RESUMEN

The aromaticity and CDFT properties of naphthalene and its aza-derivatives were theoretically investigated using density functional theory (DFT) electronic structure method. The reactivity and chemistry of Azanaphthalene (1-AN), 1, 2-diazanaphthalene (1, 2-DAN), 1, 3-diazanaphthalene (1, 3-DAN), 1, 4-diazanaphthalene (1,4-DAN), 1, 5-diazanaphthalene (1, 5-DAN), 1, 6-diazanaphthalene (1, 6-DAN), 1, 7-diazanaphthalene (1,7-DAN) and 1, 8-diazanaphthalene (1, 8-DAN) were thoroughly explored and predicted focusing more on the fuzzy atomic space analysis, quantum chemical descriptors (CDFT), natural bond orbital (NBO), and structural electronic properties. The CDFT is focused on predicting the condensed Fukui function and dual descriptors along with condensed local electrophilicity and nucleophilicity investigation. From the aromaticity computational study, 1,7-DAN gave PDI, FLU, FLU- π , PLR, HOMA, BIRD and LOLIPOP values of approximately one (1) was found to be the most aromatic in the group, and strongest π -stacking ability. The aromaticity follows the trend: 1, 7-DAN > 1, 8-DAN > 1, 5-DAN > 1, 6-DAN > 1, 4-DAN > 1, 2-DAN > 1-AN > naphthalene. The second order perturbation energy NBO analysis revealed that the 3 highest stabilization energies in the molecules are C6-Na to C3-C4 ( π ∗ - π ∗ 236.90 kcal/mol) of 1, 6-DAN, C3-C4 to C1-C2 ( π ∗ - π ∗ 236.37 kcal/mol) of 1-AN and C7-N10 to C2-C4 ( π ∗ - π ∗ 235 kcal/mol) of 1, 3-DAN.

RESUMEN

The concentrations of nine metals (Cd, Pb, Ni, Cr, Co, Cu, Fe, Mn and Zn) were measured in selected brands of medicated, moisturizing and skin-lightening soaps and shower gels with the aim of evaluating the human health risk associated with metal exposure from the use of these products. The concentrations of metals in these products were determined by means of atomic absorption spectrophotometry after sample digestion with a mixture of acids. The concentration ranges of the metals in the bathing soaps and shower gels were found to be: <0.06-3.4 µg g-1 for Cd, <0.09-26.5 µg g-1 for Pb, <0.12-43.0 µg g-1 for Cr, <0.06-32.5 µg g-1 for Ni, <0.06-40.5 µg g-1 for Cu, <0.12-8.0 µg g-1 for Co, 61.8-4000 µg g-1 for Fe, <0.09-29.5 µg g-1 for Mn, and 25.5-1000 µg g-1 for Zn. The systemic exposure dosage values for these metals obtained from the application of these brands of bathing soaps and shower gels were below their respective provisional tolerable daily intake/or recommended daily intake values. The margin of safety values obtained for the metals were greater than 100 which indicated that there was no significant risk to the users of these brands of bathing soaps and shower gels, except in the case of Co.

Asunto(s)

RESUMEN

The concentrations and compositional patterns of the USEPA 16 polycyclic aromatic hydrocarbons were investigated in three commercially available fish species, Chrysichthys nigrodigitatus, Cynoglossus senegalensis and Polydactylus quadratifilis, from the Bonny and Cross River systems in the eastern Niger Delta of Nigeria. The objective of the study was to provide useful information on the levels and sources of polycyclic aromatic hydrocarbons (PAHs) and the associated risks with their consumption. The 16 PAHs in the fish samples were extracted by ultrasonication with hexane/dichloromethane, and the concentrations of PAHs in the extracts were quantified by gas chromatography-mass spectrometry. The measured concentrations of the Æ©16 PAHs in Chrysichthys nigrodigitatus, Polydactylus quadratifilis and Cynoglossus senegalensis ranged from 106 to 491, from 43.1 to 1734 and from 96.4 to 937 µg kg(-1) in the Bonny River system and from 20.0 to 975, from 24.7 to 506 and from 24.9 to 387 µg kg(-1) in the Cross River system, respectively. The compositional patterns of the PAHs showed that the three- and four-ringed PAHs were the major contributors to the PAH burden in these fish species. The diagnostic ratios indicate that the PAHs in these fish samples originated mainly from combustion processes. The health risk assessment, as determined from the benzo[a]pyrene potency equivalent factor, margin of exposure and incremental lifetime cancer risk, indicates that PAHs in the majority of these fish species can induce potential carcinogenic effects.

Asunto(s)

RESUMEN

In the study described in this article, the concentrations of metals (cadmium, copper, chromium, aluminum, lead, nickel, zinc, cobalt, manganese, and iron) in samples of some commonly used hair dyes and tattoo inks were determined with a view to providing information on the hazards associated with the use of these products. The concentrations of metals were measured after nitric acid/perchloric acid/hydrogen peroxide digestion by atomic absorption spectrometry. Results indicated that the tattoo ink samples contained allergenic metals such as nickel, chromium, and cobalt at concentrations above the suggested limit of 1 µg/g for greater skin protection, and the toxic metals were below their respective prescribed limits, as impurities in ingredients for use for cosmetics, in the majority of the samples.

Asunto(s)

RESUMEN

The concentrations of nine metals (Cd, Pb, Ni, Cr, Co, Cu, Fe, Mn and Zn) were determined in lip sticks, lip glosses, lip balms, eye pencils, eyeliners, eye shadows, blushes, mascaras and face powders. The study was aimed at providing information on the risk associated with human exposure to metals in these facial cosmetic products. The concentrations of metals in the samples were measured by atomic absorption spectrometry after digestion with a mixture of nitric acid, hydrochloric acid and hydrogen peroxide. The mean concentrations of metals in these facial cosmetics ranged from 3.1 to 8.4 µg g-1 Cd, 12-240 µg g-1 Pb, 9.1-44 µg g-1 Cr, 18-288 µg g-1 Ni, 1.6-80 µg g-1 Cu, 7.9-17 µg g-1 Co, 2.3-28 mg g-1 Fe, 12-230 µg g-1 Mn, and from 18 to 320 µg g-1 Zn. The concentrations of Ni, Cr and Co were above the suggested safe limit of 1 µg g-1 for skin protection, while Cd and Pb were above the Canadian specified limits. The systemic exposure dosage (SED) values for these metals obtained from the use of these facial cosmetic products were below their respective provisional tolerable daily intake (PTDI)/or recommended daily intake (RDI) values. The margin of safety values obtained were greater than 100 which indicated that the concentrations of the metals investigated in these facial cosmetics do not present considerable risk to the users except in the case of face powders.

RESUMEN

The concentrations of ten metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn and Al) were measured in some commonly used moisturizing and skin-lightening creams in Nigeria with a view to providing information on the risk of exposure to metals from the use of these products. The metal concentrations in these products were measured by atomic absorption spectrometry after acid digestion of the samples. The measured concentrations of metals in the skin moisturizing creams ranged from <0.15 to 6.3 µg/g Cd, <0.02 to 17.5 µg/g Cu, 2.25 to 6.25 µg/g Cr, <0.25 to 124.3 µg/g Al, 0.2 to 7.3 µg/g Pb, <0.03 to 10.7 µg/g Ni, 17.3 to 372.0 µg/g Zn, <0.02 to 1.0 µg/g Co, 17.75 to 28.8 µg/g Mn, <0.1 to 89.8 µg/g Fe while the concentrations of metals in the skin-lightening products ranged from <0.15 to 16.5 µg/g Cd, <0.02 to 10.0 µg/g Cu, 4.25 to 8.0 µg/g Cr, <0.25 to 128.0 µg/g Al, 0.5 to 4.5 µg/g Pb, <0.03 to 1.65 µg/g Ni, 24.7 to 267.5 µg/g Zn, <0.02 to 2.5 µg/g for Co, 19.3 to 31.8 µg/g Mn, 9.5 to 211.63 µg/g Fe. In a significant number (>93%) of the samples investigated the concentrations of Pb, Cd, Ni and Co were below the specified limit, or the maximal limit for impurities in colour additives in cosmetics for external use. However, Cr was found at concentrations above the allergenic limit of 1 µg/g. The results also showed that skin-lightening creams contained higher concentrations of the studied metals than the moisturizing creams, except for Ni, which indicates that persons who uses skin-lightening creams in preference to moisturizing ones, are exposed to higher concentrations of metals.

Asunto(s)

RESUMEN

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in 10 popular fish species in the Nigerian market were determined with a view to providing information on the health hazards associated with the consumption of these fish species. The concentrations of PAHs were measured by gas chromatography-mass spectrometry after extraction by ultrasonication with acetone-dichloromethane and clean up. The concentration ranges of the Σ16 PAHs were 20 to 39.6 µg kg(-1) for Parachanna obscura (African snake head), 6.8 to 532.3 µg kg(-1) for Oreochromis niloticus (tilapia), 7.4 to 91.1 µg kg(-1) for Gymnarchus niloticus (Asa), 13.1 to 34.1 µg kg(-1) for Sebastes fasciatus (red fish), 11.2 to 80.0 µg kg(-1) for Gadus morhua (cod), 23.9 to 34.6 µg kg(-1) for Chrysicthys nigrodigitatus (silver cat fish), 63.4 to 131.4 µg kg(-1) for Sardinella aurita (sardine), 22 to 52.9 µg kg(-1) for Trachurus trachurus (Atlantic horse mackerel), 21.0 to 63.7 µg kg(-1) for Scomber scombrus (mackerel), and 27.7 to 44.5 µg kg(-1) for Pseudotolithus senegalensis (croaker). Benzo[a]pyrene occurred in 23% of these fish samples at concentrations above the European Union permissible limit of 2.0 µg kg(-1). The calculated margins of exposure based on the indicators for occurrence and effects of PAHs were greater than 10,000 indicating no potential risk for the consumers of the species evaluated in this study.

Asunto(s)

RESUMEN

The concentrations of Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn, Mg, Ca, K, and Na were determined in some traditional alcoholic beverages (oil palm wine, raphia palm wine, burukutu, pito, ogogoro) consumed in southern Nigeria, with a view to providing information on the dietary intakes of essential metals and exposure of humans to toxic metals. The concentrations of these 13 elements were determined by atomic spectrometry after nitric acid/hydrogen peroxide digestion. The mean concentrations of the metals (mg/L) in the samples ranged from 0.02 to 0.05 for Cd; 0.01 to 0.19 for Pb; nd to 0.11 for Ni, nd to 0.15 for Cr; 0.09 to 0.60 for Cu; 0.01-0.08 for Co; 0.30 to 10.3 for Fe; 0.02 to 3.97 for Mn; 0.12 to 3.84 for Zn; 2.08 to 301.3 for Mg; 2.21 to 49.2 for Ca; 35.05 to 926.1 for K; 6.30-58.1 for Na. The mean concentrations of metals in these alcoholic beverages were below statutory limits for the metals in alcoholic beverages and were similar to concentrations found in other alcoholic beverages in the literature. The estimated daily intakes of metals from the consumption of these alcoholic beverages were less than 2% of the recommended dietary allowance values except for Cd and Pb. The individual and combined metals target hazard quotient values were less than 1 except for raphia palm wine and burukutu. From the estimated target hazard, no long life health concerns of metals are associated with the consumption of these alcoholic beverages.

RESUMEN

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in commercially available infant formulae and follow-up formulae in Nigeria were determined with a view to providing information on the health risks to children from the consumption of these infant foods. The concentrations of PAHs were measured by means of gas chromatography-mass spectrometry (GC-MS) after extraction by ultrasonication with acetone/dichloromethane and clean-up. The concentrations of the Σ16 PAHs in these infant formulae ranged from 0.102 to 1.98 µg kg(-1), 0.054-1.98 µg kg(-1), 0.081-2.54 µg kg(-1) and 0.51-0.70 µg kg(-1) for infants of ages 0-6 months, 6-12 months, 1-3 years and 0-12 months respectively. The concentrations of benzo(a)pyrene (BaP) in all samples investigated were below the 1 µg kg(-1) European Commission permissible limit for BaP in foods meant for infants. The estimated daily intake of PAHs based on the European Food Safety Authority (EFSA) suggested indicators of occurrence and effects of PAHs in foods were not detected (nd) to 2.67 ng BaP kg(-1) bw day(-1), nd-5.29 ng PAH2 kg(-1) bw day(-1), nd-11.20 ngPAH4 kg(-1) bw day(-1) and nd-34.96 ng PAH8 kg(-1) bw day(-1). The estimated margin of exposure (MOE) values: BaP-MOE, PAH2-MOE, PAH4-MOE and PAH8-MOE values were greater than 10,000 which indicates that there are no health risks from the consumption of these products by infants. The concentrations and dietary exposure to PAHs from these products were similar to values reported in the literature for European Communities.

Asunto(s)

RESUMEN

The effects of culinary practices such as boiling, frying, and grilling on the proximate compositions and concentrations of metals (Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg) in commonly consumed fish species from the Nigerian coastal waters were investigated. The selected fish species were Polydactylus quadratifilis, Chrysicthys nigrodigitatus and Cynoglossus senegalensis. The culinary practices lead to increased protein, fat, and ash contents and decreased moisture contents of these fish species. The culinary practices resulted significant increase in the concentrations of most of the studied metals and decrease in the concentrations of Fe, Cr, and Pb in some fish types. The concentrations and estimated dietary intakes of Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg from consumption of the processed fish were within their statutory safe limits. The individual metal target hazard quotient (THQ) values and the total THQs were less than 1 which indicates that no health risks would arise from the long-term consumption of these fish species.

RESUMEN

The possibility of processing a ready-to-eat nutrient-rich weaning food (WF) for infants within the age group of 0.5-0.9 years from cooking banana fortified with popular and affordable legumes (cowpea and peanut) was investigated with the aid of computer software and available technology in Nigeria. A composite of 47% cowpea, 40% ripe banana, and 13% peanut was processed, analyzed to compare the actual nutrient composition to that predicted by the software and that of two popular commercial WFs produced by Gerber Products Company: rice with banana (RB) and oats with banana (OB). Proximate composition was determined by Association of Official Analytical Chemists (AOAC) methods, in vitro digestibility by the pH drop method, and amino acid was determined using high performance liquid chromatography. Essential amino acid values were comparable to the predicted values. Protein and oil contents had values of 16.89% and 8.38%, 6.9% and 1.10%, and 12.03% and 3.16% for WF, RB, and OB, respectively. Octadecenoic (oleic) acid had the highest value of 3.65% followed by octadecadienoic (linoleic) acid with a value of 2.64% amounting to 76.69% of the total fatty acid. Total sugar content of WF was recorded as 15.96 g/100 g, with fructose having the highest value of 8.07 g/100 g, followed by dextrose with a value of 7.66 g/100 g. In vitro-digestibility was in the order OB>WF>RB. The results show that it is feasible to produce precooked WF which has the potential to meet the nutritional needs of an infant, from local staples using computer-assisted technique and inexpensive technology available in Nigeria.