International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Author: search.filters.author.Manage, P.M.Author: search.filters.author.Chinthaka, S. D. M.

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    Novel solid phase micro extraction (SPME) Method for GC-MS analysis of Tributyltin.
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Bandara, K. R. V.; Chinthaka, S. D. M.; Manage, P.M.
    Tributyltin (TBT) is an organotin compound belongs to the group of Persistent Organic Pollutants (POPs) and one of the active ingredients in biocides used to control a broad spectrum of organisms. Antifouling paints which are used for boat hulls, docks, fishnets contain tributyltin to prevent the growth of aquatic fouling organisms. Increasing concentration of TBT in the environment, due to anthropogenic activities cause toxicological impact on target and non-target organisms having sexual disorders like sex changes at ultra-trace level called imposex. According to WHO, the No Observed Effective Level (NOEL) of TBT is below 1 ng L-1, thus a highly specific and sensitive analytical methods are needed to detect TBT in parts per trillion (ppt) level. In the present study, a new ultra-trace quantification method to detect TBT using Solid Phase Micro Extraction (SPME) followed by Gas Chromatography-Mass Spectrometry (GCMS) was optimized. TBT derivatization to tributyltinhydride was carried out using potassium borohydride (KBH4). Medium polar PDMS/DVB, fused silica (65 μm, 24 Ga) SPME fiber were found to be the most appropriate conditions for extraction and pre-concentration of derivatized TBT hydride compound. The best conditions for the extraction were optimized and analyses were done by using GC-MS under 270 ºC desorption temperature and 1 mL min-1 of helium gas flow rate. Field samples were collected from highly polluted and heavy boat traffic area along the coastal belt from Dikkovita to Mirissa, Sri Lanka. The optimal extraction conditions were found to be 10 minutes extraction time, pH 4.9 and the ambient temperature 30 ºC. The highest TBT concentration was detected in Colombo port (303±4.7 ng L-1) following the TBT was recorded in the fishery harbors at Beruwala (124±4.1 ng L-1), Galle (110±4.1 ng L-1), Dikkovita (97±4.3 ng L-1), Hikkaduwa (77±5.3 ng L-1) and Ambalangoda (57±5.2 ng L-1). TBT concentrations in Dehiwala, Wellawatta, Madu, Benthota and Gin ganga river mouths were recorded as 268±4.1 ng L-1, 240±3.4 ng L-1, 214±3.3 ng L-1, 145±2.7 ng L-1 and 50± 2.1 ng L-1 respectively. The recovery of the TBT extraction was 87±2.1 % for the artificial sea water while the Minimum Quantification Level (MQL) was 1 ng L-1. The Minimum Detection Level (MDL) of the method was calculated as0.3 ng L-1. The optimized method is a solvent free and the use of SPME is highly sensitive method to detect TBT in parts per trillion (ppt) levels.
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    Cyanobacteria and 2-Methylisoborneol: the influence of Nitrogen and Phosphorous
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ganegoda, S. S.; Chinthaka, S. D. M.; Manage, P.M.
    2-Methylisoborneol (2-MIB) is a key compound, which causes taste and odour (T&O) issues in water. Despite of no recorded health hazards reported associated with 2-MIB, water consumers reject the water with 2-MIB due to its unpleasant musty (moldy) T&O. The aim of this study was to study the correlation between cyanobacteria abundance, 2-MIB levels coupled with Nitrogen and Phosphorous levels. 2-MIB contamination level in sixteen raw water bodies, which are being used for drinking in six districts (Anuradhapura, Pollonnaruwa, Ampara, Batticaloa, Trincomalee and Hambanthota) were analyzed using Gas Chromatography–Mass Spectrometry coupled with Solid-phase micro extraction. Enumeration and identification of cyanobacteria was carried out using standard microscopic methods. Anabaena, Microcystis, Oscillatoria, and Cylindrospermopsis species were identified as the most abundant cyanobacteria. 2-MIB levels ranged from 5.3 ± 0.94 to 139.4 ± 0.21 ppt throughout the dry season of the sampling period, where the highest level was recorded in Kondawatuwana tank (139.4 ± 0.21 ppt) and the lowest was detected in Ridiyagama tank (5.3 ± 0.94). At wet season, 2-MIB levels ranged from 4.4 ± 0.78 to 73.8 ± 0.65 ppt, where the highest level was recorded in Jayanthi tank (73.8 ± 0.65 ppt), while the lowest was detected in Ridiyagama tank (5.3 ± 0.39 ppt). Recorded 2- MIB level was greater in dry season compared to the wet season. Seventy five percent (75%) of the sampling locations exceeded the human threshold levels of 2-MIB (5 ppt). Questionnaire survey showed that more than 95% end water consumers rejected drinking water contaminated with 2-MIB. Further it was found that the total cyanobacterial cell density (T.C.D) was positively correlated with 2-MIB and total phosphorous levels (p<0.05). Moreover, cell densities of Oscillatoria, Anabaena and Cylindrospermopsis species showed significant positive correlations (p<0.05) with 2-MIB contamination levels along with Pearson Correlation Coefficients (P.C.C) of 0.788, 0.682 and 0.731. However, no significant correlation was observed between Microcystis sp. and 2-MIB. Further, 2-MIB showed significant positive correlation (p<0.05) with total phosphorous (P.C.C 0.876), electrical conductivity (EC) (P.C.C, 0.771), and pH (P.C.C, 0.825). Increment of pH value leading to alkalinity is a known optimum condition for cyanobacteria growth while the current study shows alkalinity is favorable for 2-MIB. No significant correlation was obtained between total nitrogen (Nitrate –N, Nitrite –N, Ammonia –N) and 2-MIB nor T.C.D and total nitrogen. Thus, the results of the study indicate there is a direct positive correlation between 2-MIB, cyanobacteria and total phosphorous.