Fast sorption measurements of volatile organic compounds on building materials: Part 1 - Methodology developed for field applications

A Proton Transfer Reaction-Mass Spectrometer (PTR-MS) has been coupled to the outlet of a Field and Laboratory Emission Cell (FLEC), to measure volatile organic compounds (VOC) concentration during a sorption experiments (Rizk et al., this issue) [1]. The limits of detection of the PTR-MS for three VOCs are presented for different time resolution (2, 10 and 20 s). The mass transfer coefficient was calculated in the FLEC cavity for the different flow rates. The concentration profile obtained from a sorption experiment performed on a gypsum board and a vinyl flooring are also presented in comparison with the profile obtained for a Pyrex glass used as a material that do not present any sorption behavior (no sink). Finally, the correlation between the concentration of VOCs adsorbed on the surface of the gypsum board at equilibrium (C_se) and the concentration of VOCs C_e measured in the gas phase at equilibrium is presented for benzene, C8 aromatics and toluene.

Comparative in vivo antioxidant levels in Schistosoma mansoni infected mice treated with praziquantel or the essential oil of Melaleuca armillaris leaves

Plant extracts are continuously investigated for their extensive inclusion of biologically active constituents that exert therapeutic activities against many diseases. The aim of this study was to assess the antioxidant/anti-schistosomal activities of the essential oil of the fresh leaves of Melaleuca armillaris (M. armillaris) compared to Praziquantel (PZQ) on normal and Schistosoma mansoni-infected mice. The oil was isolated by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The oil was rich in 1,8-cineole (33.93%), terpinen-4-ol (18.79%), limonene (10.37%) and B-pinene (6.59%). M. armillaris oil (150 mg kg(-1), orally) was administered from the second week post infection twice per week for six weeks. PZQ (500 mg kg(-1), orally) was administered for two successive days 8 weeks post infection and mice sacrificed one week later. Total protein, Malondialdehyde (MDA), Glutathione (GSH), vitamins C and E, the antioxidant enzymes catalase and superoxide dismutase, as well as liver weights and liver/body weight were determined in the liver tissues. Results showed that, both treatments significantly ameliorated the disturbed levels ofGSH and MDA in infected mice. Both vitamins were significantly elevated after treatment with the oil while a significant increase in catalase accompanied by a pronounced decrease in SOD were obtained after treatment with PZQ. Both treatments markedly improved liver and body weights in infected mice compared to the infected-untreated ones. In conclusion, natural plant sources may be used as promising alternative agents to chemical drugs for schistosomiasis treatment, since the latter may result in drug-induced resistance arising from repeated use.

Capturing patient reported outcomes and quality of life in routine clinical practice: ready for prime time?

AIM

Aim of the present study was to assess the feasibility of using internet-tablets to capture patient reported outcomes (PRO) questionnaire in a busy gastroenterology clinic, and determine predictors of questionnaire completion. PRO and quality of life instruments are extensively used to estimate the burden of disease and as end-points in clinical trials. However, their collection by paper can be costly, prone to human errors, and inefficient. We hypothesized that the majority of patients, irrespective of age, gender or ethnicity, will be able to complete PRO questionnaires on Internet tablets in a timely manner with good levels of satisfaction.

METHODS

Internet-enabled tablets were used to collect PRO, and summative scores of quality of life provided to physicians. Predictors of completion were first assessed univariately and then by multivariate analysis using automated stepwise selection method on 1,000 bootstrap samples. Patient satisfaction was assessed using 5 item Likert-like scale.

RESULTS

During the 12 week period, 1625 patient visits (mean age 49.8 ± 14.3 years, females 55.2% and Whites 82.5%) entered PRO data into tablets, of which 1396 (85.9%) visits had complete response. Average completion time of PRO questionnaire was less than 10 minutes (9.3 minutes ± 7.0). Majority of the patients found tablets easy to use (69.7%) and preferred it over paper-based questionnaires (70.8%). Multivariate analysis showed that subjects who were white Caucasians (odds ratio [OR] 1.9; P=0.004), had higher Cleveland Clinic Global Quality of Life (OR 2.2; P=0.027), or had either IBD or liver disease, were more likely to complete questionnaire (OR 4.0; P=0.001).

CONCLUSION

Collection of PROs in gastroenterology clinics using internet-tablets is feasible without any additional overhead, and with good levels of patient satisfaction and completion rates.

Development and Validation of Spectrofluorimetric Method for Determination of Biotin in Bulk and Pharmaceutical Preparations via its Oxidation with Cerium (IV)

A simple and sensitive spectrofluorimetric method was developed for the determination of biotin in pure form and in pharmaceutical preparations. The proposed method is based on the oxidation of the drug with cerium (IV) ammonium sulfate in acidic medium. The fluorescence of the produced Cerium (III) was measured at 365 nm after excitation at 255 nm. The different experimental parameters affecting the development and stability of the reaction were carefully studied and optimized. The method is applicable over the concentration range of 30-120 ng/mL with correlation coefficient of 0.9998. The detection limit (LOD) of biotin was 2.41 ng/mL while quantitation limit (LOQ) was 7.29 ng/mL. The proposed procedure was successfully applied for the determination of biotin in pharmaceutical preparations with mean recoveries of 99.55 ± 0.83 and 101.67 ± 1.53 for biotin ampoules and capsules, respectively. The results obtained were in good agreement with those obtained using the official method.

Second derivative synchronous fluorescence spectroscopy for the simultaneous determination of chlorzoxazone and Ibuprofen in pharmaceutical preparations and biological fluids

A rapid, simple and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous analysis of binary mixture of chlorzoxazone (CLZ) and ibuprofen (IP). The method is based upon measurement of the synchronous fluorescence intensity of these drugs at Δλ=60 nm in methanol. The different experimental parameters affecting the fluorescence of the two drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the range of 0.2-4 μg/mL and 0.1-1.6 μg/mL for CLZ and IP, respectively with lower detection limits (LOD) of 0.028 and 8.3 × 10(-3) μg/mL and quantification limits (LOQ) of 0.086 and 0.03 μg/mL for CLZ and IP, respectively. The proposed method was successfully applied for the determination of the two compounds in synthetic mixtures and in commercial capsules. The high sensitivity attained by the proposed method allowed the determination of both drugs and real human plasma samples. The mean % recoveries in real human plasma (n=3) were 87.69 ± 6.15 and 92.57 ± 4.39 for each of CLZ and IP respectively.

Kinetic spectrophotometric determination of biotin in pharmaceutical preparations

A simple accurate kinetic spectrophotometric method was developed for the determination of biotin in pure form and pharmaceutical preparations. The proposed method is based on a catalytic acceleration of biotin on the reaction between sodium azide and tri-iodide in an aqueous solution. Concentration range of 4-16 μg/mL for biotin was determined by measuring the decrease in the absorbance of tri-iodide at 348 nm by a fixed time method. The decrease in absorbance after 14 min from the initiation of the reaction was markedly correlated to the concentration with correlation coefficient of 0.9999. The detection limit (LOD) of biotin was 0.18 μg/mL while quantitation limit (LOQ) was 0.54 μg/mL. The percentage recovery of the spiked samples was 100.08 ± 0.761. The proposed procedure was successfully applied for the determination of biotin in its pharmaceutical preparations with mean recoveries of 101.17 ± 2.05 and 97.87 ± 1.50 for biotin ampoules and capsules, respectively. The results obtained were in good agreement with those obtained using official method.

Oxidative hemolysis of erythrocytes induced by various vitamins

Hemolytic effect of some water-soluble vitamins (niacin B5, pyridoxine B6, thiamine B1 and ascorbic and acid C) on erythrocytes was studied spectrophotometrically at relatively high concentration. The oxidation mechanism of hemoglobin was the same for the used vitamins. Vitamin C was the strongest hemolytic agent in comparison with the other vitamins, while vitamin B1 is the weakest one. The results were confirmed by studying the variation in conductivity of erythrocytes with temperature in the range 20-40°C for the used vitamins at a concentration of 2 mM and after two hours from adding each vitamin to the erythrocytes suspension. The conductivity measurements show that the conductivity for the used vitamins is lower than that for control (without adding vitamin) due to hemoglobin oxidation, also may be due to the electrical reorganization of the erythrocyte membrane after the interaction of the used vitamin with it. The obtained results insure the oxidizing effect of the used vitamins on hemoglobin and consequently their hemolytic effect on erythrocytes.

Evaluation of tumour markers in molar pregnancy

METHODS

Circulating CA 125, CA 19-9, CA 15-3 and carcinoembryonic antigen (CEA) levels were studied in sixty patients with hydatidiform mole and in twenty normal pregnant women of a corresponding duration of pregnancy.

DISCUSSION

Serum levels of CA 125, CA 15-3 and CEA are not affected by molar pregnancy. The mean level of CA 19-9 in maternal serum is significantly lower in cases of molar pregnancy when compared with cases of normal pregnancy. The amnion cell origin of CA 19-9 could explain the statistically significant difference between cases of therapeutic abortion and cases of HM (complete HM lacks amniotic membrane).

Polarographic determination of flubendazole in spiked human urine and plasma

The voltammetric behavior of flubendazole was studied using direct current (DCt), differential pulse (DPP) and alternating current (ACt) polarography. The drug manifests a cathodic wave in 20% v/v formic acid solution. The wave was characterized as being irreversible, diffusion-controlled with limited adsorption properties. The diffusion current-concentration relationship was found to be rectilinear over the range 3.2-14.4 microg/ml and 0.1 to 12.8 microg/ml, using DCt and DPP modes, respectively, with minimum detectability of 0.161 microg/ml (5.14 x 10(-7) M) and 0.0.057 microg/ml (1.82 x 10(-8) M) using DCt and DPP modes, respectively. Furthermore, the proposed method was applied to the in-vitro determination of flubendazole in spiked human urine and plasma adopting the DPP technique. The percentage recoveries were 100.20+/-0.62 and 97.42+/-0.95, respectively.

A peripheral nerve stimulator for nerve location controlled by the scrubbed anaesthetist

This newly designed peripheral nerve stimulator allows the scrubbed anaesthetist performing a nerve block to adjust the electrical current output needed for localisation of the target nerve without the need for an assistant.

Voltammetric analysis of trazodone HCl in pharmaceuticals and biological fluids

The voltammetric behavior of trazodone (TRZ) HCl was studied using direct current (DC(t)), differential pulse (DPP) and alternating current (AC(t)) polarography. The drug manifests cathodic waves over the pH range of 10-14. The waves were characterized as being irreversible, diffusion-controlled with limited adsorption properties. At pH 10, the diffusion current-concentration relationship was found to be rectilinear over the range 4-32 and 0.8-24 microg ml(-1) using DC(t) and DPP modes, respectively, with minimum detectability (S/N=2) of 0.104 microg ml(-1) (2.45 x 10(-6) M) and 0.314 microg ml(-1) (7.397 x 10(-6) M) using the DPP and DC(t) modes, respectively. The diffusion-current constant (I(d)) is 4.31+/-0.02 (n=6). The proposed method was successfully applied to the determination of the studied compound either in pure form or in formulations. The results obtained were favorably compared with those given using a reference method. Furthermore, the proposed method was applied to the determination of TRZ in spiked human urine and plasma adopting the DPP technique. No prior extraction step is needed in case of urine. The percentage recoveries were 98.43+/-0.79 and 97.44+/-0.705 (n=4) in spiked human urine and plasma, respectively. A pathway for the electrode reaction was postulated.

A simple kinetic spectrophotometric method for the determination of isoxsuprine in dosage forms

A simple and sensitive kinetic method was developed for the determination of isoxsuprine in pharmaceutical preparations. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 30 min. The absorbance of the coloured manganate ion was measured at 610 nm. Alternatively, the decrease in the absorbance of potassium permanganate after addition of the drug was measured at 525 nm. The absorbance-concentration plots in both procedures were rectilinear over the range of 0.5-4 microg ml(-1) (r = 0.9998) with a minimum detectability of 0.05 microg ml (-1) (1.48 x 10(-7) M). The different experimental parameters affecting the development and stability of the colours were carefully studied and optimized. The determination of isoxsuprine by the fixed concentration and rate constant methods is also feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. Both procedures were applied to the determination of isoxsuprine in formulations. The results obtained were in good agreement with those obtained using a reference method. The proposed method was also adopted to detect isoxsuprine in spiked human plasma at its therapeutic level of concentration (0.4 microg ml(-1)). A proposal of the reaction pathway was postulated.

Pump activated by a foot switch pedal for controlled administration of local anaesthetic drugs

We describe a newly designed syringe pump which is electrically controlled by a dual foot switch pedal. The device enables the scrubbed anaesthetist performing the regional block to aspirate, as well as to inject, the local anaesthetic without the need for any additional personnel.