Application of probe electrospray ionization-tandem mass spectrometry to ultra-rapid determination of glufosinate and glyphosate in human serum

Glufosinate and glyphosate, which are non-selective herbicides that include an amino acid moiety in their structures, are frequently used worldwide to control unwanted vegetation. Unfortunately, these readily available herbicides are also used by people to commit suicide, and thus represent important chemicals of interest in the fields of clinical medicine and forensics. Because of the high water solubility of these herbicides, most analytical methods for their detection require a derivatization step, which results in longer analysis times. Therefore, derivatization-based methods do not currently contribute to judgements on treatment decisions in emergency medicine. In this study, we addressed this limiting factor by developing an ultra-rapid and simple analytical technique using a combination of probe electrospray ionization (PESI) and tandem mass spectrometry (MS/MS), which gives quantitative results within 0.3 min. Herbicide standards were added to human serum that was then subjected to analysis (N = 5 per concentration). The analysis was repeated daily over eight consecutive days. The limit of detection (LOD) was 0.59 μg/mL for glufosinate and 0.20 μg/mL for glyphosate. The limit of quantitation (LOQ), i.e., the lowest point on the calibration curves, was 1.56 μg/mL for both the herbicides. The matrix effects were observed at three different concentrations (between 95.7%-104% for glufosinate, and between 90.7%-95.7% for glyphosate). When applied to samples taken from actual poisoning cases (six samples for each herbicide), the present method gave almost the same quantitative values as those obtained by conventional high-performance liquid chromatography with fluorescence detection. Thus, we believe that PESI-MS/MS could emerge as a rapid diagnosis method in the clinical emergency field.

Serum S100 protein could predict altered consciousness in glyphosate or glufosinate poisoning patients

BACKGROUND

Central nervous system (CNS) complications such as seizures and reduced consciousness are important in glufosinate and may occur in severe glyphosate poisoning. The aim of this study was to assess the possible role of serum S100B protein as a biochemical marker of CNS complications associated with glyphosate or glufosinate poisoning.

METHODS

The study enrolled 40 patients (23 glyphosate poisoning and 17 glufosinate poisoning). Altered consciousness and seizure were observed during hospitalization. S100B level was measured with fully automated modular analytic E170 system using electrochemoluminometric immunoassay.

RESULTS

Among 40 patients, neurologic features were observed in 12 patients with a median time to onset of 21.5 (IQR 8.25-24.75) h. Serum S100B concentrations measured on admission were higher in the group with neurologic features than in the group without neurologic features [0.148 μg/L (IQR 0.128-0.248) vs. 0.072 μg/L (IQR 0.047-0.084), p < .001]. Univariate analysis of measured patient raw parameters using a ROC curve showed that S100B was a significant predictor of neurologic features in glyphosate and glufosinate poisoning. The area under the ROC curve was 0.894 (95% confidential interval 0.791-0.998). When S100B was set at 0.0965, its sensitivity and specificity for predicting neurologic features in glyphosate and glufosinate poisoning were 92% and 82%, respectively.

CONCLUSIONS

In our pilot study, S100B was a significant predictor of neurologic complications in patients with glyphosate and glufosinate poisoning. Large prospective cohorts are needed to confirm this finding.

Initial Serum Ammonia as a Predictor of Neurologic Complications in Patients with Acute Glufosinate Poisoning

PURPOSE

Glufosinate poisoning can cause neurologic complications that may be difficult to treat due to delayed manifestation. Studies assessing possible predictors of complications are lacking. Although serum ammonia level is a potential predictor of severe neurotoxicity, it has only been assessed via case reports. Therefore, we investigated factors that predict neurologic complications in acute glufosinate-poisoned patients.

MATERIALS AND METHODS

We conducted a retrospective review of 45 consecutive glufosinate-poisoning cases that were diagnosed in the emergency department (ED) of Wonju Severance Christian Hospital between May 2007 and July 2014. Patients with a Glasgow Coma Scale (GCS) score of <8, seizure, and/or amnesia were defined to a neurologic complication group.

RESULTS

The neurologic complication group (29 patients, 64.4%) comprised patients with GCS<8 (27 patients, 60.0%), seizure (23 patients, 51.1%), and amnesia (5 patients, 11.1%). Non-neurologic complications included respiratory failure (14 patients, 31.1%), intubation and ventilator care (23 patients, 51.1%), shock (2 patients, 4.4%), pneumonia (16 patients, 35.6%), acute kidney injury (10 patients, 22.2%), and death (4 patients, 8.9%). Complications of GCS<8, seizure, respiratory failure, and intubation and ventilator care appeared during latent periods within 11 hrs, 34 hrs, 14 hrs, and 48 hrs, respectively. Initial serum ammonia was a predictor of neurologic complications [odds ratio 1.039, 95% confidence interval (1.001-1.078), p=0.046 and area under the curve 0.742].

CONCLUSION

Neurologic complications developed in 64.4% of patients with acute glufosinate poisoning. The most common complication was GCS<8. Initial serum ammonia level, which can be readily assessed in the ED, was a predictor of neurologic complications.

Glufosinate herbicide intoxication causing unconsciousness, convulsion, and 6th cranial nerve palsy

Although glufosinate ammonium herbicides are considered safe when used properly, ingestion of the undiluted form can cause grave outcomes. Recently, we treated a 34-yr-old man who ingested glufosinate ammonium herbicide. In the course of treatment, the patient developed apnea, mental deterioration, and sixth cranial nerve palsy; he has since been discharged with full recovery after intensive care. This case report describes the clinical features of glufosinate intoxication with a focus on sixth cranial nerve palsy. Our observation suggests that neurologic manifestations after ingestion of a "low-grade toxicity herbicide" are variable and more complex than that was previously considered.

Determination of glyphosate, glyphosate metabolites, and glufosinate in human serum by gas chromatography-mass spectrometry

This paper describes an assay for the determination of glyphosate (GLYP), glyphosate metabolites [(aminomethyl) phosphonic acid] (AMPA), and glufosinate (GLUF) in human serum. After protein precipitation using acetonitrile and solid-phase extraction, serum samples were derivatized and analyzed by gas chromatography-mass spectrometry (GC-MS). The assay was linear over a concentration range of 3-100.0 microg/ml for GLYP, AMPA, and GLUF. The overall recoveries for the three compounds were >73%. The intra- and inter-day variations were <15%. Precision and accuracy were 6.4-10.6% and 88.2-103.7%, respectively. The validated method was applied to quantify the GLYP and AMPA content in the serum of a GLYP-poisoned patient. In conclusion, the method was successfully applied for the determination of GLYP and its metabolite AMPA in serum obtained from patient of GLYP-poisoning.

Toxicokinetics of DL-glufosinate enantiomer in human BASTA poisoning

We found that glufosinate (DL-GLUF) was distributed in the spinal fluid in glufosinate poisoning. A 50-year old Japanese man (weighing 67 kg) attempted to commit suicide by ingesting about 100 ml of BASTA (containing DL-GLUF 18.5 g; ratio of D-GLUF to L-GLUF: 1 : 1). He was transported to our hospital, where serious respiratory depression was seen 26 h after ingestion, and management with artificial ventilation was initiated. The D-GLUF concentration 1 h after ingestion was 191.1 microg/ml, almost the same as that of L-GLUF 193.5 microg/ml, but by 3 h after ingestion, these levels had sunk to 60.3 microg/ml and 52.3 microg/ml, respectively, with the concentration of L-GLUF lower than that of D-GLUF. Later, at 27 and 35 h after ingestion, the D-GLUF level was still higher than the L-GLUF level, and the total amounts of urinary excretion were 2835 mg for D-GLUF and 2298 mg for L-GLUF, each variable thus showing a difference between the enantiomers. Cerebrospinal fluid taken from the patient 27 h after poison ingestion revealed the presence of DL-GLUF on CG-MS analysis, and quantitative HPLC analysis of the enantiomers indicated that the D-GLUF concentration was 0.48 microg/ml, and the L-GLUF concentration 0.12 microg/ml. The levels in blood collected at the same time were: D-GLUF, 1.44 microg/ml, and L-GLUF, 0.35 microg/ml. Also, the cerebrospinal fluid contained about one-third of the blood levels of both DL-GLUF enantiomers. He was discharged without any sequelae after 11 d of hospitalization.

Determination of glufosinate ammonium and its metabolite, 3-methylphosphinicopropionic acid, in human serum by gas chromatography-mass spectrometry following mixed-mode solid-phase extraction and t-BDMS derivatization

A method for the analysis of glufosinate ammonium (GLUF) and its metabolite 3-methylphosphinicopropionic acid (MPPA) in human serum by gas chromatography-mass spectrometry (GC-MS) was developed. Employing a mixed-mode cartridge with both anion exchange action and weak nonpolar interaction, we extracted GLUF and MPPA from the serum and carried out GC-MS analysis of their tert-butyldimethylsilyl derivatives. The detection limits of GLUF and MPPA were 10 pg and 1 pg, respectively. Full mass spectra of 100 pg GLUF and of 10 pg MPPA were easily obtainable. The recovery rate of 90.0+/-11.9% (or better) when the serum concentrations of GLUF and MPPA were 10-0.1 microg/mL. Results of 23 serum samples, from patients with GLUF poisoning, measured by this method correlate well with those derived from the conventional high-performance liquid chromatography method (r = 0.996). The developed GC-MS method is likely to become a useful analytical technique in clinical settings.

A case of transient diabetes insipidus associated with poisoning by a herbicide containing glufosinate

BACKGROUND

The herbicide BASTA (AgrEvo, Germany), containing glufosinate ammonium (20%) and an anionic surfactant, polyoxyethylene alkylether sulfate (33%), is widely used. In acute oral BASTA poisoning, patients develop a variety of clinical signs, including disturbed consciousness, convulsions, and apnea. These effects are suspected to be due to the effects of glufosinate on the central nervous system.

CASE REPORT

A 60-year-old man ingested 500 mL of BASTA herbicide in a suicide attempt. He developed not only unconsciousness, respiratory distress, and convulsions but also an increase in urine output (7885 mL/d), elevated serum sodium (167 mEq/L), elevated plasma osmolality (332 mOsm/kg), and a decrease in both urine osmolality (200 mOsm/kg) and urine specific gravity (1.003), which suggested the development of diabetes insipidus. The plasma level of antidiuretic hormone remained within the normal range (1.3 pg/mL), despite high plasma osmolality. The administration of desmopressin was successful in normalizing urine volume, specific gravity, and osmolality. Serum sodium corrected gradually within 48 hours. The possible mechanisms causing the diabetes insipidus are discussed.

A toxicokinetic analysis in a patient with acute glufosinate poisoning

Incidents of poisoning in humans caused by the ingestion of the glufosinate ammonium containing herbicides are gradually increasing in Japan. This poisoning is characterized by various neurological symptoms such as disturbances of consciousness, convulsions and apnea which appear after an asymptomatic interval of several hours. We studied the toxicokinetics of glufosinate in a patient with this poisoning successfully treated without extracorporeal hemopurification. A 65-year-old male ingested BASTA, which contains 20% w/v of glufosinate ammonium, about 300 ml, more than the estimated human toxic dose. Four and a half hours after ingestion, he showed speech ataxia and systemic tremor. He was prophylactically intubated before the occurrence of serious respiratory failure. After 5 days of artificial ventilation he was extubated and discharged without any sequelae. We studied the serial change of serum glufosinate concentration every 3-6 h and assessed the urinary excretion of glufosinate every 24 h. The absorbed amount of glufosinate was estimated from the cumulative excreted in urine. Toxicokinetic analysis was performed using the two-compartment model. The changes in serum glufosinate concentration exhibited T1/2alpha of 1.84 and T1/2beta of 9.59 h. The apparent distribution volume at beta-phase and the total body clearance were 1.44 l/kg and 86.6 ml/min, respectively. Renal clearance was estimated to be 77.9 ml/min. The indication for extracorporeal hemopurification for this poisoning has been discussed.

Two cases of glufosinate poisoning with late onset convulsions

Glufosinate ammonium (GLA), the active ingredient in the non-selective herbicide BASTA (18.5% GLA), is a phosphinic acid analogue of glutamic acid. We report 2 cases of GLA poisoning with late onset convulsions and increased serum CK in spite of low blood concentrations of GLA after hemodialysis. A 69-y-old female was admitted to the emergency department after taking 500 ml of BASTA. On arrival she was conscious, and gut decontamination, hemodialysis and hemoperfusion were performed. However, 8 1/2 hours after ingestion, general convulsions occurred. Her serum OK increased to a peak of 24,900 IU/L on the third day of admission. An 87-y-old male was admitted to the emergency department 3 1/2 hours after taking 200 ml of BASTA and receiving gastric lavage at a local emergency room. On arrival he was conscious, and serial activated charcoal and hemodialysis was performed. Blood concentration of GLA after hemodialysis decreased from 1.56 micrograms/ml to 0.68 micrograms/ml. Thirty hours after admission he had general convulsions. GLA was not detected in the cerebrospinal fluid 6 h after the convulsions. His serum CK increased to a peak of 17,870 IU/L on the fifth day of admission.

Neurological effects of glufosinate poisoning with a brief review

Herbicides containing glufosinate ammonium are widely used in many countries including Japan. Many Japanese cases of accidental and suicidal poisoning by glufosinate have been reported since 1989. We report a case of a 64-year old man who ingested glufosinate in an attempted suicide. The patient suffered mental disturbances and hematological changes together with gastrointestinal effects shortly after ingesting the poison, and later developed generalized convulsions, impaired respiration and circulatory failure. During recovery he exhibited loss of short-term memory (retrograde and anterograde amnesia). Neurotoxicity is a characteristic of glufosinate poisoning, although the mechanism is not clear. From the analysis of clinical symptoms of previously published cases, glufosinate toxicity appears to arise both from the active ingredient and the surfactant in the formulation.

Delayed and severe toxicities of a herbicide containing glufosinate and a surfactant

We report a case of a 59-y-old woman who ingested a herbicide containing glufosinate. Though suffering from severe toxicity of this herbicide, she did not develop convulsions, which experimentally occurs in rats treated with glufosinate. The mechanisms of convulsions are not clear. Several clinical findings in poisoning by this herbicide are suspected to be caused by the surfactant components.

Overdose of lioresal

This is the first reported case of a major overdose of Lioresal (baclofen or CIBA BA-346467). A 29-year-old woman with known Huntington's disease took from 900 to 970 mg of Lioresal, a cogener of gamma amino butyric acid (GABA) used experimentally to treat muscle spasm. She was admitted in deep coma with absent brain stem reflexes and without spontaneous respiration, and she required cardiovascular support. Her pupils were fixed at 3 mm and unreactive for 48 hours. She continued to require intensive support for a total of 72 hours and had one seizure during the recovery phase. Her eventual recovery was complete. No specific antidotes are currently available for overdose of Lioresal and supportive care is the only method of treatment for overdose.