Simultaneous determination of diquat, paraquat, glufosinate, and glyphosate in plasma by liquid chromatography/tandem mass spectrometry: from method development to clinical application.

Diquat (DQ), paraquat (PQ), glufosinate (GLU), and glyphosate (GLYP) are commonly used herbicides that have been confirmed to be toxic to humans. Rapid and accurate measurements of these toxicants in clinical practice are beneficial for the correct diagnosis and timely treatment of herbicide-poisoned patients. The present study aimed to establish an efficient, convenient, and reliable method to achieve the simultaneous quantification of DQ, PQ, GLU, and GLYP in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS) without using derivatization or ion-pairing reagents. DQ, PQ, GLU, and GLYP were extracted by the rapid protein precipitation and liquid-liquid extraction method and then separated and detected by LC-MS/MS. Subsequently, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, extraction recovery, matrix effect, dilution integrity, and stability were evaluated to validate the method based on the FDA criteria. Finally, the validated method was applied to real plasma samples collected from 166 Chinese patients with herbicide poisoning. The results showed satisfactory linearity with low LOD (1 ng/mL for DQ and PQ, 5 ng/mL for GLU, and 10 ng/mL for GLYP, respectively) and low LOQ (5 ng/mL for DQ and PQ, 25 ng/mL for GLU and GLYP, respectively). In addition, the precision, accuracy, extraction recovery, and stability of the method were acceptable. The matrix effect was not observed in the analyzed samples. Moreover, the developed method was successfully applied to determine the target compounds in real plasma samples. These data provided reliable evidence for the application of this LC-MS/MS method for clinical poisoning detection.

Paraquat pharmacokinetics in primates and extrapolation to humans.

By extending our Paraquat (PQ) work to include primates we have implemented a modelling and simulation strategy that has enabled PQ pharmacokinetic data to be integrated into a single physiologically based pharmacokinetic (PBPK) model that enables more confident extrapolation to humans. Because available data suggested there might be differences in PQ kinetics between primates and non-primates, a radiolabelled study was conducted to characterize pharmacokinetics and excretion in Cynomolgus monkeys. Following single intravenous doses of 0.01 or 0.1 mg paraquat dichloride/kg bw, plasma PQ concentration-time profiles were dose-proportional. Excretion up to 48 h (predominantly urinary) was 82.9%, with ca. 10% remaining unexcreted. In vitro blood binding was similar across Cynomolgus monkeys, humans and rat. Our PBPK model for the rat, mouse and dog, employing a single set of PQ-specific parameters, was scaled to Cynomolgus monkeys and well represented the measured plasma concentration-time profiles over 14 days. Addition of a cartilage compartment to the model better captured the percent remaining in the monkeys at 48 h, whilst having negligible effect on model predictions for the other species. The PBPK model performed well for all four species, demonstrating there is little difference in PQ kinetics between non-primates and primates enabling a more confident extrapolation to humans. Scaling of the PBPK model to humans, with addition of a human-specific dermal submodel based on in vitro human dermal absorption data, provides a valuable tool that could be employed in defining internal dosimetry to complement human health risk assessments.

Integration of paraquat pharmacokinetic data across species using PBPK modelling.

Paraquat dichloride (PQ) is a non-selective herbicide which has been the subject of numerous toxicology studies over more than 50 years. This paper describes the development of a physiologically-based pharmacokinetic (PBPK) model of PQ kinetics for the rat, mouse and dog, firstly to aid the interpretation of studies in which no kinetic measurements were made, and secondly to enable the future extension of the model to humans. Existing pharmacokinetic data were used to develop a model for the rat and mouse. Simulations with this preliminary model were then used to identify key data gaps and to design a new blood binding study to reduce uncertainty in critical aspects of the model. The new data provided evidence to support the model structure, and its predictive performance was then assessed against dog and rat datasets not used in model development. The PQ-specific model parameters are the same for all three species, with only the physiological parameters varying between species. This consistency across species provides a strong basis for extrapolation to other species, as demonstrated here for the dog. The model enables a wide range of PQ data to be linked together to provide a broad understanding of PQ pharmacokinetics in rodents and the dog, showing that the key aspects of PQ kinetics in these species are understood and adequately encapsulated within the model.

Association between liberal oxygen therapy and mortality in patients with paraquat poisoning: A multi-center retrospective cohort study.

Paraquat (N, N'-dimethyl-4, 4'-bipyridinium dichloride, PQ) intoxication is a common cause of lethal poisoning. This study aimed to identify the risk of using liberal oxygen therapy in patients with PQ poisoning. This was a multi-center retrospective cohort study involving four medical institutions in Taiwan. Data were extracted from the Chang Gung Research Database (CGRD) from January 2004 to December 2016. Patients confirmed to have PQ intoxication with a urine PQ concentration ≥ 5 ppm were analyzed. Patients who received oxygen therapy before marked hypoxia (SpO2 ≥ 90%) were defined as receiving liberal oxygen therapy. The association between mortality and patient demographics, blood paraquat concentration (ppm), and liberal oxygen therapy were analyzed. A total of 416 patients were enrolled. The mortality rate was higher in the liberal oxygen therapy group (87.8% vs. 73.7%, P = 0.007), especially in 28-day mortality (adjusted odds ratio [aOR]: 4.71, 95% confidence interval [CI]: 1.533-14.471) and overall mortality (aOR: 5.97, 95% CI: 1.692-21.049) groups. Mortality in patients with PQ poisoning was also associated with age (aOR: 1.04, 95% CI: 1.015-1.073), blood creatinine level (aOR: 1.49, 95% CI: 1.124-1.978), and blood paraquat concentration (ppm) (aOR, 1.51; 95% CI: 1.298-1.766). Unless the evidence of hypoxia (SpO2 < 90%) is clear, oxygen therapy should be avoided because it is associated with increased mortality.

Prognostic value of liver and kidney function parameters and their correlation with the ratio of urine-to-plasma paraquat in patients with paraquat poisoning.

Acute paraquat poisoning resulting from multiple organ failure usually has a high mortality rate. Liver and kidney, as the key oranges of paraquat detoxification and elimination, their injuries may suppress toxin excretion and enhance the toxicity of paraquat in other organs and worsen the prognosis. Therefore, we intended to explore the prognostic value of liver and kidney function parameters, and further evaluate their correlation with a more stable index urine-to-plasma paraquat (urine paraquat concentrations/plasma paraquat concentrations) instead of considering paraquat concentrations in plasma or urine alone. The study included 33 patients with acute paraquat poisoning admitted to four centres in China from January 2018 to December 2019. Seventeen patients (10 male/7 female) survived, whereas 16 patients (7 male/9 female, 48.48%) died from paraquat poisoning. Alanine aminotransferase (ALT) and the blood urea nitrogen (BUN) represent liver and kidney function parameters, respectively. The ratio of urine-to-plasma paraquat is negatively correlated with ALT (r = -0.94, P = 0 .02) and BUN (r = -0.82, P = 0.03). For receiver operating characteristic curve (ROC) analysis, ALT, BUN and urine-to-plasma paraquat have an AUC over 0.80. The study shows that the functional indexes of liver and kidney, as well as the ratio of urine-to-plasma paraquat, could be considered for evaluating the extent of organ injury and excretion rate of paraquat.

Simultaneous determination of paraquat and diquat in human plasma by HPLC-DAD: Its application in acute poisoning patients induced by these two herbicides.

BACKGROUND: Paraquat and diquat are widely used in agricultural production in many countries, which are very toxic to human beings. Paraquat can be detected in some diquat solution sold in the market. The blood concentration of paraquat or diquat is an important indicator for clinical diagnosis of paraquat or diquat poisoning. So, it is very meaningful to develop a method for simultaneous determination of paraquat and diquat in human plasma. OBJECTIVE: To develop and validate a HPLC-DAD method for simultaneous determination of paraquat and diquat in human plasma and to apply it in the acute poisoning patients by these two herbicides. METHODS: Paraquat and diquat were simultaneously determined by HPLC-DAD. The plasma was treated using Waters OASIS® Column and then separated on a Thermo Hypersil GOLD (250 × 4.6 mm, 5 µm) Column with the mobile phase consisted of 75 mmol/L sodium heptane sulfonate (containing 0.1 mol/L phosphoric acid, pH 3.0) and acetonitrile (87:13, v:v) at a flow rate of 1.0 mL/min. The full-wavelength scanning was 200-400 nm, and the detection wavelength of paraquat and diquat was 257nm and 310nm, respectively. 120 and 30 plasma samples from patients with paraquat and diquat poisoning were collected and analyzed by the established method. RESULTS: The standard curve for paraquat and diquat ranged from 0.05 to 20 µg/mL, and the precision of LLOQ for paraquat was 16.49%, which was required to be less than 20%. The precision of other concentrations was less than 14.14%. The recovery of paraquat and diquat was 95.38%-103.97% and 94.79%-98.40%, respectively. The results showed that paraquat and diquat were stable under various storage conditions. 120 plasma samples of paraquat poisoning patients and 30 plasma samples of diquat poisoning patients were determined by the established method. The blood concentration of paraquat ranged from 0.10 to 20.62 µg/mL, with an average of 3.61 µg/mL, while for diquat, the concentration ranged from 0 to 26.59 µg/mL, with an average of 2.00 µg/mL. Among the diquat suspected poisoning samples, 5 samples were detected not only diquat but also paraquat, and 2 samples were detected only paraquat, no diquat. CONCLUSION: The HPLC-DAD method established in this study was high throughput, high sensitivity, simple operation, and wide linear ranges. It can be used for the screening analysis and quantitative detection of paraquat and diquat in acute poisoning patients, which can provide basis for the treatment and prognosis of these two herbicides poisoning patients.

Comparison of severity index and plasma paraquat concentration for predicting survival after paraquat poisoning: A meta-analysis.

BACKGROUND: Severity index and plasma paraquat (PQ) concentration can predict the prognosis of patients with PQ poisoning. However, the better parameter is yet to be systematically investigated and determined. Thus, we conduct this systematic review and meta-analysis to investigate the prognostic value of severity index and plasma PQ concentration in patients with PQ poisoning. METHODS: We searched PubMed, Embase, Web of Science, ScienceDirect, and Cochrane Library to identify all relevant papers that were published up to March 2019. All diagnostic studies that compared severity index and plasma PQ concentration to predict mortality in patients with PQ poisoning were enrolled in this meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) for individual trials were pooled using a random-effect model. We also aggregated heterogeneity testing, sensitivity analysis, and publication bias analysis. RESULTS: Ultimately, seven studies involving 821 patients were included. The pooled OR with a 95% CI of severity index was 24.12 (95% CI: 9.34-62.34, P < .001), with an area under the curve of 0.88 (95% CI: 0.85-0.90), sensitivity of 0.84 (95% CI: 0.74-0.91), and specificity of 0.81 (95% CI: 0.75-0.87). Meanwhile, the pooled OR with 95% CI of plasma PQ concentration was 34.39 (95% CI: 14.69-80.56, P < .001), with an area under the curve of 0.94 (95% CI: 0.91-0.96), sensitivity of 0.86 (95% CI: 0.75-0.93), and specificity of 0.89 (95% CI: 0.76-0.95). Sensitivity analysis demonstrated the stability of the results of our meta-analysis. No significant publication bias was observed in this meta-analysis. CONCLUSION: Overall, this study indicated that severity index and plasma PQ concentration have relatively high-prognostic value in patients with PQ poisoning, and that the sensitivity and specificity of plasma PQ concentration are superior to those of severity index.

Micelle-dominated distribution strategy for non-matrix matched calibration without an internal standard: "Extract-and-shoot" approach for analyzing hydrophilic targets in blood and cell samples.

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 (R2 = 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).

Correlation between neutrophil gelatinase-associated lipocalin and soluble CD14 subtype on the prognosis evaluation of acute paraquat poisoning patients.

OBJECTIVE: The objective of this article is to study the correlation between neutrophil gelatinase-associated lipocalin (NGAL) and soluble CD14 subtype (presepsin) on the severity and prognosis evaluation of acute paraquat poisoning (APP) patients. MATERIALS AND METHODS: We studied 120 APP patients who were divided into three groups: light (28 cases), moderate (52 cases), and heavy poisoning (40 cases) groups. Twenty healthy volunteers were enrolled as controls. RESULTS: Acute kidney injury (AKI) occurred in 86 APP patients (71.7%, 86 of 120). In AKI group, urine NGAL was elevated 3 h after treatment, serum NGAL was elevated 24 h after treatment, and serum creatine (SCr) was elevated 2 days after treatment, which were all significantly higher than non-AKI group. Compared with control group, there were significant differences in presepsin and acute physiology and chronic health status (APACHE) II score of different poisoning groups. There were significant differences in detection indices 24 h, 3 days, and 7 days after treatment among different poisoning groups. There was a positive correlation between urine NGAL and serum paraquat concentration, urine NGAL, and AKI morbidity (r 1 = 0.974, r 2 = 0.766, p < 0.001), suggesting higher urine NGAL level indicated higher AKI morbidity. Receiver operating characteristic curves analysis suggested serum presepsin level and urine NGAL level had higher sensitivity and specificity than APACHE II score when predicting 28-day mortality of APP patients. CONCLUSION: Serum and urine NGAL level is elevated earlier than SCr, which is important for the early diagnosis of APP. Serum presepsin and urine NGAL levels can be used as markers to diagnose the severity of AKI and predict the mortality of APP patients.

[Simultaneous determination of paraquat and diquat in plasma and urine by ion chromatography-triple quadrupole mass spectrometry].

Paraquat (PQ) and diquat (DQ) are widely used as non-selective contact herbicides. Several cases involving accidents, suicide, and homicide by PQ or DQ poisoning have been reported. Poising by PQ, which is mainly concentrated in the lungs, causes acute respiratory distress syndrome and leads to multiple organ toxicity. The toxic effects of DQ are similar to those of PQ but relatively less intense. The mortality rates in PQ and DQ poisoning are high. Simultaneous monitoring of the PQ and DQ concentrations in plasma and urine can provide valuable information for early clinical diagnosis and prognosis. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) is the main analytical method used to detect PQ and DQ in plasma and urine. As both these compounds are highly polar and water soluble, they cannot be retained effectively on a reversed-phase column with conventional mobile phases. The separation of PQ and DQ by ion-pair chromatography or hydrophilic chromatography has been reported. The use of an ion-pairing reagent helps in improving the retention capabilities of PQ and DQ. However, the sensitivity of MS detection is noticeably decreased because of ion suppression caused by the ion-pairing reagent in the mobile phase; furthermore, ion-pairing reagents may contaminate the MS system. The separation of PQ and DQ by hydrophilic chromatography is easily affected by matrix components in the sample, and their retention times are not stable. Considering PQ and DQ are bicharged cation species in solution, they are more suitable for separation by cation-exchange chromatography. A method based on ion chromatography-triple quadrupole mass spectrometry was established for the determination of PQ and DQ in plasma and urine. The plasma and urine samples were diluted with water, and then purified on a solid-phase extraction column containing a polymer-reversed phase and weak ion-exchange mixed-mode adsorbent (Oasis WCX). PQ and DQ were separated on an IonPac CS 18 analytical column (250 mm×2.0 mm, 6.0 µm) with gradient elution using a methylsulfonic acid solution electrolytically generated from an on-line eluent generation cartridge. An in-line suppressor was used to remove methylsulfonate and other anions from the eluent before the eluent entered the mass spectrometer. Between the suppressor and the ion source in MS, the addition of 3% (v/v) formic acid in acetonitrile as an organic modifier (using an auxiliary pump and a T-piece) aided desolvation in the ion source, resulted in a one-or two-fold improvement of the response, and eliminated the residual effects of the adsorption of PQ and DQ caused by ion source. The analytes were detected by triple quadrupole tandem mass spectrometry using positive electrospray ionization in the multiple reaction monitoring (MRM) mode. PQ-d8 and DQ-d4 were used as internal standards. The calibration curves for PQ and DQ showed good linear relationships in the ranges of 1.0-150 µg/L and 0.5-75 µg/L, respectively, and the correlation coefficients were > 0.999. The average matrix effects of PQ and DQ in plasma were 84.2%-89.3% and 84.7%-91.1%, while the average matrix effects of PQ and DQ in urine were 50.3%-58.4% and 51.9%-59.4%. The average recoveries of PQ and DQ in plasma were 93.5%-117% and 91.7%-112%, respectively, with relative standard deviations (RSDs) of 3.4-16.7% and 2.8%-13.2%, and that in urine were 90.0%-118% and 99.2%-116%, with relative standard deviations of 5.6%-14.9% and 2.4%-17.3% (n=6). The limits of detection of PQ and DQ in plasma and urine were 0.3 µg/L and 0.2 µg/L, respectively, with the corresponding limits of quantification being 1.0 µg/L and 0.5 µg/L. This method is sensitive and accurate, and it can be used to determine PQ and DQ for clinical diagnosis and prognosis in patients.

Identify the Early Predictor of Mortality in Patients with Acute Paraquat Poisoning.

BACKGROUND: Paraquat is a widely used nonselective and fast-acting contact herbicide worldwide. This study identified the early predictor of mortality in patients with acute paraquat poisoning. METHODS: Twenty-nine patients with acute paraquat poisoning admitted at Nanjing Drum Tower Hospital from January 2018 to August 2020 were included in this study. The early predictor of mortality in patients with acute paraquat poisoning based on the blood tests was identified by correlation, logistic regression, and receiver operating characteristic (ROC) analyses. RESULT: 15 of the 29 patients died after poisoning. Compared to the survivors, the neutrophilic granulocyte ratio, leukocyte count, ALB, and Crea of the nonsurvivors were significantly higher with p value < 0.05, while the lymphocyte ratio and eGFR(MDRD) of the nonsurvivors were remarkably lower with p value < 0.01. Moreover, the neutrophil-to-lymphocyte ratio (NLR) was remarkably upregulated in the nonsurvivors. The area under the ROC curve (AUC) of the neutrophilic granulocyte ratio, lymphocyte ratio, leukocyte count, ALB, Crea, eGFR(MDRD), and NLR to predict the mortality in patients with acute paraquat poisoning was 0.8905 (95% CI: 0.7589-1.022), 0.8643 (95% CI: 0.7244-1.004), 0.8500 (95% CI: 0.7133-0.9867), 0.7286 (95% CI: 0.5338-0.9233), 0.8167 (95% CI: 0.6620-0.9713), 0.8714 (95% CI: 0.7330-1.010), and 0.8667 (95% CI: 0.7277-1.006), respectively. More interestingly, we also evaluated the diagnostic values of the different combinations of six blood test biomarkers by logistic regression analysis. According to the results of the logistic regression analysis, the AUCs for the combination of the neutrophilic granulocyte ratio, leukocyte count, and eGFR(MDRD) were the largest with 0.986 (95% CI: 0.952-1), and the sensitivity and specificity were 100% and 100%. CONCLUSION: This study demonstrated that the combination of the neutrophilic granulocyte ratio, leukocyte count, and eGFR(MDRD) could serve as an ideal early predictor of mortality in patients with acute paraquat poisoning. However, further research is needed to draw a clear conclusion.

A fast paraquat quantitation method in human serum using probe electrospray ionization-tandem mass spectrometry for emergency settings.

INTRODUCTION: Paraquat (PQ) is one of the most toxic herbicides to humans. However, it is still in use in many countries, including Japan, and many incidents, such as homicides, intentional ingestions, and occupational accidents, have been reported thus far. In PQ poisoning cases, it is possible to predict severity and prognosis using nomograms. Therefore, if the serum PQ level is determined immediately, a treatment plan can be rapidly established. However, most known analytical methods are time-consuming and therefore hardly ever contribute to patient treatment. METHODS: We developed a new method for PQ quantitation in serum by combining a probe electrospray ionization technique with mass spectrometry. This method requires virtually no serum pretreatment and can yield quantitation values in 18 s. RESULTS: We applied the proposed method to samples from real poisoning cases and compared the results with those obtained via liquid-chromatography-tandem mass spectrometry, revealing the absence of any significant differences at the 5% significance level (t(8) = 1.000, p > .05). The limits of detection and quantitation were 0.004 and 0.015 µg/L, respectively, and the calibration curve exhibited good linearity over the concentration range of 0.015-4.0 µg/mL (r2 = 0.998). DISCUSSION: As the proposed method is fast and easy to perform, it should be useful in emergency medical settings.

Metabolitic profiling of amino acids in paraquat-induced acute kidney injury.

BACKGROUND: The herbicide paraquat (1, 1'-dimethyl-4, 4'-bipyridylium dichloride; PQ) is a poison well-known to cause delayed mortality due to acute kidney injuries (AKI). This study examines the changes in serum amino acids (AAs) metabolite profiles as surrogate markers of renal cell metabolism and function after paraquat poisoning. METHODS: To identify the metabolic profiling of free serum AAs and its metabolites, serum from 40 paraquat-poisoned patients with or without AKI is collected. LC-MS/GC-MS is performed to analyze AA molecules. A Cox proportional hazard model was used to assess for incidence of AKI. Receiver operating characteristic (ROC) curve is applied to evaluate AKI occurrence and prognosis. RESULTS: A total of 102 serum AAs and its metabolites were identified. Compared with non-AKI patients, 37 varied significantly in AKI patients. The univariate Cox proportional hazard model analysis revealed that the estimated PQ amount, plasma PQ concentration, urine PQ concentration, APACHE, SOFA scores and 16 amino acids correlated with the incidence of AKI. Further analyses revealed that 3-methylglutarylcarnitine, 1-methylimidazoleacetate, and urea showed higher cumulative hazard ratios for the occurrence of AKI during follow-up (P < 0.05). The area under the curve (AUC) of 3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were 0.917, 0.857, 0.872, respectively. CONCLUSION: 3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were associated with AKI in patients with paraquat intoxication.

Metabolomics Analysis in Acute Paraquat Poisoning Patients Based on UPLC-Q-TOF-MS and Machine Learning Approach.

Most paraquat (PQ) poisoned patients died from acute multiple organ failure (MOF) such as lung, kidney, and heart. However, the exact mechanism of intoxication is still unclear. In order to find out the initial toxic mechanism of PQ poisoning, a blood metabolomics study based on ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and efficient machine learning approach was performed on 23 PQ poisoned patients and 29 healthy subjects. The initial PQ plasma concentrations of PQ poisoned patients were >1000 ng/mL, and the blood samples were collected at before first hemoperfusion (HP), after first HP, and after last HP. The results showed that PQ poisoned patients all differed from healthy subjects, whatever they were before or after first HP or after last HP. The efficient machine learning approaches selected key metabolites from three UPLC/Q-TOF-MS data sets which had the highest classification performance in terms of classification accuracy, Matthews Correlation Coefficients, sensitivity, and specificity, respectively. The mass identification revealed that the most important metabolite was adenosine, which sustained in low level, regardless of whether PQ poisoned patients received HP treatment. In conclusion, decreased adenosine was the most important metabolite in PQ poisoned patients. The metabolic disturbance caused by PQ poisoning cannot be improved by HP treatment even the PQ was cleared from the blood.

[Determination of paraquat in serum by ultra performance liquid chromatography tandem mass spectrometry and toxicokinetics of paraquat in rat].

OBJECTIVE: To establish a simple and rapid ultra-performance liquid chromatography tandem mass spectrometry( UPLC-MS/MS) method for the determination of paraquat in serum, and to apply to the toxicokinetics of paraquat in rats. METHODS: The samples separated on ACQUITY UPLC BEH HILIC column( 2. 1 mm × 50 mm, 1. 7 µm)with acetonitrile-50 mmol/L ammonium formate( 0. 4% formic acid) as mobile phase. The analytes were analyzed using ESI operating in the positive multiple reaction monitoring( MRM) mode. The method was used in toxicokinetic study in poisoned rat. Toxicokinetic parameters were calculated by WinNonlin 7. 0 statistical software. RESULTS: Paraquat was linear in the range of 0. 3-1000. 0 µg/L, the recovery rate was 89. 0%-107. 7%, and the relative standard deviation( RSD) 1. 9%-13. 8%( n = 6). Toxicokinetic parameterswere as follows: C_(max), T_(max)and T_(1/2) were( 46. 50 ± 5. 11) mg/L, 0. 167 h, ( 63. 2 ±16. 2) h, respectively. CONCLUSION: This method is highly sensitive, high accuracy and is suitable for the analysis of paraquat in the toxicokinetic study in rats.

Pneumomediastinum caused by occult paraquat poisoning: Case report.

RATIONALE: Paraquat is a widely applied contact herbicide that is highly poisonous. About 20% of patients with paraquat poisoning develop pneumomediastinum as a complication with a mortality rate of almost 100%. PATIENT CONCERNS: A 15-year-old boy presented with a 1-month history of retrosternal chest pain with no obvious cause. High-resolution computed tomography showed pneumomediastinum. DIAGNOSES: After all likely causes of pneumomediastinum were eliminated, the diagnosis of occult paraquat poisoning was made when serum paraquat concentration was revealed at 467.40 ng/mL, despite the patient's denial of ingestion or contact. INTERVENTIONS: Hemoperfusion, intravenous glucocorticoid, and ulinastatin was administered for 3 days with other routine treatment against paraquat poisoning. The serum paraquat concentration decreased to zero. OUTCOMES: Despite the general high mortality and poor prognosis of paraquat poisoning, the patient recovered and was completely asymptomatic at his 3-month follow-up. LESSONS: Paraquat poisoning should be suspected as a differential diagnosis when patients present with pneumomediastinum without recognizable cause.

A survival case of intravenous paraquat intoxication: A case report.

RATIONALE: Paraquat, an agent highly toxic to humans and animals, is a widely used herbicide and also commonly used for suicide attempts in Taiwan. The most common route of intoxication is oral ingestion, and parenteral poisoning is respectively rare. PATIENT CONCERNS: A 39-year-old illicit abuser of heroin and amphetamine injected 0.5 mL of 24% paraquat directly into his right cephalic vein due to hallucination. The patient was brought to our emergency department for management 4 hours after injection. He was fully conscious and had normal vital signs. Systemic review showed mild dyspnea, abdominal pain and right wrist pain over the injection site. The only abnormal physical finding was erythema over the injection site and epigastric tenderness. DIAGNOSIS: Laboratory investigations, including complete blood count, liver and renal function, and electrolytes initially yielded normal results. Urinalysis showed normal findings except a positive urine paraquat test (4+). The initial plasma paraquat concentration was 0.51 µg/mL. INTERVENTIONS: He was admitted to the intensive care unit and underwent one session of charcoal hemoperfusion therapy. Acute kidney injury developed on the fourth day after intoxication, with the level of serum creatinine rising rapidly from 0.96 to 4.57 mg/dL and the daily urine output decreased noticeably from > 2000 to 900 mL. The serum creatinine level improved gradually with adequate fluid supplementation. OUTCOMES: The patient was discharged 13 days later in a stable condition. LESSONS: Intravenous paraquat intoxication is rare. Patients who suffer from intravenous intoxication may not directly suffer from mucosal irritation, but the clinical onset of systemic effects is more immediate and lethal. The prognosis of paraquat poisoning is determined by the time of poisoning and the plasma paraquat concentration before treatment. Proudfoot's curve provides a simple method of predicting the survival rate. The most effective mode of management is extracorporeal therapy, and immunosuppressive or antioxidant therapies have shown insufficient evidence of benefit.

A novel approach for determination of paraquat based on dried blood spot (DBS) extraction and UHPLC-HRMS analysis.

Paraquat is an effective herbicide chemical but a highly toxic compound for humans and animals. The measurement of paraquat concentration in blood is important to clinic or forensic practice. Herein, a method has been developed for the analysis of paraquat in human blood using dried blood spot (DBS) extraction and subsequent UHPLC-HRMS analysis. Three droplets (100 µL each) of blood were spotted on the Whatman® FTA classic card and then let dry by microwave irradiation (1200 W) for 5 min to prepare DBS. An 8 mm diameter punch was removed from the center of DBS and extracted with 190 µL of mobile phase (20 mM ammonium acetate with 0.1% formic acid and 5% acetonitrile in ultra-pure water) and 10 µL of internal standard (paraquat-d8, 100 ng/mL). After ultrasonic treatment for 10 min, the tube was centrifuged, and the supernatant was then filtered by 0.2 µm membrane and injected into the UHPLC-HRMS system. The method was validated considering the following parameters: selectivity, LOD and LLOQ, linearity, precision, accuracy. The method showed satisfactory linearity in the range of 1-1000 ng/mL, with high determination coefficient (0.9986). LOD was 0.5 ng/mL, and LLOQ was 1 ng/mL. Selectivity, intra and inter day precision and accuracy were acceptable. The validated method was then applied to authentic blood samples and has proved to be a simple, fast and reliable procedure for the determination of paraquat in blood.