HR GC and GC-MS Study of Steroids in Northern Croatian Petroleum

Since steranes might be of pharmaceutical utility, Northern Croatian petroleums were selected for a steroid study by HR GC: sample PI with a hilly elevated base of chromatograms at the heavy end (where steroids eluate) and with intensive re-alkanes; PII rich in re-alkanes with a comparatively flat heavy end; and PHI with a remarkably elevated heavy end, but poor in re-alkanes. The fraction of saturates was studied for steranes by GC-MS, also the fraction of aromatics for MA and TA steroids. Mass spectra and mass fragmentograms m/z 217, m/z 253 and m/z 231, were used. In 3 select samples (out of 43 petroleums), the steranes were determined in the range from norcholestanes up to re-propylcholestanes, making 3000- -9000 ppm of saturates. So, it might be considered that there are Croatian petroleum samples which contain steranes in concentrations interesting for pharmaceutical purposes. Cholestanes, ergostanes and stigmastanes are dominant while the concentrations of diasteranes are low. Pill is the sterane richest sample. Its characteristics are low epimeri- zation of sterane skeletons, regarding H at C atoms in position 14, 17 and 20, as well as re-alkanes diminishing by biodegradation. PHI also contains the relatively highest TA steroid concentration. The intensity proportion between TA steroids and MA steroids is highest for PII. This can be visualized by the thermal stress absorbed and it is in good agreement with the comparatively highest epimerization level

A Study of Residual Benzoyl Peroxide in Poly (methyl methacrylate) Resins by Gas Chromatography

Svrha rada bila je proučiti razlike nalaza zaostaloga benzoil peroksida, kao i pouzdanost plinske kromatografije u kvantificiranju zaostaloga benzoil peroksida u poli (metilmetakrilatnim) smolama. U radu su rabljeni akrilatni pripravci dobiveni toplom polimerizacijom četiriju različitih poli (metilmetakrilata): Futur aery l 2000 (Schuetz-Dental); Poli-Dent K-30S (Polident); Stelon LP (Galenika); i Biocryl-R (Galenika). Sva četiri materijala su polimerizirana kroz tri polimerizacijska postupka: a) kratkovremeni - 30 minuta na 70°C i 30 minuta na 100°C; b) srednjovremeni - 2 sata na 70°C i 1 sat na 100°C; te c) dugovremeni - 7 sati na 70°C i 3 sata na 100°C. Svi polimerizacijski postupci obavljani su u automatskom aparatu za polimerizaciju »KaVo«, tip EWL-5518 (Leutkirch, SR Njemačka). Pripravci su usitnjeni drobljenjem i otopljeni u metilen kloridu. Količina zaostaloga benzoil peroksida određena je postupkom plinske kromatografije na aparatu PYE UNCAM 304 (Cambridge, V. Britanija). Rezultati istraživanja zaostaloga benzoil peroksida iz polimerizata pokazuju ustaljeni pad vrijednosti od kratkovremenog prema dugovremenom polimerizacijskom postupku. Ne postoji statistički značajna razlika u nalazu zaostaloga benzoil peroksida niti između četiri različita proizvođača ni među različitim polimerizacijskim postupcima. Plinska kromatografija se nije pokazala pouzdanim postupkom za kvantitativno određivanje benzoil peroksida upravo zbog njegove reaktivnosti, pa bi dobivene rezultate bilo zanimljivo usporediti s rezultatima mjerenja nekom metodom »na hladno« (infracrvena spektrofotometrija ili ultraljubičasta spektrofotometrija).The aim of this study was to assess differences in the findings of residual benzoyl peroxide and the value of gas chromatography in the quantification of residual benzoyl peroxide in poly (methyl methacrylate) resins. Acrylate preparations obtained by heat polymerization o f four poly (methyl methacrylates), i.e. Futur aery I 2000 (Schuetz-Dental), Poli-Dent K-30S (Polident), Stelon LP (Galenika) and Biocryl-R (Galenika), were used in the study. All the four materials were polymerized by three different procedures of polymerization: a) short-term, 30 min at 70°C and 30 min at 100°C; b) medium-term, 2 h at 70°C and 1 h at 100°C; and c) longterm, 7 hat 70°C and 3 h atl00°C. All the three procedures of polymerization were performed in an automated KaVo, type EWL- 5518 device for polymerization (Leutkirch, Germany). The preparations were crushed into fragments and dissolved in methylene chloride. The amount o f residual benzoyl peroxide was determined by gas chromatography on a Pye Unicam 304 instrument (Cambridge, UK). Results o f the study o f residual benzoyl peroxide in polymerisates showed the values to be on a steady decline from the short-term to the long-term procedure. No statistically significant differences were observed either in the findings of residual benzoyl peroxide among the four different preparations or among the three polymerization procedures employed. Due to its reactivity, gas chromathography failed to be proved as a reliable procedure for quantitative determination o f benzoyl peroxide.Comparison o f the results of this study with those obtained by some of the so-called »cold« methods (e.g., infrared spectrophotometry or ultraviolet spectrophotometry) might produce interesting information

Chemical Composition and Physical Properties of “Pale Yellow” Naphtalan

The Pale Yellow (PY) Naphthalan is potentially a new treatment modality for some oral mucosal and dermatological diseases. Its chemical composition and physical properties were studied by standard and sophisticated methods. Special attention was paid to steranes and hopanes as favorable components and to aromatics as unfavorable compounds. PY Naphthalan is predominantly composed of saturated aliphatic hydrocarbons of different structures, and of hydrocarbons comprising aromatic ring(s) (< 15%). Among aromatics, 98% were monoaromatics and 2% diaromatics, while 16 polycyclic aromatic hydrocarbons designated by US Environmental Protection Agency as priority pollutants were found at minimum detectability levels. Steranes and hopanes appeared in native geogenic clusters of homologs and each of identified compounds was in native geogenic configuration. Steranes were in the range from norcholestanes up to propyl cholestanes and hopanes up to pentakishomohopanes. The content of steranes and hopanes was relatively high. Compared to the other naphthalan products, the composition of PY Naphthalan is remarkably improved. Physical properties make PY Naphthalan convenient for application. (doi: 10.5562/cca1886

Thermal Decomposition of Tetrabromoethylcyclohexane

Tetrabromoethyleyclohexane (TBECH),which serves as a fire retardant agent, was decomposed in defined and controlled conditions simulating some characteristic temperature and atmosphere conditions of fire development. Under the experimental conditions TBECH converted into a large portion of gases, some volatile condensable products and very little residue. The gases consisted mainly of HBr while light hydrocarbons, light bromine-containing hydrocarbons and C02 were in low concentrations. Among the volatile-condensable products, twenty one components were identified by GC-MS. They were cyclohexadiene, aromaties predominated by benzene and styrene and bromine-containing aromatics, containing one or two bromine atoms. Among the bromine-containing aromatics, the monobromine ones made up a fair concentration, especially bromoethylbenzene. As regards the yield of decomposition products, dehydrobromination highly predominated. High temperatures eaused some additional fragmentation by cleavage of C-C bonds. Secondary reactions of decomposition fragments are also stated

Geochemical Study of Oils and Oil Source Rock from the Eastern Drava and Slavonija-Srijem Depressions, Pannonian Basin, Croatia

A Middle Miocene oil source rock has been identified by geochemicallogging of exploration wells in the Eastern Drava depression (EDD) and in the Slavonija-Srijem depression (SSD) at the south-east margin of the Pannonian Basin, Croatia. The source rock contains Type II to II/III kerogen and reaches early maturity stage at depths of about 2400 m. The Mesozoic sequences were found either to be absent or to be poor in organic matter within the analysed wells.According to C27-C28-C29 sterane and C27-C28-C29 monoaromaticsteroid distributions, gamacerane indices, C35 homohopane indicesand presence of C30 steranrs, the EDD and SSD oils wrre generatedfrom the same marine source rock. The distribution of homohopanesand high Ni/(Ni + V) porphyrin ratios indicates that the related sourcerock was deposited under suboxic conditions. The oils appear to havebeen generated from the source rock during the early to middle stagesof maturity. The oils are waxy, with pour points up to 30°C and sulphurcontents not exceeding 0.7%.</div