A Pretreatment Method for GC–MS Determination of Endocrine Disrupting Chemicals in Mollusk Tissues

Automatic soxhlet extraction followed by silica gel cartridge cleanup process was developed as a pretreatment method for GC–MS determination of seven endocrine disrupting chemicals in mollusk tissues. Operation parameters including extraction time, adsorption flow rate and elution flow rate were optimized as 140 min, 2 mL min^?1 and 2 mL min^?1, respectively. Thirty percent dichloromethane in n-hexane and 70% dichloromethane in n-hexane were used as elution solvents in turn. Recovery rates were 93.7, 91.7, 84.5, 83.3, 88.4, 81.2, and 79.7% for nonylphenols (NPs), bisphenol A (BPA), 17α-ethynylestradiol (EE2), estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (E2), and estriol (E3), respectively. Acceptable relative standard derivations ranged from 8.5 to 12.1%. Method detection limits ranged from 0.27 to 0.68 ng g^?1 dry weight (dw), and quantitative detection limits ranged from 0.62 to 1.26 ng g^?1 dw. The method was successfully applied to five mollusk species in Dapeng Bay of China to verify its practicability, and NPs, BPA, EE2, E1 and 17α-E2 were detected in the range from 1.6 to 131.5 ng g^?1 dw.     

Trace analysis of benzophenone-derived compounds in surface waters and sediments using solid-phase extraction and microwave-assisted extraction followed by gas chromatography–mass spectrometry

This study describes a procedure for determining eight benzophenone-derived compounds in surface waters and sediments. These include the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type ultraviolet (UV) filters. The proposed analytical method involves the pre-concentration of water samples by solid-phase extraction (SPE) and microwave-assisted extraction (MAE) of sediment samples followed by derivatization and analysis by gas chromatography–mass spectrometry. Different parameters were investigated to achieve optimal method performance. Recoveries of 91 to 96 % from water samples were obtained using HLB Oasis SPE cartridges, whereas MAE of sediments (30 min at 150 °C) gave recoveries of 80 to 99 %. Limits of detection were between 0.1 and 1.9 ng L^?1 for water samples and from 0.1 to 1.4 ng g^?1 for sediment samples. The developed method was applied to environmental samples and revealed the presence of UV filters in the majority of the surface waters with up to 690 ng L^?1 of 2-hydroxy-4-methoxybenzophenone. By contrast, ketoprofen (≤2,900 ng L^?1) and its degradation products (≤320 ng L^?1) were found in only two rivers, both receiving wastewater treatment plant effluents. Sediment analysis revealed benzophenone to be present in concentrations up to 650 ng g^?1, whereas concentrations of other compounds were considerably lower (≤32 ng L^?1). For the first time, quantifiable amounts of two ketoprofen transformation products in the aqueous environment are reported.     

Determination of Two Pesticides in Soils by Dispersive Liquid–Liquid Microextraction Combined with LC-Fluorescence Detection

In the present work, a simple, rapid and sensitive sample pre-treatment technique, dispersive liquid–liquid microextraction (DLLME) coupled with liquid chromatography-fluorescence detection (LC-FLD), has been developed to determine carbamate (carbaryl) and organophosphorus (triazophos) pesticide residues in soil samples. Methanol was first used as extraction solvent for the extraction of pesticides from the soil samples and then as dispersive solvent in the DLLME procedure. Under the optimum extraction conditions, the linearity was obtained in the concentration range of 0.1–1,000 ng g^?1 for carbaryl and 1–5,000 ng g^?1 for triazophos, respectively. Correlation coefficients varied from 0.9997 to 0.9999. The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, ranged from 14 to 110 pg g^?1. The relative standard deviation (RSDs, for 20.0 ng g^?1 of each pesticide) varied from 1.96 to 4.24% (n = 6). The relative recoveries of two pesticides from soil A1, A2 and A3 at spiking levels of 10.0, 20.0 and 50.0 ng g^?1 were in the range of 88.2–108.8%, 80.8–110.7% and 81.0–111.1%, respectively. The results demonstrated that DLLME was a sensitive and accurate method to determine the target pesticides, at trace levels, in soils.     

Determination of Herbicides in Soil by Dispersive Solid-Phase Extraction,Dispersive Liquid–Liquid Microextraction,and High-Performance Liquid Chromatography

A method for determination of five herbicides (i.e., quinclorac, metsulfuron-methyl, bensulfuron-methyl, atrazine, prometryn) in soil was developed by dispersive solid-phase extraction combined with dispersive liquid–liquid microextraction and high-performance liquid chromatography. The analytes were removed from the soil by liquid partitioning with acetonitrile/5% acetic acid, purified using a octadecylsilane sorbent, and subsequently extracted before chromatographic analysis. Under the optimized conditions, the linear dynamic range was from 10.0 to 300 ng g^?1 with correlation coefficients (r) between 0.9971 and 0.9985. The limits of detection were between 1.5 and 3.1 ng g^?1, with relative standard deviations from 3.8% to 6.7% (n = 5). The recovery of the herbicides from soil at fortification levels of 20.0 and 100.0 ng g^?1 were between 71.5% and 94.3%. The method was successfully applied to the determination of the analytes in soil.     

Determination of Arsenic,Mercury and Barium in Herbarium Mount Paper Using Dynamic Ultrasound-Assisted Extraction Prior to Atomic Fluorescence and Absorption Spectrometry

A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic Fluorescence spectrometers as detectors was developed to analyze mercury, arsenic, and barium from herbarium mount paper originating from the herbarium collection of the National Museum of Wales. The variables influencing extraction were optimized by a multivariate approach. The optimal conditions were found to be 1% HNO₃ extractant solution used at a flow rate of 1 mL min^?1. The duty cycle and amplitude of the ultrasonic probe was found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance between the probe and the top face of the extraction chamber was found to be 0 cm. Under these conditions the time required for complete extraction of the three analytes was 25 min. Cold vapor and hydride generation coupled to atomic fluorescence spectrometry was utilized to determine mercury and arsenic, respectively. The chemical and instrumental conditions were optimized to provide detection limits of 0.01 ng g^?1 and 1.25 ng g^?1 for mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic absorption spectrometry, with a detection limit of 25 ng g^?1. By using 0.5 g of sample, the concentrations of the target analytes varied for the different types of paper and ranged between 0.4–2.55 µg g^?1 for Ba, 0.035–10.47 µg g^?1 for As, and 0.0046–2.37 µg g^?1 for Hg.     

Determination of Triazine Herbicides and Diuron in Mud from Olive Washing Devices and Soils Using Gas Chromatography with Selective Detectors

Abstract

In the present work, a method for the simultaneous determination of five herbicides, diuron, simazine, atrazine, terbuthylazine and terbutryn by GC‐electron capture detection (ECD) and GC‐thermoionic specific detector (TSD) in soil and mud samples (from olives washing devices) has been developed. Extraction of the herbicides from soil samples was carried out by liquid–solid extraction with ciclohexane/acetone under sonication. In addition, a clean‐up step by solid phase extraction (SPE) using alumina was necessary for mud samples to remove fat residues in the extracts. Spiked soil standards were used for calibration. Limit of detection (LOD) values ranged between 0.2–1.4 ng g^?1 and limit of quantitation (LOQ) between 1.4–2.0 ng g^?1. The precision of the method was satisfactory for all the herbicides analyzed, with RSD values ranging between 7.5%–32.3% and 8.5%–17.8% for 10 and 100 ng g^?1 spiking levels, respectively. The accuracy of the method was checked at three spiking levels (10, 50, and 100 ng g^?1) with recovery values ranging from 74.2%–129.1%. In the case of mud samples, mean recovery values (100 ng g^?1 spiking level) were acceptable for diuron (69.5%) and more satisfactory in the case of triazine herbicides (81.0%–123.0%). Diuron and terbuthylazine were the herbicides most frequently detected in the analyzed samples.     

An Effective High-Performance Liquid Chromatographic–Mass Spectrometric Assay for Catecholamines, as the N(O,S)-Ethoxycarbonyl Ethyl Esters, in Human Urine

The purpose of this study was to develop a simple and accurate analytical method for determination of norepinephrine, epinephrine, and dopamine in urine. The method involves liquid–liquid extraction then liquid chromatography–mass spectrometry (LC–MS). Alkyl chloroformate derivatives were prepared, as the N(O,S)-alkoxycarbonyl alkyl esters of the analytes, in the aqueous samples. The optimum derivatizing reagent for preparation of the N(O,S)-alkoxycarbonyl alkyl esters was chosen by comparing the efficiency of LC of the derivatized analytes after liquid–liquid extraction. The optimum conditions for liquid–liquid extraction from the aqueous matrix were pH 3.0, no salt, and diethyl ether as extraction solvent. Limits of detection (LOD) were 0.5 ng mL^?1 for dopamine and epinephrine and 0.1 ng mL^?1 for norepinephrine. Limits of quantification (LOQ) for urine samples were 1.0 ng mL^?1 for all three compounds. The precision of intra- and inter-day assays was 1.65–581 and 7.17–9.73% (relative standard deviation, RSD), respectively. The range of inaccuracy for intra- and inter-day assays was ?6.47 to 11.9% and ?7.5 to 7.76% (bias) at concentrations of 5 and 50 ng mL^?1, respectively.     

Simultaneous determination of ten anticoagulant rodenticides in tissues by column-switching UHPLC-ESI-MS/MS

This paper describes the development of a method for the simultaneous determination of ten anticoagulant rodenticides (coumafuryl, warfarin, pindone, coumatetralyl, coumachlor, difenacoum, bromadiolone, brodifacoum, chlorophacinone and flocoumafen) in the liver and kidney based on column-switching liquid chromatography coupled with heated electrospray ionization tandem mass spectrometry. The simple sample preparation includes extraction with methanol. A C₁₈ trapping column was used for online solid-phase extraction before analytical separation with the mobile phase comprising a mixture of 0.1 % formic acid in water, methanol and acetonitrile. Chromatographic separation was achieved using a Thermo Hypersil ultra high-performance liquid chromatography (UHPLC) C₁₈ column with the mobile phase consisting of 5 mM ammonium formate buffer (pH?=?9) and methanol. The column-switching procedure ensured no matrix effects during electrospray ionization (ESI). Extraction recoveries ranged between 91 and 100 % for liver and between 89 and 97 % for kidney. The method showed good linearity up to 750 ng g^?1. The limit of detection ranged between 0.001 and 0.022 ng g^?1 for liver and between 0.001 and 0.028 ng g^?1 for kidney. The developed method was successfully used in several animal poisoning cases.     

Preconcentration of trace cadmium ion using magnetic graphene nanoparticles as an efficient adsorbent

Graphene-based magnetic nanoparticles (G-Fe₃O₄) were prepared and used as an effective adsorbent for the solid-phase extraction of trace quantities of cadmium from water and vegetable samples. The method avoids some of the time-consuming steps associated with traditional solid phase extraction. The excellent sorption property of the G-Fe₃O₄ system is attributed to π - π stacking interaction and hydrophobic interactions between graphene and the Cd-PAN complex. The effects of pH, the amount of G–Fe₃O₄, extraction time, type and volume of eluent, desorption time and interfering ions on the extraction efficiency were optimized. The preconcentration factor is 200. Cd(II) was then quantified by flame atomic absorption spectrometry with a detection limit of 0.32 ng mL^?1. The relative standard deviation (at 50 ng mL^?1; for n?=?10) is 2.45 %. The method has a linear analytical range from 1.1 to 150 ng mL^?1, and the recoveries in case of real samples are in the range between 93.1 % and 102.3 %.

A Validated Method for the Determination of Neonicotinoid,Pyrethroid and Organochlorine Residues in Human Milk

Exposure to pesticides in the environment is sensitively indicated by the concentration of these chemicals in human milk. However, to the best of our knowledge, detection methods in human milk for the relatively new class of pesticides, neonicotinoids, are yet to be validated. We developed a method of detection of neonicotinoids in human milk, together with two other classes of pesticides, pyrethroids and organochlorines. Neonicotinoids and pyrethroids are emerging pesticides that are replacing older and more persistent chemicals such as organochlorines. We optimized a procedure for extraction of these chemicals from whole milk and report our solutions to the problems of interference by co-extracted substances. The clean-up method was optimized using a minimum amount of PSA (50 mg) and MgSO₄ (150 mg). This was followed by GC–MS/MS analysis (for organochlorines and pyrethroids) and LC–MS/MS (for neonicotinoids). The method was validated following SANTE/11945/2015 guidelines at concentrations 10, 20 and 100 ng g^?1. Limits of quantification were obtained at ≤ 2 ng g^?1 for all pesticides and lowest validated level were 10 ng g^?1, with measurement uncertainty between 0.47 and 2.6 ng g^?1. Average recovery ranged from 84 to 102% and for most compounds was found to be more satisfactory than the original QuEChERS, AOAC 2007.01 acetate buffer method and modified QuEChERS methods. The relative standard deviation was less than 16%. The method was successfully utilized for the analysis of human milk samples from Nadia, West Bengal and was found positive for organochlorines and negative for neonicotinoids and pyrethroids.     

Development of Immunoaffinity Sample-Purification for GC–MS Analysis of Ractopamine in Swine Tissue

A method combining immunoaffinity chromatography with gas chromatography–mass spectrometry (GC–MS) has been established for determination of ractopamine residues in swine liver and urine. After clean-up on an immunoaffinity chromatography column, GC–MS analysis revealed recovery from blank swine liver and urine fortified at 2.5–20 ng g^?1 (ng mL^?1 for urine), respectively, was 68.2–78.6 and 76.2–83.1%. The limits of detection and quantification were 0.5 ng g^?1 (or ng mL^?1) and 2.0 ng g^?1 (or ng mL^?1), respectively. The procedure was used for analysis of ractopamine residues in samples of swine liver and urine in which the levels were unknown. The amounts detected were 9–216 ng g^?1 (ng mL^?1).     

Simultaneous Determination of Fluoroquinolones and Sulfonamides in Chicken Muscle by LC with Fluorescence and UV Detection

A simple, rapid and sensitive liquid chromatographic method with programmable fluorescence and ultraviolet detection was developed and validated for simultaneous determination of seven fluoroquinolones (marbofloxacin, ofloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin and difloxacin) and four sulfonamides (sulfadiazine, sulfapyridine, sulfathiazole and sulfadimidine) in chicken muscle in a single run. The tissue sample was extracted with phosphate buffer (pH 6.0) and cleaned-up with a solid phase extraction cartridge. The mean recoveries for each drug in chicken muscle ranged from 78.0 to 105.2% with a relative standard deviation below 9.3% at 0.2–400 ng g^?1 fortification levels. The limit of quantification was 0.2–4.0 ng g^?1 for fluoroquinolones and 15.0 ng g^?1 for sulfonamides.     

Determination of Biogenic Amines in Cheese Using Simultaneous Derivatization and Microextraction Method Followed by Gas Chromatography–Mass Spectrometry

Microwave-assisted extraction and dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry as a sensitive and efficient method was applied to extract and determine four biogenic amines (BAs) in Iranian Lighvan cheese samples. Carrez solutions were used for the sedimentation of proteins. Effective factors on the performance of microextraction were studied and optimized. The proposed method showed good linear ranges from 5 to 500 ng mL^?1, with the coefficients of determination higher than 0.9929. Average recoveries were between 97 and 103%. Limits of detection for all analyzed BAs ranged from 5.9 to 14.0 ng g^?1, and limits of quantitation ranged between 19.7 and 46.2 ng g^?1. Compared with previous methods, the proposed method is simple, fast, accurate, and precise and gives low detection limits for investigating trace amounts of BAs in Iranian Lighvan cheese samples. The levels of four BAs were determined in five Lighvan cheese samples. Cadaverine was found as prevailing amine in the cheese samples. Putrescine, tyramine, and histamine were present at the second, third, and fourth highest levels, respectively.     

Quantification of Tacrolimus in Human Skin Samples and Ointment by LC-MS

A sensitive and simple liquid chromatography-mass spectrometry method was developed to determine the immunosuppressant tacrolimus in human skin samples after treatment with the commercially available ointment. Utilizing diffusion cell experiments according to Franz, human skin samples were treated with ointment containing tacrolimus and the extraction procedure of the drug was optimized. The analytical assay was performed using an LC system consisting of a reversed phase C₁₈ column and an isocratic mobile phase, coupled with electrospray ionization mass spectrometry. The detection was performed in the positive selected ion monitoring mode. Mycophenolate mofetil was used as internal standard to control the stability of the electrospray ionization. The calibration curve was linear for tacrolimus over the range of 5–1,000 ng mL^?1 (average correlation coefficient of r ² = 0.9941) with a limit of detection (LOD) of 2 ng mL^?1, with a limit of quantification (LOQ) of 5 ng mL^?1 and with a precision of 8.70%. The analytical assay described in this paper was successfully applied in order to quantify tacrolimus in human skin samples as well as in the commercially available ointment.     

Quantification of Imidacloprid in Honeybees: Development of a Chemiluminescent ELISA

A Chemiluminescent Enzyme-Linked Immuno-Sorbent Assay (CL-ELISA) for determination and quantification of the fungicide imidacloprid in honeybees was developed in an indirect competitive format. The assay was optimized by determining: the optimal coating conjugate concentration and anti-imidacloprid antiserum dilution, the effect of the incubation time on the competitive step, and the tolerance to organic solvents. The IC₅₀ and the limit of detection (LOD) values were 14.8 ng mL^?1 and 0.11 ng mL^?1, respectively, similar to those of colorimetric ELISA with a calibration range of 0.1–2600 ng mL^?1. Cross reactivity of some related compounds such as three imidacloprid metabolites, 6-chloro nicotinic acid, 5-hydroxy-imidacloprid, and imidacloprid olefin, and one other chloronicotinoid insecticide, acetamiprid, were tested. The assay was then applied to honeybee extracts obtained by using the liquid-liquid extraction. The calibration curves in honeybee extracts from the liquid-liquid procedure gave an IC₅₀ of 23.7 ng mL^?1 and a LOD 1.6 ng mL^?1. The average recovery value from honeybee extracts spiked with 100 and 1000 ng mL^?1 of imidacloprid were 73% and 76%, respectively. Finally, the assay was applied to honeybee samples collected during monitoring activities in Italy; it was found that only five of the 27 samples were positives, with low concentrations of imidacloprid ranging between 1.2 and 15.4 ng g^?1.     

Preconcentration of ultra-trace amounts of iron and antimony using ion pair solid phase extraction with modified multi-walled carbon nanotubes

Ion pair solid phase extraction was applied to the simultaneous preconcentration of iron and antimony. The ion pairs consisting of FeCl₄ ^? or SbCl₄ ^? anions and the benzyldimethyltetradecyl ammonium cation were formed on the surface of multi-walled carbon nanotubes, then eluted with nitric acid, and the elements finally quantified by ETAAS. The adsorption capacities of the impregnated MWCNTs are 9.2 mg g^?1 for iron and 27.5 mg g^?1 for antimony. The following analytical figures of merit were determined for iron and antimony, respectively: Enrichment factors of 210 and 230, assay precisions of ±5.3 % and ±4.8 %, linear calibration plots from 0.7 to 9.4 and 13.0 to 190 ng L^?1, and detection limits of 0.17 and 3.5 ng L^?1. The method was applied to the determination of iron and antimony in human hair, synthetic sample, and to the certified reference materials gold ore (MA-1b) and trace elements in water (SRM 1643d).

Ultrasensitive direct determination of BTEX in polluted soils using a simple and novel pressure-controlled solid-phase microextraction setup

A pressure-controlled headspace solid-phase microextraction (PC-HS-SPME) setup was developed, by reconsidering the strengths and weaknesses points of the similar reported systems. The new setup was coupled with gas chromatography–flame ionization detection (GC–FID) for direct analysis of benzene, toluene, ethylbenzene and xylene (BTEX) in contaminated soils, without any sample preparation step. The important experimental factors, affecting the performance of the method, including volumes of extraction and vacuum vials, type of SPME fiber, extraction time and temperature, moisture content of the sample, and sonication time were studied and optimized. Under the optimal conditions, good linearity of the calibration curves (R² > 0.997) was obtained in the concentration range of 0.1–20,000 ng g^?1. The limits of detections were found to be 0.001–0.08 ng g^?1. The relative standard deviations, for six repetitive analyses of 100 ng g^?1 BTEX, were obtained to be 5.7–12.3%. The PC-HS-SPME–GC–FID procedure was successfully applied for the extraction and determination of BTEX in the polluted soil samples.     

LC-Fluorescence Detection of Abamectin, Ivermectin, Doramectin, and Eprinomectin in Rabbit Feces

A simple multi-residue method was developed for the simultaneous determination of abamectin, ivermectin, doramectin, and eprinomectin in rabbit feces. Samples were extracted with acetonitrile, cleaned up with a C18 solid-phase extraction cartridge, and analysed by LC with fluorescence detection after derivatization. Abamectin, ivermectin, doramectin, and eprinomectin were detected at levels of 2–500 ng g^?1; the average recoveries ranged from 73.2 to 99.6% with relative standard deviations of 2.5–11.3%. The limits of detection were 0.1–0.4 ng g^?1.     

Accurate Determination of Tributyltin in Tannery Wastewater by a New Procedure Using ID-HPLC–ICP-MS Combined with Low Temperature Extraction

Isotope dilution mass spectrometry is recognized as a primary method to obtain traceable values in the measurement of substances including trace elements and their organometallic compounds. This paper reports a novel method where isotope dilution high performance liquid chromatography inductively coupled plasma mass spectrometry (ID-HPLC–ICP-MS) was combined with low temperature extraction for the determination of tributyltin (TBT) in tannery wastewater from the leather industry. It has been found that the liquid–liquid extraction at very low temperature is in the favor of extraction of organotin, as the enrichment factor for low temperature (?80 °C) extraction was about 1.3 times higher than for extraction at room temperature (20 °C). The method detection limit of TBT, obtained from the proposed ID-HPLC–ICP-MS procedure after extraction with a sample volume of 7.5 by 2.5 mL of organic phase, was found to be 0.13 ng g^?1. When TBT was determined in a range of 10–1000 ng g^?1 in tannery wastewater samples, the analyte recoveries were in the range 90.1–107.2% with relative standard deviations of between 2.0 and 7.2%. Finally, the new method of ID-HPLC–ICP-MS combined with low temperature extraction was applied to the determination of TBT in actual tannery wastewater. The TBT contents from three different tanning procedures (chrome tanning, vegetable tanning and aldehyde tanning), expressed as the mean ± the expanded uncertainty (k = 2) were 378.65 ± 20.38, 110.04 ± 5.96 and 690.17 ± 35.31 ng g^?1, respectively.     

Determination of Meserine,a new candidate for Alzheimer’s disease in mice brain by liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic and tissue distribution study

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of Meserine ((?)-meptazinol phenylcarbamate), a novel potent inhibitor of acetylcholinesterase (AChE), was developed, validated, and applied to a pharmacokinetic study in mice brain. The lower limit of quantification (LLOQ) was 1 ng mL^?1 and the linear range was 1–1,000 ng mL^?1. The analyte was eluted on a Zorbax SB-Aq column (2.1?×?100 mm, 3.5 μm) with the mobile phase composed of methanol and water (70:30, v/v, aqueous phase contained 10 mM ammonium formate and 0.3 % formic acid) using isocratic elution, and monitored by positive electrospray ionization in multiple reaction monitoring (MRM) mode. The flow rate was 0.25 mL min^?1. The injection volume was 5 μL and total run time was 4 min. The relative standard deviation (RSD) of intraday and interday variation was 2.49–7.81 and 3.01–7.67 %, respectively. All analytes were stable after 4 h at room temperature and 6 h in autosampler. The extraction recoveries of Meserine in brain homogenate were over 90 %. The main brain pharmacokinetic parameters obtained after intranasal administration were T _max?=?0.05 h, C _max?=?462.0?±?39.7 ng g^?1, T _1/2?=?0.4 h, and AUC_(0-∞)?=?283.1?±?9.1 ng h g^?1. Moreover, Meserine was distributed rapidly and widely into brain, heart, liver, spleen, lung, and kidney tissue. The method is validated and could be applied to the pharmacokinetic and tissue distribution study of Meserine in mice.