Monitoring and identification of residues of anabolic preparations in slaughtered cattle by HPLC with diode array detection

Rapid liquid chromatographic determination of oxytetracycline in milk

A simple method for the determination of residual oxytetracycline (OTC) in milk by high-performance liquid chromatography (HPLC) was developed. The sample preparation could be made without complex extraction and clean-up procedures. A LiChrospher 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photo-diode array detector was used. The average recoveries from spiked OTC (0.1, 0.5 and 1.0 microgram/ml) were in excess of 89.8% with coefficients of variation between 0.6 and 4.1%. The limit of detection was 0.05 microgram/ml. The total time required for the analysis of one sample was below 10 min.

Evidence for the presence of endogenous 19-norandrosterone in human urine

In 1997, in the scope of antidoping control in sport, a not inconsiderable number of urine analysed by official laboratories revealed the presence of 19-nortestosterone (19-NT: 17beta-hydroxyestr-4-en-3-one) metabolites: 19-norandrosterone (19-NA: 3alpha-hydroxy-5alpha-estran-17-one) and 19-noretiocholanolone (19-NE: 3alpha-hydroxy-5beta-estran-17-one). These repeated results on a short period of time generated some investigations and especially the verification of the possible production of these metabolites by an unknown endogenous route in adult entire male. Some experiences were led on different persons known to be non-treated with steroids and more precisely with nandrolone. Extractive methods were developed focusing on their selectivity, i.e. searching to eliminate at best matrix interferences from the target analytes. Gas chromatography coupled to mass spectrometry (quadrupole and magnetic instruments) was used to detect, identify and quantify the suspected signals. Two types of derivatization (TMS and TBDMS), a semi-preparative HPLC as well as co-chromatography proved unambiguously the presence, in more than 50% of the analysed urine (n = 40), of 19-NA at concentrations between 0.05 and 0.60 ng/ml. 19-NE was not detected with the developed methods (LOD<0.02 ng/ml). Experiments led on athletes showed that after a prolonged intense effort, the 19-NA concentration can be increased by a factor varying between 2 and 4. Even if some complementary researches have to be done in order to determine the maximal physiological level of 19-NA and 19-NE, these results should considerably change the strategy of antidoping laboratories.

High-performance liquid chromatographic separation and detection methods for anabolic compounds

The role of high-performance liquid chromatography (HPLC) in methods of analysis for anabolic compounds in biological samples is reviewed. Special attention is given to both the separation and detection of anabolic compounds. A distinction is made between on-line detection systems, such as ultraviolet detection and diode-array detection, and off-line detection methods with special emphasis on immunochemical detection methods using non-isotopic labels. A number of applications are given to elucidate the possibilities of HPLC in the analysis of anabolic compounds.

Application of optimization procedures for the separation of anabolic compounds by high-performance liquid chromatography

A simple systematic approach is presented for optimizing high-performance liquid chromatographic separations of anabolics with multi-component isocratic mobile phases. A computer program was obtained and adjusted for use with an IBM-compatible XT personal computer. The program requires experimental retention data with three quaternary solvent mixtures to calculate the optimum solvent composition using a geometric model of a prism. For each possible composition of the mobile phase the set of retention data can be calculated. Applications are shown for mixtures of anabolic compounds using a mobile phase composed of methanol, tetrahydrofuran and acetonitrile. The predicted retention data agreed very well with the experimental data.

Determination of hormone contaminants in milk replacers by high-performance liquid chromatography and immunoassay

Certain milk replacers were reported to cause 19-nortestosterone (NT)-positive urine samples after feeding them to veal calves. In order to find the possible source of contamination, milk replacers and crude fat and meat meal from homogenized veal calves and commercial crude fat from a rendering plant were analysed for NT plus its metabolites and constituents of illicit 'cocktails' (NT esters, estradiol benzoate and medroxyprogesterone acetate). The steroids were separated using different high-performance liquid chromatographic systems and measured by specific immunoassays. The results show that animal food processed from carcasses of treated animals contains hormone concentrations that may cause positive urine samples in animals fed on such feed.

Molecular spectroscopy in forensic residue analysis: a general overview of reliability, applicability and cost effectiveness

Classification of an analytical result for forensic purposes is briefly discussed, in addition to mandatory specificity and limits of appropriate analytical methods. Direct information on the molecular structure of the analyte is in general more reliable than indirect information. Direct information is obtained from molecular spectroscopic methods, in contrasts to chromatographic or immunochemical methods, which provide only indirect information. The cost effectiveness ratio as calculated per analyte is indicated for various analytical techniques.

On-line high-performance liquid chromatographic diode array spectrophotometric analysis of steroidal hormones in illegal preparations

An on-line high-performance liquid chromatographic diode array spectroscopic analytical method for the identification of more than 60 different steroidal compounds is described. For the chromatographic separation, a gradient elution that could distinguish the esterified and non-esterified steroids in the same run on a reversed-phase C18 column, using methanol as modifier, was developed. For both types of compound an internal standard was chosen to establish reproducible relative retention times that could be used as one element of the identification; the second element is the UV spectrum, which is recorded on-line during the separation. The combination of chromatographic and UV spectroscopic recordings selects only a few probable steroids, which could be the unknown. This approach has been applied to forensic analysis of illicit preparations used in cattle-breeding, some examples of which are shown. For those steroids that are very difficult to distinguish using this procedure, because of their chromatographic and spectroscopic similarity on this system, other solvent mixtures are used in place of methanol as modifier, namely acetonitrile or tetrahydrofuran, or both, with the same solvent strength, as proposed by Snyder. In this way totally different elution patterns and separations are obtained, providing complementary information for identification, as shown by the systematic analysis on two other isoeluotropic solvent systems.

Distinction between oral and parenteral application of 19-nortestosterone by residue analysis in kidney fat from veal calves using high-performance liquid chromatography and enzyme immunoassay

Kidney fat samples from animals either untreated or after different treatments with 19-nortestosterone (NT) were cleaned up and NT-17 beta and 19-norandrostenedione (NA) were purified using high-performance liquid chromatographic (HPLC) systems that allowed their complete separation from other steroids and interfering physiological compounds. HPLC fractions and urine samples were analysed by an enzyme immunoassay that measures both steroids equally well (antigen: NT-17 beta-hemisuccinate-bovine serum albumin). In samples from untreated animals no NT metabolites were detectable (less than 10 pg/g NT-17 beta and less than 10 pg/g NA in fat; less than 0.25 pg/ml NT-17 beta + NT-17 alpha in urine). After adding NT to animal feed the urine became positive, whereas in the fat no residues were detectable. After different injections of NT both the fat and urine were positive. Only after parenteral application did free steroids enter the circulation and adipose tissues.

Identification and quantitation of trenbolone in bovine tissue by gas chromatography-mass spectrometry

Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed.

A gas chromatographic/mass spectrometric screening, confirmation, and quantification method for estrogenic compounds

A method is described for the screening, quantification and confirmation of a variety of estronenic substances in animal tissues. A solid-phase extraction technique combined with a liquid/liquid extraction allows for rapid sample preparation and high throughput for the following compounds in bovine liver, muscle and kidney: diethylstilbestrol, dienestrol, hexestrol, zeranol, taleranol, zearalanone, zearalenone, zearalenol, estradiol and estriol. Gas chromatography/mass spectrometry and selected ion monitoring is used for the determination with detection limits ranging from 50 to 150 ppt.

Quantitative secondary ion monitoring gas chromatography/mass spectrometry of diethylstilbestrol in bovine liver

A procedure is described for the extraction of diethylstilbestrol (DES) from animal tissue for quantitative capillary gas chromatography/mass spectrometry (GC/MS). The procedure is based upon use of a strong anion exchange polystyrene divinylbenzene resin for sample purification. The recovery of DES from the resin clean up was 88% in the high parts per trillion (ppt) range. Criteria for identification of DES using selected ion monitoring (SIM) GC/MS are presented. Liquid chromatography/mass spectrometry (LC/MS) was used to investigate altered DES cis/trans ratios observed in biological extracts.

Pharmacokinetics of 19-nortestosterone esters in normal men

A reliable method for the isolation of 19-nortestosterone (NT), testosterone (T) and dihydrotestosterone (DHT) by high-performance liquid chromatography (HPLC) and quantitation of the individual steroids by radioimmunoassays is described. The method was used to measure serum concentrations of NT, T and DHT in a pharmacokinetic study and in a clinical trial for male fertility control. Following intramuscular injection of either 50 mg 19-nortestosterone-3-(p-hexoxyphenyl)-propionate (NP) or 50 mg 19-nortestosterone-decanoate (ND) serum NT increased rapidly to maximal concentrations of 4.6 +/- 3.2 and 2.0 +/- 1.3 nmol/l (+/-SD), respectively, in the 6 volunteers. The half-life time was 8 days for ND and 21 days for NP. Based on these findings a clinical trial with NP was performed. NP was given to 5 healthy men in doses of 100 mg/week for the first 3 weeks followed by 200 mg/week for 10 further weeks. Serum NT levels increased gradually and maximal concentrations were reached in the 13th treatment week (20.2 +/- 3.4 nmol/l). Measurable amounts of NT were detectable for 19 weeks after the last injection. The study shows that NT accumulates under this treatment regime and wider spacing of the injection intervals may be possible in future trials.

A specific radioimmunoassay for the detection of 19-nortestosterone in urine

The antisera used were raised in rabbits against a 19-nortestosterone-7 alpha-carboxyethylthioether conjugate of bovine serum albumin. Tritium-labeled nortestosterone was used as tracer. Cross reactivities with metabolites of nandrolone, other anabolics and endogenous steroids were very low. To achieve additional specificity a clean up and separation procedure was developed, using isocratic high performance liquid chromatography. So far no qualitative discrepancies have been observed between the assay described here and confirmative determinations by combined high performance liquid chromatography-gas chromatography-mass spectrometry.

A chemiluminescent immunoassay for 17 alpha-methyltestosterone

An immunoassay for the xenobiotic anabolic compound methyltestosterone (MT) is presented. The detection is based on chemiluminescence of a MT-isoluminol conjugate. Applications are presented for detection of methyltestosterone and cross-reacting compounds in bovine urine and tissues of application sites isolated from slaughtered cattle, illegally treated with hormonal anabolics.

Development of a chemiluminescent immunoassay for 19-nortestosterone (nandrolone)

An immunoassay for nortestosterone with detection by chemiluminescence is described, and applied to the urine and drug administration site of slaughtered cattle.