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Chemical Society Reviews Apr 2010
Topics: Alkenes; Alkynes; Catalysis; Copper; Organic Chemicals
PubMed: 20309482
DOI: 10.1039/c003740k -
The Science of the Total Environment Oct 2018More than half of the freshwater lakes in the Philippines are small with surface areas of <2 km. The dynamics in these lakes are different from those in the bigger...
More than half of the freshwater lakes in the Philippines are small with surface areas of <2 km. The dynamics in these lakes are different from those in the bigger lakes. This study was conducted to determine the organic pollutants and their sources in three of the seven lakes of San Pablo City in Laguna, Philippines: lakes Palakpakin, Sampaloc, and Pandin. Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS) were used in the targeted and non-targeted analysis of the lake water samples. The three lakes are all volcanic crater lakes but are exposed to different anthropogenic activities, which includes domestic activities, livelihood (farming and aquaculture) and eco-tourism. Due to the presence of rice fields and fruit plantations, chlorpyrifos was detected in the three lakes while other pesticides like cypermethrin, picolinafen and quinoxyfen were additionally found in Lake Sampaloc, which is the biggest of the three lakes and located within the urbanized section of the city. Traces of different surfactants (linear alkylbenzene sulfonates, secondary alkyl sulfonates, alkyl sulfates, alkyl ether sulfates), biocide benzalkonium chloride, insect repellent diethyltoluamide, antibiotics (sulfadiazine and sulfamethoxazole), hypertension drug telmisartan, phosphate-based fire retardants, and artificial sweeteners (acesulfame, cyclamate, saccharin and sucralose) were detected in lakes Sampaloc and Palakpakin. The same surfactants, artificial sweeteners, insect repellant and phosphate-based fire retardants were also found in Lake Pandin, which is mainly used for eco-tourism activities like swimming and boating. The results of this study suggest that the organic pollutants present in the small lakes can be linked to the various human activities in the immediate lake environment. Because small lakes are more prone to environmental stresses, human activities in the said lakes must be regulated to ensure sustainable development.
Topics: Environmental Monitoring; Humans; Lakes; Organic Chemicals; Philippines; Water Pollutants, Chemical
PubMed: 29800852
DOI: 10.1016/j.scitotenv.2018.05.217 -
Chemical & Pharmaceutical Bulletin 2017
Topics: Chemistry Techniques, Synthetic; Organic Chemicals
PubMed: 28049903
DOI: 10.1248/cpb.c17-ctf6501 -
Environmental Toxicology and Chemistry Jul 2020Field-based atrazine sampling rates (R ) obtained by the polar organic chemical integrative sampler (POCIS) method were measured in 9 headwater streams over 3 yr...
Field-based atrazine sampling rates (R ) obtained by the polar organic chemical integrative sampler (POCIS) method were measured in 9 headwater streams over 3 yr covering 5 to 6 exposure periods of 2 to 3 wk/site/yr. Rates were best in line with the model R = 148 mL/d, with a standard deviation of 0.17 log units (factor 1.5). The POCIS canisters reduced mass transfer coefficients of the water boundary layer by a factor of 2 as measured by alabaster dissolution rates. A mechanistic model that accounts for flow and temperature effects yielded a fair estimate of the effective exchange surface area (12.5 ± 0.8 cm ). This model could only be tested for higher flow velocities because of uncertainties associated with the measurement of flow velocities <1 cm/s. Pictures of sorbent distributions in POCIS devices showed that the effective exchange surface area varied with time during the exposures. Error analysis indicated that sorbent distributions and chemical analysis were minor error sources. Our main conclusion is that an atrazine sampling rate of 148 mL/d yielded consistent results for all 3 yr across 9 headwater streams. Environ Toxicol Chem 2020;39:1334-1342. © 2020 SETAC.
Topics: Atrazine; Calibration; Environmental Monitoring; Models, Theoretical; Organic Chemicals; Rivers; Temperature; Water Pollutants, Chemical
PubMed: 32408378
DOI: 10.1002/etc.4731 -
Die Nahrung Aug 2002Hazard analysis by critical control points (HACCP) is a systematic approach to the identification, assessment and control of hazards. Effective HACCP requires the...
Hazard analysis by critical control points (HACCP) is a systematic approach to the identification, assessment and control of hazards. Effective HACCP requires the consideration of all hazards, i.e., chemical, microbiological and physical. However, to-date most 'in-place' HACCP procedures have tended to focus on the control of microbiological and physical food hazards. In general, the chemical component of HACCP procedures is either ignored or limited to applied chemicals, e.g., food additives and pesticides. In this paper we discuss the application of HACCP to a broader range of chemical hazards, using organic chemical contaminants as examples, and the problems that are likely to arise in the food manufacturing sector. Chemical HACCP procedures are likely to result in many of the advantages previously identified for microbiological HACCP procedures: more effective, efficient and economical than conventional end-point-testing methods. However, the high costs of analytical monitoring of chemical contaminants and a limited understanding of formulation and process optimisation as means of controlling chemical contamination of foods are likely to prevent chemical HACCP becoming as effective as microbiological HACCP.
Topics: Consumer Product Safety; Decision Trees; Food Analysis; Food Contamination; Food Handling; Food Inspection; Food-Processing Industry; Humans; Organic Chemicals; Proportional Hazards Models; Safety Management
PubMed: 12224422
DOI: 10.1002/1521-3803(20020701)46:4<258::AID-FOOD258>3.0.CO;2-2 -
Talanta Apr 2018Rapid, on-site analysis was achieved through significantly simplified operation procedures for a wide variety of toy samples (crayon, temporary tattoo sticker, finger...
Rapid, on-site analysis was achieved through significantly simplified operation procedures for a wide variety of toy samples (crayon, temporary tattoo sticker, finger paint, modeling clay, and bubble solution) using a miniature mass spectrometry system with ambient ionization capability. The labor-intensive analytical protocols involving sample workup and chemical separation, traditionally required for MS-based analysis, were replaced by direct sampling analysis using ambient ionization methods. A Mini β ion trap miniature mass spectrometer was coupled with versatile ambient ionization methods, e.g. paper spray, extraction spray and slug-flow microextraction nanoESI for direct identification of prohibited colorants, carcinogenic primary aromatic amines, allergenic fragrances, preservatives and plasticizers from raw toy samples. The use of paper substrates coated with CoO nanoparticles allowed a great increase in sensitivity for paper spray. Limits of detection as low as 5μgkg were obtained for target analytes. The methods being developed based on the integration of ambient ionization with miniature mass spectrometer represent alternatives to current in-lab MS analysis operation, and would enable fast, outside-the-lab screening of toy products to ensure children's safety and health.
Topics: Amines; Child; Cobalt; Coloring Agents; Humans; Nanoparticles; Odorants; Organic Chemicals; Oxides; Paper; Plasticizers; Play and Playthings; Spectrometry, Mass, Electrospray Ionization; Time Factors
PubMed: 29332799
DOI: 10.1016/j.talanta.2017.12.050 -
Talanta Aug 2018The calibration of two passive samplers for the determination of 20 emerging organic compounds in seawater is described in this work: i) a new version of polar organic...
The calibration of two passive samplers for the determination of 20 emerging organic compounds in seawater is described in this work: i) a new version of polar organic chemical integrative sampler (POCIS) containing 100 mg of mixed-mode anion exchanger (Strata X-AW) and 100 mg of polymeric HLB (Plexa) sorbent materials and using a highly porous Nylon membrane (30-μm pore size) and ii) polyethersulfone (PES) hollow fibre. Among the studied contaminants, herbicides, hormones, life style products (stimulants and artificial sweeteners), industrial chemicals (corrosion inhibitor and fluorinated compounds), personal care products and several pharmaceuticals were included. In the case of POCIS, both the sorbents and the Nylon membranes were extracted and analysed independently. The calibration set up consisted on a continuous-flow tank that was fed with a continuous flow of seawater (2 L/h) and a stock mixture of contaminants (20 mL/h), assuring a nominal concentration of ~ 600 ng/L (each analyte) in the tank. The uptake was linear in POCIS sorbent and Nylon membranes but exponential for PES hollow fibres. Furthermore, the highest sampling rates (Rs) values were obtained in POCIS sorbent (between 2.7 for acetaminophen and 491 mL/day for perfluoro-n-octanoic acid, PFOA) followed by Nylon membranes (between 3.6 for OBT and 50 mL/day for telmisartan) and the lowest were those from PES fibres (between 1.7 for bezafibrate and 157 mL/day for butylparaben). Additionally, five deuterated compounds ([H]-atrazine, [H]-amitriptyline, [H]-irbesartan, [H]-ketoprofen and [H]-progesterone) were studied as candidates for performance reference compounds (PRCs) in both POCIS and PES, and though [H]-atrazine, [H]-progesterone and [H]-amitriptyline showed acceptable results in the case of POCIS, only [H]-atrazine provided a good validation. In the case of PES fibres, the PRC corrections did not provide acceptable results due to a low dissipation of the PRCs. Finally, POCIS were deployed in two sites of the low part of the estuary of Bilbao (northern Spain) from where water samples were also taken and analysed. As a result, in addition to the overall good agreement between the passive and active samplings, passive samplers allowed the determination of several compounds that were below the detection limits in the active sampling.
Topics: Nylons; Organic Chemicals; Particle Size; Polymers; Porosity; Seawater; Sulfones
PubMed: 29759229
DOI: 10.1016/j.talanta.2018.03.103 -
Microwave: An Important and Efficient Tool for the Synthesis of Biological Potent Organic Compounds.Current Medicinal Chemistry 2017Green Chemistry is an interdisciplinary science or it can also be explained as a branch of chemistry. It is generally described as the chemistry to aim to synthesize... (Review)
Review
BACKGROUND
Green Chemistry is an interdisciplinary science or it can also be explained as a branch of chemistry. It is generally described as the chemistry to aim to synthesize chemical compounds to trim down the utilization of harmful chemicals proposed by the Environmental Protection Agency (EPA). Recently, the plan of academicians, researchers, industrialists is to generate greener and more efficient methodologies to carry out various organic syntheses.
OBJECTIVE
In the present scenario, green chemistry utilizes the raw materials economically, minimizes the waste and prevents the uses of harmful or hazardous chemicals to make the organic reactions simple and efficient.
CONCLUSION
Microwave technique is a new, simple and efficient technology which opens new prospects to the chemists to carry out various organic and inorganic reactions, which are difficult via conventional methodology. It is used to decrease the duration of time to carry various organic transformation along with maximum yield, minimum by-products, minimum energy utilization, less manpower etc. e.g. various famous organic reactions have been carried out by various research groups like Aldol condensation, Knoevenagel condensation, Beckmann rearrangement, Vilsmeier reaction, Perkin reaction, Benzil-Benzilic acid rearrangement, Fischer cyclization, Mannich reaction, Claisen-Schmidt condensation, etc. Further, reduction, oxidation, coupling, condensation reaction were also performed using microwave technology.
Topics: Green Chemistry Technology; Microwaves; Molecular Structure; Organic Chemicals
PubMed: 28554323
DOI: 10.2174/0929867324666170529100929 -
Environmental Toxicology and Chemistry May 2020The present study pertains to a polar organic chemical integrative sampler (POCIS) laboratory calibration to estimate the sampling rates for 44 pharmaceuticals featuring...
The present study pertains to a polar organic chemical integrative sampler (POCIS) laboratory calibration to estimate the sampling rates for 44 pharmaceuticals featuring a wide range of polarity (-0.6 < octanol/water partition coefficient [log K ] < 5.4). The calibration was performed at 16.0 ± 1.5 °C for 4 water flow velocities (0, 2-3, 6-7, and 20 cm/s) in both a tank (for calibration at 0 cm/s) and a laboratory-scale artificial river filled with 200 and 500 L of tap water spiked with 0.3 µg/L of each compound, respectively. Twelve new sampling rates and 26 sampling rates already available in the literature were determined, whereas the sampling rates for 6 pharmaceuticals could not be determined due to nonlinearity or poor accumulation in POCIS. An increase in the sampling rate value with flow velocity was observed, which is consistent with a decrease in the effective thickness of the water boundary layer at the POCIS membrane surface. Environ Toxicol Chem 2020;39:1186-1195. © 2020 SETAC.
Topics: Calibration; Environmental Monitoring; Models, Theoretical; Organic Chemicals; Pharmaceutical Preparations; Rivers; Water Movements; Water Pollutants, Chemical
PubMed: 32222997
DOI: 10.1002/etc.4717 -
Chemosphere Aug 2018The toxicity towards the algal species Pseudokirchneriella subcapitata of 425 organic chemical substances was tested in a growth inhibition test. Precautions were taken...
The toxicity towards the algal species Pseudokirchneriella subcapitata of 425 organic chemical substances was tested in a growth inhibition test. Precautions were taken to prevent loss of the compounds from the water phase and the test system (closed test system, low biomass, shorter test duration, silanized glass) and to keep pH constant by applying a higher alkalinity. Chemical phase distribution was modelled taking ionization, volatilisation, and adsorption to glass and biomass into consideration. If the modelled water concentration was below 90% of the nominal concentration the calculated EC values were corrected accordingly. The model helped to identify substances, where the calculated water concentration was too uncertain. Substances covering a wide range of physical-chemical properties and different modes of action were tested. Median effect concentrations (EC) lower than 1000 mg/L were found for 310 substances; 216 of these were in the range from 1 to 1000 mg/L and 94 substances had ECs below 1 mg/L and should be classified as "Very toxic". 36 substances fell in the group with EC > 1000 mg/L. An EC could not be established for 79 substances. These 425 different organic substances were tested under uniform conditions and thus considered a valuable source of information for administrators, industry, risk assessors and QSAR modellers.
Topics: Chlorophyta; Organic Chemicals; Toxicity Tests; Water Pollutants, Chemical
PubMed: 29677648
DOI: 10.1016/j.chemosphere.2018.04.047