the use of solar panels as an alternative source of electric energy should be encouraged. Further study on the occurrence of other priority contaminants in indoor and outdoor environments should be determined in the land-use sites.

HPLC-Based Quantitative Detection of Tylosin in Soil

The sample was extracted under the ultrasonic assistance and purified through the solid-phase extraction, and then the residual tylosin in soil was detected via the high-performance liquid chromatography (HPLC). Acetonitrile-aqueous solution was used as the extracting agent in the ultrasound-assisted extraction. The HLB solid-phase extraction column was activated using 5 mL of methanol and 5 mL of ultrapure water, leached with 5 mL of water and 5 mL of 2% ammonium hydroxide + 5% methanol solution, and eluted with 5 mL of methanol in the end. The determination was implemented using the HPLC method, where the detected wavelength λ value was 290 nm, the sample size was 20μL, and the column temperature was 30°C. Acetonitrile -0.01 mol/L monopotassium phosphate solution (pH=2.5) = 60:40 (V: V) was taken as the mobile phase in the detection of response degree to tylosin in soil. The detection results were as follows: LOD was 0.019mg/kg, LOQ was 0.062mg/kg, the coefficient of variation of intra-day precision was smaller than 10%, and that of inter-day precision was smaller than 15%.

Monitoring Lipophilic Toxins in Seawater Using Dispersive Liquid-Liquid Microextraction and Liquid Chromatography with Triple Quadrupole Mass Spectrometry.

The use of dispersive liquid–liquid microextraction (DLLME) is proposed for the preconcentration of thirteen lipophilic marine toxins in seawater samples. For this purpose, 0.5 mL of methanol and 440 µL of chloroform were injected into 12 mL of sample. The enriched organic phase, once evaporated and reconstituted in methanol, was analyzed by reversed-phase liquid chromatography with triple-quadrupole tandem mass spectrometry. A central composite design multivariate method was used to optimize the interrelated parameters affecting DLLME efficiency. The absence of any matrix effect in the samples allowed them to be quantified against aqueous standards. The optimized procedure was validated by recovery studies, which provided values in the 82–123% range. The detection limits varied between 0.2 and 5.7 ng L−1, depending on the analyte, and the intraday precision values were in the 0.1–7.5% range in terms of relative standard deviation. Ten water samples taken from different points of the Mar Menor lagoon were analyzed and were found to be free of the studied toxins.