Distribution of natural and artificial radioactivity in soils, water and tuber crops.

Activity concentrations of radionuclides in water, soil and tuber crops of a major food-producing area in Ghana were investigated. The average gross alpha and beta activities were 0.021 and 0.094 Bq/L, respectively, and are below the guidelines for drinking water and therefore not expected to pose any significant health risk. The average annual effective dose due to ingestion of radionuclide in water ranged from 20.08 to 53.45 µSv/year. The average activity concentration of (238)U, (232)Th, (40)K and (137)Cs in the soil from different farmlands in the study area was 23.19, 31.10, 143.78 and 2.88 Bq/kg, respectively, which is lower than world averages. The determined absorbed dose rate for the farmlands ranged from 23.63 to 50.51 nGy/year, which is within worldwide range of 18 to 93 nGy/year. The activity concentration of (238)U, (232)Th, (40)K and (137)Cs in cassava ranges from 0.38 to 6.73, 1.82 to 10.32, 17.65 to 41.01 and 0.38 to 1.02 Bq/kg, respectively. Additionally, the activity concentration of (238)U, (232)Th, (40)K and (137)Cs in yam also ranges from 0.47 to 4.89, 0.93 to 5.03, 14.19 to 35.07 and 0.34 to 0.89 Bq/kg, respectively. The average concentration ratio for (238)U, (232)Th and (40)K in yam was 0.12, 0.11 and 0.17, respectively, and in cassava was 0.11, 0.12 and 0.2, respectively. None of the radioactivity is expected to cause significant health problems to human beings.

A sensitivity study of Surface Wind simulations over Coastal Ghana to selected Time Control and Nudging options in the Weather Research and Forecasting Model.

Over the years, the Weather Research and Forecasting Model (WRF) has been gaining popularity as a low-cost alternative source of data for wind resource assessments. This paper investigates the impact of selected time control, and nudging options on wind simulations in WRF. We conducted 15 numerical experiments, combining 5 simulation run-times and 3 options for disabling nudging in the Planetary Boundary Layer (PBL) in WRF. Hourly wind speed and direction predictions were compared with actual measurements at 40 m, 50 m and 60 m a.g.l. From our results, we recommend that, for optimum performance, the method of disabling nudging in the PBL should be chosen with simulation run times in mind. For wind simulations in our study area, up to 2 days run-times with nudging disabled below 1600 m in model configurations gives the best wind speed predictions. However, disabling nudging below the model-calculated PBL height offers more consistent results and produces relatively less prediction error with longer run times.

Human Health Risk and Bioaccessibility of Toxic Metals in Topsoils from Gbani Mining Community in Ghana.

BACKGROUND: Anthropogenic activities such as artisanal mining pose a major environmental health concern due to the potential for discharge of toxic metals into the environment. OBJECTIVES: To determine the distribution and pollution patterns of arsenic (As), iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), manganese (Mn), copper (Cu) and zinc (Zn) in the topsoil of a mining community in Ghana, along with potential human health risks and in vitro bioaccessibility. METHODS: Concentrations of metals were determined using X-ray fluorescence techniques and validated using inductively coupled plasma-mass spectrometry. RESULTS: Concentrations of the metals in topsoil were in the order of magnitude of Cu (31.38 mg/kg) < Ni (45.39 mg/kg) < As (59.66 mg/kg) < Cr (92.87 mg/kg) < Zn (106.98 mg/kg) < Mn (1195.49 mg/kg) < Fe (30061.02 mg/kg). Geo-statistical and multivariate analyses based on hazard indices including contamination, ecological risks, geo-accumulation, and pollution load suggest that the topsoils are contaminated in the study area. The potential ecological risk index (PERI) showed high ecological risk effects (PERI=269.09), whereas the hazard index (1×10-7) and carcinogenic risk index (1×10-5) indicated low human health risks. Elevated levels of As, Cr, Ni, and Zn were found to emanate from anthropogenic origins, whereas Fe, Mn, and Cu levels were attributed mainly to geological and atmospheric depositions. Physicochemical parameters (pH, electrical conductivity and total organic carbon) showed weak positive correlations to the metal concentrations. Elemental bioaccessibility was variable, decreasing in the order of Mn (35± 2.9%) > Cu (29± 2.6%) > Ni (22± 1.3%) > As (9± 0.5%) > Cr (4± 0.6%) > Fe (2± 0.4%). CONCLUSIONS: Incorporation of in-vitro bioaccessibility into the risk characterization models resulted in a hazard index of less than 1, implying low human health risks. However, due to accumulation effects of the metals, regular monitoring is required. COMPETING INTERESTS: The authors declare no competing financial interests.

Validated RP-HPLC method for simultaneous determination and quantification of chlorpheniramine maleate, paracetamol and caffeine in tablet formulation.

Chlorpheniramine maleate-paracetamol-caffeine tablet formulation is one of the common over-the-counter drugs used for the treatment of cold and cough. A reversed-phase high-performance liquid-chromatography method has been successfully developed for the simultaneous determination of chlorpheniramine maleate, paracetamol and caffeine in a drug formulation. The RP-HPLC method employed a Phenomenex C18 reversed phase column (Luna 5µ, 250 × 4.6 mm) with an isocratic mixture of methanol and 0.05 M dibasic phosphate buffer pH 4.0 in the ratio of (30:70; v/v) as the mobile phase. The column temperature was kept at 30 °C. The flow rate was 1.0 mL/min and detection was by means of a UV detector at wavelength of 215 nm. All the active components were successfully eluted with mean retention times of 2.4, 4.2, 7.2 min for chlorpheniramine maleate, paracetamol and caffeine respectively. The method was found to be linear (R(2) > 0.99), precise (RSD < 2.0 %), accurate (recoveries 97.9-102.8 %), specific, simple, sensitive, rapid and robust. The validated method can be used in routine quality control analysis of fixed dose combination tablets containing chlorpheniramine maleate, paracetamol and caffeine without any interference by excipients.

Determination of triacylglycerol regioisomers using electrospray ionization-quadrupole ion trap mass spectrometry with a kinetic method.

The kinetic method was applied to differentiate and quantify mixtures of regioisomeric triacylglycerols (TAGs) by generating and mass selecting alkali ion bound metal dimeric clusters with a TAG chosen as reference (ref) and examining their competitive dissociations in a quadrupole ion trap mass spectrometer. This methodology readily distinguished pairs of regioisomers (AAB/ABA) such as LLO/LOL, OOP/OPO and SSP/SPS and consequently distinguished sn-1/sn-3, sn-2 substituents on the glycerol backbone. The dimeric complex ions [ref, Li, TAG((AAB and/or ABA))](+) generated by electrospray ionization mass spectrometry were subjected to collision induced dissociation causing competitive loss of either the neutral TAG reference (ref) leading to [Li(AAB and/or ABA)](+) or the neutral TAG molecule (TAG((AAB and/or ABA))) leading to [ref, Li](+). The ratio of the two competitive dissociation rates, defined by the product ion branching ratio (R(iso)), was related via the kinetic method to the regioisomeric composition of the investigated TAG mixture. In this work, a linear correlation was established between composition of the mixture of each TAG regioisomer and the logarithm of the branching ratio for competitive fragmentation. Depending on the availability of at least one TAG regioisomer as standard, the kinetic method and the standard additions method led to the quantitative analysis of natural TAG mixtures.

Simple complementary liquid chromatography and mass spectrometry approaches for the characterization of triacylglycerols in Pinus koraiensis seed oil.

A new simple strategy to identify triacylglycerols (TAGs) in oils and fats was performed using on line coupling of non aqueous reversed phase chromatography-electrospray ionization-mass spectrometry (NARP-LC-ESI-MS(2)) with silver nitrate (AgNO(3)) as post-column additive, and chromatographic data (partition number information and both the graphs of log k vs. number of double bond (DBN) and carbon number (CN)). NARP liquid chromatography permitted to separate TAGs composed of Δ5 and Δ9 but not from Δ11 double bond location on alkyl chain of fatty acid residues. Silver cationization improved the sensitivity by a factor one hundred. MS(2) information gave unambiguously the nature of three fatty acid residues bonded to glyceryl backbone of TAGs while log k against DBN and CN curves discriminated between the same molecular mass TAG isomers (whose constitutive fatty acid residues are double bond position and configuration isomers). Combination of structural information given by MS with chromatographic retention laws led to the development of a general methodology for determination of the structure of TAGs in lipids. This methodology was applied to Pinus koraiensis seed oil for which some uncommon TAGs are present. It permitted the identification of 58 TAGs in this oil. The experimental proof of 29 uncommon TAGs as component of this oil is demonstrated. Among them 26 were minor constituents.