First GC/MS identification of aqueous ammonia: utilization of ethenesulfonyl fluoride as a selective and rapid derivatization reagent of ammonia in aqueous media.

Identification as well as quantification of ammonia are required in some analytical fields including forensic science. For this purpose, gas chromatography/mass spectrometry (GC/MS) analysis is one of the most suitable techniques. Although ammonia needs to be derivatized for GC/MS analysis, conventional derivatization reagents require anhydrous conditions because they are highly reactive with water. Here, we investigated ethenesulfonyl fluoride (ESF) as a selective reagent for ammonia derivatization in aqueous media to develop a rapid identification method for ammonia in aqueous media. The Michael addition reaction of ammonia with ESF rapidly produced a tri-ESF derivative suitable for GC/MS analysis. We optimized the derivatization reaction conditions and extraction solvent. With the optimized protocol, the detection limit for aqueous ammonia was 0.05 µg mL-1. The calibration curve showed good linearity (R2 = 0.9998) in the range of 0.10-100.0 µg mL-1, and the accuracy (% bias) and the precision (% relative standard deviation) for concentrations of 0.10, 0.25, 10.0, and 75.0 µg mL-1 were within ± 10% (intra- and inter-day). The proposed ESF-based method could quantify ammonia in samples containing interfering nucleophilic substances. This method was successfully applied to ammonia-containing commercial products.

Rapid derivatization of phosphorus-containing amino acid herbicides in plasma and urine using microwave heating.

We developed a derivatization technique that involves microwave heating to reduce the overall forensic analysis time of phosphorus-containing amino acid herbicides (PAAHs). Combined with an extraction method that uses titanium (IV) oxide (TiO2), we were able to obtain a practical analytical method for PAAHs and their metabolites in samples intended for poisoning cases. The optimized derivatization conditions were 700 W power and 5-min irradiation time, which is a significant time-saving. The plasma samples extracted using TiO2-packed Tip columns and derivatized under the optimized conditions had an intra-day accuracy and precision within 9.3% and 9.0%, respectively. The intermediate accuracy and precision were within 8.8% and 8.5%, respectively, and the recoveries were more than 91.2%. Similarly, for urine samples, the intra-day accuracy and precision were within 13.3% and 9.1%, respectively. The intermediate accuracy and precision were within 13.6% and 10.3%, respectively, and finally, the recoveries were more than 88.2%. In addition to reducing the pretreatment time, this method was suitable for reducing the overall labor burden on laboratories responsible for routine analysis because of its stable validation data.

Quantitative Determination of H2 in Human Blood by 22Ne-aided Gas Chromatography-Mass Spectrometry Using a Single Quadrupole Instrument.

Here, we present a quantitative method for H2 detection by gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) using a single quadrupole instrument. Additionally, the developed method was applied to the detection of H2 in human blood by GC-SIM-MS analysis using the existing 22Ne in air as an internal standard (IS). H2 was analyzed by GC-SIM-MS using a single quadrupole instrument with double TC-Molsieve 5A capillary columns for the separation of permanent gases. The detections of H2 (analyte) and 22Ne (IS) were performed at m/z 2 and 22, respectively, by GC-SIM-MS. The analyte and IS were separated using He as the carrier gas. The ratio of the peak area of H2 to 22Ne was employed to obtain a calibration curve for H2 determination in the gas phase. The proposed GC-SIM-MS method exhibited high sensitivity in terms of the limits of detection (LOD) (1.7 ppm) and quantitation (LOQ) (5.8 ppm) for H2 analysis. The developed quantitative assay of H2 in the headspace of blood samples achieved high repeatability with a relative standard deviation (RSD) of 1.4 - 4.7%. We successfully detected and quantified H2 in the headspaces of vacuum blood-collection tubes containing whole blood from 11 deceased individuals with several causes of death by employing the developed GC-SIM-MS method. The quantitative value of H2 ranged from 5 to 905 ppm. The proposed GC-SIM-MS method was applicable to the quantitative assay of H2 in biological samples without tedious pretreatment requirements.

A new and sensitive method for quantitative determination of helium in human blood by gas chromatography-mass spectrometry using naturally existing neon-21 as internal standard.

PURPOSE: In this study, we proposed a new sensitive quantitative method for detecting helium in human blood by gas chromatography-selected-ion monitoring (SIM)-mass spectrometry (GC-SIM-MS) using naturally existing neon-21 in air as internal standard (IS). METHODS: GC-SIM-MS analysis was performed on a double TC-Molsieve 5A capillary column (total length 60 m) for the separation of permanent gases by a single-run experiment. By using hydrogen as the carrier gas, the analyte (helium) and IS (neon-21) were separated on the double column, and detected at m/z 4 and 21, respectively. The ratio of the peak area of helium-to-neon-21 was used for obtaining the calibration curve for helium determination. RESULTS: The limits of detection and quantification of helium under the present GC-SIM-MS conditions were as low as 1.8 and 6.0 ppm, respectively. The proposed GC-SIM-MS method also showed high repeatability with relative standard deviation at 1.3-5.1%, indicating that the use of neon-21 as IS was valid for reliable helium assays. The successful quantification of helium in the headspace of vacuum blood collection tubes containing the whole blood from four humans who died of helium inhalation was achieved using the proposed neon-21-aided GC-SIM-MS method; the values obtained for helium were 24-497 ppm. CONCLUSIONS: The proposed GC-SIM-MS method in combination with the naturally existing neon-21 as IS is most recommendable for quantitative assays of helium in biological samples because of its simplicity and extremely high sensitivity.

Rapid and selective determination of free chlorine in aqueous solution using electrophilic addition to styrene by gas chromatography/mass spectrometry.

We developed a rapid and selective method for determination of free chlorine in aqueous solution by gas chromatography/mass spectrometry for the first time. Free chlorine was converted to styrene chlorohydrin using electrophilic addition to styrene in sodium acetate buffer solution (pH 5). The chlorine derivative obtained was extracted with chloroform, and then analyzed by GC/MS. The calibration curve showed good linearity from 0.2-100 µg/mL (as available chlorine). The detection limit was 0.1 µg/mL, and the intra- and interday accuracy were measured at concentrations of 10, 50, and 75 µg/mL to be -1.3 to 6.9% (intraday) and 3.8-8.0% (interday) as % Bias. The precision was between 1.4 and 4.5% as % RSD. These results indicate that this method is a superior technique for the identification of free chlorine. This method was successfully applied to quantification in commercial samples and in samples of a criminal case.

Analysis of hallucinogenic constituents in Amanita mushrooms circulated in Japan.

The constituents of seven mushrooms sold as Amanita muscaria or Amanita pantherina (five A. muscaria and two A. pantherina) and four "extracts purported to contain A. muscaria" products that are currently circulated in Japan were determined. All mushroom samples were identified as A. muscaria or A. pantherina by macroscopic and microscopic observation. The dissociative constituents, ibotenic acid (IBO) and muscimol (MUS), were extracted with 70% methanol twice and determined by gas chromatography/mass spectrometry. The IBO (as the hydrate)/MUS contents were in the range of <10-2845ppm/46-1052ppm in the cap of A. muscaria and 188-269ppm/1554-1880ppm in the cap of A. pantherina. In the caps, these compounds had a tendency to be more concentrated in the flesh than in the cuticle. On the other hand, the IBO/MUS contents in the stem were far lower than in the caps. In the "extracts purported to contain A. muscaria" products, IBO/MUS were detected below the lower limit of calibration curve (<10ppm/<25ppm) or not detected. However, these samples contained other psychoactive compounds, such as psychoactive tryptamines (5-methoxy-N,N-diisopropyltryptamine and 5-methoxy-N,N-dimethyltryptamine), reversible monoamine oxidase inhibitors (harmine and harmaline) and tropane alkaloids (atropine and scopolamine), which were not quantified. This is the first report of the chemical analysis of Amanita mushrooms that are circulated in the drug market.