Electron capture gas chromatographic analysis of the amine metabolites of pesticides: derivatization of anilines

Analysis of polycyclic aromatic hydrocarbons, phenols and aromatic amines in particulate phase cigarette smoke using simultaneous distillation and extraction as a sole sample clean-up step

Polycyclic aromatic hydrocarbons (PAHs), phenols and aromatic amines can be analyzed in particulate phase mainstream cigarette smoke using simultaneous distillation and extraction (SDE) as a unique sample clean-up step. All analytes are determined from the same smoke sample using GC-MS. The smoke from 20 cigarettes is collected on a Cambridge smoke pad where a mixture of internal standards is added. The Cambridge smoke pad is extracted in a SDE apparatus using water-CH2Cl2. The SDE extract is analyzed directly for PAHs, for phenols after silylation, and for amines after derivatization with heptafluorobutyric anhydride. Excellent results in agreement with data reported in the literature are obtained by this procedure.

Gas chromatographic determination of aromatic amines in water samples after solid-phase extraction and derivatization with iodine. I. Derivatization

A new method for the selective determination of aromatic amines is presented, which is based on the solid-phase extraction at pH 9 and subsequent derivatization of the analytes to the corresponding iodobenzenes. These can selectively and sensitively be determined with gas chromatography and electron-capture detection. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were investigated, and only in six cases no derivatives were obtained. Limits of quantitation were between 0.5 and 8 micrograms 1(-1), but may still be lowered with higher sample volumes or different injection techniques. The application to water samples revealed the suitability for the investigation of ground, leachate and wastewater.

Derivatization reactions for the determination of amines by gas chromatography and their applications in environmental analysis

The environmental analysis of amines is important to preserve human health because these compounds often have toxic effects. Gas chromatography (GC) of free amines is generally unsatisfactory owing to the adsorption and decomposition of the solutes on the column. Derivatization of amines is employed to reduce the polarity and to improve the GC properties. Derivatization reactions for the determination of amines by GC are reviewed with respect to reactivity, selectivity and sensitivity. Their applications to the determination of individual amines, ammonia and N-nitrosamines in various environmental samples are also described.

Determination of toluenediamine isomers by capillary gas chromatography and chemical ionization mass spectrometry with special reference to the biological monitoring of 2,4- and 2,6-toluene diisocyanate

The determination of 2,3-, 3,4-, 2,6-, 2,4- and 2,5-toluenediamine (TDA) in hydrolysed human urine and blood plasma was studied by GC-MS. The TDA isomers as their perfluoro-fatty acid anhydride derivatives were investigated. Chemical ionization with ammonia and isobutane as reagent gas and monitoring both positive and negative ions are studied. Negative ion monitoring using ammonia and the TDA pentafluoropropionic anhydride (PFPA) derivatives were chosen owing to the low detection limits and good separations of the isomers studied. The ions monitored were m/z 394 and 374 corresponding to the (M-20)- and (M-40)- ions and the m/z = 397 and 377 ions of the tri-deuterium-labelled TDA used as an internal standard. The performance of 2,4-, 2,5- and 2,6-TDA-PFPA in the ion source was studied by varying the ammonia pressure, temperature and electron energy. A 1-ml volume of human urine was added to 1.5 ml of 6 M HCl containing 0.5 micrograms/l of each of the trideuterated 2,6- and 2,4-TDA and the solution was hydrolysed at 100 degrees C overnight. TDA was extracted into 2 ml of toluene by the addition of 5 ml of saturated NaOH solution. Derivatization was performed in toluene by the addition of 10 microliters of PFPA. The excesses of the reagent and acid formed were removed by extraction with 1 M phosphate buffer solution (pH 7.5). Analyses of 2,6-, 2,4- and 2,5-TDA-spiked human urine (0.2-2.5 micrograms/l) were performed. The correlation coefficients were 0.999 (n = 6). The precision (R.S.D.) for human urine spiked at 1 micrograms/l was 1.6% for 2.6-TDA, 3,5% for 2,4-TDA and 3.2% for 2,5-TDA (n = 10). The detection limit, defined as twice the signal-to-noise ratio, was 1-5 fg injected, corresponding to less than 0.05 micrograms/l of TDA in human urine or plasma.

Determination of clenbuterol and mabuterol in equine plasma by ion-pair liquid chromatography with electrochemical detection. Chromatographic and electrochemical characteristics

A method for the routine determination of the beta-adrenergic drugs clenbuterol and mabuterol in equine plasma has been developed. The drugs were isolated from alkalinized plasma by liquid-liquid extraction. The organic phase was evaporated to dryness and the residue was dissolved in the mobile phase prior to injection. The recoveries were 98% and 95% for clenbuterol and mabuterol, respectively. The drugs were separated by reversed-phase high-performance liquid chromatography and quantitated by a use of a coulometric detector set at +0.75 V vs. the internal reference electrode. The influence of pH and amounts of organic modifier and ion-pairing agent on the retention times was investigated. The relationship between peak current and concentration was linear up to 1 microgram/ml for both compounds. The limits of detection were 0.5 ng/ml for clenbuterol and 2 ng/ml for mabuterol with a signal-to-noise ratio of 3. A brief discussion of the electrochemistry of the compounds is given.

Analytical approaches for determining human exposure to pesticides

The presence of pesticides, both persistent and biodegradable, in the environment is a problem which is both significant and potentially dangerous to humans. An index of biodegradability is presented which is based on the correlation between environmental stability and fat solubility. Halogenated pesticides are, therefore, both more fat soluble and more resistant to biodegradation, while methylated pesticides are more water soluble and, therefore, more biodegradable. Three methods for detecting low-levels of halogenated pesticides are presented: the Macro, the Micro "Florisil," and the Micro "Silica." A method is also presented to detect these chemicals in blood. Two methods for the detection of nonpersistent, organophosphorus and carbamate insecticides, Cholinesterase inhibition and urinary metabolites, are described. Finally, methods of monitoring human exposure through the detection of phenols, phenoxy acids, alkyl phosphates, and anilines are presented.