Determination of 73 multi-class pesticides in okra (Abelmoschus esculentus L.) fruits using LC-MS/MS and GC-MS/MS and estimation of analytical uncertainty of measurement.

This study developed a method to simultaneously determine 73 multi-class pesticides in okra fruit using LC-MS/MS and GC-MS/MS. The sample was extracted with acetonitrile and subsequent clean-up through dispersive-SPE method. The quantification level of the technique was 0.01 µg g-1 and compliance to the MRLs fixed by the regulatory bodies like EU and FSSAI. The recovery at 10, 50, and 100 µg kg-1 spiked levels; intra and inter-day precision at 50 µg kg-1 were found within 70-120% with RSD less than 15% with LC-MS/MS and GC-MS/MS. Measurement uncertainty was in the range of 1.81 to 12.91 µg kg-1 estimated at 50 µg kg-1. The matrix effects were slightly higher for LC than GC-compatible pesticides. Risk assessment for pesticides detected in the field and market samples found no hazardous to the consumers except profenofos. The proposed method is highly sensitive, reproducible for the complex matrix like okra, and meets the regulatory standards.

Simultaneous determination of pesticide residues in pomegranate whole fruit and arils using LC-MS/MS.

An analytical method in pomegranate whole fruits and arils was developed in LC-MS/MS and validated as per SANTE/12682/2019. Samples were extracted following acetonitrile-based modified QuEChERS protocol. The method was linear and the coefficient of determination ranged between 0.998 and 0.999. Through this method, all the pesticides were detected and quantified at 10 µg kg-1. The accuracy test at 10, 50, and 100 µg kg-1 spiking level recorded recovery between 70 and 120% and RSD less than 15% in both matrices. No significant matrix effect was observed for most pesticides. Intra (RSDr) and inter-day (RSDwr) precision estimated at 50 µg kg-1 found acceptable RSD in both matrices. Measurement uncertainty at 50 µg kg-1 was in the range of 4.02 to 16.12 µg kg-1. Quantifying pesticides in pomegranate whole fruits, peel, and arils using the proposed method is highly suitable and reproducible for 74 pesticides in a short run time of 25.00 min.

Testing neocortical slice viability in non-perfused no-magnesium artificial cerebrospinal fluid solutions.

The acute in vitro brain slice model is a widely used neurophysiological research tool. When applying this method, most researchers continuously perfuse slices with carbogenated artificial cerebrospinal fluid (ACSF) to maintain pH balance and tissue oxygen delivery. Common wisdom suggests that static recordings are incompatible with submerged bath methodology because of deficiency in tissue oxygen supply. However, to our knowledge this has not been tested. In this study, we wanted to determine whether neocortical mouse slice viability could be maintained in the medium term (up to 2h) in a shallow, submerged recording bath under non-perfused, static conditions. Seizure-like events (SLEs) were generated in the slices utilizing no-magnesium ACSF and recorded for 2h under three conditions: (1) perfused ACSF condition (n=8), where slices were perfused continuously with carbogenated no-magnesium ACSF; (2) static ACSF condition (n=12), where slices were recorded in pre-carbogenated, but non-perfused (static) no-magnesium ACSF; and (3) static HEPES ACSF condition (n=12), where slices were recorded in non-perfused (static) no-magnesium ACSF with no pre-carbogenation but buffered with HEPES. SLE activity was stable for 2h across all three conditions. There was no statistically significant difference in SLE frequency, amplitude or length between static and perfused conditions. SLE frequency and amplitude were generally lower in the static HEPES buffer condition. The data indicate that robust and stable neocortical SLE activity can be generated for at least 2h in a submersion bath without ACSF perfusion if pH is adequately controlled.