ABSTRACT
Attention-deficit/hyperactivity disorder (ADHD) is male predominated, and the etiology of this disorder remains unclear. Past studies have assessed the association of low-level organophosphate pesticide exposure with childhood ADHD cross-sectionally and prospectively. However, the results have been inconsistent. A first case-control study was performed to investigate the relationship between organophosphate pesticide exposure and ADHD with adjusted covariates. We recruited 97 doctor-diagnosed ADHD cases and 110 non-ADHD controls who were 4-15 years of age. Exposure was assessed using urinary levels of dialkylphosphate metabolites, which are biomarkers of OP pesticide exposure. Blood lead levels and polymorphisms of two commonly verified dopaminergic-related genes (the D4 dopamine receptor gene DRD4 and the dopamine transporter gene DAT1) were also analyzed. The sociodemographics and lifestyles of the children and of the mothers during pregnancy were collected using a questionnaire. The blood lead levels of both groups were similar (1.57 ± 0.73 vs. 1.73 ± 0.77 µg/dL, p = 0.15). Significant urinary concentration differences in one of the six dialkylphosphate metabolites, dimethylphosphate (DMP), were found between ADHD and control subjects (322.92 ± 315.68 vs. 224.37 ± 156.58 nmol/g cr., p < 0.01). A dose-response relationship was found between urinary concentrations of DMP and ADHD in both crude and adjusted analyses (p for trend<0.05). Children with higher urinary DMP concentrations may have a twofold to threefold increased risk of being diagnosed with ADHD. We report a dose-response relationship between child DMP levels and ADHD. Organophosphate pesticide exposure may have deleterious effects on children's neurodevelopment, particularly the development of ADHD.
Subject(s)
Attention Deficit Disorder with Hyperactivity/etiology , Environmental Exposure/adverse effects , Organophosphates/toxicity , Pesticides/toxicity , Adolescent , Attention Deficit Disorder with Hyperactivity/chemically induced , Attention Deficit Disorder with Hyperactivity/genetics , Attention Deficit Disorder with Hyperactivity/metabolism , Biomarkers/urine , Case-Control Studies , Child , Child, Preschool , Dopamine Plasma Membrane Transport Proteins/genetics , Dose-Response Relationship, Drug , Female , Humans , Lead/blood , Male , Organophosphorus Compounds/urine , Polymorphism, Single Nucleotide , Receptors, Dopamine D4/genetics , Risk Factors , TaiwanABSTRACT
A rapid liquid chromatography-electrospray mass spectrometry (LC-ES-MS) method with in vivo microdialysis for the determination of free-form of cocaine (COC) in rat brain has been developed. A C18 column and a gradient elution were employed for the separation. The [M+H]+ (m/z=304) and a fragmented ion (m/z=182) were detected using positive ion mode detection. Selective ion monitoring was utilized for quantitative measurement. The linearity of this assay was good ranging from 0.01 to 1.0 microM (r2=0.999). The inter- and intra-day precisions showed relative standard deviations ranging from 1.0% to 3.3% and 1.0% to 3.6%, respectively. In addition, the detection of one COC metabolite, benzoylecgonine (BE), by this assay was also investigated. The linearity, precision, and detection limit associated with this method for BE were determined. The application of this newly developed method was demonstrated by examining the pharmacokinetics of COC in rat brain.
Subject(s)
Brain/metabolism , Chromatography, High Pressure Liquid/methods , Cocaine/metabolism , Spectrometry, Mass, Electrospray Ionization/methods , Animals , Cocaine/chemistry , Cocaine/pharmacokinetics , Rats , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
This paper describes a newly developed liquid chromatography-electrospray-mass spectrometry (LC-ES-MS) method for the quantitative determination of nine commonly used sulfonamides (sulfadiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamonomethoxine, sulfisoxazole, sulfadimethoxine, sulfaquinoaline and sulfaphenazole) in meat. [M+H](+) and [M+Na](+) were the two major ions detected in positive ion mode. Selective ion monitoring was employed for quantitative determination. Satisfactory linearity, 0.1-10 mugml(-1), of each compound was obtained. Blank meat samples were fortified at levels between 50 and 500 mugkg(-1). [Phenyl-(13)C6]sulfamethazine was used as internal standard. Sulfonamides were isolated from meat with a solvent extraction procedure and then determined by LC-ES-MS. The limits of detection were below 10 mugkg(-1). The application of this newly developed method was demonstrated by analyzing various beef, pork and chicken samples from local markets.
ABSTRACT
This paper describes a newly developed liquid chromatography-electrospray-mass spectrometry (HPLC-ES-MS) method for the determination of 13 antibacterial reagents (olaquindox, trimethoprim, clopidol, ormethoprim, morantel, carbadox, thiamphenicol, pyrimethamine, furazolidone, oxolinic acid, difurazon, nalidixic acid, piromidic acid). The optimization for the detection of these compounds by HPLC-ES-MS was investigated. A C(18) column with gradient elution was utilized for the separation of thirteen antibacterial chemicals. Collision induced dissociation (CID) was used to induce fragmentation of analyte molecules and enhance the specificity of the method. Selective ion monitoring (SIM) was employed for quantitative determination. The detection limit of this method proved to be much better than previously reported ones. Satisfactory linearity, 0.5-10 ppm, of each compound was obtained. A solvent extraction method to extract analyte compound from pork was developed. The application of this newly developed method was demonstrated by analyzing antibacterial reagent added pork samples.
ABSTRACT
A rapid liquid chromatography-electrospray mass spectrometry (LC-ES-MS) assay for the determination of flunarizine (FZ) in rat brain has been developed. A C18 column and an isocratic elution were employed for the separation. Using post-column split, 64% of the eluent was introduced into the ES-MS system for detection. The [M+H]+ (m/z 406) and a fragmented ion (m/z 203) were detected using selected ion monitoring. The linear range of this assay was good, ranging from 0.05 to 5 microM (r2=0.99). The intra- and inter-day precisions showed relative standard deviations ranging from 1.4% to 2.0% and 1.3% to 2.9%, respectively. The application of this newly developed method was demonstrated by examining the pharmacokinetics of FZ in rat brain.
Subject(s)
Brain Chemistry , Calcium Channel Blockers/analysis , Chromatography, Liquid/methods , Flunarizine/analysis , Histamine H1 Antagonists/analysis , Mass Spectrometry/methods , Animals , Brain/metabolism , Flunarizine/pharmacokinetics , Male , Quality Control , Rats , Rats, Sprague-Dawley , Sensitivity and SpecificityABSTRACT
A study of liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) for the determination of methylamphetamine and related compounds (amphetamine, ephedrine, phenylpropanolamine) in human urine was undertaken. We assessed the effect of collision induced dissociation (CID) spectra generated by varying exit voltage of capillary and skimmer. The responses of ES/MS in different mobile phase and the effects of mobile phase modifier were examined. An isocratic LC method using methanol/water (80/20) and acetic acid (0.001%) as a modifier to separate these compounds was developed. Microporous ultrafiltration technique was employed to pre-treat urine sample prior to LC/ES/MS analysis. Good recoveries for methylamphetamine and amphetamine were determined as well as linearity, detection limit and precision associated with this method were determined. Drug spiked urine samples and urine samples of methylamphetamine addicts were successfully measured by this newly developed method.
ABSTRACT
This paper describes a newly developed high performance liquid chromatography/electrospray/mass spectrometry (HPLC/ES/MS) method for the determination of flunarizine (FZ) in artificial cerebrospinal fluid. The optimization for the detection of FZ in biological fluid by LC/ES/MS was investigated. The effects of solvent composition, the addition of modifier and flow rate on the detection of FZ by ES/MS were examined. The detection limit of this method ( approximately 0.8 nM) proved to be much better than previously reported methods. Satisfactory accuracy (98.2-106.0%) of this newly developed method was obtained. The application of this method was demonstrated by analyzing FZ in rat microdialysis samples.
ABSTRACT
This article describes a newly developed method of gas chromatography (GC) for the rate study of the reduction of organic compounds by samarium iodide. Solvent extraction was used to reduce the interference of GC analysis by inorganic species. Adequate recoveries ranged from 88.3 to 94.5 % and good linearity ranging from 0.1 to 2.1 mM was determined. An internal standard, decane, was used to enhance the precision of this test. The coefficient variations of intra-day and inter-day ranged from 0.22 to 3.00%. The stability of the reacted sample was also assessed. In addition, the reaction rates of the reduction of 2-heptanone by samarium iodide in the presence of hexamethylphosphoramide were examined. The results presented hererin demonstrate the utility of this method in kinetic studies.
ABSTRACT
A preparative supercritical fluid extraction system is described and was used with supercritical carbon dioxide to extract the active insecticide components pyrethrin I (PI) and pyrethrin II (PII) successfully from pyrethrum flower. A high-performance liquid chromatography method was developed and was used to separate and analyze the supercritical carbon dioxide extracts. Extraction efficiencies under several different extraction conditions were examined. Under the conditions examined, the most effective extractions of PI and PII (140 +/- 18 mg and 55 +/- 9 mg per 100 g of dry pyrethrum flower powder) were performed at 40 degrees C and 1200 psi. The results showed that extraction efficiencies of supercritical carbon dioxide are much better than those of n-hexane for pyrethrins I and II. During the extraction process, the most efficient extraction period was the first 3 h of the experiment.
ABSTRACT
Poly(p-phenylene benzoxazole), PBO, is a rigid rod polymer which is polymerized in polyphosphoric acid. Oriented POB film shows good mechanical strength, excellent thermal stability and solvent resistance, and low dielectric constant. The measurement of residual phosphorus in the film is necessary since residual phosphorus may impact the physical and electrical properties of the film. A rapid and non-destructive XRF method has been developed for the analysis of residual phosphorus content in PBO thin films (0.1-2 mil). The XRF method demonstrated good linearity over the range of 150-4100 ppm, with a detection limit of ca 40 ppm. The residual phosphorus in several PBO thin film samples was also measured using NMR spectroscopy, and excellent agreement with the XRF analysis was obtained.
