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Quaternary Ammonium Compounds (quaternary + ammonium_compound)
Selected AbstractsKinetic study of the reaction of dimethyl carbonate with trialkylaminesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2010Duane E. Weisshaar Quaternary ammonium compounds are produced worldwide in hundreds of millions of pound volume annually for a plethora of end-uses from fabric-care formulations to asphalt emulsifiers, typically from nongreen alkylating reagents. The kinetics of a reaction employing dimethyl carbonate (DMC) as a green alkylating agent was investigated using three trialkylamines (tributylamine, trihexylamine, and trioctylamine) at several temperatures. Arrhenius and Eyring analysis of the data showed that values of Ea (79 kJ/mol), ,H, (75 kJ/mol), and ,S, (220 J/(mol K)) were the same for all three amine reactants, consistent with a report that Ea is independent of alkyl chain length when the chain length is greater than three carbons. Although rates are significantly slower with DMC than with other alkylating reagents, the resulting methyl carbonate anion has advantages for clean anion metathesis, which is important for some applications, especially those involving ionic liquids. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 221,225, 2010 [source] REDUCTIONS OF ESCHERICHIA COLI, COLIFORMS, AEROBIC PLATE COUNTS AND CAMPYLOBACTER JEJUNI BY A SMALL-SCALE, HIGH-PRESSURE SYSTEM DEVISED TO CLEAN A MINIATURIZED POULTRY GIBLETS TRANSPORT SYSTEMJOURNAL OF FOOD SAFETY, Issue 4 2009OMAR A. OYARZABAL ABSTRACT The efficacy of using direct high-pressure hot water (60C, 140F) and a quaternary ammonium compound to clean the inside of stainless steel pipe used to transport chicken giblets was evaluated. The giblets were collected from a commercial processing plant and were inoculated with Campylobacter jejuni. The cleaning system was effective in reducing the numbers of inoculated C. jejuni and naturally occurring mesotrophic bacteria (aerobic plate counts) on the inside surface of the stainless steel pipe used to transport the giblets. However, the decreases in naturally occurring Escherichia coli and coliforms were not significant. These results suggest that additional improvements are needed to better disinfect the piping system used to transport giblets to reduce the potential for cross-contamination with C. jejuni and E. coli. The devised cleaning system could be optimized to reduce the use of chemical agents, the cleaning time and the cost of cleaning pipes in poultry processing facilities. PRACTICAL APPLICATIONS These experiments suggest that the traditional use of hot water and quaternary ammonium compounds to clean the inside of the piping system used to transport chicken giblets may not be sufficient to reduce the contamination with Campylobacter jejuni and mesotrophic bacteria (aerobic plate count). Poultry processors should be aware of the limitations of cleaning closed piping systems and develop and test high-pressure systems to thoroughly clean the pipes used to transport giblets after processing to avoid potential sources of cross-contamination with C. jejuni and mesotrophic bacteria. [source] In vitro new dialysis protocol to assay the antiseptic properties of a quaternary ammonium compound polymerized with denture acrylic resinLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2004C. Pesci-Bardon Abstract Aims:, To develop an in vitro protocol in order to assess the antiseptic properties of a quaternary ammonium compound polymerized with acrylic denture resin base, using experimental resin discs and dialysis membranes. Methods and Results:, Experimental acrylic resin discs were polymerized with Poly 202063A, an ammonium compound (2,50%). Antiseptic properties were assayed against two reference strains (Escherichia coli, Staphylococcus aureus) and a laboratory strain (Candida albicans), using three different conditions (test A, B and C). In test A, according to classical protocols the resin discs were first soaked in large volumes of microbial inoculum (45 ml). An original dialysis protocol was then designed to recreate the small biofilm volume on the prosthetic surface. In test B, discs and bacterial inoculum (600 ,l) were introduced in a dialysis bag and dialysed against a sterile buffer. A bactericidal effect was observed against E. coli and Staph. aureus (<0·1% viable cells in initial bacterial suspension). A dose-dependent fungistatic effect was observed against C. albicans. Finally, in test C discs and sterile buffer (600 ,l) were introduced in a dialysis bag and dialysed against microbial inoculum. Reduced activity was found outside the dialysis bag, demonstrating that free ammonium was able to diffuse through the dialysis membrane, displaying antiseptic properties. Conclusions:, The present protocol demonstrated that a quaternary ammonium compound remains efficient after heat polymerization with an acrylic denture base resin, both in immediate and distant microbial environments. Significance and Impact of the Study:, Such removable prosthetic devices with intrinsic antiseptic properties would contribute to improve the long-term management of denture stomatitis. [source] Complete sequence of the IncP-9 TOL plasmid pWW0 from Pseudomonas putidaENVIRONMENTAL MICROBIOLOGY, Issue 12 2002Alicia Greated Summary The TOL plasmid pWW0 (117 kb) is the best studied catabolic plasmid and the archetype of the IncP-9 plasmid incompatibility group from Pseudomonas. It carries the degradative (xyl) genes for toluenes and xylenes within catabolic transposons Tn4651 and Tn4653. Analysis of the complete pWW0 nucleotide sequence revealed 148 putative open reading frames. Of these, 77 showed similarity to published sequences in the available databases predicting functions for: plasmid replication, stable maintenance and transfer; phenotypic determinants; gene regulation and expression; and transposition. All identifiable transposition functions lay within the boundaries of the 70 kb transposon Tn4653, leaving a 46 kb sector containing all the IncP-9 core functions. The replicon and stable inheritance region was very similar to the mini-replicon from IncP-9 antibiotic resistance plasmid pM3, with their Rep proteins forming a novel group of initiation proteins. pWW0 transfer functions exist as two blocks encoding putative DNA processing and mating pair formation genes, with organizational and sequence similarity to IncW plasmids. In addition to the known Tn4651 and IS1246 elements, two additional transposable elements were identified as well as several putative transposition functions, which are probably genetic remnants from previous transposition events. Genes likely to be responsible for known resistance to ultraviolet light and free radicals were identified. Other putative phenotypic functions identified included resistance to mercury and other metal ions, as well as to quaternary ammonium compounds. The complexity and size of pWW0 is largely the result of the mosaic organization of the transposable elements that it carries, rather than the backbone functions of IncP-9 plasmids. [source] Intrinsic and acquired resistance to quaternary ammonium compounds in food-related Pseudomonas spp.JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003S. Langsrud Abstract Aims: To determine the sensitivity of a strain used for disinfectants testing (Pseudomonas aeruginosa ATCC 15442) and food-associated isolates to benzalkonium chloride and didecyl dimethylammonium chloride (DDAC). To determine whether the increase in bacterial resistance after adaptation to DDAC can be associated with phenotypic changes. To test the activity of alternative disinfectants to eliminate resistant Pseudomonas spp. Methods and Results:Pseudomonas aeruginosa ATCC 15442 was among the most resistant strains tested using a bactericidal suspension test. Growth of a sensitive Ps. fluorescens in gradually higher concentrations of DDAC resulted in stable higher resistance and to some cross-resistance to several antibacterial agents, with the exception of disinfectants containing chloramine T, glutaraldehyde or peracetic acid. It was shown by microscopy that adaptation was followed by loss of flagella, and slime formation. Removal of the slime by sodium dodecyl sulphate resulted in partial loss of the acquired resistance. Conclusions:Pseudomonas spp. may adapt to survive against higher concentrations of quaternary ammonium compounds (QACs), but resistant strains can be eliminated with chemically unrelated disinfectants. Significance and Impact of the Study: The work supports the rotation of disinfectants in food processing environments for avoiding the development of bacterial resistance to QACs. The alternating disinfectants should be chosen carefully, because of possible cross-resistance. [source] REDUCTIONS OF ESCHERICHIA COLI, COLIFORMS, AEROBIC PLATE COUNTS AND CAMPYLOBACTER JEJUNI BY A SMALL-SCALE, HIGH-PRESSURE SYSTEM DEVISED TO CLEAN A MINIATURIZED POULTRY GIBLETS TRANSPORT SYSTEMJOURNAL OF FOOD SAFETY, Issue 4 2009OMAR A. OYARZABAL ABSTRACT The efficacy of using direct high-pressure hot water (60C, 140F) and a quaternary ammonium compound to clean the inside of stainless steel pipe used to transport chicken giblets was evaluated. The giblets were collected from a commercial processing plant and were inoculated with Campylobacter jejuni. The cleaning system was effective in reducing the numbers of inoculated C. jejuni and naturally occurring mesotrophic bacteria (aerobic plate counts) on the inside surface of the stainless steel pipe used to transport the giblets. However, the decreases in naturally occurring Escherichia coli and coliforms were not significant. These results suggest that additional improvements are needed to better disinfect the piping system used to transport giblets to reduce the potential for cross-contamination with C. jejuni and E. coli. The devised cleaning system could be optimized to reduce the use of chemical agents, the cleaning time and the cost of cleaning pipes in poultry processing facilities. PRACTICAL APPLICATIONS These experiments suggest that the traditional use of hot water and quaternary ammonium compounds to clean the inside of the piping system used to transport chicken giblets may not be sufficient to reduce the contamination with Campylobacter jejuni and mesotrophic bacteria (aerobic plate count). Poultry processors should be aware of the limitations of cleaning closed piping systems and develop and test high-pressure systems to thoroughly clean the pipes used to transport giblets after processing to avoid potential sources of cross-contamination with C. jejuni and mesotrophic bacteria. [source] Do Biocides Select for Antibiotic Resistance?,JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2000A. D. RUSSELL Some similarities exist between bacterial resistance to antibiotics and to biocides, and gram-negative bacteria that have developed resistance to cationic biocides may also be insusceptible to some antibiotics. Outer membrane changes are believed to be responsible for this non-specific increase in resistance. Efflux, another important resistance mechanism, is associated with the qacA/B gene system in staphylococci that confers low-level resistance to cationic agents including chlorhexidine salts and quaternary ammonium compounds. It has been proposed that the introduction into clinical practice of Chlorhexidine and quaternary ammonium compounds has resulted in the selection of staphylococci containing qacA genes on multiresistance plasmids. A linkage between low-level resistance to triclosan and to antibiotics has recently been claimed to occur in Escherichia coli, with the bisphenol selecting for chromosomally-mediated antibiotic resistance. A key issue in many studies has been the use of biocides at concentrations significantly below those used clinically. It remains to be determined how an increase to low-level resistance to cationic biocides can be held responsible for the selection of antibiotic-resistant bacteria. [source] Homes for the orphans: utilization of multiple substrate-binding proteins by ABC transportersMOLECULAR MICROBIOLOGY, Issue 1 2010Gavin H. Thomas Summary Acquiring nutrients from the environment is essential for all microbes, and the ATP-binding cassette (ABC) transporters are one of the major routes by which bacteria achieve it. In this issue of Molecular Microbiology, Chen et al. describe their characterization of what appeared at first glance a simple ABC transporter for acquisition of quaternary ammonium compounds (QACs) in Pseudomonas sp., but their persistence in fully determining the properties of this system led to the experimental demonstration that QAC uptake utilizes three different substrate-binding proteins (SBPs), two of which are encoded at remote locations on the genome as ,orphan' SBPs that are each able to function with a single core ABC transporter. Building on the unusual nature of this system, in which multiple SBPs with non-overlapping substrate specificities compete for the same transporter binding site, they designed elegant in vivo experiments that suggest that only substrate-bound SBPs are able to form functional complexes with the membrane domains. This new finding provides an important piece of in vivo data leading to further insight into how this ubiquitous family of transporters operates. [source] Drug impurity profiling by capillary electrophoresis/mass spectrometry using various ionization techniquesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2009Paul Hommerson Capillary electrophoresis/mass spectrometry (CE/MS) is predominantly carried out using electrospray ionization (ESI). Recently, atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) have become available for CE/MS. With the VUV lamp turned off, the APPI source may also be used for CE/MS by thermospray ionization (TSI). In the present study the suitability of ESI, APCI, APPI and TSI for drug impurity profiling by CE/MS in the positive ion mode is evaluated. The drugs carbachol, lidocaine and proguanil and their potential impurities were used as test compounds, representing different molecular polarities. A background electrolyte of 100,mM acetic acid (pH 4.5) provided baseline separation of nearly all impurities from the respective drugs. APPI yielded both even- and odd-electron ions, whereas the other ionization techniques produced even-electron ions only. In-source fragmentation was more pronounced with APCI and APPI than with ESI and TSI, which was most obvious for proguanil and its impurities. In general, ESI and TSI appeared the most efficient ionization techniques for impurities that are charged in solution achieving detection limits of 100,ng/mL (full-scan mode). APPI and APCI showed a lower efficiency, but allowed ionization of low and high polarity analytes, although quaternary ammonium compounds (e.g. carbachol) could not be detected. Largely neutral compounds, such as the lidocaine impurity 2,6-dimethylaniline, could not be detected by TSI, and yielded similar detection limits (500,ng/mL) for ESI, APPI and APCI. In many cases, impurity detection at the 0.1% (w/w) level was possible when 1,mg/mL of parent drug was injected with at least one of the CE/MS systems. Overall, the tested CE/MS systems provide complementary information as illustrated by the detection and identification of an unknown impurity in carbachol. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||