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The analysis of trace hydrophilic targets in complex aqueous-rich matrices is considerably challenging, generally requiring matrix-matched calibration, internal standard, or time-and-labor-intensive sample preparation. To address this analytical bottleneck, a non-matrix-matched calibration strategy without using internal standard was reported for the first time to analyze complicated biosamples such as whole blood, plasma, serum, and cell samples. This strategy, termed micelle-dominated distribution, also aimed at realizing the simple "extract-and-shoot" analytical process for such complex matrices. The micelle-matrix interaction was found to efficiently eliminate the matrix effect by dominating phase separation and analyte distribution between the extraction and matrix phases. Thus, calibration linear curves prepared in water were applicable to the analysis of all the above-mentioned sample types. Rapid distribution equilibrium within 4 min was achieved. This strategy could tolerate direct large volume injection, thereby providing two-order-of-magnitude enhancement in the sensitivity of ion-pair chromatography. The analytical method integrated cell rupture, matrix cleanup, analyte extraction, and on-column preconcentration into a fast and high-throughput operation. The successful application to the determination of exogenous pesticides and endogenous glutathione exhibited low limits of detection (0.0085-0.015 μg mL -1 for pesticides; 0.52 μg mL -1 for glutathione), wide linear ranges (0.028-50 μg mL -1 and 0.049-50 μg mL -1 for pesticides; 1.7-1000 μg mL -1 for glutathione), good linearies (R 2  = 0.9994-0.9999), excellent accuracy (recoveries of 91.3-105.2%), and good precision (0.7-6.2% at the levels of 0.028 (or 0.049), 0.1, 0.5, and 50 μg mL -1 for pesticides; 0.5-8.7% at 1.7, 500, and 1000 μg mL -1 for glutathione)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This work reports a study about the adsorption of the herbicides diquat and difenzoquat from aqueous medium employing polyurethane foam (PUF) as the adsorbent and sodium dodecylsulfate (SDS) as the counter ion. The adsorption efficiency was shown to be dependent on the concentration of SDS in solution, since the formation of an ion-associate between cationic herbicides (diquat and difenzoquat) and anionic dodecylsulfate is a fundamental step of the process. A computational study was carried out to identify the possible structure of the ion-associates that are formed in solution. They are probably formed by three units of dodecylsulfate bound to one unit of diquat, and two units of dodecylsulfate bound to one unit of difenzoquat. The results obtained also showed that 95% of both herbicides present in 45mL of a solution containing 5.5mgL -1 could be retained by 300mg of PUF. The experimental data were well adjusted to the Freundlich isotherm (r 2 ≥ 0.95) and to the pseudo-second-order kinetic equation. Also, the application of Morris-Weber and Reichenberg equations indicated that an intraparticle diffusion process is active in the control of adsorption kinetics., (Copyright © 2017 Elsevier Inc. All rights reserved.)

CdSe/ZnS QDs have demonstrated capacity to act as reducing agent in organic media such as acetonitrile and ethanol. By using fluorescence and Raman spectroscopy, it has been demonstrated that QDs reduce diquat herbicide to its monocation radical. The reaction is characterized to present a high reaction rate making possible to perform the reaction by simple filtration of the solution containing the herbicide through a QDs modified filter. The monocation radical presents a high fluorescence emission spectrum which was selected as the analytical signal to quantify the diquat herbicide. The method described here for the analysis of diquat herbicide in oat grains is simple and fast allowing the analysis of trace level of herbicide in only 6 min. The excellent sensitivity and reproducibility of the methods indicate that the reaction is favoured from both thermodynamic and kinetic point of view. The results presented open up the possibility to use QDs as redox agent. The sensitivity of the method expressed as detection limit was only of 0.01 mg kg(-1).The lineal range was between 0.05 and 0.5 mg kg(-1). The time of analysis per sample, including extraction, reaction and fluorescent measurement was only of 6 min., (Copyright © 2011 Elsevier B.V. All rights reserved.)

In the present work, a method was developed and optimized aiming to determinate the herbicides paraquat (PQ) and diquat (DQ) in human plasma and urine samples. An initial procedure of chemical reduction of the analytes by adding NaBH4 directly in the buffered samples (pH 8.0) was performed. This procedure was necessary to convert the quaternary ammonium substances into more volatile compounds for gas chromatographic analysis. The reduction compounds were extracted with C18 cartridges (solid-phase extraction). Ethyl paraquat (EPQ) was used as internal standard (IS). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring (SIM) mode. The limits of detection were 0.05 mg/l for both PQ and DQ. By using the weighted least squares linear regression (1/x1/2 for plasma and 1/y for urine), the accuracy of the analytical method was improved at the lower end of the calibration curve (from 0.1 to 50 mg/l; r>0.98). This method can be readily utilized as an important tool to confirm the suspicion of PQ and/or DQ poisoning and evaluate the extent of the intoxication.