Steroids detection

Immunosensors have made a great contribution in the field of androgenic steroid detection, giving detection limits comparable to those obtained with standard ELISA procedures. Several electrochemical immunosensors have been developed for detecting testosterone, methyltestosterone,... 

RADIOIMMUNOASSAY (RIA) One method used for anabolic steroid detection. This method is inadequate as it produces false positive and negative readings. 

The purpose of this experiment is to describe a simple TLC procedure for the quantification of cholesterol. This procedure is based on the densitometric determination of steroids detected with phosphomolybdic acid (Wortmann and Touchstone, 1973 Wortmann et al., 1974). 

Vims, C. and Bernhardt, R. (2008) Molecular evolution of a steroid hydroxylating cytochrome P450 using a versatile steroid detection system for screening. Lipids, 43 (12), 1133-1141. 

Whatever the physiology of odor perception may be, the sense of smell is keener than that of taste (22). If flavors are classed into odors and tastes as is common practice in science, it can be calculated that there are probably more than 10 possible sensations of odor and only a few, perhaps five, sensations of taste (13,21,35—37). Just as a hereditary or genetic factor may cause taste variations between individuals toward phenylthiourea, a similar factor may be in operation with odor. The odor of the steroid androsterone, found in many foods and human sweat, may eflcit different responses from different individuals. Some are very sensitive to it and find it unpleasant. To others, who are less sensitive to it, it has a musk or sandalwood-like smell. Approximately 50% of the adults tested cannot detect any odor even at extremely high concentrations. It is befleved that this abiUty is genetically determined (38). 

One anabohc steroid, the presence of which has proven difficult to analyze, is stanozolol [10418-03-8] C2 H22N20. A metaboUte of the parent dmg, hydroxy stanozolol, detected in equine urine eight hours after ingestion of the parent dmg is actually identified, usually at very low levels. Analysis was done by Ic/ms/ms which had a shortened analysis time advantage over gc/ms procedures because of the elimination of the need for a derivatization step (33). 

We have developed the method of the determination of steroids in biological fluids (semm and urine) by MEKC with on-line concentration (sweeping) with detection limit for about 3 ng/ml (S/N=3). 

On reversed phase layers, in contrast, detergents yield dark blue zones on a pale background. Here it is the lipophilic part of the detergent molecule that is aligned with the surface RP chain and the dye is attracted to the anionic part of the molecule. Steroid derivatives can also be detected with aqueous solutions of dyes [91]. 

Bile acids also yield fluorescence when an only 5% perchloric acid is employed as reagent and the chromatogram is only heated to 100°C until coloration commences [9]. Steroids can also be detected with 2% methanohc perchloric acid [4]. 

In the case of carbohydrates blue chromatogram zones are produced on a yellow background that slowly fades [2]. Steroids, vitamins, antioxidants, phenols and aromatic amines yield, sometimes even at room temperature, variously colored chromatogram zones [5]. -Blockers and laxatives also acquire various colors [7, 10]. The detection hmits are in the nanogram to microgram range [5]. 

Note The reagent can be employed on sihca gel, kieselguhr. Si 50 000 and RP layers. Hydrochloric or sulfuric acid can be employed in place of phosphoric acid (q.v.). The detection limits for steroids and digitahs glycosides are several nanograms per chromatogram zone. 

If the ketone function is adjacent to a hydrogen-bearing asymmetric center, the compound can undergo epimerization. In steroids with a normal skeletal configuration (8/3, 9a, 14a) there is no detectable epimerization at C-8 or C-9 during the exchange of and 11- ketones. 

Oxiranes are more readily detected by infrared spectroscopy than aziridines and thiiranes. Bands for steroid oxiranes appear consistently either between 800-900 cm or 1035-1050 cm h The oxirane band at 1250 cm is not... 

A restricted number of applicable fluonne markers may also be viewed as a Imutabon The tnfluoroacetyl moiety has been the most commonly used group, used m sbidies of ammo acids, steroids, and carbohydrates Enhanced F NMR detection should be possible with specifically designed agents of opumal biological and spectral properbes... 

Conversion of A -3-ketosteroids or their trimethylsilyl or acetyl derivatives in fluorescent components, whereby the detection limits were improved by 65% for the acetates. A -3-keto- and A -3-OH-steroids also react with the same sensitivity. 

Note It is reported that the use of chlorobenzene as solvent is essential when the reagent is to be used to detect aromatic amines [1]. In the case of steroids, penicillins, diuretics and alkaloids the reaction should be accelerated and intensified by spraying afterwards with dimethylsulfoxide (DMSO) or dimethylformamide (DMF), indeed this step makes it possible to detect some substances when this would not otherwise be possible [5,9-11] this latter treatment can, like heating, cause color changes [5,9]. Penicillins and diuretics only exhibit weak reactions if not treated afterwards with DMF [10, 11]. Steroids alone also yield colored derivatives with DMSO [9]. Tlreatment afterwards with diluted sulfuric acid (c = 2 mol/L) also leads to an improvement in detection sensitivity in the case of a range of alkaloids. In the case of pyrrolizidine alkaloids it is possible to use o-chloranil as an alternative detection reagent however, in this case it is recommended that the plate be treated afterwards with a solution of 2 g 4-(dimethyl-amino)-benzaldehyde and 2 ml boron trifluoride etherate in 100 ml anhydrous ethanol because otherwise the colors initially produced with o-chloranil rapidly fade [12]. 

Detection with phosphoric acid at room temperature (with no heating afterwards) is specific for trenbolone, since related steroids such as progesterone and testosterone do not interfere under these conditions [12]. 

The detection limits (substance per chromatogram zone) are 10 to 20 ng for arom amines [1], 100 ng for phenothiazines [8], 0.5 to 2 pg for secondary amine alkaloids 5 to 50 pg for N-ethyl derivatives [7], 1 to 3 pg for penicillins [10], 1 to 4 pg for dime and 1 to 2 pg for a range of steroids [9]. There have been some repmrts of apprecis lower detection limits of 40-400 ng substance per chromatogram zone and even less alkaloids [6]. 

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