The simultaneous determination of amitriptyline and nortriptyline in post mortem blood and urine using gas-liquid chromatography

Reliable routine method for the determination of plasma amitriptyline and nortriptyline by gas chromatography

A gas chromatographic method has been developed for the determination of amitriptyline and nortriptyline in plasma. OV-17 is used in a 1 m long packed column, with a flame ionization detector and an electronic integrator. Five internal standards are added. The base-specific extraction procedure and the method of calibrating the chromatograph are described in detail. The accuracy, precision and reliability of the method are demonstrated by the results of nearly 700 determinations of each drug, at concentrations ranging from 5 to 400 ng/ml in the plasma. An interlaboratory comparison with a double radioactive isotope derivative assay for nortriptyline has also shown satisfactory agreement.

A rapid and simple method for the quantification in human plasma of tricyclic antidepressant drugs taken in overdose

A rapid and simple extraction procedure followed by gas chromatography using a nitrogen detector is described for the analysis of amitriptyline, nortriptyline, imipramine, and desipramine in 100 microliter plasma. No derivitisation of the drugs is required. Recoveries ranged from 93.7 to 104.6%. Within-batch precision and day-to-day variation showed coefficients of variation of less than 10% with the exception of desipramine, for which the day-to-day coefficient of variation was 15.2%. The method was developed to measure plasma concentrations in patients who had taken non-fatal and fatal overdoses of the drugs.

Ion-pair liquid chromatography of steady-state plasma levels of chlorimipramine and demethylchlorimipramine

A method for the determination of chlorimipramine and its metabolite demethylchlorimipramine in the plasma of depressed patients during treatment is described. The method involves extraction of the parent drug, its metabolite and the internal standard from plasma, back-extraction into an acidic aqueous phase and re-extraction into a small volume of organic phase. Separation and quantitation are carried out by ion-pair partition chromatography with UV detection. Accurate determination if possible down to levels of 30 and 60 nmole per liter of plasma for chlorimipramine and the metabolite, respectively, when 1 ml of plasma is used. The coefficient of variation is 7.3% or less at different levels for chlorimipramine and demethylchlorimipramine. Plasma levels of the parent drug and the metabolite measured by this liquid chromatographic method and by a gas chromatographic procedure with electron-capture detection were in good agreement (r = 0.98). The steady-state plasma level of the metabolite was always higher than that of the parent drug in the 34 depressed patients investigated. The mean ratio between the metabolite and the parent drug was 2.7 +/- 1.1 (S.D.) Large inter-individual differences in the levels of the two compounds in patients receiving similar doses were found.

Combined thin-layer and gas-liquid chromatographic identification of tricyclic antidepressants in urine

A combined thin-layer and gas-liquid chromatographic (TLC-GLC) procedure for determination of tricyclic antidepressant drugs in urine is described. GLC on 1.5% OV-17 was utilized to analyzed basic urine extracts directly for the tricyclics and to confirm the identity of spots extracted from thin-layer chromatograms, and TLC was used to confirm the results of these GLC screens. Lower limits of sensitivity for the thin-layer spot extraction procedure were found to range from 2 mug/ml for amitriptyline and imipramine to 10 mug/ml for desipramine and nortriptyline. Turn-around-times for the GLC tricyclic screens were usually less than 1 h. The finding that nortriptyline and desipramine were chemically altered under various extraction conditions was used as a means of confirming the identity of these drugs, and the identity of these chemically altered derivatives was discussed with reference to their low resolution mass spectra.

Determination of dextropropoxyphene and norpropoxyphene in autopsy material by gas chromatography

A gas chromatographic method for the simultaneous determination of dextropropoxyphene and norpropoxyphene in autopsy material is described. The esters were hydrolyzed before the final determination. The mass spectra of the hydrolyzed esters are presented together with the results of an investigation of 6 cases of fatal intoxications.

Estimation of amitriptyline and its metabolites in serum and urine by GLC using nitrogen-specific detector

1. A gas-chromatographic procedure for the estimation of amitriptyline and its metabolites in serum and urine using a nitrogen-specific detector is described. Specially cleaned glassware and purified solvents are used for the extraction of serum to further minimize extraneous peaks. Trimethylamine is added to serum before extraction to improve the recovery of drugs. Urine is refluxed at pH approximately 1 to hydrolyze the conjugates and to convert hydroxymetabolites to corresponding dehydro compounds. Serum is not hydrolyzed. 2. Two internal standards, one a tertiary amine similar in structure to amitriptyline and the other a secondary amine similar in structure to nortriptyline, are added to the specimen prior to extraction to obviate the need for accurate measurements of volumes during extraction and analysis. Urine and serum are washed with organic solvents at acidic pH to remove neutral and acidic impurities. Secondary bases are converted to their acetyl derivatives. 3. In the serum of a patient who is on amitriptyline therapy or who has ingested an overdose of amitriptyline, nortriptyline, a pharmacologically active metabolite is also measured. However, detection or estimation of hydroxymetabolites in serum is not clinically relevant. Hydroxylation index of an individual patient is determined by measuring the ratio of nortriptyline to its hydroxymetabolite in urine. 4. Amitriptyline and nortriptyline can be estimated in serum at a lower level of 10 and 20 ng/ml respectively. The procedure is linear over a wide range of amitriptyline and its metabolites. The use of an electronic integrator allows the estimation of different compounds with 100 fold difference in their concentration from the same chromatogram.

Determination of plasma amitriptyline by electron-capture gas chromatography after oxidation to anthraquinone

A selective procedure is described for the determination of amitriptyline in plasma. The method involves extraction, separation of amitriptyline from its metabolites and subsequent oxidation by ceric sulphate in 5.4 M sulphuric acid. The oxidation product, anthraquinone, is determined by means of electron-capture gas chromatography. The metabolites were separated by a column chromatographic extraction technique. The choice of oxidation reagent, optimum conditions for the oxidation, and the electron-capture properties of anthraquinone are discussed. The method can be used to determine down to 2 ng of amitriptyline in a plasma sample; the relative standard deviation at the 50-ng level was 4.0% (n = 8). The levels of amitriptyline found in a series of plasma samples are compared with those obtained by gas chromatography with use of nitrogen-specific detection; the two techniques gave coincident results.

Sensitive method for the routine determination tricyclic antidepressants in plasma using a specific nitrogen detector

The sensitivity of the alkali flame ionization detector to the tricyclic antidepressant drugs has been studied and limits of detection measured. A backflush system has been used to enable measurement in plasma extracts. A general method for the estimation of tricyclic plasma levels has been developed and exemplified by the measurement of imipramine at therapeutic levels.