Diethylstilbestrol methods

Table 18. Statistical comparison (F-test [125]) of the methods. Standard deviation Sxo of the calibration curves for diethylstilbestrol and ethinylestradiol [114].

Use of hormonal-type substances for growth promotion and fattening purposes in food-producing animals is prohibited or restricted in many countries. Administration of diethylstilbestrol, in particular, has been totally banned worldwide. This implies that adequate analytical methods should be available for regulatory control. Due to its sensitivity, radioimmunoassay has have become most important in diethylstilbestrol analysis and represents the final detection step in the EU reference method for stilbene residues analysis (100). 

Since many interferences with diethylstilbestrol analysis are caused by undefined sources, use of a highly specific antibody would probably not correct the problem. Nevertheless, several attempts to prepare a drug-specific antibody have been made without success. Thus, more emphasis was finally placed on developing more efficient extraction and cleanup procedures to ensure selectivity. Current methods combine several cleanup steps based on different isolation principles to provide adequately purified sample extracts for the determination of diethystilbes-trol by radioimmunoassays (Table 28.4). 

Apart from diethylstilbestrol, several other anabolics including nortestosterone, methyltestosterone, hexestrol, trenbolone, zeranol, and medroxyprogesterone have also gained importance from a regulatory point of view. Examples of immunochemical methods applied in the analysis of edible animal products for residues of these anabolics are presented in Table 28.4. 

A three-phase liquid-liquid partitioning consisting of hexane, acetonitrile, and dichloromethane has also proven to be a preferred cleanup method for diethylstilbestrol and zeranol (455), trenbolone and epitrenbolone (445), trenbolone and nortestosterone (446), and melengestrol residues (456) in tissues. Following adjustment of the initial aqueous acetonitrile sample extract at pH 13, most of the polar and ionic acidic matrix components were directed into the aqueous layer during the partitioning process, while the low-polarity components were extracted... 

LIQUID CHROMATOGRAPHIC METHODS Diethylstilbestrol Bovine Tetr.-butyl methyl... 

Natural and synthetic hormones are used worldwide to improve meat production There are, however, possible hazards for the consumer. Therefore, in most European countries the use of hormonal anabolics is restricted or even prohibited by law. Among the banned synthetic anabolics diethylstilbestrol (DES) takes the most important place at the moment. Analytical control is carried out in various ways. Frisch-kom and Smyth have described an HPLC method with electrochemical detection for the determination of growth promoting hormones in meat. 

The early work on requirements for confirmatory mass spectrometric methods was undertaken to address a regulatory requirement for the analysis of carcinogens established in 1977 by the US Food and Drug Administration. A paper published in 1978 demonstrated the minimum number of peaks and the specifications for relative ion abundances for each peak required to uniquely identify diethylstilbestrol from a GC-MS spectral library containing El spectra of... 

A method has been developed to detect residual stilbenes such as diethylstilbestrol (DES), dienestrol (DIS), and hexestrol (HS) in animal tissues using solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS) [153]. The... 

Supported liquid membranes (SLMs) consisting of 5% tri-n-octylphosphine oxide (TOPO) dissolved in di-w-hexylether/n-undecane (1 1) have been used in the simultaneous extraction of a mixture of three stUbene compounds (dienestrol, diethylstilbestrol, and hexestrol) in cow s milk, urine, bovine kidney, and liver tissue matrices [183]. The efficiencies obtained after the enrichment of 1 ng/1 stilbenes in a variety of biological matrices of milk, urine, liver, kidney, and water were 60-70, 71-86, 69-80, 63-74, and 72-93%, respectively. A new method to contribute to the discrimination of polyphenols including resveratrol with synthetic pores was proposed [184]. The work [185] evaluated two types of commonly available chiral detectors for their possible use in chiral method development and screening polarimeters and CD detectors. Linearity, precision, and the limit of detection (LOD) of six compounds (trans-stilbene oxide, ethyl chrysanthemate, propranolol, 1-methyl-2-tetralone, naproxen, and methyl methionine) on four common detectors (three polarimeters and one CD detector) were experimentally determined and the limit of quantitation calculated from the experimental LOD. trans-Stilbene oxide worked well across all the detectors, showing good linearity, precision, and low detection limits. However, the other five compounds proved to be more discriminating and showed that the CD detector performed better as a detector for chiral screens than the polarimeters. 

Th. Reuvers, E. Perogordo and R. Jimenez, Rapid screening method for the determination of diethylstilbestrol in edible animal tissue by column liquid chromatography with electrochemical detection, J. Chromatogr., 1991, 564, 477-484. 

The term gel-permeation is reserved for separations effected with hydrophobic resins like polystyrene in non-aqueous media (non-polar solvents). This latter method is especially suitable for removal of interfering lipids, e.g. diethylstilbestrol can be removed completely from fatty tissues. 

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