Neutral bidentate organophosphorus compounds as novel ionophores for potentiometric membrane sensors for barium(II).

Bis(diarylphosphine oxide) naphthalene compounds are used as novel ionophores in plasticized poly(vinyl chloride) matrix membrane sensors for barium ions. The most favorable sensor was 1,2-bis(diethylphenylphosphine oxide)naphthalene containing potassium tetrakis(4-chlorophenyl)borate as lipophilic salt and o-nitrophenyloctyl ether as plasticizer for ion-selective electrode membrane construction. The electrode showed excellent properties. It gave a linear response with a Nernstian slope of 30 mV per decade within the concentration range 10(-1)-10(-5) mol L(-1) BaCl2. The electrode exhibits a high selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+, Mg2+, Ca2+, Sr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Al3+, La3+, and Ce3+ ions. The electrode response was stable over a wide pH range (3-11). The lifetime of the electrode was about 2 months. It was successfully applied to the determination of Ba2+ contents in some rocks.

Novel mercury (II) ion-selective polymeric membrane sensor based on ethyl-2-benzoyl-2-phenylcarbamoyl acetate.

Mercury (II) ion-selective PVC membrane sensor based on ethyl-2-benzoyl-2-phenylcarbamoyl acetate (EBPCA) as a novel nitrogen containing sensing material is successfully developed. The sensor exhibits good linear response of 30 mV per decade within the concentration range 10(-6)-10(-3) mol l(-1) Hg(II). The sensor shows good selectivity for mercury (II) ion in comparison with alkali, alkaline earth, transition and heavy metal ions. The EBPCA-based sensor is suitable for use with aqueous solutions of pH 2.0-4.5 and exhibits minimal interference by Ag(I) and Fe(III), which are known to interfere with other previously suggested sensors. The nature and composition of the sensing material and its mercury complex are examined using Fourier-transform infrared analysis, elemental analysis and X-ray fluorescence techniques. The proposed sensor is applied as a sensor for the determination of Hg(II) content in some amalgam alloys. The results show good correlation with data obtained by atomic absorption spectrometric method.

New cesium ion-selective electrodes based on anilino-(1,3-dioxo-2-indanylidene) acetonitrile derivatives.

Cesium ion-selective PVC membrane electrodes based on anilino-(1,3-dioxo-2-indanylidene) acetonitrile derivatives as a novel class of neutral ionophores were examined. The ionophores were p-methoxyanilino-(1,3-dioxo-2-indanylidene) acetonitrile, p-methylanilino-(1,3-dioxo-2-indanylidene) acetonitrile and p-N,N-dimethylanilino-(1,3-dioxo-2-indanylidene) acetonitrile. The anilino-(1,3-dioxo-2-indanylidene) acetonitrile proved to work well with cesium, the corresponding electrodes display a response to this ion. The most favourable ionophore was p-methoxyanilino-(1,3-dioxo-2-indanylidene) acetonitrile, especially when the secondary ion exchanger potassium tetrakis (4-chlorophenyl) borate was incorporated in 2-nitrophenyl octyl ether for ion-selective electrode membrane construction. The response function was linear within the concentration range 10(-1)-2.5x10(-5) mol l(-1) and the slope was 52 mV decade(-1). The detection limit remained at 6.3x10(-6) mol(-1). The selectivity and response time of the electrode was studied and it was found that the electrode exhibited good selectivity for cesium over alkali, alkaline earth and some transition metal ions. The electrode response was stable over a wide pH range. The lifetime of the electrode was about 1 month.

Isolation, purification and ultrastructure of bacteriophages from natural mosquito breeding places in Egypt.

Two bacteriophages were isolated from field collected samples representing two different mosquito breeding places. The phage AB-1 (isolated from Abheit village, Faiyoum Governorate "seepage water") and the phage GA-2 (isolated from El-Gabal El-Asfer Qualyobia Governorate "sewage drain water") were purified. Both bacteriophages were ultrastructurally described with respect to their morphology, dimensions, phases of bacterial attack and lysogeny. No major differences were observed between both isolated phages in relation to specificity, however; they were isolated from two different types of breeding places and two different geographic areas as well. This study may assume a wide host range of the isolated phages and reflect how bacterial insecticides used for mosquito larval control could be inhibited by such bacteriophage.

Comparative inhibitory action of 4 standard bacteriophages on the larvicidal activity of certain mosquito pathogenic bacteria against Culex pipiens larvae.

Four bacteriophage (CP-51, CP-54, Yousten-4 and Yousten-14) were assayed against 7 entemopathogenic bacterial strains. The two CP ones, indicating variability of the host range of the tested phages which was suggested to be related to the environmental characteristics of the tested strains. On testing the susceptibility of 5 bacterial strains to the phage Yousten-4 at different cultural ages, a correlation was found between incubation time and level of bacterial susceptibility to the tested phage. This observation was explained to be due to the number of vegetative cells and/or sporulation.

A field survey of bacteriophage contamination of mosquito breeding places, inhibiting bacterial insecticide.

Twelve geographically different mosquito breeding places were described and sampled for the detection of naturally existed bacteriophage viruses which could transduct and lysate 5 entomopathogenic bacteria. The surveyed places are classified into seepage, sewage, and irrigation breeding water. Bacterial free filtrates of the collected samples were assayed against the tested bacteria in vitro and against 3rd instar Culex pipiens larvae as well. Nine out of the twelve places could demonstrate the presence of phages. Bacillus thuringiensis H-14 was foud susceptible to phage(s) present in polluted and irrigated water of 5 location, while, B. thuringiensis Berliner was susceptible to only a specific phage of one breeding place (polluted, sewage water). With regard to Bacillus sphaericus strains 1593 and 114, bacteriophages of sewage and irrigated water could lysate them and these phages are characterized by being of a moderate host range, except one phage which showed high specificity with strain 114 and was detected in a polluted sewage water sample collected from Dakahliya Governorate. The detected phages proved to lysate both B. thuringiensis H-14 and B. sphaericus 1593 on their larvicidal action through a series of bioassay experiment, almost all results indicate the presence of a significant inhibitory activity.

Antibacteriophage action on the larvicidal activity of Bacillus thuringiensis H-14 and Bacillus sphaericus against Culex pipiens.

An organically polluted mosquito breeding water was tested for the presence of bacteriophages which could inhibit the larvicidal activity of B. thuringiensis H-14 and B. sphaericus. More than one bacteriophage were isolated which could inhibit the tested bacteria. The sensitivity of the two bacterial species to 12 antibiotics was tested. Two of them, showed no antibacterial action, were selected and considered as antivirus agents in the bacteriophage assays; namely, Amoxycillin and Co-Trimoxazole. Results indicated their antivirus activity as the addition of the antibiotics to the isolated phages could permit normal bacterial growth as well as persistence of larvicidal activity against Culex pipiens larvae.