Biomedical subjects

X P Lee

Publications and source records attributed to X P Lee.

8 recordsLinked to original sources

PubMed1999

Analysis of methanol or formic acid in body fluids by headspace solid-phase microextraction and capillary gas chromatography.

Methanol and its metabolite formic acid have been found extractable from human whole blood and urine by headspace solid-phase microextraction (SPME) with a Carboxen/polydimethylsiloxane fiber. The headspace SPME for formic acid was carried out after derivatization to methyl formate under acidic conditions. The determinations of both compounds were made by using acetonitrile as internal standard (IS) and capillary gas chromatography (GC) with flame ionization detection. The headspace SPME-GC gave sharp peaks for methanol, methyl formate and I.S.; and low background noises for whole blood and urine samples. Extraction efficiencies were 0.25-1.05% of methanol and 0.38-0.84% formic acid for whole blood and urine. The calibration curves for methanol and formic acid showed excellent linearity in the range of 1.56 to 800 and 1.56 to 500 microg/0.5 ml of whole blood or urine, respectively. The detection limits were 0.1-0.5 microg/0.5 ml for methanol and 0.6 microg/0.5 ml for formic acid for both body fluids. The within-day relative standard deviations in terms of extraction efficiency for both compounds in whole blood and urine samples were not greater than 9.8%. By using the established SPME method, methanol and formic acid were successfully separated and determined in rat blood after oral administration of methanol.

Acetonitriles↗

PubMed1999

Improved extraction of thinner components from human body fluids by headspace solid-phase microextraction with a Carboxen/polydimethylsiloxane-coated fiber.

An improved method for extraction of thinner components in human whole blood and urine samples by headspace solid-phase microextraction (SPME) with a Carboxen/polydimethylsiloxane-coated fiber is presented. The body fluid samples, containing ethyl acetate, benzene, 1-butanol, toluene, butyl acetate, isoamyl acetate and ethylbenzene as internal standard (IS), were heated at 70 degrees C in a silicone-rubber septum-capped vial in the presence of distilled water plus NaCl; a Carboxen/polydimethylsiloxane-coated SPME fiber was then exposed to the headspace of the vial to allow adsorption of the compounds before capillary gas chromatography (GC) with flame-ionization detection. For whole blood, extraction efficiencies of 1-butanol, ethyl acetate and isoamyl acetate were 8.72-31.1%, and those of IS, butyl acetate, toluene and benzene were 42.9-74.1%. For urine, those of all compounds were 10.7-75.4%. The regression equations for six thinner components extracted from whole blood and urine were linear in the range of 3-500 ng/0.5 ml for ethyl acetate and 1-butanol, and 0.5-500 ng/0.5 ml for benzene, toluene, butyl acetate and isoamyl acetate. The detection limits for each of the components were 0.25-1.5 ng/0.5 ml for both samples. The coefficients of within-day and day-to-day variation for all components were satisfactory and not greater than 11 and 13%, respectively. The data obtained from actual determination of ethyl acetate, benzene and toluene in rat whole blood and urine after inhalation of the compounds were also presented.

Journal Article↗

PubMed1998

Determination of solvent thinner components in human body fluids by capillary gas chromatography with trapping at low oven temperature for headspace samples.

A simple and sensitive method is presented for determination of solvent thinner components in human body fluids by capillary gas chromatography (GC) with a low oven temperature for trapping headspace vapor components. After heating a blood or urine sample containing ethyl acetate, benzene, butan-1-ol, toluene, butyl acetate, isoamyl acetate and ethylbenzene (internal standard) in a 7.5 ml vial at 90 degrees C for 30 min, 5 ml of headspace vapor were drawn into a glass syringe. All vapor was introduced through an injection port in the splitless mode into a DB-624 medium-bore capillary column at a 5 degrees C oven temperature for trapping the volatile compounds, and the oven temperature was programmed up to 110 degrees C for their detection by GC. These conditions gave sharp peaks, a good separation of each peak and low background noise for both whole blood and urine samples. As much as 3.58-55.1 and 3.52-57.9% of the six compounds, which had been added to vials, could be introduced to the GC instrument for whole blood and urine, respectively. The intra-day RSD values in terms of the introduction rate (net recovery) of the six compounds in whole blood and urine samples were < or = 8.1%. The calibration curves showed linearity in the range 0.78-400 ng per 0.5 ml whole blood or urine. The detection limits were 0.5-5 ng per 0.5 ml. The data on toluene in post mortem blood in an actual case are also presented.

Adult↗

PubMed1997

Detection of tricyclic antidepressants in whole blood by headspace solid-phase microextraction and capillary gas chromatography.

A simple method for the extraction of four tricyclic antidepressants from whole blood by headspace solid-phase microextraction (SPME) is presented. The whole blood samples contain four drugs (amitriptyline, chlorimipramine, imipramine, and trimipramine) and are heated at 100 degrees C in a septum-capped vial in the presence of distilled water and NaOH solution; a polydimethylsiloxane-coated SPME fiber is exposed to the headspace of the vial to allow adsorption of the drugs before capillary gas chromatography (GC) with flame-ionization detection. The headspace SPME-GC produces intense peaks for each drug with very little background noise. Recoveries of the four drugs by the present method are 5.3-12.9%. The calibration curves for the drugs show linearity in the range of 31-1000 ng/0.5 mL. The detection limits of each drug are 16-25 ng/0.5 mL. Imipramine is detectable from rat blood 5 h after oral administration of imipramine (500 mg/kg body weight); the concentration is 1.44 +/- 0.209 micrograms/mL.

Amitriptyline↗

PubMed1995

Rapid extraction and capillary gas chromatography for diazine herbicides in human body fluids.

A simple and rapid method for the extraction of four diazine herbicides (terbacil, bromacil, norflurazon and PAC) from human whole blood, plasma and urine with use of Bond Elut C18 cartridges is presented. Whole blood, plasma and urine samples containing the herbicides, after mixing with distilled water, were loaded on Bond Elut C18 cartridges and the herbicides were eluted with chloroform/methanol (9:1). They were detected by capillary gas chromatography with flame ionization detection (FID) with splitless injection. Separation of the four diazine herbicides from each other and from impurities was generally satisfactory with the use of an intermediately polar DB-17 capillary column. The recovery of all compounds, which had been added to whole blood, plasma and urine, was > 89%. The calibration curve for the herbicides, which has been added to whole blood, plasma and urine, showed linearity in the range 1.6-100 ng on column. Their detection limits were 1.2-1.4 ng on column for whole blood and plasma, and 1.1-1.2 ng on column for urine.

Bromouracil↗

PubMed1995

A simple analysis of 5 thinner components in human body fluids by headspace solid-phase microextraction (SPME).

A simple method for the extraction of 5 thinner components from human whole blood and urine, using the headspace solid-phase microextraction (SPME) method is presented. After heating a vial containing the samples with 5 compounds (toluene, benzene, n-butyl acetate, n-butanol and n-isoamyl acetate) at 80 degrees C, a polydimethylsiloxane-coated SPME fiber was exposed to the headspace of the vial to allow adsorption of the compounds. The fiber needle was then injected into a capillary gas chromatography (GC) port. The headspace SPME-GC gave intense peaks for each compound and a low level of background noise was seen only for whole blood. Recovery rates of the 5 compounds by use of the headspace SPME-GC were 50-70%. Reproducibility for headspace SPME-GC data were excellent for both body fluids. The calibration curves showed linearity in the range 2-100 ng/0.5 ml whole blood or urine. The detection limits of each compound were 1.1-2.4 ng/0.5 ml sample. The present results on the analysis of 5 thinner components by headspace SPME-GC suggest its applicability to a number of other volatile compounds in forensic toxicology.

1-Butanol↗

PubMed1993

Sex differences in respiratory and cardiovascular effects of beta-endorphin.

An attempt was made to determine sex differences in the effects of beta-endorphin (beta-EP) on respiratory and cardiovascular systems using Wistar rats. By the intracerebroventricular administration of beta-EP (0.18 mg/kg) to normal male and female rats, respiratory rate (RR), heart rate (HR) and mean arterial blood pressure (MABP) were depressed significantly (p < 0.01 or 0.001) and CO2 in expired gas increased significantly (p < 0.01). These suppressive effects of the peptide were transiently blocked by the intravenous injection of naloxone (0.2 mg/kg). No differences in the effects of beta-EP between estrous and diestrous female rats could be detected. The effects of the peptide were significantly stronger in RR, HR and MABP for females than for males (0.001 < p < 0.05). Testectomized rats showed suppressive effects of the peptide to the same extent as intact females, but the effects in ovariectomized rats did not differ from those for intact females. In testectomized and ovariectomized rats treated with testosterone, the former showed the same results as intact males, but not the latter. The suppressive effects of beta-EP on the respiratory and cardiovascular systems are thus remarkably relieved by androgen in male rats.

Animals↗

PubMedDate not supplied

Sensitive determination of n-hexane and cyclohexane in human body fluids by capillary gas chromatography with cryogenic oven trapping.

A sensitive method was developed for determination of n-hexane and cyclohexane in human body fluids by headspace capillary gas chromatography (GC) with cryogenic oven trapping. Whole blood and urine samples containing n-hexane and cyclohexane were heated in a 7.5 mL vial at 70 degrees C for 15 min, and 5 mL of the headspace vapor was drawn into a glass syringe. All vapor was introduced through an injection port of a GC instrument in the splitless mode into an Rtx-Volatiles middle-bore capillary column at an oven temperature of -40 degrees C for trapping volatile compounds. The oven temperature was programmed to 180 degrees C for GC with flame ionization detection. These conditions gave sharp peaks for both n-hexane and cyclohexane, a good separation of each peak, and low background impurities for whole blood and urine. The extraction efficiencies of n-hexane and cyclohexane were 13.2-30.3% for whole blood and 12.7-20.7% for urine. The coefficients of within-day variation in terms of extraction efficiency of both compounds were 5.0-9.5% for whole blood and 3.8-10.8% for urine; those of day-to-day variation for the compounds were not greater than 16.6%. The regression equations for n-hexane and cyclohexane showed good linearity in the range of 5-500 ng/0.5 mL for whole blood and urine. The detection limits (signal-to-noise ratio = 3) for both compounds were 1.2 and 0.5 ng/0.5 mL for whole blood and urine, respectively. The data on n-hexane or cyclohexane in rat blood after inhalation of each compound are also presented.

Animals↗