Injection Of Toluene Research Articles

Stable MAPbBr3@PbBr(OH) composites with high photoluminescence quantum yield: Synthesis, optical properties, formation mechanism, and catalytic application

The disappointing stability of perovskites against polar solvent and light irradiation severely hinders their application in photocatalysis. Here, we design a facile and reliable approach to synthesize MAPbBr3@PbBr(OH) composites with outstanding photoluminescence quantum yield (PLQY) of 74.4–90.6% and high stability under various harsh environments by simply introducing ZIF-67 or ZIF-8 in perovskite precursor solution. Benefiting from the preferential interaction between ZIF-67/ZIF-8 and MABr in the precursor step, the transformation of PbBr2 to PbBr(OH) triggered by ZIF-67/ZIF-8 occurs simultaneously with the formation of MAPbBr3 during the subsequent injection of toluene. PL intensity of the MAPbBr3@PbBr(OH) obtained by self-assembly of MAPbBr3 into PbBr(OH) can maintain above 95% of the initial after soaking in a wide variety of polar solvents for 210 days. Meanwhile, the composite also shows enhanced stability against continuous ultraviolet illumination. Moreover, the MAPbBr3@PbBr(OH) can be used in aqueous solution as photocatalyst for degradation of organic dye methylene green (MG) at room temperature. The MG degradation efficiency is observed to above 90% within 3 h. This work not only provides a reliable and controllable method for the synthesis of stable perovskites with high PLQY, but also pave the way for the use of perovskites as efficient photocatalyst in catalytic applications.

Soot Formation and Growth in Toluene/Ethylene Combustion Catalyzed by Ruthenium Acetylacetonate

ABSTRACT Ruthenium-based compounds are efficient catalysts to enhance combustion performance and suppress soot emission. However, systematic mechanism and in-situ research on reducing soot are rarely addressed. In this study, ruthenium acetylacetonate (Ru(C5H7O2)3, Ru(acac)3) was utilized as the catalyst precursor in different concentration conditions to investigate its impacts on the size, volume, and morphology of the soot particles in the ethylene flames with central toluene injection. The soot particles were detected by in-situ small-angle X-ray scattering (SAXS) and ex-situ transmission electron microscopy (TEM). This study confirms that Ru(acac)3 can suppress the surface growth for the primary soot particles, but no significant change of the morphology has been discovered for the aggregates. Compared with the undoped flame, the volume of the soot particles in the Ru(acac)3-doped flames is lower and the particle size is smaller, indicating a valid inhibition effect of Ru(acac)3 on the soot emission by affecting its surface growth and oxidation process. Despite the remarkable distinction between the undoped and doped flames, no obvious difference is found between the flames with different catalyst concentrations.

Development of a new chemical solvent package for increasing the asphaltene removal performance under static and dynamic conditions

In this work, a new solvent package (named TPMDS) for asphaltene removal under static and dynamic conditions was developed through a set of experiments. TPMDS consists of toluene, pyridine, methanol, surfactant dodecylbenzenesulfonic and sodium hydroxide. The optimum concentrations of TPMDS components were determined based on the efficiency evaluation of the chemical reagents to eliminate the asphaltene precipitation under static conditions. The highest effectiveness of the developed solvent package under static conditions was found to be 98%, which was observed at a soaking time of 6 h and a mass concentration of 1%. TPMDS had high performance (more than 97.5%) for asphaltene removal in four different oil samples containing various asphaltene concentrations. The results of the turbidity and dissolution rate experiments of asphaltene in the presence of TPMDS and toluene showed that the performance of TPMDS for asphaltene removal is significantly better than toluene. In addition, core flood tests were carried out with the use of TPMDS and toluene. Pressure drop due to asphaltene precipitation in the carbonate core samples was reduced eight times using the developed solvent package. The damaged permeability due to asphaltene deposition was 51% of the initial rock permeability before injection of any solvent. The results of core flood tests showed that the rock permeability has reached about 94% and 71% of the initial permeability after injection of TPMDS and toluene, respectively. Despite the increase in the amount of asphaltene precipitation in the core samples by increasing injection rate, the efficiency of the developed solvent was not decreased by changing the injection rate since the performance of the TPMDS was improved by the appearance of a synergistic effect for asphaltene dissolution. Furthermore, oil viscosity reduction with the use of TPMDS was more significant than with the use of toluene. The corrosion rate of the metal samples in the presence of the developed solvent package solution was less than 0.08 mm/year in a temperature range from 25 °C to 100 °C, which is less than an acceptable threshold corrosion rate of 0.1 mm/year. Moreover, the results of field analysis showed that the oil production rate could be enhanced by 3.3 times after treatment by TPMDS. Asphaltene removal effectiveness in the production wells using the industrial reagent and TPMDS has reached 84 and 96%, respectively. The rock permeability after treatment by TPMDS was increased by about 290%. TPMDS can be used for asphaltene removal in the near-wellbore region, production equipment, and tubing.

Evaluation of a linear free energy relationship for the determination of the column void volume in hydrophilic interaction chromatography

The application of a linear free energy relationship (LFER) to a variety of hydrophilic interaction chromatography columns with different bonded ligands and pore sizes was studied in order to determine their void volume Vm. The method was based on the determination of the elution volume of a series of alkylbenzene standards from C1 (toluene) to C17 (heptadecylbenzene). Results were compared with those obtained by injection of toluene alone, which has traditionally been used as a simple Vm marker. Vm was smaller when derived from the LFER plot than when measured with toluene with differences between the two methods ranging from 2.7 to 12.7 % for the columns studied. This result could be due to the small but appreciable retention of toluene due to its solubility in the water rich layer, which partially constitutes the stationary phase in HILIC. Larger pore size columns showed less difference in Vm between LFER and toluene procedures. This result may be due to size sieving effects of non-excluded solutes in the pores of the stationary phase, or to differences in phase ratio between columns of different pore size.

Low-volume PEEK gas cell for BTEX detection using portable deep-UV absorption spectrophotometry.

Monitoring of indoor air quality by detecting individual airborne pollutant is essential for maintaining a healthy indoor environment. UV absorption spectrophotometry coupled with gas chromatography offers a reliable, self-referenced and non-destructive technique for the identification and detection of gas molecules. This paper presents a deep-UV absorption spectrophotometer coupled with a micro gas-chromatography (μGC) for the detection of benzene, toluene, ethylbenzene and xylenes (BTEX). The spectrophotometer was developed using a low-volume gas cell made of PolyEther Ether Ketone (PEEK) polymer tube, connected with a portable deep-UV LED and photomultiplier tube. The performance of the detection unit was evaluated with different concentrations of toluene (5-100ppm) in nitrogen and a sensitivity of 107.1μAU/ppm with a limit of detection of 1.41ppm was obtained. The detector was incorporated into a micro gas-chromatography setup and high quality chromatograms, having all the peaks separated with good repeatability were obtained for BTEX molecules. The deep-UV absorption spectrophotometer has low-volume, low-cost, and ease of development and integration. While demonstrated for BTEX in a nitrogen carrier gas, the spectrometer has the potential to be applied to chromatographic analysis of different analytes in gas or liquid media.

Exacerbation of Toluene’s Neuro- and Hepato-Toxicity by Amiodarone or Chlorpropamide: Involvement of Oxidative Stress

Volatile solvent abuse is an important health problem and results in serious injury to the central nervous system. Neuroprotective effects were reported for the sulfonylurea group of drugs and for the anti-arrhythmic agent amiodarone, and these drugs have a K+ channel-blocking effect. The K+ channels are of interest for their ability to modulate brain damage. The aim of this study was to investigate the effect of amiodarone and chlorpropamide on the development of oxidative stress and brain and liver damage induced by toluene injection in rats. Toluene (900 mg/kg) was intraperitoneally (ip) administered alone or in combination with amiodarone or chlorpropamide (18 or 36 mg/kg, orally) once a day for 2 consecutive days. The brain and liver content of malondialdehyde (MDA), reduced glutathione (GSH), and nitric oxide (NO), and the activity of paraoxonase-1 (PON-1) were determined. In addition, butyrylcholinesterase (BChE) and the concentration of the anti-apoptotic protein (Bcl-2) were determined in brain homogenates. Histopathological examination of brain and liver sections was also performed. Results showed that compared to controls, toluene resulted in increased oxidative stress in the brain and liver tissues. MDA and NO concentrations were markedly raised along with decreased levels of GSH and PON-1 activity. Toluene also inhibited BChE activity and decreased Bcl-2 level in the brain tissue. The biochemical changes induced by toluene were aggravated by the administration of either amiodarone or chlorpropamide. Rats treated with toluene exhibited dead neurons, perineuronal vacuolations, infiltrative cells, glial cells, and degeneration of some Purkinje cells. In the liver, massive hepatic inflammatory infiltrate, hemorrhage, vacuolar degeneration, apoptosis, and degeneration of hepatocytes were observed. The co-administration of either amiodarone or chlorpropamide caused dose-dependent exacerbation of the toluene-induced pathological changes. These findings suggest the involvement of oxidative stress in the neuro- and hepato-toxicity by toluene and imply a greater toxicity in toluene abusers treated with either amiodarone or chlorpropamide.

Experimental investigation of the asphaltene deposition in porous media: Accounting for the microwave and ultrasonic effects

This study examines the effects of ultrasonic waves (US) and microwaves (MW) on the permeability in carbonate cores with different permeabilities of asphaltenes deposited therein. Using US with toluene injection restores permeability in cores with a permeability of less than 20 md, about 18.8% and 29% higher than injection of toluene without US. The US creates turbulence and cavitation, causing a change in the structure of the asphaltene conglomerations deposited in the cores. These structural changes may be due to increased levels of contact between precipitates and better penetration of the injected fluid which facilitate the process of removing them from the cores. MW, in addition to changing the structure of asphaltene clusters within the cores, reduces the amount of their polar elements, including sulfur (S), nitrogen (N), and oxygen (O). Under MW irradiation, the sulfur, nitrogen, and oxygen values were 23.5%, 18.4% and 48%, respectively. This decrease in the amount of asphaltene polar elements, which is due to their high capacity to absorb MW can reduce the negative charges in asphaltene particles. The zeta potential results also indicated that the negative charges of asphaltene particles decreased and became more positive as a result of MW radiation (from −12.31 mV to −7.59 mV). Fourier transform infrared spectroscopy (FTIR) spectra tests also confirmed these results. The polar bands of the asphaltene particles deposited inside the cores (OH, S-H; C=O) had a decreasing trend and escaped from the structure of the asphaltene clusters. Decreasing the polar values, especially those of the compounds with negative electrical charge (SO) actually reduces the adhesive force between asphaltene and limestone that has positive electrical charges. This phenomenon causes the removal of asphaltene particles from the porous rock media. The rate at which permeability is restored also indicates that MW radiation is much higher than the previous one (US + Toluene), especially cores with low permeability. The results of this study could be a major step towards removing asphaltene precipitates in oil reservoirs using US and MW technologies.

Flow and Solute Transport through a Single Fracture during the Biodegradation of Residual Toluene

A series of bench scale experiments were performed to assess the effects of biofilm and bio-enhanced toluene dissolution on flow and solute transport through a rough fracture. The fracture was cast from a real shale rock fracture. Sterilized artificial groundwater was used as the nutrition source to support the growth of microorganisms which were obtained from local groundwater. Hydraulic and tracer tests were carried out before and after the injection of toluene, and during the toluene biodegradation as well. The normalized hydraulic conductivity decreased sigmoidally during the experiment, and reached 0.02 at the end of the experiment. Biofilm growth was the main cause for hydraulic conductivity reduction after the injection of liquid toluene. The presence of separate phase toluene extended the tracer tailing compared to tracer tests without toluene. The longitudinal dispersion coefficient DL was proportional to the 1.5th power of the mean velocity in the rough fracture with or without residual toluene. Though a biofilm developed in the fracture during bio-treatment, the effect of secondary biofilm-associated porosity on solute transport in the fracture had negligible effect on tracer transport due to its small thickness. It is also found that DL decrease exponentially with Pe reduction during the bio-treatment.

Development of Carbotrap B-packed needle trap device for determination of volatile organic compounds in air

Carbotrap B as a highly pure surface sorbent with excellent adsorption/desorption properties was packed into a stainless steel needle to develop a new needle trap device (NTD). The performance of the prepared NTD was investigated for sampling, pre-concentration and injection of benzene, toluene, ethyl benzene, o-xylene, and p-xylene (BTEX) into the column of gas chromatography-mass spectrometry (GC–MS) device. Response surface methodology (RSM) with central composite design (CCD) was also employed in two separate consecutive steps to optimize the sampling and device parameters. First, the sampling parameters such as sampling temperature and relative humidity were optimized. Afterwards, the RSM was used for optimizing the desorption parameters including desorption temperature and time. The results indicated that the peak area responses of the analytes of interest decreased with increasing sampling temperature and relative humidity. The optimum values of desorption temperature were in the range 265–273°C, and desorption time were in the range 3.4–3.8min. The limits of detection (LODs) and limits of quantitation (LOQs) of the studied analytes were found over the range of 0.03–0.04ng/mL, and 0.1–0.13ng/mL, respectively. These results demonstrated that the NTD packed with Carbotrap B offers a high sensitive procedure for sampling and analysis of BTEX in concentration range of 0.03–25ng/mL in air.

Improving oil recovery in the CO2 flooding process by utilizing nonpolar chemical modifiers

By means of experiments of CO2 miscibility with crude oil, four nonpolar chemicals were evaluated in order to enhance the miscibility of CO2 with crude oil. Through pre-slug injection and joint injection of toluene in CO2, crude oil displacement experiments in the slim-tube were conducted to investigate effects of the toluene-enhanced CO2 flooding under simulated subterranean reservoir conditions. Experimental results showed that toluene can enhance extraction of oil into CO2 and dissolution of CO2 into oil with the increment of 251% and 64% respectively. Addition of toluene can obviously improve the oil recovery in either pre-slug injection or joint injection, and the crude oil recovery increased with the increase of the toluene concentration. The oil recovery can increase by 22.5% in pre-slug injection with the high toluene concentration. Pre-slug injection was recommended because it can consume less toluene than joint injection. This work could be useful to development and application of the CO2 flooding in the oil recovery as well as CO2 emission reduction.

Acute administration of toluene affects memory retention in novel object recognition test and memory function‐related gene expression in mice

The present study was designed to investigate the acute effect of a single administration of toluene (300 mg kg(-1), i.p.) on memory retention in the hippocampus-dependent novel object recognition test and N-methyl-D-aspartate (NMDA) receptor subunit expression in the hippocampus of C3H/HeN female mice using real-time RT-PCR. We performed a novel object recognition test including a habituation phase, training phase and test phase in each mouse. Twenty-four hours after the training phase, to determine the effect of acute toluene administration on memory retention, half of the mice (n=10) were injected with toluene 60 min before the test phase. Toluene-injected mice did not prefer novel objects and showed poor discrimination between novel and familiar objects and decreased expression of NMDA receptor subunit NR2B mRNA in the hippocampus. This is the first study to show that acute toluene injection impairs hippocampus-dependent nonspatial memory retention accompanied by selective modulation of NMDA receptor subunit expression.

Role of Asphaltene Precipitation in VAPEX Process

Abstract VAPEX (vapour extraction) is an oil recovery process, in which heavy oil or bitumen is mobilized by injection of a low molecular weight hydrocarbon solvent and is drained by gravity to a horizontal production well. It has attracted considerable attention because of its potential applicability to problematic reservoirs and the potential for in-situ upgrading of heavy oil during the process. Oil drainage rate under VAPEX is controlled by the viscosity of solvent diluted oil and can be affected substantially by de-asphalting. In-situ de-asphalting can be advantageous because it reduces the oil viscosity and leads to production of upgraded oil. However, the precipitated asphaltenes can also plug the pores of the formation and cause severe damage to the permeability. The objective of the current work was to determine whether the beneficial effects of asphaltene precipitation would outweigh any formation damage. The effects of in-situ precipitation and deposition of asphaltenes on the rate of oil drainage and the quality of the produced oil under different operating conditions were experimentally evaluated. The experiments were conducted in a physical model, packed with 140 - 200 mesh sand, and propane was used as the solvent. The quality of the produced oil samples was evaluated through the SARA technique and viscosity measurements. The experimental results show that the oil produced at higher injection pressures was substantially upgraded, but the viscosity reduction by asphaltene precipitation did not lead to higher production rates. The effect of viscosity reduction was negated by the accompanying damage to formation permeability. The huff and puff injection of toluene into the production well, to remove damage from the near well zone, was tried but proved to be ineffective. It led to production of oil with higher asphaltene content with no improvement in the rate of oil production compared to the lower pressure operation without asphaltene precipitation. However, co-injection of toluene with propane was successful in increasing the rate of production and the extent of upgrading obtained was encouraging.

Strain Differences in Extracellular Amino Acid Neurotransmitter Levels in the Hippocampi of Major Histocompatibility Complex Congenic Mice in Response to Toluene Exposure

Objective: The aim of the present study was to investigate the possible role of the major histocompatibility complex locus in neurotransmitter systems in the mouse hippocampus following toluene exposure. Methods: We compared the changes in toluene-induced extracellular amino acid neurotransmitter levels in the hippocampi of 2 strains of male congenic mice, C57BL/10 (H-2^b) and B10.BR/Sg (H-2^k). In vivo microdialysis was performed in each freely moving mouse after a single intraperitoneal injection of toluene (300 mg/kg), and neurotransmitters in the hippocampal microdialysates were measured using high-performance liquid chromatography. Results: The basal extracelluar glutamate and glycine levels in the hippocampi of the C57BL mice were significantly higher than those in the B10.BR mice. However, the basal extracellular taurine levels in the hippocampi of the C57BL mice were significantly lower than those in the B10.BR mice. Although no changes in the glutamate levels were observed after toluene injection in either strain, the glycine levels increased significantly after toluene injection in the C57BL mice. On the other hand, significantly lower taurine levels were observed after toluene injection in both strains of mice. Conclusions: Our data demonstrate the existence of a relationship between H-2 haplotypes and hippocampal neurotransmitter levels in mice.

Gas chromatography analysis of benzene, toluene, ethylbenzene and xylenes using newly designed needle trap device in aqueous samples

A newly designed needle trap device with Carbopack X as a sorbent material is used for sampling, preconcentration and injection of volatile analytes benzene, toluene, ethylbenzene and xylenes (BTEX) into gas chromatograph. The closed system of stripping the analytes from water samples was used. An injection port with a modified metal liner was used to desorb analytes trapped in needle trap device. The main advantage of needle trap device consists in the simple methodology and easiness and rapidity of the analysis. Needle trap device is suitable for sampling in field. The experimental parameters as breakthrough volume of stripping gas, linearity, repeatability and limit of detection (LOD) and quantification (LOQ) were investigated. LOD ranges from 0.05 to 0.07 μg L −1 and relative standard deviation ranges from 0.5% to 11.6% at concentrations 5 and 0.1 μg L −1, respectively.

Semicontinuous microcosm study of aerobic cometabolism of trichloroethylene using toluene

A semicontinuous slurry-microcosm method was applied to mimic trichloroethylene (TCE) cometabolic biodegradation field results at the Que–Jen in-situ pilot study. The microcosm study confirmed the process of aerobic cometabolism of TCE using toluene as the primary substrate. Based on the nucleotide sequence of 16S rRNA genes, the toluene-oxidizing bacteria in microcosms were identified, i.e. Ralstonia sp. P-10 and Pseudomonas putida. The first-order constant of TCE-degradation rate was 0.5 day −1 for both Ralstonia sp. P-10 and P. putida. The TCE cometabolic-biodegradation efficiency measured from the slurry microcosms was 46%, which appeared pessimistic compared to over 90% observed from the in-situ pilot study. The difference in the TCE cometabolic-biodegradation efficiency was likely due to the reactor configurations and the effective time duration of toluene presence in laboratory microcosms (1 days) versus in-situ pilot study (3 days). The results of microcosm experiments using different toluene-injection schedules supported the hypothesis. With a given amount of toluene injection, it is recommended to maximize the effective time duration of toluene presence in reactor design for TCE cometabolic degradation.

Effect of intraventricular injection of toluene on learning and memory of mice and its mechanism

目的 研究甲苯对小鼠学习记忆功能及海马胆碱能神经元的毒性作用,探讨其神经毒性及相关机制.方法 86只昆明种小鼠随机分成5组,2.5、1.0 μl剂量组和生理盐水组每组22只,假手术组及空白对照组每组10只.运用脑立体定位仪将甲苯直接注入2月龄小鼠脑室,于注射后3、5 d及1、2、3周检测小鼠水迷宫潜伏期的变化,并于注射后1、2、3周分批处死小鼠,通过免疫组织化学染色,观测小鼠海马胆碱乙酰转移酶(ChAT)阳性神经元的变化.结果 与对照组比较,1.0 μl及2.5 μl剂量组水迷宫潜伏期延长,差异有统计学意义(P＜0.01);1.0 μl剂量组与对照组海马ChAT阳性细胞数量未见明显变化,2.5 μl剂量组在注射后1、2周时ChAT阳性细胞明显减少,至3周则基本恢复正常.结论 脑室直接注射甲苯能明显降低小鼠学习记忆功能,对海马胆碱能神经元具有较强毒性作用,且是可逆的、剂量依赖性的。

Toluene toxicokinetics and metabolism parameters in the rat and guinea pig

Cochlear disruptions induced by toluene were shown in the rat but not in the guinea pig. To better understand the differences between species, three investigations were carried out to study (1) the blood affinity and the pulmonary uptake of the solvent, (2) its clearance and (3) its urinary elimination in both species. The blood affinity of toluene was +44% higher in the rat than in the guinea pig (14.4 μg/g versus 10 μg/g). Similarly, the pulmonary uptake of toluene was approximately 46.5% more efficient in the rat than in the guinea pig (75.4 μg/g versus 40.3 μg/g) after 3 h inhalation of 1500 ppm toluene. Therefore, the physicochemical composition of the blood could explain the difference in the uptake performances between rats and guinea pigs. The clearance of the toluene showed that 10 min after an intravenous administration of 400 μL of vehicle containing 28 μL (43 mg kg −1) of toluene, the solvent concentration was approximately threefold higher in the rat than in the guinea pig blood. The last experiment was carried out to compare the concentrations of the urinary metabolites. The concentrations of o-cresol, hippuric and benzyl mercapturic acids measured in the urines were different before and after the toluene injection. These data give evidence for large differences of toluene uptake and metabolism between rat and guinea pig. Therefore, it seems reasonable to claim that guinea pigs cochleas are not susceptible to toluene as the blood burden of solvent does not reach the concentration required to induce permanent damages.

Immunohistochemical localization of toluene-induced c-Fos protein expression in the rat brain

Although toluene is a widely abused substance, the neuronal populations and pathways mediating its effects are not well understood. Using c-Fos protein as a marker for neuronal activation, the present study investigated the pattern of c-Fos induction at 1 h after various doses (0, 300, 750, and 1000 mg/kg, i.p.) of toluene injection in adult male rats. Quantitative analysis of Fos-immunoreactive neurons indicated toluene dose-related induced c-Fos immunoreactivity in the majority of structures examined. The structures included several cortex subareas (primary motor cortex, secondary motor cortex, somatosensory cortex, frontal association cortex, cigulate cortex area 1, cigulate cortex area 2, prelimbic cortex, infralimbic cortex, retrosplenial agranular cortex, ventral orbital cortex, lateral orbital cortex, and piriform cortex), ventral tegmental area, nucleus accumbens shell, thalamic nuclei (mediodorsal, lateral posterior, and laterodorsal ventrolateral) and pontine nuclei. However, the substantia nigra, caudate putamen, nucleus accumbens core, subthalamic nucleus, hippocampus and cerebellum were almost unaffected. The data demonstrate that toluene dose-related induced a unique pattern of c-Fos immunoreactivity. The widespread distribution of toluene-induced c-Fos expression seen in this study can be linked to the profound alterations in physiological function and behavior produced by this solvent.

Pilot studies for in-situ aerobic cometabolism of trichloroethylene using toluene-vapor as the primary substrate

In-situ pilot studies of aerobic cometabolism were conducted to evaluate the injection of toluene-vapor and air into TCE-contaminated aquifer. Delivery of primary substrate (toluene) in a vapor state with air enhanced the growth of indigenous toluene-utilizing bacteria that would degrade TCE by aerobic cometabolism. Meanwhile, delivering toluene in a vapor state effectively reduced potential clogging near the injection points due to excessive microbial growth, which was observed in the field when the injection of neat toluene was employed. Over 90% removal of TCE was achieved with primary substrate (toluene) degraded to a concentration below 10 microg/L.

Brain microdialysis study of the effects of hazardous chemicals on the central nervous system 2. Toluene exposure and cerebral acetylcholine.

The microdialysis technique was applied to detect the changes in the activity of acetylcholine (ACh) neurons in the rat brain. The effects of intraperitoneal (i.p.) injection of toluene on the amount of ACh release from the nerve terminals of the brain cholinergic neurons were investigated in freely moving rats. In the striatum, injection of toluene decreased the extracellular concentration of ACh in a dose dependent manner in the range 200 to 2,000 mg/kg. Similar effects of toluene on ACh release were observed in the hippocampus after i.p. administration. The increases in ACh content in brain homogenate after i.p. injection of toluene seemed to be caused by the decreased release of ACh from cholinergic nerve endings. Injection of toluene at doses higher than 200 mg/kg decreased ACh release and a similar decrease was suggested to occur in 8-h inhalation exposure to toluene at 1,000 ppm or higher concentrations.