Steroids fractionation

We measure unconjugated 18-OHF by GC-MS [62]. Values for 18-OHF (measured in the free steroid fraction) are typically <150 pg/24 h for normals and > 500 pg/24 h for patients with GRA or adenoma [39]. Another important diagnostic analyte in the hydrolyzed extract is 18-oxo-THF patients with GRA have values > 15 pg/24 h compared to the normal value of < 5 pg/24 h. Selected ratios are reported for GRA, including a cortisol 18-oxygenation quotient, which is the 18-OHF cortisol ratio, giving a value about 4 for normals and >25 for patients with GRA (Table 5.3.10) and 18-oxo-THF(xl00) THF + 5aTHF, which is < 0.2 for normals and > 1.0 for those with GRA. 

Sutinasterol contains a C12 side chain that is presumably the product of quadruple bioalkylation. It represents the 94% of the steroid fraction of a Xestospongia sponge. 

For analytical purposes cholesterol oxidase has been immobilized on various carriers (Table 6). Electrochemical, optical, and calorimetric indication have been used as detection methods. Combination of a thermistor-coupled flow-through system with immobilized COD permitted the measurement of 0.03-0.15 mmolA cholesterol (Mattiasson et al., 1976). Ogren et al. (1980) described an immobilized COD reactor for the analysis of steroid fractions obtained by high pressure liquid chromatography. The UV absorption at 240 nm of enzymatically formed cholestenone was used as the measuring signal. Linearity was found between 10 and 80 pmol/1. 

However, the utilization of Qg SPE prior to shotgun negative-ESI-MS, or online Qg LC-ESI-MS, allows the facile analysis of steroid sulphates [38]. Shown in Figure 2.6 is a negative-ion ESI-MS of the steroid fraction from infant plasma (Figure 2.7). 

Prior to GC-MS analysis, the steroid fractions require derivatization. Ketosteroids are usually converted to oximes using methoxylamine, benzylamine, or hydroxylamine hydrochloride in pyridine. Two epimers of the oxime are formed (E and Z). Hydroxyl groups are then derivatized as trimethylsilyl (TMS) ethers. After formation of the TMS derivative, the extract is further purified by chromatography on a small column of Lipidex 5000. An alternative to TMS is the use of t-butyldimethylsilyl (t-BDMS) ethers, but although conferring desirable mass spectrometric properties, namely an intense M — 57 ion, the t-BDMS group is 42 U heavier than TMS and the formation of poly t-BDMS ethers may increase the relative molecular mass of the steroid derivative beyond the mass range of small quadru-poles. 

Not only do oocytes take up progesterone from the medium, but also they appear to retain a substantial proportion of the hormone (about 50%) for prolonged periods of time when incubated in hormone-free medium (Smith and Ecker, 1971). This bound steroid fraction was not competed out by the presence of a 100-fold excess of unlabeled progesterone. However, the additional observation that intracellular hormone could be coprecipitated with a protein extract (Smith and Ecker, 1971 see also Horton, 1969) led to the idea that this intracellular hormone might be responsible for the initiation of maturational events, possibly through interaction with a specific protein receptor. This appears not to be the case. 

Bejger, M., and Targonski, R. Determination of 17-Keto Steroid Fractions in Urine by Gas Chromatography... 

A Simple Method for the Determination of Urinary 17-Ketogenic Steroid Fractions by Differential Solvent Extraction. I. Study of the Feasibility of Solvent Fractionation by Gas Chromatography Horumon to Rinsho 27(8) 903-908 (1979) CA 92 2788m... 

Determination of the Neutral Steroids Fraction in Urine by Gas-Liquid Chromatography Igaku No Ayumi 75(4) 176-182 (1970) CA 75 105820u... 

Gas chromatographic-mass spectrometric studies have also revealed the presence of 4,4-dimethylsterols in the steroid fraction of many plant oils ... 

The prepared column was loaded with the steroid fraction and developed with mixtures of cyclohexane and methylene chloride, which were saturated with glycol. The sequence of developer mixtures was regulated by the automatic fraction cutter to produce the results shown in Table V. The steroid distribution was corroborated by spot paper chromatograms. Negligible failing could be observed in this separation. 

It has been known for quite some time that the administration of testosterone resulted in increased urinary a-ketosteroid (3a-hydroxy-17-ketosteroids) excretion and only a very small increase in the /8-keto-steroid (3/3-hydroxy-17-ketosteroids) and nonketonic steroid fractions. Careful chemical separation and characterization have shown that after the administration of testosterone (L) to normal and diseased human subjects and other mammals, increased amounts of androsterone (XLVIII)... 

---