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A highly selective, sensitive, and rapid high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of darifenacin in mouse plasma. Bisoprolol was used as an internal standard (IS). Darifenacin and the IS were extracted using the deproteinisation technique, followed by injection of an aliquot of the supernatant into the chromatographic system. The chromatographic separation was achieved on a reversed phase C18 column with a mobile phase of acetonitrile: 0.1% diethyl amine (pH 3.5) (60:40, v/v) pumped at a flow rate of 1.0 mL min(-1). The analytes were detected at 210 and 314 nm for excitation and emission, respectively. The assay exhibited a linear range of 100-3000 ng mL(-1), with a lower detection limit of 35 ng mL(-1). The method was statistically validated for linearity, accuracy, precision, selectivity and stability according to the FDA guidelines. The intra- and inter-assay coefficients of variation did not exceed 13.5% from the nominal concentration. The accuracy for darifenacin was within ±15% of the theoretical value. The assay was successfully applied in a pharmacokinetic study.

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A novel poly (vinyl chloride) PVC membrane sensor for Fe(2+) ions is described. The sensor is based on the use of newly synthesized chiral 2,6-bis-(carboxamide methyl ester)pyridine derivative as neutral ionophore in plasticized PVC membrane. The sensor display a fast, stable and near-Nernstian response over a relative wide ferrous concentration range (1 × 10(-3) to 6 × 10(-6) M), with cationic slope of 31.5 ± 0.5, mV per concentration decade over a pH range of 5.0-9.0. The direct determination of 0.25-56.0 µg/ml of ferrous in aqueous solution shows an average recovery of 98.5% and a mean relative standard deviation of 1.5% at 20.0 µg/ml. The sensor displays long life-span, long-term stability, high reproducibility, and short response time. Selectivity coefficients for Fe(II) relative to a number of interfering substances were investigated. The sensor shows high significantly for Fe(2+) over Fe,(3+) Cu,(2+) Zn,(2+) Cd,(2+) Hg,(2+) Pb,(2+) Ni,(2+) Co,(2+) Mn,(2+) Al,(3+) alkaline earth and alkali metal ions. The sensor is successfully applied for measurement of ferrous in drug formulations. The results obtained for the determination of ferrous using the proposed sensor are comparable favourably with those obtained using the spectrophotometric method. Copyright © 2010 John Wiley & Sons, Ltd.

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OBJECTIVES: Many children are harmed by low-level lead exposure which impairs cognitive development with subsequent poor scholastic achievement. We investigated blood lead levels in children in relation to cognitive function. MATERIALS AND METHODS: Blood lead levels were measured in 100 children recruited from high (n = 50) and low (n = 50) lead-polluted areas. RESULTS: Blood lead levels ranged between 3 and 28 microg/dl (median 9, interquartile range 6 microg/dl). In addition, 43% of children had levels > or =10 microg/dl, of whom 90.1% were living in high-risk areas for lead pollution. Cognitive dysfunction was found in 37% of children. Children with cognitive dysfunction had significantly higher blood lead and lower hemoglobin than those without (P < 0.001). CONCLUSIONS: Increased blood lead level in many children is one of the health problems in Egypt which may be the reason, at least in part, for cognitive dysfunction with subsequent poor scholastic achievement. Thus, interventions to control lead exposure are mandatory.

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BACKGROUND: Neurogenic inflammation may participate in the development and progression of bronchial asthma. The molecular mechanisms underlying neurogenic inflammation are orchestrated by a large number of neuropeptides including tachykinins such as neurokinin A (NKA) and substance P. Tachykinins are secreted from sensory airway nerves and inflammatory cells after allergens exposure. In clinical practice, assessment of airway inflammation is difficult. Therefore, detection of biological markers of airway inflammation in sputum might offer help for proper monitoring of asthma severity. AIM OF THE STUDY: We aimed to measure sputum NKA in relation to acute asthma exacerbations of varying severity. METHODS: Sputum NKA was measured by enzyme-linked immunosorbent assay in 24 children and adolescents during and after acute asthma exacerbation and 24 healthy matched controls. RESULTS: Sputum NKA was significantly higher in asthmatic patients during acute exacerbation than controls [217.5 (284) vs 10 (7) ng/ml, P < 0.001]. When patients with acute asthma exacerbation were followed-up till remission, sputum NKA levels decreased significantly, but they remained significantly higher than controls. Sputum NKA levels were significantly higher in severe than moderate and in moderate than mild exacerbations, and was negatively correlated to peak expiratory flow rate (r = -0.9, P < 0.001). Sputum NKA had significant positive correlations to eosinophil counts in blood and sputum (r = 0.6, P < 0.001 and r = 0.7, P < 0.001 respectively). CONCLUSIONS: Sputum NKA is up-regulated during acute asthma exacerbation and it positively correlates to its severity. Thus, NKA may aid in objective classification of the exacerbation severity. In addition, NKA may be a target for new asthma therapy.

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The construction and general performance characteristics of two novel potentiometric carbon paste electrodes (CPE) responsive to antimony are described. These sensors are based on the use of the ion associate complexes of tetraiodoantimonate (TIA) anion with cetylpyridinium (CP) and triphenyl tetrazolium (TPT) counter cations as ion exchange site in a carbon paste matrix. The two sensors exhibits fast, stable and near-Nernstian for the mono charged TIA anion over the concentration range 1x10(-3) to 10(-6)M at 25 degrees C in the pH range 4-10 with anionic slope of 58.0+/-0.5 and 55.0+/-0.7 per concentration decade for TIA-CP and TIA-TPT, respectively. The lower detection limits are 4 and 5x10(-6)M and response time are 20 and 30s in the same order of both electrodes. Selectivity coefficients for antimony relative to a number of different cations and anions were investigated. There is negligible interference from many inorganic cation and anion except for Hg(2+), Cd(2+), and Bi(3+); however, their effect were eliminated by EDTA. The determination of 1.0-120.0mug/ml of antimony in aqueous solutions shows an average recovery of 99.0 and 97.5% with relative standard deviation of 2.0% for both electrodes at 40mug/ml. The determination of antimony in wastewater and some antibilharzial compounds using the proposed electrodes gave results that compare favorably with those obtained by the atomic absorption spectrometric method. Precipitation titrations involving cetylpyridinium chloride as titrant are monitored with both electrodes with inflection point of 180 and 100mV for TIA-CP and TIA-TPT, respectively.

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The construction and characteristic performance of s-benzylthiuronium (s-BT)-PVC membrane sensor responsive for cetylpyridinium chloride (CPC) are described. The sensor is based on the use of s-BT-tetraphenylborate (TPB) ion pair as electroactive material in PVC matrix in presence of dioctylphthalate as solvent mediator. The membrane sensor shows a fast, stable and near Nernstian response for CPC over the concentration range of 6 x 10(-6)-1 x 10(-3)M at 25 degrees C and pH range 6-12 with cationic slope of 57.0+/-0.4. The lower detection limit is 4 x 0(-6)M and the response time is 10-30 s. Selectivity coefficients for CPC relative to a number of different species were investigated, which there is negligible intereferences are caused by most of investigated cations, anions, and some organic compounds. The determination of 2.0-350.0 microg/ml of CPC in aqueous solutions shows an average recovery of 98.8%and a mean relative standard deviation of 1.87% at 64.0 microg/ml. The determination of CPC in mouthwash pharmaceutical solution gave results that compare favorably with those obtained by the British pharmacopoeia method. The s-benzylthiuronium electrode has been utilized as an end point indicator electrode for some precipitation titration reactions involving CPC as titrant.

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The construction and characteristic performance of metoclopramide (MCP)-polyvinyl chloride (PVC) membrane sensor are described. The sensor is based on the use of MCP-tetraiodomercurate ion pair as electroactive material in PVC matrix in presence of dioctylphthalate (DOP) as solvent mediator. MCP membrane sensor shows a stable, near Nernstian response over the concentration range 1 x 10(-2)-6 x 10(-5) M of MCP at 25 degrees C in the pH range 3-7 with cationic slope of 53.0+/-0.5. The detection limit of 4 x 10(-5) M and the response time of 30-60 s have been attained. Selectivity coefficient data for some common ions show negligible intereferences. Direct potentiometric determination of 15-3540 microg/ml MCP show an average recovery of 98.5% and a mean relative standard deviation (R.S.D.) of 1.6% at 100.0 microg/ml. The determination of MCP in Primperan tablets, injection, and syrup gave results that compare favorably with those obtained by the British pharmacopoeia method. Precipitation titrations involving MCP as titrant are monitored with the MCP sensor for some potentiometric precipitation reaction, e.g. sodium tetraphenylborate (STPB) and phosphomolybdic acid (PMA).

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The construction and general performance of a novel modified carbon paste electrode for the determination of gallamine triethiodide have been developed. The electrode shows a stable, potentiometric response for gallamine in the concentration range 1 x 10(-3)-2 x 10(-6) M at 25 degrees C independent of pH in the range 5-8. The electrode passes a near-Nernstian cationic slope of 17.0+/-0.7 mV and lower detection limit of 1 x 10(-6) M with a fast response time of 20-45 s. Selectivity coefficients for gallamine relative to a number of interfering substances were investigated. There is a negligible interference from the studied cations, anions, and pharmaceutical excipients. The determination of gallamine in aqueous solution shows an average recovery of 99.5% and a mean relative standard deviation (RSD) of 1.4% at 100 microg/ml. The direct determination of gallamine in injection solution gave results that compare favorably with those obtained by the British pharmacopoeia method. Potentiometric titration of gallamine with sodium tetraphenylborate and phosphotungstic acid as a titrant has been monitored with the modified carbon paste electrode as an end-point indicator electrode.

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A novel tetrachlorothallate (III) (TCT)-selective membrane sensor consisting of tetrachlorothallate (III)-2,3,5-triphenyl-2-H-tetrazolium ion pair dispersed in a PVC matrix plasticized with dioctylphthalate is described. The electrode shows a stable, near-Nernstian response for 1x10(-3)-4x10(-6) M thallium (III) at 25 degrees C with an anionic slope of 56.5+/-0.5 over the pH range 3-6. The lower detection limit and the response time are 2x10(-6) M and 30-60 s, respectively. Selectivity coefficients for Tl(III) relative to a number of interfering substances were investigated. There is negligible interference from many cations and anions; however, iodide and bromide are significantly interfere. The determination of 0.5-200 mug ml(-1) of Tl(III) in aqueous solutions shows an average recovery of 99.0% and a mean relative standard deviation of 1.4% at 50.0 mug ml(-1). The direct determination of Tl(III) in spiked wastewater gave results that compare favorably with those obtained by the atomic absorption spectrometric method. The electrode was successfully applied for the determination of thallium in zinc concentrate. Also the tetrachlorothallate electrode has been utilized as an end point indicator electrode for the determination of thallium using potentiometric titration.

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A novel cetylpyridinium chloride-selective membrane sensor consisting of cetylpyridinium-ferric thiocyanate ion pairs dispersed in a PVC matrix placticized with dioctylphthalate is described. The electrode shows a stable, near-Nernstian response for 1 x 10(-3)-1 x 10(-6) mol l-1 cetylpyridinium chloride (CPC) at 25 degrees C over the pH range 1-6 with a cationic slope of 57.5 +/- 0.4. The lower detection limit is 8 x 10(-7) mol l-1 and the response time is 30-60 s. Selectivity coefficients for CPC relative to a number of interfering substances were investigated. There is negligible interference from many cations, anions and pharmaceutical excipients; however, cetyltrimethylammonim bromide (CTMAB) interfered significantly. The determination of 0.5-350 micrograms/ml of CPC in aqueous solutions shows an average recovery of 98.5% and a mean relative standard deviation of 1.6% at 56.0 micrograms/ml. The direct determination of CPC in Ezafluor mouthwash gave results that compare favorably with those obtained by the British Pharmacopoeia method. Precipitation titrations involving CPC as titrant are monitored with a CP sensor. The CP electrode has been utilized as an end point indicator electrode for the determination of anionic surfactants in some commercial detergents.

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A novel PVC membrane electrode selective for the determination of pentachlorophenolate (PCP) ion based on 2,3,5-triphenyl-2H-tetrazolium (TPT) pentachlorophenolate ion pair as an electroactive material is described. The electrode shows a linear response for PCP ion over the concentration range of 6x10(-5) to 1x10(-2) M with lower detection limit of 4x10(-5) M at 25 degrees C. The electrode posses a Nernstian slope of -55.0+/-1.0 mV/decade and a fast potential response of 45 s, which is almost constant over a pH range of 5.5-10.5. Selectivity coefficient data for some common ions show negligible interference, however, 2,4,6-trichlorophenolate and cetylpyridinium ions interfere. An average recovery of 96.2% with relative standard deviation of 2.3% has been achieved for the determination of 75.0 ppm PCP in wastewater samples. The determination of PCP in soil and wood samples gave results that compare favorably with those obtained by gas chromatography. The electrode has been utilized as an end point indicator electrode for the determination of PCP using potentiometric titration.

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A simple, rapid and selective procedure for the indirect spectrophotometric determination of Se(IV) and As(V) has been developed. It is based on the reduction of Se(IV) to Se(0) and As(V) to As(III) with hydroiodic acid (KI + HCl). The liberated iodine, equivalent to each analyte, is quantitatively extracted with oleic acid (HOL) surfactant. The iodine-HOL system exhibits its maximum absorbance at 435 nm. The different analytical parameters affecting the extraction and determination processes have been examined. The calibration graphs were found to be linear over the ranges 5-120 and 0.25-20 ppm of Se(IV) and As(V), with lower detection limits of 2.5 and 0.15 ppm and molar absorptivities of 1 x 10(4) and 0.5 x 10(4) dm3 mol(-1) cm(-1), respectively. Sandell's sensitivity was calculated to be 0.0078 and 0.0149 microg/cm2 in the same order. The relative standard deviation for five replicate analyses of 40 ppm Se(IV) and 4 ppm As(V) were 1.0 and 0.9%, respectively. The proposed procedure in the presence of EDTA as a masking agent for foreign ions has been successfully applied to the determination of Se(IV) in a reference sample and As(V) in copper metal, in addition to their determination in spiked and polluted water samples.

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A potentiometric method is described for the determination of cetylpyridinium (CP) cation using a polyvinyl chloride powder (PVC) membrane sensor based on CP-iodomercurate ion pair as an electroactive material. The sensor shows a linear response for CP ion over the concentration range of 2x10(-6)-1x10(-3) M at 25 degrees C. The electrode posses a sub-Nernstian slope of 29.0+/-0.4 mV decade(-1), which has been thoroughly discussed.The electrode shows a fast potential response of approximately 50 s, which is almost constant over a pH range of 3.0-6.0. Selectivity coefficient data for some common ions show negligible interference, however, cetyltrimethylammonium bromide (CTMAB) interferes significantly. An average recovery of 98.8% for CP with an average relative standard deviation (R.S.D.) of 1.2% has been achieved. The determination of CPC in Ezafluor mouth wash gave result that compare favorably with those obtained by the British Pharmacopoeia method. The CP electrode has been utilized as an end point indicator electrode in potentiometric titration of some anions, and applied for the determination of anionic surfactants in some commercial detergents and waste water.

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Aliphatic hydrocarbon residues were monitored in two fish species, Indian mackerel (Rastrelliger Kanaguria) and Indian scad (Decapterus russelli) collected from local markets in three different cities in Oman. Residues were also monitored in water samples collected from two sites of the Gulf of Oman. Sampling was conducted twice, in July and again in February to have a thorough understanding of the dynamics of aliphatic hydrocarbon residues. Results indicated the presence of petrogenic aliphatic hydrocarbons ranging from C12-C28 in fish and water samples alike. Fish and water chromatograms were characterized by an unresolved complex mixture (UCM), a confirmatory sign of petrogenic origin of monitored hydrocarbons. Residue levels showed some variations related to sampling sites and time of sampling.

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