Shellie blanks biography samples
Analysis of Nucleosides in Municipal Wastewater by Large-Volume Liquid Chromatography Tandem Mass Spectrometry
Abstract
Nucleosides are components of both DNA and RNA, and contain either a ribose (RNA) or 2deoxyribose (DNA) sugar and a purine or pyrimidine base. In addition to DNA and RNA turnover, modified nucleosides found in urine have been correlated to a diminished health status associated with AIDS, cancers, oxidative stress and age. Nucleosides found in municipal wastewater influent are potentially useful markers of community health status, and as of now, remain uninvestigated. A method was developed to quantify nucleosides in municipal wastewater using large-volume injection, liquid chromatography, and mass spectrometry. Method accuracy ranged from 92 to 139% when quantified by using isotopically labeled internal standards. Precision ranged from 6.1 to 19% of the relative standard deviation. The method’s utility was demonstrated by the analysis of twenty-four hour composite wastewater influent samples that were collected over a week to investigate community nucleoside excretion. Nucleosides originating from RNA were more abundant that DNA over the study period, with total loads of nucleosides ranging from 2 to 25 kg/day. Given this relatively high amount of nucleosides found over the study period they present an attractive analyte for the investigation of community health.
INTRODUCTION
Municipal wastewater contains community scale information . There have been numerous methods developed for the quantification of illicit drugs , personal care products , and pharmaceuticals in municipal wastewater influent and effluent. Endogenous compounds such as steroids have also been investigated in municipal wastewater . The concentrations of these substances are converted to mass loads by the multiplication of wastewater volume in order to account for dilution . Community drug use, which is an important indication of community h
Development of a generic sample preparation method using dispersive liquid–liquid microextraction for the monitoring of leachable compounds in hospital pharmacy-prepared prefilled drug products†
DOI: 10.1039/D3AY02234J (Paper) Anal. Methods, 2024, 16, 1697-1707
Received 14th December 2023 , Accepted 12th February 2024
First published on 13th February 2024
Abstract
Performant sample preparation is mandatory in any leachable study to clean and preconcentrate analytes within the sample to offer the best possible extraction recovery as well the best precision for any given substance. The aim consists in developing a sample preparation method for hospital pharmacy-prepared drug products such as long-term storage prefilled syringes, vials and IV bags for the screening of leachable compounds. The Quality Control Laboratory of the Pharmacy of the Lausanne University Hospital (Switzerland) has developed a time- and cost-effective, highly sensitive, robust, and fast method using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) for the analysis of 205 plastic additives. An innovative setup, based on postcolumn infusion (PCI) using 2% ammonium hydroxide in methanol was used to boost the signal intensity of the analytes in MS detection. A database for extractable and leachable trace assessment (DELTA) was built to assist in the screening process of 205 plastic packaging-related compounds. The development of the sample preparation was based on 33 plastic additive candidates in different hospital pharmacy compounding solutions, and their extraction recovery rates as well as their relative standard deviation were taken into consideration. In conclusion, the developed DLLME was assigned with ultrasound assistance and triple extraction, which brought about extraction recovery rates between 67% and 92%, a good RSD <10%, and a preconcentration factor of 50×. Therefore, DLLME could be considered suitable for the semiquantitative screening of The reliability and suitability of sample preparation, data acquisition, data preprocessing and data analysis are prerequisites for correct biological interpretation in metabolomics studies. The significance of differences between samples can only be determined when the performance characteristics of the entire method (from sample preparation to data preprocessing) are known. Therefore it is important to perform method validation to assess the performance and the fitness-for-purpose of a method or analytical system for metabolomic research, including ultimately error models per metabolite. In the following sections the challenges and recommendations for method development and data processing and some commonly used data analysis tools are discussed. Furthermore, strategies for method validation and quality control are provided. The development of silylation based GC-MS methods poses serious challenges for analytical chemists considering the large range of compound classes and the large differences in concentrations within and between biological samples. Inconsistencies in quantification of metabolites can arise from many sources during sampling, sample storage, sample extraction, derivatization, analysis and/or detection. For example, during sampling, sample storage and extraction of the metabolites, undesired changes in metabolite composition may occur due to for example enzyme activity, high reactivity and/or breakdown of metabolites. One way to avoid this is to use ‘snapshot’ sampling, i.e. fast cooling of the sample to low temperatures, maintain low storage temperatures (−80°C) and/or use low temperatures and appropriate additives to inhibit enzyme activity during extraction. Furthermore, irreproducible extraction and/or derivatization as well as degradation of derivatized metabolites in the analytical system are inQuantitative metabolomics based on gas chromatography mass spectrometry: status and perspectives
2.1 Analytical method development and analysis
Shellie blanks biography of mahatma
THE CEASELESS CRUSADER
Who said, ‘Frailty, thy name is woman’? Mahatma Gandhi was a ceaseless crusader of women’s equality. He brought
the women out of their homes and made them equal participants in all walks of life
– social as well as political. His entourage always consisted of several women and
many of his closest associates were women. Under Gandhi’s leadership thousands
of women took leading roles in several movements. Gandhi never considered
women to be unfit for any position or task. Because of Gandhi’s support and
initiative, women’s groups were formed all over India and there was hardly a week
when Gandhi did not address a women’s group. It was mainly because of Gandhi
that the first Cabinet of Independent India consisted of two women ministers. What
is significant here is his image of woman and his hope for her, so radically different
from that of any earlier reformer. He was not the first to address women’s issues
in India. Be