Revisiting Formic Acid Decomposition by a Graph-Theoretical Approach.

Formic acid (HCOOH) is a suitable hydrogen storage material because of its high gravimetric and volumetric H2 capacities. Although H2 is produced by the thermal decomposition of HCOOH (HCOOH → H2 + CO2, dehydrogenation), the production of water and carbon monoxide (HCOOH → H2O + CO, dehydration) is the major pathway in HCOOH decomposition despite the thermodynamic favorability of the dehydrogenation process over the dehydration process. A large number of experimental and theoretical studies have suggested that both processes are competitive or that the dehydrogenation process has a lower activation energy in HCOOH decomposition. In the present work, we revisit the factors hindering the progress of the dehydrogenation process, using a whole chemical reaction network based on the graph theory. The calculated chemical reaction network shows that the factor controlling the dehydrogenation and dehydration processes is simple and fundamental and can be explained by the oxidation number of carbon and the betweenness centrality. Based on this understanding of the factors hindering the progress of dehydrogenation, the advantage of the dehydration process in HCOOH decomposition is discussed.

Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection.

A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d(5) was used as an internal standard. The linear ranges were 0.01-5.0 microg mL(-1) for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 microg mL(-1) for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation > or = 0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 microg mL(-1) of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio > or = 3) in urine was 5 ng mL(-1) for MA and MDMA and 10 ng mL(-1) for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation.

Determination of dimethyl sulfoxide and dimethyl sulfone in urine by gas chromatography-mass spectrometry after preparation using 2,2-dimethoxypropane.

A method for routinely determination of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO(2)) in human urine was developed using gas chromatography-mass spectrometry. The urine sample was treated with 2,2-dimethoxypropane (DMP) and hydrochloric acid for efficient removal of water, which causes degradation of the vacuum level in mass spectrometer and shortens the life-time of the column. Experimental DMP reaction parameters, such as hydrochloric acid concentration, DMP-urine ratio, reaction temperature and reaction time, were optimized for urine. Hexadeuterated DMSO was used as an internal standard. The recoveries of DMSO and DMSO(2) from urine were 97-104 and 98-116%, respectively. The calibration curves showed linearity in the range of 0.15-54.45 mg/L for DMSO and 0.19-50.10 mg/L for DMSO(2). The limits of detection of DMSO and DMSO(2) were 0.04 and 0.06 mg/L, respectively. The relative standard deviations of intra-day and inter-day were 0.2-3.4% for DMSO and 0.4-2.4% for DMSO(2). The proposed method may be useful for the biological monitoring of workers exposed to DMSO in their occupational environment.

Survival case of colchicine intoxication following ingestion of a lethal dose.

INTRODUCTION: There have been few reports of cases where the ingestion of colchicine was utilized as a method of suicide and accordingly, its effect on the human body is not fully understood. It has been reported that all individuals who ingested more than 0.8 mg/kg of colchicine died of shock within 72 hours. CASE REPORT: A 46-year-old man was sent to the hospital after ingesting a lethal amount of colchicine (total dose, 71 mg; body weight, about 70 kg) in a suicide attempt. On admission, his vital signs were stable and physical examination was unremarkable. Laboratory findings were normal. He was admitted to the intensive care unit, and severe diarrhea and vomiting commenced approximately 4 hours after ingestion, accompanied by electrolyte disturbance, coagulopathy and renal dysfunction. Bone marrow suppression, bradycardia, alopecia and myoneuropathy also occurred, these findings being the typical symptoms of colchicine poisoning. The symptoms were almost resolved after about 1 week and he was discharged on the 19th day of admission. CONCLUSION: Immediate and precise care for colchicine poisoning successfully saved the patient's life.

Preliminary screening method for the determination of inorganic arsenic in urine.

A simple and rapid method was developed for the routine determination and classification of inorganic arsenic based on its clinical and forensic properties. Inorganic arsenic was isolated from urine by using copper granules, which was then made to react with ammonium molybdate in order to detect its presence with the naked eye. Based on studies of extraction and reaction conditions, e.g., reaction temperature and time, a colorimetric screening method was established. The reaction mixture was measured by a spectrophotometer, and there was linearity from 0.05 to 2.0microg/ml and the correlation coefficients of the calibration curves were greater than 0.99. The coefficients of intra-day variation at 0.2 and 2.0microg/ml of inorganic arsenic in urine were 9.6 and 4.2%, respectively (n=5). The minimum detectable level in urine is 0.03microg/ml, and it is possible to detect the lowest level of poisoning according to the published reports. The proposed method was applied to a poisoning case wherein the patient ingested NEOARSEN BLACK with alcohol, which contained 45% of arsenic trioxide. This method produced positive results in all the urine samples tested, and this method is useful for the screening of inorganic arsenic based on its clinical properties because it enables the detection of inorganic arsenic in urine without expensive equipment.

Extraction of amphetamines and methylenedioxyamphetamines from urine using a monolithic silica disk-packed spin column and high-performance liquid chromatography-diode array detection.

To overcome the limitations of solid-phase extraction, we developed a device comprising a spin column packed with octadecyl silane-bonded monolithic silica for extracting amphetamines and methylenedioxyamphetamines from urine. Urine (0.5mL), buffer (0.4mL), and methoxyphenamine (internal standard) were directly put into the preactivated column. The column was centrifuged (3000rpm, 5min) for sample loading and washed. The adsorbed analytes were eluted and analyzed by high-performance liquid chromatography, without evaporation. The results were as follows: linear curves (drug concentrations of 0.2-20microg/mL); correlation coefficients >0.99; detection limit, 0.1microg/mL. The proposed method is not only useful for drugs from biological materials but also highly reproducible for the analysis of these drugs in urine.

Simultaneous determination of dibucaine and naphazoline in human serum by monolithic silica spin column extraction and liquid chromatography-mass spectrometry.

A simple, sensitive, and specific liquid chromatography-mass spectrometry (LC-MS) method for simultaneous determination of dibucaine and naphazoline from serum was developed and validated. The extraction procedure was performed using a monolithic silica spin column. Chromatographic separation of dibucaine and naphazoline was achieved on a C(18) reverse phase column with a mobile phase gradient (mobile phase A: 10 mM ammonium formate and mobile phase B: acetonitrile) at a flow rate of 0.2 mL/min. LC-MS was operated under the selective ion monitoring mode using the electrospray ionization technique in the positive mode. The retention times for naphazoline, dibucaine, and the internal standard (IS) were 6.7, 7.8, and 8.0 min, respectively. A linear graph was obtained for dibucaine and naphazoline with correlation coefficients >0.998 for all analytes by this method. The limit of quantification of dibucaine and naphazoline was 10 and 25 ng/mL, respectively. The mean recoveries were greater than 70%. Both compounds were stable under conditions of short-term storage, long-term storage as well as after freeze-thaw cycles. Monolithic spin column extraction and LC-MS analysis enabled the separation of dibucaine and naphazoline within 20 min.

Simultaneous determination of amitraz and its metabolite in human serum by monolithic silica spin column extraction and liquid chromatography-mass spectrometry.

A simple, rapid, sensitive, and specific liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the quantification of amitraz and its metabolite in human serum. Both the compounds were extracted using monolithic silica spin columns with acetonitrile. The chromatographic separation was performed on a reverse-phase C(18) column with a mobile phase of 10 mM ammonium formate-acetonitrile. The protonated analyte was quantitated in positive ionization by mass spectrometry. The method was validated over the concentration range of 25-1000 ng/ml for amitraz and its metabolite in human serum. For both compounds, the limit of detection was 5 ng/ml. The method was applied to serum samples taken from an attempted suicide patient, and only small volumes of serum were required for the simultaneous determination of these compounds.

[Simplified rapid test for poisons in emergency and critical care medicine].

In emergency and critical care medicine, it is important to guess which poisons that patients have taken or been exposed to. The assumption and identification of save lives. Therefore an accurate screening system is required to treat acute poisoning patients in clinical toxicology. However, the ability of a medical center is not sufficient to analyze poisonous substances using analytical equipment. Moreover, the handling and maintenance of the equipment are tedious and costly. To improve these problems, a simple detection method should be established to identify poisons and to treat acute patients in emergency and critical care medicine. In our laboratory, various supports have been attempted for the training of analysts who cope with poisoning incidents and accidents due to toxic substances. Moreover, a simple detection method for toxic substances utilized in the medical center was developed without using expensive analysis apparatus. However, it is impossible to detect and identify chemical warfare agents in a clinical laboratory, because of possible secondary exposure to such dangerous substances in insufficient analytical laboratory equipment. Therefore it is necessary to contact related organizations possessing the proper facilities.

Histological brain alterations following prenatal methamphetamine exposure in rats.

When pregnant women abuse methamphetamine, the foremost concern is the potential adverse effect of this substance on fetal development. Clinical studies in humans have found that exposure to methamphetamine during brain development can cause neurobehavioral abnormalities, such as aggressive behavior, learning problems, and poor social adaptation. In the present study, we examined the effects of prenatal methamphetamine exposure on brain development in rats. The first group of pregnant rats was administered methamphetamine at a dose of 5 mg/kg/day during gestational day (GD 10 to GD 20 [MA]. The second group of pregnant rats was injected with saline vehicle only [SAL]. On GD 21 their fetuses were removed and fetal brains were observed. We found various types of morphological damage in MA fetal brains, including microgyria, ectopia, and hemorrhage. In some cases, abnormal distribution of the leptomeninx, such as breach or accumulation, was observed in addition to these histological abnormalities. Therefore, we examined the expression of laminin, which is an important component of the pia mater, in the fetal brains. However, Western blot analysis revealed that there was no difference in expression amount of laminin in whole fetal brain between the MA and SAL groups. We concluded that methamphetamine use during pregnancy can cause histological brain alterations in fetuses. Morphological alterations of brain seen in the present study and previous human studies following prenatal exposure to methamphetamine might be related to the neurobehavioral abnormalities seen in patients who had been exposed to methamphetamine in utero.

Single hair analysis of methamphetamine and amphetamine by solid phase microextraction coupled with in matrix derivatization.

A sensitive method for detection of methamphetamine (MA) and amphetamine (AP) in human hair was developed using solid phase microextraction (SPME) and one-pot derivatization. MA and AP were directly derivatized to N-propoxycarbonyl derivatives in an aqueous solution by propylchloroformate in a one-pot reaction before extraction by SPME. The derivatives were extracted to a coating of SPME from a headspace of the vial. The adsorbed derivatives were thermally desorbed in the injection port of a gas chromatograph. Pentadeuterated MA was used as an internal standard. The absolute recoveries of MA and AP from the spiked hair were 2.80-17.5%, respectively. The calibration curves showed linearity in the range of 0.05-20 ng/0.08 mg/vial for MA and 0.1-20 ng/0.08 mg/vial for AP in hair. Detection limits (S/N = 3) of MA and AP were 0.02 and 0.05 ng/0.08 mg/vial. The coefficients of variation of intraday were 1.04-26.4%. Additionally, this proposed method was applied to segmental analysis in clinical and medico-legal cases of MA intoxication.

[Development of salicylic acid detector tube].

A detector tube was successfully devised for the screening of salicylic acid in urine. It, named "salicylic acid detector tube", consists of glass tube in which silica gel coated with 5% (w/w) of ferric chloride is enclosed. A pipette rubber cap was attached to an end of the tube, and another end was inserted into urine sample. The sample was then introduced into the tube, the color of the reagent immediately turned purple under the condition of more than 50 microg/ml of salicylic acid in urine. This device was useful for the emergency screening of salicylic acid in acute poisoning cases with aspirin.

[On-site screening of toxic substances in clinical laboratory and poisoning information system].

An accurate screening system is required to treat acute poisoning patients in clinical toxicology. However, the medical center analysis of poisonous substances using machines is not sufficient. Moreover, the handling and maintenance of such machines are tedious and costly. To improve these problems and employ effective information, we have developed a simple detection method and constructed a support system using the Internet. Various support systems have been attempted for the training of analysts who can cope with a poisoning incident (accident) involving toxic substances. Our simple detection method for toxic substances in the medical center was developed without using expensive analysis apparati. As technical support for the analysts of medical laboratories, the following items were completed: 1) training for analysts, 2) research of analytical techniques in the medical centers (accuracy management), 3) creation of an analysis manual, 4) construction of on-line analysis manuals, 5) construction of the poisoning information system on the Internet, 6) construction of a system for requesting analysis of poisoning, 7) a quick-detection method for toxic substances and 8) examination of the insurance application.

Miniaturized sample preparation method for determination of amphetamines in urine.

A simple and miniaturized sample preparation method for determination of amphetamines in urine was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). Urine was directly applied to the extraction column that was pre-packed with Extrelut and sodium carbonate. Amphetamine (AP) and methamphetamine (MA) in urine were adsorbed on the surface of Extrelut. AP and MA were then converted to a free base and derivatized to N-propoxycarbonyl derivatives using propylchloroformate on the column. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 100 and 102%, respectively. The calibration curves showed linearity in the range of 0.50-50 microg/mL for AP and MA in urine. When urine samples containing two different concentrations (0.50 and 5.0 microg/mL) of AP and MA were determined, the intra-day and inter-day coefficients of variation were 1.4-7.7%. This method was applied to 14 medico-legal cases of MA intoxication. The results were compared and a good agreement was obtained with a HPLC method.

Routine analysis of amphetamine and methamphetamine in biological materials by gas chromatography-mass spectrometry and on-column derivatization.

A simple determination method of amphetamine (AP) and methamphetamine (MA) in biological materials was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). AP and MA in biological materials were adsorbed on the surface of Extrelut and then extracted and derivatized simultaneously on the Extrelut column. AP and MA were derivatized to the N-propoxycarbonyl derivatives using propylchloroformate. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 88.2 and 92.5%, and those from blood were 89.7 and 90.3%, respectively. The calibration curves showed linearity in the range of 12.5-2000 ng/ml (ng/g) for AP and MA in urine and blood, and 0.25-20 ng/mg in hair. When urine samples containing two different concentrations (200 and 1000 ng/ml) of AP and MA, blood samples containing two different concentrations (200 and 1000 ng/g) of AP and MA, hair samples containing two different concentrations (0.5 and 5.0 ng/mg) of AP and MA, the coefficients of variation of intra-day and inter-day were 0.68-3.60% in urine, 0.42-4.58% in blood, and 1.20-13.1% in hair. Furthermore, this proposed method was applied to a medico-legal case of MA intoxication.

Direct extract derivatization for determination of amino acids in human urine by gas chromatography and mass spectrometry.

The purpose of this study was to develop a simple and accurate analytical method to determine amino acids in urine samples. The developed method involves the employment of an extract derivatization technique together with gas chromatography-mass spectrometry (GC-MS). Urine samples (300 microl) and an internal standard (10 microl) were placed in a screw tube. Ethylchloroformate (50 microl), methanol-pyridine (500 microl, 4:1, v/v) and chloroform (1 ml) were added to the tube. The organic layer (1 microl) was injected to a GC-MS system. In this proposed method, the amino acids in urine were derivatized during an extraction, and the analytes were then injected to GC-MS without an evaporation of the organic solvent extracted. Sample preparation was only required for ca. 5 min. The 15 amino acids (alanine, aspartic acid, cysteine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, tryptophan, valine) quantitatively determined in this proposed method. However, threonine, serine, asparagine, glutamine, arginine were not derivatized using any tested derivatizing reagent. The calibration curves showed linearity in the range of 1.0-300 microg/ml for each amino acid in urine. The correlation coefficients of the calibration curves of the tested amino acids were from 0.966 to 0.998. The limit of detection in urine was 0.5 microg/ml except for aspartic acid. This proposed method demonstrated substantial accuracy for detection of normal levels. This proposed method was limited for the determination of 15 amino acids in urine. However, the sample preparation was simple and rapid, and this method is suitable for a routine analysis of amino acids in urine.

Acute liver failure following intravenous methamphetamine.

A 41-y-o Pakistani man presented with psychosis, hyperthermia, rhabdomyolysis, and liver dysfunction approximately 6 h after i.v. injection of methamphetamine. Serum concentrations of methamphetamine and amphetamine on admission were 0.30 microg/mL and 0.04 microg/mL, respectively. Total serum bilirubin and alanine aminotransferase concentrations peaked on the 3rd hospital day at 8.6 mg/dL and 4155 IU/L, respectively, and gradually returned to normal with supportive care. The patient had no evidence of infectious hepatitis or intake of other drugs. Histologic examination of a liver biopsy specimen obtained on the 11th d showed confluent necrosis and ballooning degeneration in centrilobular zones. No inflammatory changes were seen in portal tracts. Liver damage can be a complication of illicit methamphetamine use, even in patients without viral infection or intake of other drugs.

On-column derivatization for determination of amphetamine and methamphetamine in human blood by gas chromatography-mass spectrometry.

A simple determination method of amphetamine (AP) and methamphetamine (MA) in human blood was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). AP and MA were adsorbed on the surface of Extrelut and then derivatized the N-propoxycarbonyl derivatives using propylchloroformate. Pentadeuterated MA was used as an internal standards. The recoveries of AP and MA from the spiked blood were 89.7 and 90.3%, respectively. The calibration curves showed linearity in the range of 12.5-2000 ng/g for AP and MA in blood. The coefficients of variation of intraday and interday were 0.42-4.58%. Furthermore, this proposed method was applied to some medico-legal cases of MA intoxication. MA and its metabolite AP were detected in the blood samples, and the correlation of the blood level of amphetamines and the behaviors of the victims was in good agreement with the criteria proposed by Nagata [Jpn. J. Legal Med. 37 (1983) 513].