Atrazine characterization: An update on uses, monitoring, effects, and environmental impact, for the development of regulatory policies in Argentina.

Atrazine (ATZ) is the third most widely used herbicide in Argentina (10 000 t year-1 ) and is approved for sugar cane, flax, corn, sorghum, and tea. An assessment of the ATZ environmental impacts was conducted at the request of the Ministry of Environment and Sustainable Development of Argentina. A review of 541 national and international technical and scientific reports and a survey among agricultural technicians, applicators, and producers was done. The survey revealed that 94% of ATZ applications are terrestrial and use diversion exists, associated mainly with soybean cultivation. Atrazine was reported at high frequencies (50%-100%) in surface and groundwater, sediments, and soils, sometimes exceeding permitted limits. Several sublethal effects induced by ATZ on invertebrate and vertebrate species were found, sometimes at concentrations lower than those in water quality guidelines (<3 µg L-1 ) or the environmental concentrations found in Argentina. Available epidemiological or human health studies of local populations are extremely scarce. This assessment also demonstrated that herbicides are ubiquitous in the environment. The investigation highlights the need for further studies assessing the adverse effects of ATZ on local species, ecosystems, and human health. Therefore, the precautionary principle is recommended to promote better application standards and product traceability to reduce volumes entering the environment and to avoid use deviation. In addition, this work concluded that there is a need for reviewing the toxicological classification, establishing buffer zones for ATZ application, introducing specific management guidelines, and expanding local studies of toxicity, ecotoxicity, and human epidemiology for environmental and health risk assessments. This study could also serve as a preliminary risk evaluation for establishing a final regulatory action and for considering ATZ inclusion in Annex III of the Rotterdam Convention. Finally, the requirements to consider its inclusion in Annex A (Elimination) or B (Restriction) of the Stockholm Convention were evaluated and discussed, and information on the potential of long-range transport was the only criterion with no information to consider. Integr Environ Assess Manag 2023;19:684-697. © 2022 SETAC.

Wastewater-Based Epidemiology: Detection of SARS-CoV-2 RNA in Different Stages of Domestic Wastewater Treatment in Santa Fe, Argentina.

The COVID-19 pandemic affected human life at every level. In this study, we analyzed genetic markers (N and ORF1ab, RNA genes) of SARS-CoV-2 in domestic wastewaters (DWW) in San Justo City (Santa Fe, Argentina), using reverse transcription-quantitative real-time PCR. Out of the 30 analyzed samples, 30% were positive for SARS-CoV-2 RNA. Of the total positive samples, 77% correspond to untreated DWW, 23% to pre-chlorination, and no SARS-CoV-2 RNA was registered at the post-chlorination sampling site. The viral loads of N and OFR1ab genes decreased significantly along the treatment process, and the increase in the number of viral copies of the N gene could anticipate, by 6 days, the number of clinical cases in the population. The concentration of chlorine recommended by the WHO (≥ 0.5 mg L-1 after at least 30 min of contact time at pH 8.0) successfully removed SARS-CoV-2 RNA from DWW. The efficiency of wastewater-based epidemiology (WBE) confirms the need to control and increase DWW treatment systems on a regional and global scale. This work could contribute to building a network for WBE to monitor SARS-CoV-2 in wastewaters during the pandemic waves and the epidemic remission phase. Supplementary Information: The online version contains supplementary material available at 10.1007/s11270-022-05772-w.

Second-, third- and fourth-generation quinolones: Ecotoxicity effects on Daphnia and Ceriodaphnia species.

We conducted the first complete toxicological study of six quinolones, including acute, chronic, and recovery assays on Daphnia magna and Ceriodaphnia dubia. The assayed quinolones were second-generation ciprofloxacin (CIP), norfloxacin (NOR), enrofloxacin (ENR), and marbofloxacin (MAR); third-generation levofloxacin (LEV), and fourth-generation moxifloxacin (MOX). The median lethal concentrations (LC50) obtained for both species by acute ecotoxicity assay ranged from 14 to 73 mg L-1 and from 3 to 23 mg L-1 at 48 and 72 h, respectively; while the median effective concentration (EC50) ranged from 4 to 28 mg L-1 in the chronic ecotoxicity assays. C. dubia surviving the chronic exposure assay was monitored in recovery assays free of quinolones. A fluorometric method was used to confirm that there was no significant loss of quinolone concentrations during the acute assays. We also used this method to show that quinolone concentrations fell below 80% of the nominal value after 9-11 d if exposure solutions were not renewed. This study on the ecotoxicological and chemical behavior of quinolones in two cladoceran species fills a data gap about how these emerging contaminants affect nontarget aquatic organisms and how long they persist in the environment.

Magneto immunofluorescence assay for diagnosis of celiac disease.

A magneto immunofluorescence assay for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The ATG2 were recognized by transglutaminase enzyme immobilized on the magnetic beads and then the immunological reaction was revealed by antibodies labeled with peroxidase. The fluorescent response of the enzymatic reaction with o-phenylenediamine and H2O2 as substrates was correlated with anti-transglutaminase titer, showing EC50 and LOD values of 1:11,600 and 1:74,500 of antibody titers, respectively. A total number of 29 sera samples from clinically confirmed cases of celiac disease and 19 negative control samples were tested by the novel magneto immunofluorescence assay. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 8.1 U was the most effective cut-off value to discriminate correctly between celiac and non-celiac patients. The immunofluorescence assay exhibited a sensitivity of 96.6%, a specificity of 89.5% and an efficiency 93.8% compared with the commercial optical ELISA kit.

Electrochemical magneto immunosensor for the detection of anti-TG2 antibody in celiac disease.

An electrochemical magneto immunosensor for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The immunological reaction is performed on magnetic beads (MBs) as a solid support in which the transglutaminase enzyme (TG2) is covalently immobilized (TG2-MB) and then ATG2 were revealed by an antibody labeled with peroxidase. The electrochemical response of the enzymatic reaction with o-phenilendiamine and H2O2 as substrates by square wave voltammetry was correlated with the ATG2. Graphite-epoxi composite cylindrical electrodes and screen printed electrodes were used as transducers in the immunosensor. A total number of 29 sera from clinically confirmed cases of celiac disease and 19 negative control sera were tested by the electrochemical magneto immunosensor. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 16.95 units was the most effective cut-off value (COV) to discriminate correctly between celiac and non-celiac patients. Using this point for prediction, sensitivity was found to be 100%, while specificity was 84%.

Enzymatic electrochemical detection coupled to multivariate calibration for the determination of phenolic compounds in environmental samples.

An approach based on the electrochemical detection of the horseradish peroxidase enzymatic reaction by means of square wave voltammetry was developed for the determination of phenolic compounds in environmental samples. First, a systematic optimization procedure of three factors involved in the enzymatic reaction was carried out using response surface methodology through a central composite design. Second, the enzymatic electrochemical detection coupled with a multivariate calibration method based in the partial least-squares technique was optimized for the determination of a mixture of five phenolic compounds, i.e. phenol, p-aminophenol, p-chlorophenol, hydroquinone and pyrocatechol. The calibration and validation sets were built and assessed. In the calibration model, the LODs for phenolic compounds oscillated from 0.6 to 1.4 × 10(-6) mol L(-1). Recoveries for prediction samples were higher than 85%. These compounds were analyzed simultaneously in spiked samples and in water samples collected close to tanneries and landfills.

Biotin determination in food supplements by an electrochemical magneto biosensor.

An electrochemical magneto biosensor for the rapid determination of biotin in food samples is reported. The affinity reaction was performed on streptavidin-modified magnetic microbeads as a solid support in a direct competitive format. The biotinylated horseradish peroxidase enzyme (biotin-HRP) competes with free biotin in the sample for the binding sites of streptavidin on the magnetic microbeads. The modified magnetic beads were then easily captured by a magneto graphite-epoxy composite electrode and the electrochemical signal was based on the enzymatic activity of the HRP enzyme under the addition of H(2)O(2) as the substrate and o-phenilendiamine as cosubstrate. The response was electrochemically detected by square wave voltammetry. The limit of detection was 8.4×10(-8) mol L(--1) of biotin (20 µg L(--1)) with a dynamic range from 0.94 to 2.4×10(-7) mol L(--1). Biotin-fortified commercial dietary supplement and infant formula samples were evaluated obtaining good performances in the results. Total time of analysis was 40 min per 20 assays.

Evaluation of seven cosubstrates in the quantification of horseradish peroxidase enzyme by square wave voltammetry.

The electrochemical detection for horseradish peroxidase-cosubstrate-H(2)O(2) systems was optimized. o-Phenilendiamine, phenol, hydroquinone, pyrocatechol, p-chlorophenol, p-aminophenol and 3,3'-5,5'-tetramethylbenzidine were evaluated as cosubstrates of horseradish peroxidase (HRP) enzyme. Therefore, the reaction time, the addition sequence of the substrates, the cosubstrate:H(2)O(2) ratio and the electrochemical techniques were elected by one-factor optimization assays while the buffer pH, the enzymatic activity and cosubstrate and H(2)O(2) concentrations for each system were selected simultaneously by response surface methodology. Then, the calibration curves for seven horseradish peroxidase-cosubstrate-H(2)O(2) systems were built and the analytic parameters were analyzed. o-Phenilendiamine was selected as the best cosubstrate for the HRP enzyme. For this system the reaction time of 60s, the phosphate buffer pH 6.0, and the concentrations of 2.5×10(-4)molL(-1) o-phenilendiamine and of 1.25×10(-4)molL(-1) H(2)O(2) were chosen as the optimal conditions. In these conditions, the calibration curve of horseradish peroxidase by square wave voltammetry showed a linearity range from 9.5×10(-11) to 1.9×10(-8)molL(-1) and the limit of detection of 3.8×10(-11)molL(-1) with RSD% of 0.03% (n=3).

Development and validation of a simple stability-indicating high performance liquid chromatographic method for the determination of miconazole nitrate in bulk and cream formulations.

A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB - C18 (4.6 mm x 150 mm, 5 microm particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 degrees C and 10 microL of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis.