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This paper presents a developed analytical technique for risk assessment of colloidal fullerene in surface waters by ultrasonic-assisted dispersive liquid-liquid extraction (UADLLE) and high-performance liquid chromatography ultraviolet-visible detector (HPLC-UV). Fullerene colloidal nanoparticles were synthesised and characterized by high-resolution transmission electron microscopy (HRTEM) and ultraviolet-visible spectroscopy (UV-Vis). Ultrasonication step, disperser solvent, and sodium chloride salt enhance the surface area of fullerene derivative aggregates for better contact and lowers the solubility of fullerene derivative to the aqueous solution, respectively promoting mass transfer of fullerene from aqueous into the organic phase. Several extraction parameters were optimized, and the optimal conditions were established: 5 mL toluene as extraction solvent (2 cycles); 200 mL water sample; 1% sodium chloride salt; 15 min ultrasonication, and 400 µL methanol as disperser solvent. The mean absolute recoveries established in drinking water, wastewater, and river water were 117%, 103%, and 93%, respectively. The proposed analytical technique was linear in the ranges between 0.25 µg L-1 - 250 µg L-1 with an r-squared of 0.9958. The limit of detection (LOD) determined from the signal-to-noise ratio of 3 was 0.11 µg L-1 and the limit of quantification (LOQ) from a signal-to-noise ratio of 10 was 0.38 µg L-1. The precision ranges from 2% to 11% and accuracy percent error ranged from 7%-14% for spiked concentration levels of 0.25 µg L-1, 50 µg L-1, and 250 µg L-1. The measured environmental concentration (MECs) for the fullerene in water samples ranged from not detected to 10.54 µg L-1 and ecological assessment showed the concentration level of the fullerene can pose risk. Overall, according to the author's knowledge, this is the earlier work on the occurrence and risk assessment of fullerene colloidal nanoparticles (C61-PCBM) in potable and wastewater on the African continent.

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This study investigated the levels of polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples of the Diep River freshwater system of Western Cape Province, South Africa. A solid-phase extraction - gas chromatography - flame ionisation detection (SPE-GC-FID) method was utilised to simultaneously determine the 16 United States Environmental Protection Agency (US EPA) listed priority PAHs in water and sediment samples. The seasonal averages of individual PAH detected at the studied sites, ranged between not detected (Nd) and 72.38 ± 9.58 µg/L in water samples and between Nd and 16.65 ± 2.63 µg/g in the corresponding sediment samples. The levels of PAHs measured in water and sediment samples were subjected to probabilistic risk assessment to predict the possibility of regulatory values being exceeded. The average percentage exceedence of 63.26 was obtained for PAHs in water samples of the Diep River, while the corresponding average percentage exceedence obtained for sediment sample was 63.71. Sufficient exposure of humans and aquatic organisms to the exceedance levels obtained, would cause adverse health effect.

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Persistent organic pollutants (POPs) are dangerous and toxic pollutants that may cause adverse effects on human and animal health, including death. POPs such as polychlorinated biphenyls (PCBs) and pesticides are subtly released into the environment from industrial and agricultural use. Global circulation is due to their trans-boundary transport capacity, contingent on aerodynamic and hydrological properties. Plants have capacity to take-up POPs, and these bio-magnify along heterotrophic transfer pathways. In this study, levels of selected 6-PCB congeners and 3- DDTs in some leaf and root vegetables were investigated. Leaf and root vegetables were collected from different horticultural farms areas in Cape Town. The 6-PCBs and 3-DDTs were recovered from the samples using solid phase extraction(SPE), followed by GC-MS analysis. The ΣPCBs and ΣDDT (on-whole basis), were ranged: 90.9-234 ng/g and 38.9-66.1 ng/g respectively. The 3-PCBs and 6-DDTs levels were slightly higher in leaf vegetables compared to root vegetables. The detection of PCBs and DDTs in the vegetables suggest the probable use of PCBs containing pesticides. Although the observed concentrations were below the WHO maximum residue limits, consumption of such contaminated leaf and root vegetables portend a health risk.

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A multi-residue method for the determination of the occurrence and prevalence levels of selected veterinary pharmaceutical residues in surface water was developed on a high performance liquid chromatography coupled to ultraviolet-visible (HPLC-UV) detector, and tested with the intent of profiling their distribution. The limit of detection (LOD) and limit of quantitation (LOQ) achieved for the selected pharmaceuticals; acetaminophen, diclofenac, salicylic acid, tetracycline, chloramphenicol, ciprofloxacin, bisphenol-A, 17ß-estradiol, estriol, and ivermectin ranged between 0.06-3.45 µg L-1 and 0.17-10.35 µg L-1 respectively. Other International Conference on Harmonization (ICH) parameters for validation of analytical procedures were also evaluated and discussed. Pharmaceutical residues were recovered from surface water samples collected from around livestock farms in Cape Town, South Africa by solid phase extraction (SPE), and thereafter separated and quantified using a validated method on a HPLC-UV-detector. Most frequently detected residues were: acetaminophen (56%), diclofenac (53), tetracycline (72%), 17ß-estradiol (73%); chloramphenicol (68%), and salicylic acid (67%), with significantly high (p > 0.05) spatial variability in the concentration distributions of the pharmaceuticals in the surface waters.

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In this study, a method for the simultaneous determination of two steroid hormones, 17ß-estradiol (E2) and estriol (E3), and a hormone mimicking polycarbonate, bisphenol-A (BPA), was developed and validated. This was thereafter used for the determination of the levels of the hormones in surface water collected around some livestock farms. The sensitivity of the method allowed the LODs and LOQs of the hormones and mimic hormone in the range 1.14-2.510 and 3.42-7.53 µg/L, respectively. The results revealed wide variability in the concentrations of E2 and E3, while BPA was not detected at any of the sampling stations. The concentration of E3 ranged between <1.14 and 45.5 µg/L (N = 120) in station 2 water. The highest concentration of E2 (15.7 µg/L, N = 80) was observed in water from station 1. The varied concentrations may be connected with the nature and sources of release, inconsistencies in analyte distribution due to dynamics of water flow pattern and the physical/chemical properties of the receiving water bodies.

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In this study, the concentration levels of the probable carcinogenic PAH fractions, benzo[a]pyrene (BaP) and benzo[k]fluoranthrene (BkF) in fillets of some processed fish species were investigated. Fish species comprising Merluccius poli (hake), Tyrsites atun (snoek), Seriola lalandi (yellow-tail) and Brama brama (angel fish) were bought in fish shops at Gordon's Bay, Western Cape, South Africa. The fish were gutted, filleted and prepared for edibility by frying, grilling and boiling. Polycyclic aromatic hydrocarbons were extracted from each homogenized fish sample, cleaned-up using solid phase extraction (SPE), and analysed for the PAH fractions, BaP and BkF using a Gas Chromatograph coupled with a Flame Ionization Detector (GC-FID). The sum of the two PAHs (∑2PAH) i.e., BaP and BkF ranged between 0.56 and 1.46 µg/kg, in all boiled, grilled and fried fish species. The fried fish extracts showed significantly higher (p < 0.05) abundance of ∑2PAH, than grilled and boiled fish. Dietary safety and PAHs toxicity was also discussed.

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The concentrations of polycyclic aromatic hydrocarbons (PAHs) in smoked, grilled and boiled meats were determined using gas chromatography - flame ionization detector (GC-FID). PAHs in the processed meats were extracted in n-hexane after hydrolysis with methanolic KOH. Clean-up was achieved using solid phase extraction in neutral-Si/basic-Si/acidic-Si/neutral-Si frits. The fractions, benzo[k]fluoranthene (BkP), benzo[a]pyrene (BaP), indeno[123-cd]pyrene (IP) and benzo[ghi]perylene (BghiP) were separated and quantified using GC-FID. The method and instrument limits of detections were 0.1, 0.1, 0.2, 0.3µg/kg and 0.5, 0.5, 1.0, 1.5µg/kg, respectively, for BkP, BaP, IP and BghiP. The method's recovery and precision generally varied between 83.69% and 94.25% with relative standard deviation (RSD) of 3.18-15.60%; and 90.38-96.71% with relative standard deviation (RSD) of 1.82-12.87% respectively. The concentration of BkP, BaP, IP and BghiP in smoked, grilled and boiled meat samples were ranged 0.64-31.54µg/kg, 0.07-7.04µg/kg, 0.09-15.03, 0.51-46.67µg/kg and 0.01-5.11µg/kg, respectively.

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