Fatal poisoning of four workers in a farm: Distribution of hydrogen sulfide and thiosulfate in 10 different biological matrices

GC/MS-based quantitative analysis of sulfide ion in whole blood using ethenesulfonyl fluoride as a derivatization reagent

PURPOSE

Identification and quantification of sulfide ion in biological samples are required in forensic purpose. Gas chromatography-mass spectrometry (GC/MS) has been used for the analysis of sulfide ion by using derivatization reagents. However, conventional derivatization reagents require special attention for derivatization. To simplify the derivatization protocol, we examined ethenesulfonyl fluoride (ESF) as a derivatizing reagent of sulfide ion.

METHODS

To 100 μL of whole blood sample containing sulfide ion, 100 μL of boric acid buffer (pH 8.0), 100 μL of acetone solution containing internal standard, 100 μL of acetone solution containing 600 mM concentration of ESF, and 100 μL of hexane were added in a 1.5-mL plastic tube. The mixture was vortexed at room temperature, the tubes were centrifuged, and the organic layer was injected into the GC/MS.

RESULTS

ESF exhibited higher reactivity toward sulfide ion than interfering compounds present in whole blood, allowing for selective derivatization. With the optimized protocol, the detection limit for sulfide ion was 0.01 μg/mL. The calibration curve showed good linearity (R2 = 0.9999) in the range of 0.05-10.0 μg/mL, and the precision (% relative standard deviation) and the accuracy (% bias) were within ± 10% (intra- and inter-day).

CONCLUSION

This GC/MS-based method is a valuable tool for forensic investigations and various analytical fields, offering reliable quantification of sulfide ion in whole blood.

Influence of blood thiosulfate produced by postmortem changes for the diagnosis of hydrogen sulfide poisoning in forensic autopsy

Background

Thiosulfate concentration in blood is an important indicator for the diagnosis of hydrogen sulfide poisoning. It may also be detected at high levels in postmortem decomposition cases.

Objectives

To determine the effect of postmortem decomposition on blood thiosulfate concentration and define precautions for diagnosing hydrogen sulfide poisoning based on thiosulfate concentration.

Methods

A total of 57 cadavers (37 males and 20 females) of non-hydrogen sulfide poisoning-related deaths that underwent forensic autopsy in our department between 2016 and 2019 were classified into the non-decomposed (19 cases), partially decomposed (19 cases), and severely decomposed (19 cases) groups based on forensic findings. Blood samples collected from each case were analyzed for thiosulfate concentration using liquid chromatography-tandem mass spectrometry.

Results

The mean concentration of thiosulfate detected in the blood was 70.9 (10.5-266.6) μmol/L in the severely decomposed group, 16.3 (0.1-52.7) μmol/L in the partially decomposed group, and 1.1 (0.1-3.6) μmol/L in the non-decomposed group. There was a statistically significant difference between each of the 3 groups (P < 0.01).

Conclusions

Previous studies have reported a blood thiosulfate concentration of >14 μmol/L in hydrogen sulfide poisoning cases and <4 μmol/L in normal cases. Thus, thiosulfate concentration is believed to have a significant impact on the diagnosis of hydrogen sulfide poisoning. This study revealed that postmortem decomposition produced thiosulfate in the blood, and the concentration of thiosulfate was often as high as that observed in cases of hydrogen sulfide poisoning-related death. In addition to cases of advanced decomposition, an increase in thiosulfate concentration was also observed in cases of partial decomposition. Therefore, when measuring thiosulfate concentration as an indicator of hydrogen sulfide poisoning, it is necessary to carefully consider the influence of decomposition.

A serial analysis of hydrogen sulfide poisoning: three group accidents

Hydrogen sulfide (H2S) is a powerful toxic gas in workplace incidents, and it poses a threat to colleagues or family members involved in rescues, leading to a "domino effect" of multiple deaths. In this report, we describe three incidents in which 10 people died, and we present the results of the analyses performed in different incidents, including paper pulp pit, sewer, and sewage well. We provide the macroscopic and morphological findings of ten victims, which include conjunctival hemorrhage, corneal erosion, pulmonary edema, and pulmonary hemorrhage. Additionally, we observed large amounts of waste paper pulp or black sludge in the upper and lower respiratory tracts or upper and lower gastrointestinal tracts of six victims. Furthermore, we conducted a toxicological examination of the victims' blood sulfide using an alkylation extraction approach combined with gas chromatography/mass spectrometry. The sulfide concentrations in the 10 victims ranged from 0.06 to 6.72 mg/L.

Variability in Background Urinary Concentrations of the Hydrogen Sulfide Biomarker Thiosulfate

Hydrogen sulfide is a toxic gas at high concentrations but has recently attracted attention as a naturally produced gaseous signaling molecule in various tissues of the human body, playing key physiological roles at low nanomolar concentrations. This has wide implications for chronic exposure to this gas in air at low levels far below toxicity. Thiosulfate is the currently used biomarker for exposure to hydrogen sulfide via inhalation but has been mainly employed for acute exposure. It is unknown how background thiosulfate concentrations vary on an intraindividual and interindividual basis in humans at normal ambient hydrogen sulfide levels (<1 μg m^-3), which is key for the interpretation of its levels as biomarker for low-level hydrogen sulfide exposure. In the current work, the variability in thiosulfate urinary excretion in a total of 168 urine samples collected from eight volunteers over a period of 8 weeks was investigated. The determination of thiosulfate in urine was carried out by UHPLC-MS/MS. The total average concentration ± SD was 16 ± 6 μM (n = 168). Average urinary thiosulfate concentrations in the studied volunteers were within the range of 10-20 μM, but it was found that urinary thiosulfate can show significant day-to-day and week-to-week variability in some individuals (up to 10-fold), despite adjusting for urine specific gravity. In light of the presented variability data and previous studies about the lack of consistent response of thiosulfate to low levels of hydrogen sulfide inhalation exposure, and based on a review of the biochemistry of the production of thiosulfate and its various biological sources, it can be argued that thiosulfate might not be suitable as a biomarker for chronic environmental exposure to low levels of hydrogen sulfide via inhalation.

Hydrogen sulfide poisoning in forensic pathology and toxicology: mechanism and metabolites quantification analysis

Historically, hydrogen sulfide (H₂S) poisoning has extremely high and irreparable mortality. Currently, the identification of H₂S poisoning needs to combine with the case scene analysis in forensic medicine. The anatomy of the deceased seldom had obvious features. There are also a few reports about H₂S poisoning in detail. As a result, we give a comprehensive analysis of the related knowledge on the forensic aspect of H₂S poisoning. Furthermore, we provide the analytical methods of H₂S and its metabolite-which may assist in H₂S poisoning identification.

Decomposition kinetics and postmortem production of hydrogen sulfide and its metabolites

BACKGROUND

Hydrogen sulfide (H₂S), an endogenous gas, can also be generated from organics putrefaction. It is difficult for suspected cases of H₂S poisoning to determine whether H₂S in specimens is ingested by antemortem poisoning or generated from organics putrefaction. The aim of this study was to find the biomarkers of acute H₂S poisoning via comparing the concentrations of H₂S and its metabolites over time in specimens.

METHODS

The H₂S-spiked blood and blank blood group were established. The decomposition kinetics and the postmortem production of H₂S were studied due to organics putrefaction. The specimens were placed under 4 conditions of 37, 20, 4 and - 20 ℃. The content of H₂S in specimens was quantified by gas chromatography-mass spectrometry, and the contents of its metabolites (thiosulfate and trimethylsulfonium) were measured by liquid chromatography-mass spectrometry, and the variation of its concentration was evaluated.

RESULTS

In H₂S-spiked blood, H₂S decreased sharply in the initial stage at 37, 20 and 4 °C, and increased first and then decreased later; but it was relatively stable at - 20 °C. In spiked blood, thiosulfate was 9-fold higher than endogenous concentrations, which increased at first and then decreased during storage. Except for thiosulfate at 37 °C, H₂S and thiosulfate in blank blood both increased at first and then decreased in storage; but trimethylsulfonium (TMS) gradually decreased over time in both groups.

CONCLUSIONS

Thiosulfate is a reliable biomarker of acute H₂S poisoning at - 20℃ within 7 days. But H₂S, because of instability and volatility, is not an ideal poisoning marker. TMS is not an appropriate biomarker due to extremely low concentration in blood.