Statistical Analysis for Quality Adjustment of the Analytical Curve for Determination of Pesticide Multiresidue in Pineapple Samples

Multiclass Pesticide Residues in Fruits and Vegetables from Brazil: A Systematic Review of Sample Preparation Until Post-Harvest

Brazil annually produces around 43 million tons of fruits and vegetables. Therefore, large amounts of pesticides are needed to grow these foods. The use of unauthorized or indiscriminate pesticides can lead to the adherence of residues of these compounds to the product in a concentration above the maximum residue limit (MRL). Pesticide residues (PRs) monitoring is a continuous challenge due to several factors influencing the detection of these compounds in the food matrix. Currently, several adaptations to conventional techniques have been developed to minimize these problems. This systematic review presents the main information obtained from 52 research articles, taken from five databases, on changes and advances in Brazil in sample preparation methods for determining PRs in fruits and vegetables in the last nine years. We cover the preexisting ones and some others that might be suitable alternatives approaches. In addition, we present a brief discussion on the monitoring of PRs in different Brazilian regions, and we found that residues belonging to the organophosphate and pyrethroid classes were detected more frequently. Approximately 67% of the residues detected are of irregular use in 28 types of fruits and vegetables commonly consumed and exported by Brazil.

Statistical evaluation of analytical curves for quantification of pesticides in bananas

The aim of this paper is to statistically validate the analytical curves of a chromatography method to identify and quantify azoxystrobin, difenoconazole and propiconazole residues in banana pulp, using QuEChERS and GC-SQ/MS. A matrix-matched calibration was used and analytical curves were estimated by weighted least squares regression (WLS), confirming heteroscedasticity for all compounds. Statistical tests were performed to confirm the quality adjustment of the proposed linear model. The correlation coefficient for azoxystrobin, difenoconazole and propiconazole were, respectively, 0.9985, 0.9966 and 0.9997 (concentration range: 0.05 and 2.0 mg kg^-1). The limits of detection and quantification were, respectively, between 0.007 and 0.066 mg kg^-1, and between 0.022 and 0.199 mg kg^-1, below the maximum limits stipulated by Brazilian, American, and European legislation. Only difenoconazole had an insignificant matrix effect (6.8%). Thus, the weighted least squares method is shown to be a safe linear regression model, providing greater reliability of the results.

Evaluation of different strategies for determination of selenomethionine (SeMet) in selenized yeast by asymmetrical flow field flow fractionation coupled to inductively coupled plasma mass spectrometry (AF4-ICP-MS)

This manuscript exemplifies the prospective use of asymmetrical flow field flow fractionation (AF4) coupled to inductively coupled plasma mass spectrometry (ICP-MS) as a simple tool for chemical speciation of selenomethionine (SeMet) in selenized yeast. Several popular sample preparation methods were evaluated for their suitability to determine selenomethionine (SeMet) in selenized yeast by AF4-ICP-MS. These included water, methanesulfonic acid (MSA), formic acid (FA) and alkaline extractions. Alkaline extraction (using sodium dodecyl sulfate buffer) provided the best recovery/determination conditions for SeMet based on analysis of NRC certified reference material (CRM) SELM-1 since it minimized hydrolysis of the protein peptide bonds optimally required for the AF4 separation. The analytical performance of three different AF4 membranes (5, 10 and 500 kDa regenerated cellulose) was also evaluated. No significant difference in the recovery of SeMet was observed when using 5 and 10 kDa RC membranes, whereas the 500 kDa membrane resulted in a significant loss. The proposed method presents appropriate instrument and intra-assay precisions of 4.4-9.2% and 3.8% RSD, respectively, a detection limit of 0.49 μg L-1 SeMet as Se and good linearity with correlation coefficients (R) between 0.996 - 0.999. This is the first report of use of AF4-ICP-MS for species specific quantitation of SeMet in selenized yeast demonstrating its efficient use as an alternative method to other traditional chromatographic techniques.

Effect of ozonization in degradation of trifluralin residues in aqueous and food matrices

This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9 mg O₃ L^-1 h^-1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20 min. Treatment at 5 min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20 min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025-0.1 mg kg^-1) were conducted with ozonation at 20 min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.

Simultaneous quantification of lipopeptide isoforms by UPLC-MS in the fermentation broth from Bacillus subtilis CNPMS22

The rapid and accurate quantification of lipopeptide families in biological samples are challenging. We present the development and validation of a method for simultaneous quantification of three families of lipopeptides (iturins, fengycins, and surfactins) and their isoforms, as well as the homologous series. The method was optimized in UPLC-MS for a column temperature at 65 °C, injection volume of 5 μL, and sample temperature of 10 °C. The SIM mode was used for detection and quantification of lipopeptides exhibiting ions [M + H]⁺ and [M + 2H]²⁺. Since the maximum mass detection threshold of the equipment is 1250 Da and the fengycins have ions between 1435 and 1505 Da, the ions [M + 2H]²⁺ were chosen for fengycin identification. The monitored ions were as follows: m/z 1043.5, 1057.5, 1071.5, 718.3, 725.4, 739.4, 732.4, 746.4, 753.4, 1008.6, 1022.6, and 1036.6. The compounds were separated by reverse-phase chromatography using a C18 analytical column in a total time of 19 min. Standard curves were linear with r_w 0.99 for all analytes. Intra- and inter-day precision for samples (50, 250, and 750 μg L^-1) were within recommended limits. The proposed analytical method was capable of simultaneously quantifying 12 isoforms and homologous series of lipopeptide families in biological samples, thus making it an important industrial tool in the evaluation of lipopeptide production processes. Graphical abstract ᅟ.