Synthesis of polyalkylacrylate nanolatexes by microemulsion polymerization method

The paper concerns with the radical polymerization of [octadecyl acrylate (ODA), isooctyl acrylate (iso-OA) and α-olefins 1-Octene (n-O)]. These microemulsions were stabilized by sodium dodecyl sulfate (SDS) and initiated by water-soluble initiator potassium persulfate (KPS). The nanolatex particle sizes were determined by transmission electron microscope (TEM). They were situated between 10 and 100 nm. The microstructures were confirmed by FT-IR and molecular weights determined by Gel permeation chromatography (GPC). The obtained M. wt. were (≈70 × 10³, 101 × 10³ and 153 × 10³ g/mol). The polydispersity, molecular weights, and particle sizes were discussed in the light of micelle formation and shape of the alkyl group via emulsion polymerization.     

丙烯酸酯改性棉短绒高吸油性材料的研制与性能

以棉短绒为基材,丙烯酸长链酯为单体,双丙烯酸二元醇酯为交联剂,采用悬浮接枝共聚法合成了高吸油性材料,考察了棉纤维与单体的投料比、交联剂种类与用量、引发剂用量、聚合反应温度与时间等因素对该材料吸油性能的影响,得到了不同丙烯酸长链酯与棉纤维接枝聚合制备吸油材料的最佳工艺条件。当以丙烯酸辛酯为单体,对棉纤维和单体总重量的比为60％,以1,4-二丙烯酸丁二醇酯为交联剂,其用量为0.6％时,制得吸油材料的最高吸油倍率为16.0g／g。     

Adsorption separation of condensate oil from produced water using ACTF prepared of oil palm leaves by batch and fixed bed techniques

A novel method is applied to produce amorphous carbon thin film (ACTF) from oil palm leaves. The novel prepared ACTF is in the form of thin films like graphene sheets having winding surface. ACTF was characterized by different methods of characterization: FTIR, BET, SEM, EDX, TEM, and Raman. ACTF employed as an adsorbent to separate emulsified condensate oil from synthetic produced water as a treatment process before reinjection in oil reservoirs. The adsorption performance of batch and fixed bed adsorption systems were investigated. Contact time, initial concentration of condensate oil ($C_o$ = 100–2500 mg/l) and temperature were studied by batch experiments. The obtained results indicated that the adsorption capacity and the removal efficiency increased with time up to 132.77 mg condensate/g adsorbent and 66.38% respectively, within 6 h equilibrium time at 308 K. The thermodynamic adsorption experiments conducted at 288, 308 and 318 K, referring exothermic nature of the adsorption process.The performance study of fixed bed adsorption described through the breakthrough curves concept with two parameters: column bed heights (5, 10 and 15 mm) and flow rate (2.2, 5 and 8.4 ml/min). Two models (Thomas and Yoon-Nelson models) were applied to expect different parameters of fixed bed as adsorption capacity and time need for 50% breakthrough. The results exhibited that 2.2 ml /min feed flowrate and 5 mm bed height at 1000 mg/l initial oil condensate concentration were the optimum conditions for the ACTF column. The experimental breakthrough curves showed acceptable fit with the calculated breakthrough profiles obtained by Thomas model.     

Direct conversion of natural gas into COx-free hydrogen and MWCNTs over commercial Ni–Mo/Al2O3 catalyst: Effect of reaction parameters

A commercial hydrotreating nickel molybdate/alumina catalyst was used for the direct conversion of natural gas (NG) into CO_x-free hydrogen and a co-valuable product of multi-walled carbon nanotubes (MWCNTs). The catalytic runs were carried out atmospherically in a fixed-bed flow reactor. The effect of reaction temperature between 600 and 800 °C, and dilution of the NG feed with nitrogen as well as pretreatment of the catalyst with hydrogen were investigated. At a reaction temperature of 700 °C and dilution ratio of NG/N₂ = 20/30, the optimum yield of H₂ (～80%) was obtained with higher longevity. However, using the feed ratio of NG/N₂ = 30/20, the optimum yield of MWCNTs was obtained (669%). X-ray diffraction pattern for the catalyst after the reaction showed that the MWCNTs were grown on the catalyst at all reaction temperatures under study. TEM pictures revealed that the as-grown MWCNTs at 600, 650 and 800 °C are short and long with a low graphitization degree. At 700 °C a forest of condensed CNTs is formed, whereas both carbon nanofibers and CNTs were formed at 750 °C.     

Mineralogy and rheology of raw and activated Turonian to Coniacian clays from Benue Trough,northeastern Nigeria

Since the discovery of oil and gas in Oloibiri, an onshore oilfield located in Oloibiri in Ogbia Local Government Area of Bayelsa State, Nigeria on Sunday 15th January 1956 by Shell Darcy, hundreds of oil wells have been drilled and not a single of these oil wells was drilled without the use of bentonite. This work is aimed at evaluating the rheological properties of raw and beneficiated Nigerian clays to ascertain their worth for use as drilling mud in oil and gas well drilling. This will save foreign earnings used in the importation of bentonite by the oil and gas development companies, create employment opportunity and open a new frontier for solid mineral development. Five clay samples from Pindiga Formation in Benue Trough, northeastern Nigeria were collected and subjected to elemental, rheological and other physical properties tests and analysis, while another portion of same samples were beneficiated using sodium carbonate, gum Arabic and poly-anionic cellulose for rheological enhancement then subjected to same cycle of tests and analysis above. Results obtained indicates that wet beneficiation as adopted in this study has proved to be more effective in Ca and Na ionic exchange. The rheological and other physical properties of the clays attained the standard that is required for use in oil and gas well drilling after addition of 12% sodium carbonate and 1.5 g poly-anionic cellulose. It was also discovered that when the formulation was allow to age (stay for 24 h), it attained optimum rheological requirement with 12% sodium carbonate and just 0.8 g poly-anionic cellulose. The clays studies do not require addition of weighing additive such as barite because of their high iron content which made their density attain the require standard even without additives.     

An upgraded bio-oil produced from sugarcane bagasse via the use of HZSM-5 zeolite catalyst

The pyrolysis upgrading of bio-oil from sugarcane bagasse (SB) using ZSM-5 zeolite catalyst was carried out in a fixed bed reactor to determine the effects of heating rate, temperature, and catalyst/biomass ratio on yield of bio-oil and their chemical compositions. Proximate analysis indicated that SB has 13.2% moisture content. The ultimate analysis carried out established that the percentage of carbon content is higher (48.2%) than oxygen content (44%) while the fibre content analysis showed 26.4% lignin, 33.3% cellulose, 30.1% hemicellulose. The heating rate, temperature and catalyst/biomass ratio were varied in the range of 10–50 °C/min, 400–600 °C and 0.05–0.25 respectively. The non-catalytic pyrolysis gave the maximum percentage yield (45.67 wt%) of bio-oil at a pyrolysis temperature of 600 °C, heating rate of 50 °C/min, sweeping gas flow rate of 40 mL/min and the catalytic pyrolysis gave 40.83 wt% of bio-oil at the same conditions. The FT-IR spectra showed that the non-catalytic bio-oil is dominated by oxygenated compounds (acids, ketones, aldehydes, alcohols), while the catalytic bio-oil had preponderances of desirable compounds (alkanes, alkenes, aromatics, phenols). The chemical composition of the bio-oils was analyzed using GC–MS, which revealed that the quality of the bio-oil has been improved using HZSM-5 catalyzed pyrolysis.     

Effects of pulsed electric field treatments on quality of peanut oil

The effects of pulsed electric fields (PEF) treatment on physicochemical properties of peanut oil were investigated in this paper. Compositions of fatty acid, acid value (AV), peroxide value (PV), as well as carbonyl group value (CGV) of various PEF-treated peanut oil samples with different storage time were determined by GC/MS and AOCS standard methods. GC/MS analysis showed that little change of the oil composition was observed after PEF treatment. However, after being treated by various PEF treatments and stored at 40 °C for 100 days, the biggest increment of AV was 0.69 mg g⁻¹, which was lower than that of untreated peanut oil (0.79 mg g⁻¹). The PV significantly increased from 4.8 meq kg⁻¹ untreated oil to 11.5 meq kg⁻¹ PEF treated oil (50 kV cm⁻¹). And the increase extent of CGV of oil samples during the 100 d’ storage period was decreased with increasing electric field strength. During the storage period, the differences of AV, PV, and CGV of PEF-treated sample during storage period were less than that of untreated oil, which implied that the PEF treatment could restrain the speed of lipid oxidation reaction thus extending the shelf-life of oil rich products.     

Highly effective ionic liquids for biodiesel production from waste vegetable oils

As conventional energy sources deplete, the need for developing alternative energy resources which are environment friendly becomes more imperative. Vegetable oils are attracting increased interest in this purpose. The methanolysis of vegetable oil to produce a fatty acid methyl ester (FAME, i.e., biodiesel fuel) was catalyzed by commercial ionic liquid and its chloride modification. The imidazolium chloride ionic liquid was frequently chosen for the synthesis of biodiesel. The dual-functionalized’ ionic liquid is prepared by a direct combination reaction between imidazolium cation and various metal chlorides such as CoCl2, CuCl2, NiCl2, FeCl3 and AlCl3. Imidazolium tetrachloroferrate was proved to be a selective catalyst for the methanolysis reaction at a yield of 97% when used at 1:10, catalyst: oil ratio for 8 h at 55 °C. Operational simplicity, reusability of the used catalyst for 8 times at least, high yields and no saponification are the key features of this methodology. The dynamic viscosity and density of the upgraded vegetable oil decreased from 32.1 cP and 0.9227 g/cm³ to 10.2 cP and 0.9044 g/cm³ respectively, compared to those of the base vegetable oil. The objective of this study was the synthesis and characterization of biodiesel using commercial ionic liquid and its chloride modification. The ionic liquid catalysts were characterized using FTIR, Raman spectroscopy, DSC, TG and UV.     

In vitro evaluation of antibacterial and antioxidant activities of the essential oil and methanol extract of endemic Zataria multiflora Boiss

The present study was conducted to evaluate in vitro antibacterial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Zataria multiflora Boiss. The antibacterial test results showed that the essential oil of the plant strongly inhibited the growth of all of the microorganisms studied especially the Gram-negative strains. The polar fraction of methanol extract has been effective against Gram-positive strains, while the non-polar fraction has shown activity similar to essential oil. The antioxidant potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ammonium thiocyanate systems. Sub fractions of the methanol extract were able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 11.7 ± 1.58 and 16.2 ± 1.61 μg/ml, respectively for non-polar and polar ones, which the activity of the latter almost is equal to synthetic antioxidant BHA (18.2 ± 1.94 μg/ml). Inhibition values of linoleic oxidation were calculated to be 82.4% and 80.3% for the polar and non-polar fractions, respectively. The essential oil to be showed more inhibition (89.7 ± 2.5), similar to the synthetic antioxidants BHA (97.8 ± 2.94) and ascorbic acid (93.2 ± 2.1). The chemical composition of hydrodistilled essential oils of Z. multiflora was analyzed by GC/MS. A total of 25 compounds representing 99.78% of the oil were identified: thymol (37.59%), carvacrol (33.65%); para-cymene (7.72%), γ-terpinene (3.88%) and β-caryophyllene (2.06%) were the main components comprising 84.9% of the oil. Results here show that the essential oil and methanol extract of Z. multiflora possess antioxidant and antibacterial activity, and therefore it could be used as a natural preservative ingredient in food and/or pharmaceutical industries.     

Desalting and dewatering of crude oil in ultrasonic standing wave field

A standing wave field of ultrasound was established in the designed standing wave tube. The enhancement of ultrasound irradiation on desalting and dewatering process of LU-NING pipeline oil was studied. The results showed that the best conditions of the oil pretreatment was: adding 30 mg/L demulsifier, injecting 5% (v.) wash water, irradiating the crude oil 5 min by 10 kHz ultrasound (intensity 0.38 W/cm², standing wave field), settling for 90 min. The final results of salt and water contents were 3.851 mg/L and 0.37%, respectively. The effect of standing wave field combined with demulsifier was better than that of the demulsifier only. High temperature (80 °C) in the process was better than low temperature. Salt balance study showed that the key of desalting was: the wash water and the oil should be mixed sufficiently to extract the salts into the water as more as possible, the water added in should be provided to be separated out. If one stage of desalting process could not achieve the norm, two stages of desalting process should be considered.     

Levels of aflatoxin M1 in milk,cheese consumed in Kuwait and occurrence of total aflatoxin in local and imported animal feed

A total of 321 milk samples (177 fresh, 105 long-life and 27 powdered milk, and 12 human milk), 40 cheese samples and 84 feed samples were analyzed for aflatoxin M1 (AFM1) and total aflatoxin. The samples were collected randomly during January 2005–March 2007, from Kuwaiti markets. The method used was ELISA technique. Results showed that all fresh milk samples except one were contaminated with AFM1 ranging from 4.9 to 68.7 ng/kg. Eight samples exceeded the EC’s regulatory limit. For the long-life milk samples, the ranges of AFM1 were from below the detection limit to 88.8 ng/kg, with four samples above the action limit of the EC. In the powdered milk samples, AFM1 ranged from 2.04 to 4.14 ng/kg. Of the human milk samples, only five were contaminated, with AFM1 levels ranging from 8.83 to 15.2 ng/kg with a mean 9.7 ng/kg. The cheese samples recorded 80% contamination with AFM1 with a range 23.8–452 and mean of 87.6 ng/kg, with one sample being above the regulatory limit (250 ng/kg) while the feed samples, showed 79.8% contamination with total aflatoxin.     

Effect of packaging material headspace,oxygen and light transmission,temperature and storage time on quality characteristics of extra virgin olive oil

The effect of packaging parameters (transmission to light and oxygen, headspace volume) and storage temperature on quality characteristics of extra virgin olive oil (EVOO) was studied as a function of storage time (0–12 months). Packaging materials tested included clear glass, clear polyethylene terephthalate (PET), clear PET + UV blocker, clear PET covered with aluminum foil and clear polypropylene (PP) bottles. Quality parameters monitored over the 12 month storage period included: acidity, peroxide value (PV), spectrophotometric indices (K₂₃₂, K₂₇₀) and color. Results showed that the best packaging material for olive oil packaging was glass followed by PET. PP proved to be unsuitable for such an application. Exposure of olive oil samples to light, high storage temperatures (35 °C) and large headspace volumes caused substantial deterioration in product quality parameters. The most pronounced effect was that of temperature and light while the smallest effect was that of headspace volume and packaging material permeability to oxygen. Olive oil color was not substantially affected by storage conditions with the exception of storage of olive oil at 35 °C exposed to light for 12 months. Shelf life of extra virgin olive oil was 6 months packaged in clear glass in the dark at temperatures up to 22 °C; 3 months in clear PET in the dark at 22 °C and less than 3 months in clear PP in the dark at 22 °C. When exposed to light, shelf life of olive oil was 9 months when packaged in PET + aluminum foil; 3 months in PET + UV blocker and less than 3 months in clear PET at 22 °C. Product shelf life was less than 3 months at 35 °C. Finally oxygen in the headspace of olive oil resulted in deterioration of product quality. The relative contribution of parameters studied to the retention of olive oil quality was: temperature ≈ light > container headspace > packaging material oxygen permeability.     

丙烯酸十八酯-苯乙烯共聚物对含蜡原油改性效果与分子动力学模拟

合成了单体配比不同的丙烯酸十八酯-苯乙烯共聚物(OAS)降凝剂,采用实验与分子动力学模拟相结合的方法对降凝剂的性能进行评价。实验结果表明,OAS降凝剂的降凝减黏性能随丙烯酸十八酯比例的增加呈现出先增大后减小的趋势。在2000 mg/kg加剂量下,苯乙烯与丙烯酸十八酯摩尔比为1∶3的降凝剂OAS-4能使含蜡原油凝点降低4℃,降凝效果最好,并能有效改善原油的黏度和屈服值。模拟结果表明,加入OAS降凝剂能有降低石蜡体系和沥青质-胶质体系的平均密度,提高体系的势能与非键能;OAS降凝剂的加入能有效阻止蜡晶形成三维网状结构,拆散沥青质和胶质的堆砌结构;加入OAS-4的体系平均密度最低、势能上升最多,效果最佳。分子动力学模拟结果与实验结果一致。     

Essential oils to control Alternaria alternata in vitro and in vivo

The inhibitory effects of five essential oils (thyme, sage, nutmeg, eucaptus and cassia) against Alternaria alternata were tested at different concentrations (100–500 ppm) in vitro. The cassia oil and thyme oil both exhibited antifungal activity against A. alternata. The cassia oil inhibited completely the growth of A. alternata at 300–500 ppm. The thyme oil exhibited a lower degree of inhibition 62.0% at 500 ppm. Spore germination and germ tube elongation of the pathogens in potato dextrose broth was strongly inhibited in the presence of 500 ppm cassia oil. Irreversible inhibition of fungal growth could be caused by exposure to 300 ppm and 400 ppm cassia oil for 6 days and 500 ppm cassia oil for 3 days. Cassia oil at 500 ppm reduced the percentage of decayed tomatoes. The experiments on reducing natural decay development of tomatoes gave similar results. Therefore, essential oils could be an alternative to chemicals for control of postharvest phytopathogenic fungi on fruits or vegetables.     

Comparison of the effects of sesame and Thymbra spicata oil during the manufacturing of Turkish dry-fermented sausage

Effects of sesame, Thymbra spicata oil and BHT (butylated hydroxy toluene) on the quality and safety (pH, biogenic amine, TBARS values, colour and sensory attributes) of Turkish dry-fermented sausage were investigated during the ripening periods. A sharp decrease (P < 0.05) in pH values were observed from 5.84 to about 4.40 during the first 2 days of ripening. The TBARS value and putrescine concentration in recipes were found in the following order: control (S1) > BHT (S2) > sesame oil (S4) > Thymbra spicata oil (S3). Histamine and tyramine concentrations were highest (P < 0.05) in the control recipe, while lowest (P < 0.05) in Thymbra spicata and sesame oil added recipes. The most acceptable recipes were found to be the sesame oil added recipes with respect to their highest overall sensory quality scores. The order of acceptability was found to be S4 = S3 = S2 > S1. The pH, L, b, and YI-values were not significantly changed (P > 0.05) by the addition of Thymbra spicata oil, sesame oil, and BHT. These results indicated that the most effective antioxidant was found to be Thymbra spicata oil. This study pointed out that natural antioxidants could be easily utilized in sausages to enhance quality and get safe products.     

Preliminary hydrocarbon analysis of crude oils from Umutu/Bomu fields,south west Niger Delta Nigeria

Seven different crude oil samples were collected from two oil fields in the Niger Delta Nigeria. The bulk properties of these crude oils which include API gravity, reid vapour pressure; kinematic viscosity, dynamic viscosity, moisture, gum content and cloud point were analysed. Aliphatic biomarkers were used as supporting tool to deduce the geochemical characteristics such as thermal maturity, depositional environments, source of organic matter and extent of biodegradation. Results show that API° gravity ranged from 29.00° to 85.00°, specific gravity 0.65 to 0.88, 3.00 to 9.00, reid vapour pressure 3.00 to 9.00 kPa, kinematic viscosity 0.90 to 10.10 cSt, dynamic viscosity 0.70 to 8.90 cP, moisture content 0.13% to 26.00%, gum content 6.27 to 45.84 mg/L, cloud point 3.00 to 12.00 °C, pour point ?7.00 to 4.00 °C and flash point <30.00 °C. Distribution of n-alkanes (Pr/Ph, and isoprenoide/n-alkanes ratios) reflects that the oil samples originated mainly from terrestrial organic sources deposited in an oxic paleoenvironment.     

Antimicrobial activity of clove (Syzgium aromaticum) oil in inhibiting Listeria monocytogenes on chicken frankfurters

The ability of Listeria monocytogenes to survive and grow at refrigeration temperature in some ready to eat (RTE) poultry products is a public health concern. The inhibitory effect of clove oil (1% and 2%, v/w) applied to the surface of RTE chicken frankfurters was determined on seven strains of L. monocytogenes inoculated at low (10²–10³ cfu/g) or high cell numbers (10⁴–10⁶ cfu/g), and stored at 5 °C for 2 weeks or at 15 °C for 1 week. All strains of L. monocytogenes survived and grew on control frankfurters at 5 °C and 15 °C but growth was inhibited under both storage conditions in the presence of either 1% or 2% clove oil. Depending on the sensory considerations, the addition of clove oil to frankfurters may be an effective strategy to control L. monocytogenes in chicken frankfurters.     

长脂肪链改性疏水缔合聚丙烯酰胺的制备与表征

本文以丙烯酸十八酯（ODA）为疏水单体,与丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）、丙烯酸（AA）通过自由基聚合法制得长脂链改性疏水缔合聚丙烯酰胺（PAMBA）,研究了共聚反应中各种因素的影响,以黏度为指标确定合理的聚合工艺条件,并通过红外光谱仪、X-射线衍射仪和透射电镜对聚合物性能进行了表征。结果表明,PAMBA的最佳合成配方为ODA用量（占总单体质量）0.6%、AMPS用量20%、AA用量10%、引发剂KPS用量0.3%。在常温、剪切速率170 s^-1下,由最佳配方得到的质量分数为0.2%的PAMBA溶液黏度为56.2mPa·s,PAMBA在水溶液中存在强烈的分子间缔合作用。     

Characterization of biosurfactants produced by novel strains of Ochrobactrum anthropi HM-1 and Citrobacter freundii HM-2 from used engine oil-contaminated soil

Microbial surfactants are widely used for industrial, agricultural, food, cosmetics, pharmaceutical, and medical applications. In this study, two bacterial strains namely, Ochrobactrum anthropi HM-1 and Citrobacter freundii HM-2, previously isolated from used engine oil contaminated soil, and capable of producing biosurfactants, were used. Their cell-free culture broth showed positive results toward five screening tests (hemolysis in blood agar, drop collapse, oil displacement, emulsification activity (E₂₄), and surface tension (ST) reduction). They reduced the ST of growth medium (70 ± 0.9) to 30.8 ± 0.6 and 32.5 ± 1.3 mN/m, respectively. The biosurfactants were classified as anionic biomolecules. Based on TLC pattern and FT-IR analysis, they were designated as glycolipids (rhamnolipid). Waste frying oil was feasibly used as a cheap and dominant carbon source for biosurfactants production; 4.9 and 4.1 g/l were obtained after 96 h of incubation, respectively. Compared with non-irradiated cells, gamma-irradiated cells (1.5 kGy) revealed enhanced biosurfactant production by 56 and 49% for HM-1 and HM-2, respectively. The biosurfactants showed good stability after exposure to extreme conditions [temperatures (50–100 °C for 30 min), pH (2–12) and salinity (2–10% NaCl)], they retained 83 and 79.3% of their E₂₄, respectively, after incubation for a month, under extreme conditions. Biosurfactants effectively recovered up to 70 and 67% of the residual oil, respectively, from oil-saturated sand pack columns. These biosurfactants are an interesting biotechnological product for many environmental and industrial applications.     

Assessment of n-alkanes and acyclic isoprenoids (geochemical markers) in crudes: A case study of Iraq and Niger delta,Nigeria

This study was designed to determine the ratios of the isoprenoids and n-alkanes in an imported crude oil sample (Bassrah from Iraq) and four crude oil samples (Bodo, Bonny-Export, Escravos and Penningston) from the Niger Delta region of Nigeria to ascertain the levels of maturity and as an indicator of the depositional environment of the crudes. The physical properties of the crudes: viscosity, density and °API gravity were also determined. Fractionation of the crudes was done using a new approach coded NAASAR, (n-alkanes, asphaltenes, aromatics and resins) comprising urea adduction followed by gas chromatographic analyses (for n-alkanes), n-heptane precipitation (for asphaltenes) and column chromatography (for resins). Results showed °API gravities Bassrah 28.03°, Bodo 31.89°, Bonny-Export 33.8°, Escravos 33.8°, and Penningston 33.8° indicating that Escravos, Penningston and Bonny-Export crudes are light crudes while Bodo and Bassrah crudes are medium crudes. The n-alkanes profiles of the five crudes were determined by gas chromatography ranged from n-C₈H₁₈ to n-C₄₀H₈₂ with total weight percent n-alkane yield Bassrah 11.2, Bodo 47.41, Bonny-Export 32.47, Escravos 5.58, Penningston 30.75 were obtained by urea adduction. The pristane to phytane ratios were computed, Bassrah 1.51, Bodo 1.48, Bonny-Export 1.08, Escravos 1.01 and Penningston 2.41. Isoprenoids to n-alkane ratios Pr/n-C₁₇ in the same order of the crudes were 0.85, 0.83, 0.67, 0.65, 0.95 while phytane to n-C₁₈ ratios were 0.61, 0.55, 0.62, 0.61 and 0.43. The results established the increasing level of maturity as obtained from Pr/n-C₁₇ ratio in the order: Penningston < Bassrah < Bodo < Bonny-Export < Escravos. The result of Pr/Ph ratios show the same trend in the level of maturity. Penningston crude with Pr/Ph ratio 2.41 shows that the crude is deposited in fluviomarine and coastal swamp environment while Bassrah, Bodo, Bonny-Export and Escravos crudes indicate aquatic depositional environment (anoxia) condition.