Simple SPE–HPLC determination of some common drugs and herbicides of environmental concern by pulsed amperometry

Pulsed-sonochemiluminescence combined with molecularly imprinted polymerized high internal phase emulsion adsorbent for determination of bentazone

A small low-power humidifier with a simple programmable on/off switch was used as a pulsed ultrasound generator. Using this tool, a novel sonochemiluminescence (SCL) method was developed to determine bentazone. To the best of our knowledge, no chemiluminescence method has been proposed to determine this pesticide. Only five studies have been proposed for SCL quantitative applications so far. Therefore, revealing new aspects of SCL promises to develop analytical methods for the quantitative determination of different substances. A molecularly imprinted polymerized high internal phase emulsion (MIP-polyHIPE) was synthesized, bentazone separated from aqueous solutions, and pre-concentrated by the MIP-polyHIPE foam. The adsorption of bentazone on the MIP-polyHIPE adsorbent was theoretically studied by density functional theory through molecular dynamics simulation. Both experimental and simulation results indicated removal and pre-concentration of bentazone by the MIP-polyHIPE adsorbent. Using the proposed SCL method and without pre-concentration process, a linear dynamic range (LDR) of 2.5 × 10^-7-5.0 × 10^-5 mol L^-1 and a limit of detection (LOD) of 8.4 × 10^-8 mol L^-1 were obtained for bentazone with a relative standard deviation of 2.64%. The LDR and LOD were improved to 2.6 × 10^-9-2.0 × 10^-7 mol L^-1 and 8.8 × 10^-10 mol L^-1, respectively, using MIP-polyHIPE adsorbents. The method's application was evaluated by removing and pre-concentration of bentazone from water samples, including well, river, and tap water. The results showed that the pre-concentration factor and recovery percentages were 113-131 times and 93-106%, respectively, using the MIP-polyHIPE absorbent.

A Comprehensive Review on Metal Organic Framework Based Preconcentration Strategies for Chromatographic Analysis of Organic Pollutants

Organic pollutants (OPs) are of worldwide concern for being hazardous to human existence and natural flora and fauna in view of their contaminating nature, bio-aggregation properties and long range movement abilities in environment. Metal organic frameworks (MOFs) are a new kind of crystalline porous material, composed of metal ions and multi dentate organic ligands with well-defined co-ordination geometry exhibiting promising application respect to adsorptive evacuation of OPs for chromatographic analysis. Applications of MOFs as preconcentration material and column packing material are reviewed. Key analytical characteristics of MOF based preconcentration techniques and coupled chromatographic procedures are summarized in detail. MOF based preconcentration strategies are compared with conventional sorbent based extraction techniques for thorough evaluation of performance of MOF materials.

Amino groups modified SBA-15 for dispersive-solid phase extraction in the analysis of micropollutants by QuEchERS approach

In the analysis of contaminants in food products, sample preparation is performed by proper adsorbents, whose choice is crucial to eliminate matrix interference. In this work we modified SBA-15 adsorbents by functionalization with (3-aminopropyl)-triethoxysilane (SBA-15-APTES) and N-[3-(trimethoxysilyl)propyl]aniline (SBA-15-AN) aiming to use them for the first time in the clean-up step of a QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction of micropollutants from strawberry, a sugar rich fruit. After physico-chemical characterization by nitrogen adsorption, infrared spectroscopy and thermogravimetric analysis, the adsorption capabilities of SBA-15 sorbents and possible interaction mechanisms were studied at different pH (2.1-8.5) for glucose, sucrose and fructose at concentrations characteristic of those found in strawberries. The performance of the two SBA-15 sorbents was compared with that of commercial PSA (primary secondary amine), usually proposed in QuEChERS protocols. Both SBA-15 materials exhibit up to 30% higher adsorption than PSA, suggesting their possible QuEChERS application. Synthesized SBA-15 adsorbents were hence used as innovative dispersive sorbents in the QuEChERS extractions of 13 PAHs and 14 PCBs from strawberry. For PCBs, SBA-15-AN provides better matrix removal than PSA and comparable extraction recoveries around 90%. For PAHs, the use of SBA-15-AN has the advantage of lower relative standard deviation (7%) than PSA (19%).

Preparation of a new three-component deep eutectic solvent and its use as an extraction solvent in dispersive liquid-liquid microextraction of pesticides in green tea and herbal distillates

BACKGROUND

A new solvent, deep eutectic solvent, in which there is growing interest, has been prepared and used as an extraction solvent in the dispersive liquid-liquid method of microextraction. To prepare the solvent, dichloroacetic acid, l-menthol, and n-butanol are mixed at a molar ratio of 4:1:1 and the deep eutectic solvent is formed after heating. Then a dispersive liquid-liquid microextraction method using the prepared solvent is used for the extraction and preconcentration of some pesticides from an aqueous sample. To carry out the procedure, the deep eutectic solvent is mixed with methanol and rapidly injected by a syringe into the aqueous sample containing the analytes. After centrifuging, an aliquot of the sedimented phase is injected into the gas chromatograph. The influence of several variables on the extraction efficiency was investigated and optimized.

RESULTS

Extraction recoveries and enrichment factors were obtained in the ranges of 53-86% and 1760-2853, respectively. The intra- (n = 6) and inter-day (n = 5) precision of the method was satisfactory, with relative standard deviations ≤ 7% obtained at two concentrations of 10 and 50 μg L^-1 of each analyte. Moreover, detection and quantification limits for the target analytes were obtained in the ranges of 0.11-0.23 and 0.38-0.74 μg L^-1 , respectively.

CONCLUSION

Different samples, including green tea, rose water, lemon balm, mint, and pussy willow distillates were analyzed successfully using the method that was developed, and chlorpyrifos was found in rose water at a concentration of 17 ± 1 μg L^-1 (n = 3). © 2019 Society of Chemical Industry.

Chromatographic determination of biogenic amines in four typical Italian cheeses: correlations with processing and nutritional characteristics through a chemometric approach

BACKGROUND

The presence of biogenic amines (BAs) fermented food is well known. They may affect food quality, posing health risks. In this work, four typical Italian cheeses, exported worldwide, were analyzed to determine the possible presence of BAs. The cheese samples were analyzed untreated and having been subjected to common or incorrect consumer handling (domestic grating, unrefrigerated storage).

RESULTS

A chromatographic-amperometric method was developed and validated. Extraction of BAs was performed by the addition of eluent, determining matrix effect and recovery of biogenic amines directly within the cheeses. Biogenic amines were present in the range of 0.019-0.044 g kg^-1 , well below the current EU limit. Home-manipulation confirmed recontamination of the cheese. The contents of BAs were correlated with the main processing parameters and with the nutritional properties of the four cheeses through the multivariate statistical analysis (principal component analysis). This is believed to be the first study that presents these correlations.

CONCLUSION

This study highlights correlations among BAs and carbohydrates, and anticorrelations with pH and, to a lesser extent, with moisture. Interestingly, BAs are correlated with fat content. This correlation was confirmed by a new principal component analysis performed on our data set with additional data from the literature. © 2019 Society of Chemical Industry.

Effects of waterborne antidepressants on non-target animals living in the aquatic environment: A review

After application, antidepressants, like other pharmaceuticals, are excreted from human body in their native form or as metabolites and enter the aquatic environment via different pathways. As concentrations of antidepressant residues in water continue to increase, their effects on non-target animals are being discussed. The aim of this study is to summarize current knowledge about the effects of wateborne antidepressants on non-target animals living in surface waters - invertebrates, fish and amphibians. Selective serotonin reuptake inhibitors such as fluoxetine, sertraline, and citalopram have been found to effect behavior, reproduction, and development in both invertebrates and vertebrates. Venlafaxine, belonging to the group of selective serotonin-noradrenalin reuptake inhibitors, not only affected behavior but also showed the potential to reduce survival in fish. Tricylic antidepressants are known to have various side-effects when consumed by humans. Moreover, in fish, exposure resulted in a significant increase in mortality, developmental retardation, morphological anomalies, and pathological changes in brain, heart, and cranial and caudal kidney. In addition, changes in antioxidant enzyme activity as well as increased lipid peroxidation were observed, even at the lowest tested concentrations. According to current knowledge, antidepressants occuring in surface water are able to affect the behavior, reproduction, development, and survival of aquatic invertebrates and vertebrates.

Simultaneous determination of five common additives in insulating mineral oils by high-performance liquid chromatography with ultraviolet and coulometric detection

Dielectric mineral oils are used to impregnate power transformers and large electrical apparatus, acting as both liquid insulation and heat dissipation media. Antioxidants and passivators are frequently added to mineral oils to enhance oxidation stability and reduce the electrostatic charging tendency, respectively. Since existing standard test methods only allow analysis of individual additives, new approaches are needed for the detection of mixtures. For the first time we investigate and discuss the performance of analytical methods, which require or do not require extraction as sample pretreatment, for the simultaneous reversed-phase high-performance liquid chromatography determination of passivators (benzotriazole, Irgamet(®) 39) and antioxidants (N-phenyl-1-naphtylamine, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol), chosen for their presence in marketed oils. Quick easy, cheap, effective, rugged and safe and solid phase extractions were evaluated as sample pretreatments. Direct sample-injection was also studied. Ultraviolet spectrophotometry and direct-current coulometry detection were explored. As less prone to additive concentrations variability, the direct-injection high-performance liquid chromatography with ultraviolet and coulometric detection method was validated through comparison with Standard Method IEC 60666 and through an ASTM interlaboratory proficiency test. Obtained detection limits are (mg kg(-1) ): benzotriazole (2.8), Irgamet(®) 39 (13.8), N-phenyl-1-naphtylamine (11.9), 2,6-di-tert-butylphenol (13.1), 2,6-di-tert-butyl-p-cresol (10.2). Simultaneous determination of selected additives was possible both in unused and used oils, with good precision and accuracy.

Adsorption of bentazone herbicide onto mesoporous silica: application to environmental water purification

Within the last few years, the presence of bentazone herbicide has been observed in many water resources. For the first time, removal of bentazone using mesoporous silica was investigated revealing reversible adsorption. The adsorption isotherm was well described using the Freundlich model. The affinity towards bentazone is strongly affected by pH in the range of 2-7, decreasing with the increase of the pH, becoming negligible at the neutrality. Regeneration of the adsorbent was possible, and a recovery as high as 70 % was obtained using CH3OH-NaOH solution. Furthermore, appreciable recovery (47 %) was also obtained using water. Applications on the purification of lake water and wastewaters, both characterized by a significant organic carbon load, spiked with 2 mg L(-1) bentazone were tested, observing removal yields in the range of 61-73 %. Taking advantage of the fast adsorption kinetics observed, an in-flow purification treatment was set-up, with quantitative removal of bentazone from polluted water.