Phosphoric Acid Esters Research Articles

Preparation and structural characterization of epoxidized soybean oils-based pressure sensitive adhesive grafted with tea polyphenol palmitate

Vegetable oils-based pressure sensitive adhesives (PSAs) are green and sustainable but face unsatisfactory adhesion strengths and are prone to aging during storage and application due to the existence of residual double bonds and massive ester bonds. Nine common antioxidants (tea polyphenol palmitate (TPP), caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, and tea polyphenols) were grafted into epoxidized soybean oils-PSA (ESO-PSA) system to enhance antiaging properties and adhesion strengths. Results showed ESO-PSAs grafted with caffeic acid, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, tea polyphenols, or TPP didn't occur failure with TPP having best performance. The optimal conditions were ESO reacted with 0.9 % TPP, 70 % rosin ester, and 7.0 % phosphoric acid at 50 °C for 5 min, under which peel strength and loop tack increased to 2.460 N/cm and 1.66 N, respectively, but peel strength residue reduced to 138.09 %, compared with control (0.407 N/cm, 0.43 N, and 1669.99 %). Differential scanning calorimetry and thermogravimetric results showed TPP grafting increased the glass transition temperature of ESO-PSA slightly but improved its thermal stability significantly. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance results showed TPP, phosphoric acid, and rosin ester all partially participated in the covalently crosslinking polymerization of ESO-PSAs and the rest existed in the network structures in the free form.

HISTOCHEMICAL LOCALIZATION OF ACID AND ALKALINE PHOSPHATASES IN MONIEZIA EXPANSA (RUDOLPHI, 1805)

Cestodes or true tapeworms are important group of the Platyhelminthes, endoparasitic in the alimentary tract and associated ducts of various vertebrates and therefore, of great interest to the medical and veterinary profession.Moniezia expansa, the tapeworm under study is the common parasite of oldest domesticated animal sheep. It inhabits the small intestine especially the lower portion and absorb the nutrition of host from the intestine and deprive it of many important nutrients and thus deteriorates the quality of meat, wool, skin of host which leads to ecomical losses as well.Phosphatases are enzymes hydrolysing esters of phosphoric acid and play an important role in many metabolic processes. The histochemical localization of acid and alkaline phosphatase has been studied in Moniezia expansa as an effort to study some of its biological aspects which would help in its control and chemotherapy.Acid phosphatase was found to be localized in tegument, subtegumental cells, parenchymal muscles, interproglottidal gland tegument, Mehlis glands, testes, uterine wall and eggs and was not observed in parenchyma, interproglottidal gland cells, excretory vessels, ovaries and vitellaria. Alkaline phosphatase activity was observed in tegument, subtegumental cells, parenchymal muscles, parenchyma, interproglottidal glands, excretory vessels, membranes enclosing ovaries, vitellaria, Mehlis gland, testes, uterine wall and eggs.The presence of acid phosphatase in testes, mehlis' glands, uterine wall and eggs as well as alkaline phosphatase in eggs in Moniezia expansa has been reported for the first time.Both the acid and alkanine phosphatases showed the variations in their activity in the tegument along the strobila with highest in mature region. This gives the idea of high metabolic activity in the mature region of the cestode. These phosphatases play important role in metabolism of the parasite and seems to be involved in transportation, digestion, distribution of nutrients and metabolites and absorption of metabolic end products.

A highly durable reactive flame retardant with –N=P–(N)3– and phosphoric acid ester groups for cotton fabrics

A highly durable reactive flame retardant with –N=P–(N)3– and phosphoric acid ester groups for cotton fabrics

α-нуклеофилы – основа супернуклеофильных организованных микрогетерогенных систем для разложения фосфорорганических соединений

Peroxyhydrolysis of 4-nitrophenyl esters of phosphoric and phosphonic acids has been studied in organized microheterogeneous systems based on dimeric cationic imidazole-containing surfactants (AlkIm+-(CH2)m-Im+Alk ∙ 2Br- , m = 2,3,4, Alk = C12H25, C14H29). Micellar effects of the surfactants (at pH = const and [surfactant]0 = const) reach ~ 10–100 times. Physicochemical parameters of the peroxyhydrolysis process (such as substrate binding constants, hydroperoxide anion nucleophilicity in micellar pseudophase) are described in terms of the pseudophase distribution model. Observed rate enhancement mainly depends on reagent concentration increasing directly connected to hydrophobicity of the substrate and surfactant. Changes of HOO- nucleophilicity under the displacement of the peroxyhydrolysis from water to surfactant micelles also contributed to the micellar effects. Comparative analysis of the regularities of peroxyhydrolysis and alkaline hydrolysis testifies for generality of such features in OMS for nucleophilic substitutions. In this regard, the α-effect as rate constants ratio of peroxyhydrolysis (𝑘𝑘2,𝐻𝐻𝐻𝐻𝑂𝑂− 𝑚𝑚 ) to base hydrolysis (𝑘𝑘2,𝐻𝐻𝑂𝑂− 𝑚𝑚 ) in micellar pseudophase 𝑘𝑘2,𝐻𝐻𝐻𝐻𝑂𝑂− 𝑚𝑚 /𝑘𝑘2,𝐻𝐻𝑂𝑂− 𝑚𝑚 ) reaches ~ 80–100 times. Therefore, the α-effect appears not only in water, but in OMS, too.

Friedel-Crafts-Type Acylation and Amidation Reactions in Strong Brønsted Acid: Taming Superelectrophiles.

In this review, we discuss Friedel-Crafts-type aromatic amidation and acylation reactions, not exhaustively, but mainly based on our research results. The electrophilic species involved are isocyanate cation and acylium cation, respectively, and both have a common +C=O structure, which can be generated from carboxylic acid functionalities in a strong Brønsted acid. Carbamates substituted with methyl salicylate can be easily ionized to the isocyanate cation upon (di)protonation of the salicylate. Carboxylic acids can be used directly as a source of acylium cations. However, aminocarboxylic acids are inert in acidic media because two positively charged sites, ammonium and acylium cation, will be generated, resulting in energetically unfavorable charge-charge repulsion. Nevertheless, the aromatic acylation of aminocarboxylic acids can be achieved by using tailored phosphoric acid esters as Lewis bases to abrogate the charge-charge repulsion. Both examples tame the superelectrophilic character.

Influence of solar activity on water clusters. Annual variations 2015—2019

The variations of solar activity and distribution of solar energy due to the rotation of the Earth around its axis and around the Sun exert a strong influence on water clusters, as a result of which their chemical reactivity in hydrolytic processes can vary in a very wide range. This phenomenon is well manifested in the hydrolysis of the phosphoric acid esters. The 5-year regular investigations (2015—2019) of the hydrolysis of triethylphosphite in acetonitrile show that the rate of this reaction with all other conditions being equal displays diurnal, very large annual variations, and is also modulated by the 11-year cycles of solar activity. Since water is a necessary constituent in all forms of life, the discovered diurnal and annual variations of water clusters’ reactivity may underlie the biological circadian and circannual rhythms. The results obtained also point to the fact that the chemical reactivity of water clusters depends on the geographic latitude, and, in summer and winter, it can be significantly different at the same time in the Northern and Southern hemispheres. At the equator, where there should be no seasonal differences, measurements of the rate of triethylphosphite hydrolysis may become an independent method for assessing the solar activity.

НОВЫЕ ИНГИБИТОРЫ СОЛЕОТЛОЖЕНИЙ НА ОСНОВЕ МОДИФИЦИРОВАННЫХ ОТХОДОВ ПОЛИЭТИЛЕНТЕРЕФТАЛАТА

For the first time, the synthesis of new scaling inhibitors – esters of phosphoric acids, based on the reactions of phosphorylation of hydroxyethylterephthalamide with polyphosphoric acid, was theoretically substantiated and experimentally carried out. The esterification with polyphosphoric acid of bishydroxyethyterephthalamide was carried out at a temperature of 130-140°C for 4-6 hours. Bishydroxyethyl terephthalamide is a product of the aminolysis of polyethylene terephthalate, including in the form of production waste or recycling of polyethylene terephthalate. Using 1 H-, 31P spectroscopy the structure and composition of new reagents were proved. The inhibitory activity of phosphoric acid esters of bishydroxyethyl terephthalamide was studied on model water-salt solutions. It has been established that inhibitors have complex actions in relation to carbonate and sulfate deposits. An effective amount to inhibit sulfate scale is 2-10 ppm, carbonate scale 10-30 ppm. The degree of inhibition reaches 100%. Inhibitors can be recommended to protect pipelines from scale deposits during oil transportation.

Recovery of Catapleiite and Eudialyte from Non-Magnetic Fraction of Eudialyte ore Processing of Norra Kärr Deposit

Eudialyte ores from Norra Kärr (Sweden) and Kringlerne (Greenland) are considered a potential source of rare-earth elements (REE) for the development of a sustainable REE industry outside China. Magnetic separation is successfully applicated to recover eudialyte as a magnetic fraction. In the case of the Norra Kärr deposit, up to 20% of the REE and up to 40% of the Zr are lost during mineral processing in the non-magnetic fraction. Zr and REE are associated with non-magnetic minerals such as catapleiite, low- or non-magnetic eudialyte species, and both their intergrowths. Besides zirconosilicates such as catapleiite and eudialyte, the non-magnetic fraction has valuable and already-liberated minerals such as alkali feldspars and nepheline, which should not be considered as tailings. In this investigation, a possible way to recover REE bearing zirconosilicates from the non-magnetic fraction using flotation is presented. First, a low-grade eudialyte concentrate (1.8% Zr, 0.94% REE) from ground ore was obtained using magnetic separation. The non-magnetic fraction was then treated using froth flotation, and a Zr-REE bearing product (9% Zr, 1.5% REE) was obtained as froth product. For this purpose, phosphoric acid esters were used as selective collectors for zirconosilicates at a pH between 3.5 and 4.5. The reagent regime could be proposed not only to recover Zr- and REE-bearing minerals, but also simultaneously to remove Fe, Ti, and other colored impurities from the nepheline-feldspar product and to minimize the tailings volume.

Flame retardant polyurethane foams with starch unit

Polyurethane foams with incorporated starch described in up to date literature have good functional properties except flame resistance. Their oxygen index falls within 19.3–20.5%, while flame rate is 2.25–12.50 mm/s. We have obtained and tested polyurethane foams with following flame retardants: melamine, and two phosphoric(V) acid esters: Fyrol PNX and Fyrol PCF. The functional properties of the flame retardant modified foams were compared with non-modified foams using horizontal flaming tests, determination of oxygen index and combustion in microcalorimeter. According to horizontal flaming tests all modified foams were self-extinguishing. The oxygen index of modified foams was within 22.9–24.4%. The foams could stand long-term heating at 150 °C temperature. Moreover, the polyurethane foams have a biodegradation potential.

Adsorption performance and mechanism of the commonly used collectors with Oxygen-containing functional group on the ilmenite surface: A DFT study

Flotation is the main method to purify ilmenite, the success of flotation is closely related to the effective adsorption of collectors on the mineral surface. Herein, the coordination chemistry adsorption mechanism of the commonly used collectors with oxygen-containing functional groups on ilmenite surface were systematically investigated by first-principles DFT calculations. Adsorption energy results shows that the O bearing pnictogen compounds are the best for ilmenite beneficiation among all the oxygen-containing collectors. In the O-bearing pnictogen compounds, the collection performance of arsenic acid is the best, followed by phosphorous acid and phosphoric acid ester. The frontier molecular orbital analysis predicted that the collectors possessed a good chemical bonding ability with ilmenite, which is confirmed by the charge population analysis that there is significant electron transfer (bonding evidence) between collectors and ilmenite. Partialdensityofstates analysis further confirmed that the physicochemical nature of the adsorption of the collectors on the surface Ti site were ascribed to the hybridization of O 2p and Ti 3d, in which the O 2p electrons of the collectors occupied the empty orbital of Ti 3d to complete the coordination shell of surface Ti atom. This work sheds new light on the screening of solidophilic functional groups for the collector design of ilmenite beneficiation and helps to explain the adsorption mechanism of oxygen-containing collectors on the oxidized mineral surface.

Chitin Cryogels Prepared by Regeneration from Phosphoric Acid Solutions.

Cryogelation is a developing technique for the production of polysaccharide materials for biomedical applications. The formation of a macroporous structure during the freeze-drying of polysaccharide solutions creates biomaterials suitable for tissue engineering. Due to its availability, biocompatibility, biodegradability, and non-toxicity, chitin is a promising natural polysaccharide for the production of porous materials for tissue engineering; however, its use is limited due to the difficulty of dissolving it. This work describes the preparation of cryogels using phosphoric acid as the solvent. Compared to typical chitin solvents phosphoric acid can be easily removed from the product and recovered. The effects of chitin dissolution conditions on the structure and properties of cryogels were studied. Lightweight (ρ 0.025–0.059 g/cm3), highly porous (96–98%) chitin cryogels with various heterogeneous morphology were produced at a dissolution temperature of 20 ± 3 °C, a chitin concentration of 3–15%, and a dissolution time of 6–25 h. The crystallinity of the chitin and chitin cryogels was evaluated by 13C CP-MAS NMR spectroscopy and X-ray diffractometry. Using FTIR spectroscopy, no phosphoric acid esters were found in the chitin cryogels. The cryogels had compressive modulus E values from 118–345 kPa and specific surface areas of 0.3–0.7 m2/g. The results indicate that chitin cryogels can be promising biomaterials for tissue engineering.

Inhibition of the activated sludge-associated enzyme phosphatase by transition metal oxyanions.

Organic esters of phosphoric acid and other organophosphorous compounds are enzymatically hydrolyzed during wastewater treatment by microbial phosphoesterases, especially by phosphomonoesterase (phosphatase). For physiological reasons, the enzyme is inhibited by its main inorganic reaction product, ortho-phosphate. It is known that oxyanions of transition metals, resembling the molecular topology of ortho-phosphate, e.g. vanadate and tungstate, are more potent inhibitors for microbial alkaline phosphatase than phosphate. To proof this effect for activated sludge, a multitude of samples from a communal wastewater treatment plant was exposed at pH values from 7.00 to 8.50 to tungstate, vanadate, and molybdate. Inhibition effects were determined by a sensitive fluorimetric microplate assay and characteristic parameters (IC50 and IC20 concentrations) were deduced from modelled dose-response functions. Mean inhibitor concentrations (in brackets: ranges) causing 50% inactivation (IC50) at pH 7.50 were 2.5 (1.3-4.1) μM tungstate, 2.9 (1.6-5.5) μM vanadate, and 41.4 (33.6-56.7) μM molybdate. Vanadate and tungstate concentrations between 0.6 and 0.7 μM provoked a 20% (IC20) inhibition. The inhibition efficiency of tungstate and molybdate decreased with increasing pH, whereas vanadate reacted pH independently. These results underline the necessity to consider enzyme inhibition assessing the limitations and potentials of biological wastewater treatment processes.

Synthesis of alkyl phosphates and investigation of their surface-active properties in an alkaline surfactant polymer system for enhanced oil recovery

Chemical flooding is a technique of enhanced oil recovery (CEOR) using formulations containing alkaline components, surfactants and polymers (ASP technology). The development and synthesis of novel highly efficient industrial surfactants take this technology to a new level, allowing the chemical composition of reagents to be tailored to the reservoir conditions of fields in Western Siberia. Alkyl phosphates with various structures are one type of the surfactants that can be used in ASP technology. This work aimed to synthesize and examine the properties of commercial (semi-industrial) alkyl phosphates and alkoxylated alkyl phosphates of mixed composition that meet the requirements of an efficient surfactant component of an ASP-flooding formulation. The synthesis was carried out using industrial fatty alcohols by the phosphating reaction with phosphorus pentoxide. A mixture of monoand disubstituted phosphoric acid esters of a defined ratio can be obtained by target tailoring of the feedstock properties (structural changes, molecular weight distribution in alcohols) and the synthesis conditions. This mixture, requiring no addition of cosurfactants, is an effective multi-component surfactant for an ASP-system. In this work, three effective alkyl phosphates and alkoxylated alkyl phosphates blends were synthesized. The composition of the synthesized phosphoric esters was evaluated by high-resolution mass spectrometry (HRMS), infrared (IR) spectroscopy and potentiometric titration. At reservoir temperature, the obtained samples provided sufficient solubility in an oil-displacing aqueous solution in the technologically required salinity interval, compatibility with other components, low interfacial tension (IFT) values at the interface between ASP solution and oil from Western Siberia fields, and the formation of the sufficient volume of the emulsion phase in a phase experiment. The primary laboratory research data proved the efficiency of the synthesized surfactants in ASP technology in the fields of Western Siberia.

Cellulose cryogels prepared by regeneration from phosphoric acid solutions

The supermacroporous structure and ease of preparation of polysaccharide-based cryogels have led to their wide use in many areas and make them promising biomaterials for tissue engineering. One polysaccharide of particular interest for the production of tissue engineering scaffolds is cellulose, a natural biocompatible and nontoxic polymer. However, the complex supramolecular structure of cellulose creates difficulties in its dissolution and further processing into biomedical products. Conventional cellulose solvents have significant disadvantages, including poor removal from the resulting products. Therefore, this work proposes the preparation of cellulose-based cryogels using orthophosphoric acid, which can be easily removed and recovered. The effect of cellulose dissolution conditions on the structure and properties of cryogels were studied. Highly porous (88.3–93.4%) and light (ρ 0.091–0.161 g/cm3) cryogels with complex hierarchical morphologies were produced using a dissolution temperature of (20 ± 2) °C, a cellulose concentration in the solution > 3%, a dissolution time of 24–48 h (depending on the cellulose concentration), and precipitation with water or acetone. 13C CP-MAS NMR spectroscopy results confirmed that the regenerated cellulose is predominantly amorphous, with a crystallinity of 6.8–30.6% in the structure of cellulose II. The compressive modulus E for cryogels was from 330 to 3675 kPa. FTIR spectroscopy results showed that the regenerated cellulose had an increased number of aldehyde groups and a decreased number of hydrogen bonds decreases, indicating a decrease in crystallinity. No phosphoric acid esters of cellulose were detected in the cryogels by FTIR spectroscopy. These results pave the way for the easy preparation of biomaterials for tissue engineering.

Multifunctional Cotton Fabrics Obtained by Modification with Silanes Containing Esters of Phosphoric Acid as Substituents.

The development of novel flame retardants for cotton textiles that form a stable layer on textile fiber is of high economical and practical relevance. A novel flame retardant fluorinated phosphoric acid esters modified silicone resins for cotton modification were synthesized. The investigated phosphoric acid esters based compounds were substituted by a fluorinated chain or ring, and alkoxysilyl groups. The presence of alkoxysilyl groups allowed the formation of bonds with cellulose, while derivatives of phosphoric esters reduced the flammability of fabrics. Additionally, the presence of fluoride in their structures affected the hydrophobic properties. Cotton fabrics were modified in a simple one-step process by dip-coating method. The flame retardant properties of modified textiles were examined by performing microcalorimetric analysis, thermogravimetry analysis, and measuring oxygen index. The hydrophobicity was evaluated by measuring the water contact angle. The modified fabrics were characterized by SEM-EDS (Scanning Electron Microscopy with Energy Dispersive Spectroscopy) analysis and surface morphology. As a result of the tests, multifunctional fabrics were obtained.

Using compatibility charts to optimize research into fire retardants

Introduction.Interdisciplinary research is a most relevant issue in science and education. The integration of intellectual resources with research and production infrastructure is acknowledged as the main goal of interdisciplinary research in the international practice.The main (analytical) part.The authors propose the following methodological approach to the study, based on the distribution of interdisciplinary methods into groups by the scale of the research subject (material). In this case, the studies have the following levels: microlevel, supramolecular level, material research, design research. The paper presents research methods used at each of these levels. The co-authors propose to optimize the study of performance characteristics of building materials and fire retardants through the use of a compatibility chart with regard for the study levels and the analysis of methods of experimental research at each level.Using a compatibility chart.The methodology of the study. A research into the fire retardant efficiency of esters of phosphoric acid, used to modify wood, was selected as a practical example for compatibility diagrams. The project encompasses a number of methods applicable to compatibility charts: the method of elemental analysis, the Gibbs energy assessment method, the sample surface assessment method, the electron microscopy method, methods of assessing fire-hazardous characteristics of wood, the water sorption method, strength and biosecurity assessment methods.Conclusions.The co-authors first proposed an algorithm for generalizing the empirical data on mechanochemical characteristics of materials using interdisciplinary methods in the form of a compatibility chart. This methodology optimizes research into any composite materials though it preserves targeted research methods and eliminates impractical and concomitant experimental studies, thus, reducing labour costs and environmental impacts.

A novel high durability flame retardant with phosphoric acid ester groups and a reactive ammonium phosphorus acid group for cotton fabrics

A novel reactive flame retardant with two phosphoric acid ester groups and one ammonium phosphorus acid group, the ammonium salt of 2,7-bis(dimethoxyphosphoryl)-3,7-dimethyl-3-phosphonic acid (FR–LO), was synthesized. The treated cotton fabrics displayed a high flame retardancy and excellent durability because the FR–LO molecule contains two phosphoric acid ester groups without an ammonium ion that can be eliminated and decrease the flame retardancy. The cotton fabrics treated with 30% FR–LO had limiting oxygen indexes of 43.4, and 29.7 after 50 laundry cycles according to AATCC 61–2013 2A standard. Scanning electron microscope images and energy-dispersive X-ray spectroscopy showed that the treated cotton fibers retained their complete structure after combustion, and nitrogen and phosphorus were present in the treated cotton fibers. Thermogravimetric and thermogravimetric-infrared analyses showed that the treated cotton produced more carbon residue and released fewer combustible gases during thermal decomposition. Microscale combustion calorimetry showed that the heat release rate and total heat release of the treated cotton during combustion were much lower than those of pre-treated cotton. The stiffness of cotton treated with FR–LO increased, and its tensile strength decreased compared with pre-treated cotton.

Effect of three structurally different epoxy resins on fire resistance, optical transparency, and physicomechanical properties of intumescent fire-retardant transparent coatings

Transparent intumescent fire-retardant (IFR) coatings are the newest passive fireproofing materials which maintain structural integrity without losing aesthetic appearance of the substrate. In this present paper, effects of three IFR coatings with structurally different epoxy resins, namely aliphatic, cycloaliphatic, and aromatic, on the fire resistance, transparency, and physicomechanical properties were investigated. Different phosphate resin acids (PRA) were prepared by reacting synthesized phosphate ester acid (PEA) with aliphatic, cycloaliphatic, and aromatic epoxy resins. The chemical structures of the above PEA and PRAs were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance spectroscopy (1H-NMR), and 31P-nuclear magnetic resonance spectroscopy (31P-NMR). Subsequently, transparent IFR coatings were prepared by mixing these PRAs with hexamethoxy methyl melamine resin. Transparency of the coatings was confirmed by UV–Vis–NIR spectrophotometeric studies. Fire protection property and char compressive strength were done to investigate the fire protection ability of the coatings, and the quality of the char formed was analyzed by field emission scanning electron microscope. The decomposition process of prepared fire-retardant coatings was studied by thermogravimetric analysis. Results showed that aliphatic epoxy-based transparent coating produced tough and compact char, but the char height was negligible, and aromatic epoxy-based transparent coating produced soft and fluffy char having excellent char height; however, the fluffy char reduced protection for longer duration. Cycloaliphatic epoxy-based transparent coating produced tough and compact char with good char height, thereby reducing heat transfer during combustion, and also showed superior scratch, abrasion, impact, and water resistance compared to other compositions.

Per- and Polyfluoroalkyl Substances in Dust Collected from Residential Homes and Fire Stations in North America.

Over the past few years, human exposure to per- and polyfluoroalkyl substances (PFAS) has garnered increased attention. Research has focused on PFAS exposure via drinking water and diet, and fewer studies have focused on exposure in the indoor environment. To support more research on the latter exposure pathway, we conducted a study to evaluate PFAS in indoor dust. Dust samples from 184 homes in North Carolina and 49 fire stations across the United States and Canada were collected and analyzed for a suite of PFAS using liquid and gas chromatography-mass spectrometry. Fluorotelomer alcohols (FTOHs) and di-polyfluoroalkyl phosphoric acid esters (diPAPs) were the most prevalent PFAS in both fire station and house dust samples, with medians of approximately 100 ng/g dust or greater. Notably, perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate, perfluorononanoic acid, and 6:2 diPAP were significantly higher in dust from fire stations than from homes, and 8:2 FTOH was significantly higher in homes than in fire stations. Additionally, when comparing our results to earlier published values, we see that perfluoroalkyl acid levels in residential dust appear to decrease over time, particularly for PFOA and PFOS. These results highlight a need to better understand what factors contribute to PFAS levels in dust and to understand how much dust contributes to overall human PFAS exposure.

MOLLUSCICIDAL AND ANTIFEEDANT IMPACTS OF SOME WEED EXTRACTS ON THE LAND SNAIL MONACHA OBSTRUCTA (PFEIFFER)

The molluscicidal and antifeedant activity of three weeds extracts namely primpernel (Anagallis arvensis L.) (Primulaceae), nightshade (Solanum nigrum L.) (Solanaceae) and nutsedge (Cyperus longus L.) (Cyperaceae) were evaluated against the adult stage of Monacha obstructa (Pfeiffer, 1842) under laboratory conditions. Three methods of bioassay were used i.e. bait, residual film (contact) and antifeeding techniques. The results indicated that chloroform and hexane extracts of primpernel appeared highly toxic when applied as baits on M. obstructa adults while nutsedge was found to be lower toxicity based on LC50 values. Also, chloroform extract of nightshade and hexane extract of primpernel were the most potent with contact whereas nutsedge was the least effective. On the other hand, of either chloroform or hexane extract primpernel tended to be more effective as antifeedant compound than nightshade. In contrast, nutsedge chloroform extract revealed no action as a feeding deterrent whereas the same hexane extract was effective based on SC50 levels. Moreover, fifteen compounds were identified by GC/MS analysis in the chloroform extract of primpernel. Palmatic acid methyl ester (fatty acid) was the dominant compound representing 25.8% followed by aromadendrene (sesquiterpene) forming 15.2% and 2 – tertbutyl - 4- isopropyl – 5- methylphenol (phenolic compound) having 13.9%. In addition to the presence of two steroids, two dicarboxylic acids and only one ketone compound was identified. Finally, the salt of carbamic acid (ammonium carbamate) and the ester of phosphoric acid (tributyl phosphate) were also detected. This study reveals that chemical compounds present in chloroform extract of primpernel has effective source as a molluscicide extracted of plant origin and has potential beneficial control against M. obstructa snails.