Modified carbon paste sensor for the potentiometric determination of neostigmine bromide in pharmaceutical formulations, human plasma and urine.

A novel, simple, rapid, selective and sensitive method for the determination of neostigmine (Ns) ion in its bulk powder, different pharmaceutical dosage forms, and biological fluids (plasma and urine) using four modified carbon paste electrodes was developed. Sensor 1 is based on ion-association Ns-TPB, sensor 2 used Ns-PT, sensor 3 comprises a mixture of (Ns-PT+Ns-TPB) and sensor 4 was constructed using (Ns-PT+ß-CD). Solvent mediator 2-NPPE exhibited a proper behavior including Nernstian slope ranging from 61.5±0.5 to 64.5±0.5 mV per decade over the pH range of 3.8-10 for the four sensors. Linear responses of Ns within the concentration range 1.0×10(-7)-1.0×10(-2) mol/L were obtained. The response time is very short (≤10s) with a detection limit 6.3×10(-8) M. In flow injection analysis (FIA), sensor 3 shows a Nernstian slope value 75.5±0.5 mV per decade within the concentration range of 1×10(-6)-1×10(-2) mol/L and with a detection limit 7.5×10(-7) mol/L. The utility of mixed or additives of ß-CD had a significant influence on increasing the sensitivity of sensors 3 and 4 compared to sensors 1 and 2. The sensors were applied for the determination of neostigmine (Ns) ion in its bulk powder, different pharmaceutical dosage forms, and biological fluids (plasma and urine). The results obtained were satisfactory with excellent percentage recovery comparable with official method for the assay based on non-aqueous titration using perchloric acid as a titrant.

Underreporting of food intake by dietary recall is not universal: a comparison of data from egyptian and american women.

Underreporting of dietary intake has been observed consistently in food consumption surveys in affluent societies and in clinical studies in a variety of settings. Almost one third of quantitative 24-h recalls provided by adults in U.S. surveys appear to result in estimates that are biologically implausible. Underreporting has been linked to obesity in both the U.S. and Europe, with heavier individuals underreporting to a greater degree than lean persons. A relative dearth of data exists from developing countries and those in transition to address the question whether such underreporting is universal. We present the first data from a large survey of women in a rapidly urbanizing developing country to address this question. More than 4500 adult women in Egypt provided quantitative 24-h recalls of food intake on the previous day in 1993-1994, and weights and heights were measured. We compared the data, in terms of the ratio of reported energy intake to estimated basal metabolic rate, to data from 3010 women in the 1994-1996 U.S. Continuing Survey of Food Intake by Individuals, on whom quantitative 24-h recalls were also conducted. The Egyptian women reported food intakes consistent with FAO/WHO recommendations for energy intakes for women of comparable activity levels, whereas the data for U.S. women showed underreporting consistent with other U.S. surveys. Only 10% of Egyptian women reported energy intakes below accepted criteria for plausibility, compared with one third of American women. We discuss possible reasons for this difference, including cultural and food supply differences, and methodological differences between the two surveys.