Potentiometric determination of oxybutynin hydrochloride in pharmaceutical formulations at modified carbon paste electrodes

A new potentiometric sensitive and selective modified carbon paste (MCPE) electrodes based on phosphotungestic acid (PTA),  sodium tetraphenyl borate (NaTPB),  phosphomolybdic acid (PMA) or ammonium reineckate (RN) ion pairing agents for determination of (Ox.HCl) were developed. The proposed electrodes have a Nernstian slope values of 58.50±0.71, 58.71±1.20, 54.80±1.30 and 59.20±0.70 mV decade-1for electrodes modified with 20, 10, 5 and 10 mg of Ox-TPB (electrode I), Ox-RN (electrode II), Ox-PMA (electrode III) and Ox-PTA (electrode IV) ion pairs, respectively, with a dynamic drug concentration range at 25 (C was 1.0x10-5 - 1.0x10-2 mole L-1 with detection limit of 1.0× 10-5 mol L-1. The response of MCPEs were pH independent in the range 2.0-6.0 with a fast response time of 10 s for electrode I and 12 s for electrodes II-IV. The MCPEs showed a relatively long life time of 36 days. A pure and pharmaceutical formulation of Ox.HCl was quantified using calibration and standard addition methods and the obtained results agreed with that of the official HPLC method. Validation parameters were optimized according to ICH recommendations.

Letter: The Impact of the Coronavirus (COVID-19) Pandemic on Neurosurgeons Worldwide

This article is made available for unrestricted research re-use and secondary analysis in any form or be any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.The aim of our study was to explore the impact of this pandemic on neurosurgeons with the hope of improving preparedness for future crisis. We created a 20-question survey designed to explore demographics (nation, duration and scope of practice, and case-burden), knowledge (source of information), clinical impact (elective clinic/surgery cancellations), hospital preparedness (availability of personal protective equipment [PPE] and cost of the supplies), and personal factors (financial burden, workload, scientific and research activities). The survey was first piloted with 10 neurosurgeons and then revised. Surveys were distributed electronically in 7 languages (Chinese, English, French, German, Italian, Portuguese, and Spanish) between March 20 and April 3, 2020 using Google Forms, WeChat used to obtain responses, and Excel (Microsoft) and SPSS (IBM) used to analyze results. All responses were cross-verified by 2 members of our team. After obtaining results, we analyzed our data with histograms and standard statistical methods (Chi-square and Fisher's exact tests and logistic regression). Participants were first informed about the objectives of our survey and assured confidentiality after they agreed to participate (Helsinki declaration). We received 187 responses from 308 invitations (60.7%), and 474 additional responses were obtained from social media-based neurosurgery groups (total responses = 661). The respondents were from 96 countries representing 6 continents (Figure ​(Figure11A-​A-11C)