Health Risk Assessment of Arsenic in the Drinking Water of Upper Sindh, Pakistan

Water is a valuable compound for plants, animals, and humans. Various contaminating agents pollute it, with arsenic being one of them. Measurements of arsenic in potable water in Upper Sindh were conducted during this study. The samples were prepared by microwave-assisted digestion and analyzed by an atomic absorption spectrophotometer. A total of 240 potable water samples were collected from 8 Talukas of Upper Sindh. DMS coordinates were also recorded with the help of the Global Positioning System (GPS). The highest arsenic content of 50µg/L was observed in Garhi Khairo Taluka. The average arsenic content in water samples of all of the Talukas, except Miro Khan, was found higher than the WHO permissible limit. The 69.2% of samples were found to be contaminated by arsenic. Therefore, the water of the studied area is concluded to be in poor condition for cooking and drinking.

Development of a Single-Step Microwave-Assisted Digestion Method using Dilute Nitric Acid for Determination of Bismuth in Bismuth-containing Pharmaceuticals by Hydride Generation-Atomic Fluorescence Spectrometry

A single-step microwave assisted digestion (MWAD) procedure employing very dilute solutions of HNO3 was developed for the quantitative determination of bismuth in bismuth-containing pharmaceuticals by hydride generation-atomic fluorescence spectrometry (HG-AFS). Experimental parameters affecting MWAD process such as acid concentration (HNO3), digestion time and temperature were optimized to get quantitative recovery of bismuth. The studies indicated that the method is rapid (within 15 min) including cooling time and recovery > 98% was obtained using 10mL of 5% (v/v) HNO3 as digestion medium with ~0.1g of sample. The optimum microwave digestion parameters obtained were: temperature – 180oC, pressure – 25 bar and hold time - 10 min. A clear solution with negligible residue was obtained after microwave digestion. The digested sample solution was appropriately diluted with 2% (v/v) HCl for subsequent analysis by HG-AFS. The reproducibility, expressed as % RSD was lower than 2% for the allopathic medicine. Under optimal conditions, the limit of detection (LOD) for Bi was calculated to be 0.024mg/kg. The methodology was optimized using a bismuth-containing pharmaceutical – Pylobis, purchased from a local pharmacy. The optimized MWAD approach was further applied to few other bismuth-containing pharmaceutical products. The developed method has significant advantages when compared to the conventional hot-plate digestion methods reported for Bi-containing pharmaceuticals, employing large volumes of concentrated acids. These investigations revealed that the proposed MWAD method in combination with HG-AFS can be utilized for the rapid determination of Bi in pharmaceutical products on regular basis.

ICP-OES elemental impurities study on different pharmaceutical dosage forms of Ibuprofen using microwave-assisted digestion procedure

Fast and simple closed-vessel microwave-assisted digestion procedure was developed for decomposition of three pharmaceutical dosage forms of ibuprofen such as tablets, suspension and gel, prior to elemental impurity analysis by one robust and precise ICP-OES method. Samples were digested by four-step microwave program consisting of a 10 min temperature gradient to 180°C, maintained at 180°C for 10 min, followed by 5 min ramping time to 210°C with holding time of 10 min on 210°C. Subsequently, ICP-OES method was developed and validated for simultaneous determination of selected elemental impurities. Results of recovery studies range between 77% and 105% for each element in all analyzed formulations. Correlation coefficients of the regression equations were higher than 0.999 for all analyzed elements. Validation results reveal that the proposed method is specific, accurate, and precise and could be applied for simultaneous quantitative analysis of multi element solutions in different pharmaceutical dosage forms of ibuprofen.