Desarrollo de una metodología para el análisis de residuos de plaguicidas en leches mediante cromatografía líquida acoplada a espectrometría de masas

Se desarrolló un método multirresiduo para el análisis de plaguicidas en leche mediante el empleo de cromatografía líquida acoplada a espectrometría de masas. Se estudiaron diferentes variaciones al método de extracción QuEChERS utilizando siete diferentes fases extractantes, dos sales amortiguadoras, tres concentraciones de ácido fórmico en la fase extractante y cuatro tiempos de ultrasonido. De los 58 plaguicidas analizados solo tiociclam y tiodicarb presentaron porcentajes de recuperación inferiores al 70%. Los mejores porcentajes de recuperación y menores coeficientes de variación se obtuvieron empleando el buffer de citrato y acetonitrilo con ácido fórmico al 0,5% como extractante. Por otro lado, no se observaron diferencias estadísticas (P > 0,05) a los tiempos de ultrasonido evaluados. Finalmente, se encontró que el método aplicado es preciso y exacto para el análisis de residuos de plaguicidas de diferentes grupos químicos como: azoles, organofosforados, bencimidazoles, carbamatos, entre otros.It was developed a multi-residue method for determining pesticides of different physicochemical characteristics presents on milk. The extraction process is based on the QuEChERS method and determination of the compounds was performed using ultra performance liquid chromatography coupled to mass spectrometry. Also, were evaluated seven different phases of extraction, the effect of different times of ultrasound and three concentrations of formic acidon the extraction process. The repeatability of the method results indicated that for most of the compounds showed coefficients of variation below 10%. Furthermore, it was found that there were no statistical differences (P> 0.05) at different times of ultrasound evaluation. Finally, it was found that the developed method is precise and accurate for the analysis of pesticide residues from different chemical groups such as azoles, organophosphorus, benzimidazoles, carbamates, among others

Final report of the CCQM-K145: toxic and essential elements in bovine liver

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples. 30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation. Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix. Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids / semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population