Multiwalled carbon nanotubes as a solid-phase extraction adsorbent for the determination of three barbiturates in pork by ion trap gas chromatography-tandem mass spectrometry (GC/MS/MS) following microwave assisted derivatization.

A new method was developed for the rapid screening and confirmation analysis of barbital, amobarbital and phenobarbital residues in pork by gas chromatography-tandem mass spectrometry (GC/MS/MS) with ion trap MSD. The residual barbiturates in pork were extracted by ultrasonic extraction, cleaned up on a multiwalled carbon nanotubes (MWCNTs) packed solid phase extraction (SPE) cartridge and applied acetone-ethyl acetate (3:7, v/v) mixture as eluting solvent and derivatized with CH3I under microwave irradiation. The methylated barbiturates were separated on a TR-5MS capillary column and detected with an ion trap mass detector. Electron impact ion source (EI) operating MS/MS mode was adopted for identification and external standard method was employed for quantification. One precursor ion m/z 169 was selected for analysis of barbital and amobarbital and m/z 232 was selected for phenobarbital. The product ions were obtained under 1.0 V excitation voltage. Good linearities (linear coefficient R > 0.99) were obtained at the range of 0.5-50 microg kg(-1). Limit of detection (LOD) of barbital was 0.2 microg kg(-1) and that of amobarbital and phenobarbital were both 0.1 microg kg(-1) (S/N > or = 3). Limit of quantification (LOQ) was 0.5 microg kg(-1) for three barbiturates (S/N > or = 10). Satisfying recoveries ranging from 75% to 96% of the three barbiturates spiked in pork were obtained, with relative standard deviations (R.S.D.) in the range of 2.1-7.8%.

[Ultraviolet spectrophotometric determination of psychotropic drug mixtures]. / Psichotropiniu vaistu misinio tyrimas ultravioletines spektrofotometrijos metodu.

The mixture of psychotropic drugs aminazine, barbamylum and nitrazepam using ultraviolet (UV) spectrophotometric method was researched. As the solvent, most acceptable for identification and differentiation of these preparation was found 0.1N solution of sulphuric acid. By measuring the optical density of the solutions in different concentration the calibration diagrams for all preparations were made. The standard deviation, by determining the quantity of aminazine is 2.8; 4.0; 4.3; barbamylum--1.0; 2.5; 1.15; nitrazepam--2.64; 1.0; 1.35.

[Poisonings with psychotropic drug mixtures: analysis using the thin-layer chromatography method]. / Apsinuodijimu psichotropiniu vaistu misiniu tyrimas plonasluoksnes chromatografijos metodu.

It is observed increase in number of remedy intoxications in Lithuania, especially important is intoxication with psychotropic drugs and their mixtures. The thin-layer chromatography (TLC) method was proposed for separation and identification of drugs in mixture aminazine: nitrazepam: barbamylum. The mixture of these drugs excreted from body fluids (blood and urine) was investigated by TLC. Most acceptable these mobile phases: 1. Diethyl ether: dioxane--40:60. Rf values for drugs: aminazine 0.23-0.25; barbamylum 0.85-0.9; nitrazepam 0.75-0.8. 2. Diethyl ether: NH3 (25%): benzenum--80:10:10. Rf values for drugs: aminazine 0.55-0.58; barbamylum 0.32-0.35; nitrazepam 0.17-0.2.

[Determination of three principal components in chuanjing tablets by using high performance liquid chromatography].

Uniform design method was employed to optimize the mobile phase of HPLC in order to determine simultaneously three principal components, theophylline, amobarbital and methylephedrine hydrochloride, in Chuanjing tablet, a compound preparation for asthma and cough. The stationary phase was ODS and the optimal mobile phase composition was V (0.015 mol/L phosphate buffer containing 0.3% triethylamine, pH 4.9): V (methanol) = 35:65. The detection was performed at 215 nm and the sensitivity was time programmed for simultaneous determination of minor and major components. Caffeine was selected as the internal standard. A baseline separation was achieved within 10 min. The linear ranges for theophylline, amobarbital and methylephedrine hydrochloride were 0.03 g/L-0.20 g/L, 7.5 mg/L-50.0 mg/L and 7.5 mg/L-50.0 mg/L, recoveries 99.7%-102.6%, 98.5%-100.2% and 98.0%-102.7%, inter-day RSDs 0.23%-1.2%, 0.35%-2.5%, 0.33%-1.6% respectively. This HPLC method is rapid and accurate, and suitable for the quality control of the preparation.

Identification of 5-ethyl-5-(2-methylbutyl)barbituric acid as an impurity of manufacture in amobarbital.

Amobarbital [5-ethyl-5-(3-methylbutyl)barbituric acid], USP, was found to contain an impurity that was not associated with hydrolysis and decomposition of the barbiturate ring. The impurity was isolated by semipreparative HPLC and was identified as 5-ethyl-5-(2-methylbutyl)barbituric acid (1) by MS (electron impact and chemical ionization) and 1H NMR. The substitution pattern on the alkyl side chain was verified by using the achiral NMR shift reagent tris(6,6,7,7,8,8,8-heptafluoro-2,2- dimethyl-3,5-octanedionato)europium(III). Older samples of amobarbital, USP, contained greater than 6% of 1, whereas recent samples of amobarbital, USP, contained less than 1% of 1. Because the pharmacological profiles of 1 and amobarbital in rodents are comparable, the impurity probably does not constitute a clinically significant problem for humans.

Fourier transform infrared analyses of some particulate drug mixtures using a diamond anvil cell with a beam condenser and an infrared microscope.

Although the diamond anvil cell (DAC) has been used in many forensic science laboratories for the analysis of trace evidence, few applications of this technique for the analysis of controlled substances have been reported. This may be due to both an unfamiliarity on the part of forensic drug chemists with this accessory and the nature and quality of spectra that result from use of a DAC on a dispersive instrument. Along with low energy throughput, which results in relatively high noise levels, strong broad diamond absorptions occur. With the use of a Fourier transform infrared instrument, these do not present a problem and nanogram quantities of materials can be analyzed when the DAC is used with an infrared microscope. Since single crystals can be sampled with the DAC, simple physical separations (involving particle-picking) can be used in certain cases to isolate drugs from particulate mixtures for infrared analysis. This method is especially useful for some "difficult" mixtures and residues, and several examples of such analyses involving samples of forensic science interest are presented.

Liquid chromatographic determination of barbiturates using a hollow-fibre membrane for postcolumn pH modification.

A sensitive, high-performance liquid chromatographic method is described for the determination of barbiturates by postcolumn pH modification. The barbiturates (barbital, phenobarbital, hexobarbital and amobarbital) were separated on a C18 column using a mixture of methanol and water as an eluent. Then the pH of the eluent was raised to 10 by introducing ammonia or ammonium ion through a sulphonated hollow-fibre membrane inserted between the column and the detector. The detection was based on the primary ionized barbiturates at 240 nm. At barbiturate concentrations of 2.0 micrograms/ml, the within- and between-experiment precision (relative standard deviation) was 0.65-3.28 and 0.76-1.90%, respectively. The limits of detection were about 0.5-2.5 ng at a signal-to-noise ratio of 3. The method was applied to the determination of amobarbital in saliva.

Postmortem stability of barbiturates in blood and tissues.

The stability of five commonly prescribed barbiturates and thiopental in blood and liver at room temperature and at 4 degrees C was studied. Gas chromatography was used for oxybarbiturate analysis while liquid chromatography was used to quantitate thiopental. In blood and liver, greater than 75% of the drugs were detected at the end of the two- to three-month period. These changes were not considered significant; therefore, barbiturates appear to be stable in blood and liver under the conditions of these experiments.

Direct derivatization and gas chromatographic determination of barbiturates in autopsy liver tissues.

A new gas chromatographic procedure is presented for the determination of barbiturates in autopsy tissues (liver and blood). The barbiturates are separated from the interference of co-extracted, free fatty acids in an acid-catalyzed methylation of the fatty acids and quantified as the N,N-dimethyl derivatives following reaction with dimethyl sulphate. Derivatization and recovery are shown to be simple, efficient procedures leading to substantially higher analytical results.

Analysis of trace amounts of barbiturates in saliva.

A simple gas chromatographic method is presented for the determination of trace quantities (0.1-1.0 microgram/ml) of amobarbital, pentobarbital and phenobarbital in saliva. The barbiturate is extracted with chloroform, alkylated with bis(2-chloroethyl) sulphate, and quantified using a non-polar (SE-30) column and electron-capture detection. The procedure has been applied to the determination of the salivary half-lives of amobarbital and, for the first time, pentobarbital following administration of the drugs to human volunteers. The scale and sensitivity of detection are suitable for use in forensic or other medico-legal work.

[Demonstration of hypnotic agents in bone tissue]. / Altatószerkimutatás csontszövetböl.

Investigating the skeletons of 25 suicide victims the authors have found that the toxic materials taken can rather comfortably and safely be detected in the compactbony substance. Especially important that the poisonous drug residues can remain in the bones for a long time, even for years after death.

UV spectrophotometric determination of aminophylline, amobarbital, and ephedrine hydrochloride in an antiasthma capsule preparation.

A simple and rapid procedure for the determination of aminophylline, amobarbital, and ephedrine hydrochloride in a capsule preparation is described. Aminophylline and amobarbital are determined simultaneously using differential UV spectrophotometry; ephedrine hydrochloride is determined separately after elution from an alginic acid column with 0.1 N hydrochloric acid.

N-hydroxyamobarbital: the second major metabolite of amobarbital in man.

After oral administration of 14C-labeled amobarbital to healthy subjects, most of the radioactivity was recovered in urine and only 4-5% in feces over a period of 6 days. No unchanged amobarbital was excreted. Two major metabolites were found and isolated. One was 3'-hydroxyamobarbital, which has been previously identified by Maynert. The second could be identified as N-hydroxyamobarbital on the basis of its spectral and chemical properties.

Column chromatographic analysis of barbiturates in their dosage forms. II. secobarbital, amobarbital, and pentobarbital.

A general method for the analysis of barbiturates, using column parition chromatography, was extended to the assay of secobarbital, amobarbital, and pentobarbital. A solution of the barbiturate constitutes the immobile phase in the chromatographic system. It is eluted with ether-isooctane (1+9) and passed onto a K3PO4 column, which retains the barbiturate while extraneous materials are washed out. The barbiturate is removed from the column with etherisooctane (3+1), extracted from the eluate with NH3, and measured spectrophotometrically.