Browsing by Author "Cooray, A."

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Development of an lc-ms/ms method for the detection of prednisolone doping using human fingernails
(Postgraduate Institute of Science (PGIS) , University of Peradeniya, 2024-11) Kanishka, W. A. S.; Fernando, P. N. J.; Rashani, S. A. N.; Jayakody, R. S.; Cooray, A.; De Silva, A. P.
Sports doping detection mainly relies on urine and blood samples. Nails are less commonly used, even though they can provide long-term drug use, due to challenges in preparation and pulverization. This study developed a Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method to detect prednisolone in human fingernails. Nails from volunteers not administered with prednisolone were ethically collected, cleaned, dried, and pulverized for analysis. The extraction of prednisolone was optimized for solvent type, extraction frequency, and shaking rate. The optimized sample preparation was followed by cleaning of Nail clippings by vortexing at 2200 rpm using ultrapure water at 50 °C for 75 secs, drying at 50 °C for 80 mins, cutting into small pieces, and subjected to methanol extraction by shaking for 18 hrs at 300 rpm. LC-MS/MS analysis used a biphenyl column (100 mm × 2.1 mm, 2.7 μm) with a binary gradient of acidified (0.1% formic acid) acetonitrile and an aqueous phase to identify prednisolone. The run time for the LC-MS/MS method was 7.50 minutes. The retention time of prednisolone was 2.18 minutes. The method was validated according to International Council for Harmonization (ICH) guidelines, showing strong linearity (R² > 0.99) and high specificity with no carryover. Within-run accuracy and precision were ± 3.24% and 3.76% coefficient of variation (CV), respectively, while between-run accuracy and precision were ± 4.18% and 3.5% CV, respectively. LOD and LOQ were 0.0003 mg/L and 0.00154 mg/L, respectively. Using a cost-effective pulverization setup, the validated The LC-MS/MS method effectively detected prednisolone in fingernails. Further studies with prednisolone-doped nails are needed to advance nail-based doping detection in sports and forensics.
Novel fluorescence sensors for determination of Fe3+ in biological systems using sulfonamide derivatives of dipicolylamine ligands
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Vitharana, K. V. N. N.; Perera, N. T.; Cooray, A.; Deraniyagala, S. P.
Since fluorescence techniques are highly demanded area in biological species detection, the main objective of this research was to develop real-time, ratiometric fluorescence sensors which can be used for iron cation detection in physiological systems with high sensitivity and selectivity. Previously synthesized and characterized two new ligand systems were developed into ratiometric fluorescence probes for biological Fe3+ ion detection. Both ligands were sulfonamide derivatives of dipicolylamine with two different R groups, biphenyl (L1=N(SO2biphenyldpa) and azobenzene (L2=N(SO2azobenzdpa). The ligands were soluble at 0.2%(v/v) methanol solutions. Both L1 and L2 displayed ratiometric change with Fe3+ ions at 319 and 458 nm respectively. L2 had a relatively high photostability, fluorescence increasing mechanism and a lower detection limit of 18.22 nM which is a suitable concentration for biological iron detection with high sensitivity and high selectivity. L1 had a lower detection limit of 0.674 μM and fluorescence increasing and decreasing mechanisms. Since both ligands had minimum interferences from other common metal cations such as K+, Na+, Ca2+, Mg2+, Ba2+, Fe2+, Cu2+ and Zn2+, the selectivity was considered to be very high. The pH sensitivity of the both ligands were also considerably low. L2-Fe3+ complex was blue green in color with a possible applicability for common fluorescence microscopes. Both ligands metal complexes had higher UV-Visible absorbance than their respective free ligands. The ligands could be recovered from the metal complexes with the addition of ethylenediaminetetraacetic acid (EDTA). All the experimental procedures were carried out at physiological pH, 7.4 using HEPES buffer system. Beside the biological systems the probes are applicable for other environmental and industrial samples to ferric iron detection.
Screening for prednisolone in anti-asthmatic herbal remedies using lc-ms/ms in sri lanka.
(Postgraduate Institute of Science (PGIS), University of Peradeniya, 2024-11) Fernando, S. S. D.; Fernando, P. N. J.; Rashani, S. A. N.; Cooray, A.; De Silva, A. P.
Prednisolone, a corticosteroid used to treat asthma, poses significant concerns when adulterated in herbal remedies, particularly for athletes subjected to anti-doping regulations. Despite their widespread use, comprehensive studies to determine the extent of prednisolone adulteration in herbal products are lacking in Sri Lanka. This study aimed to fill this research gap by screening commonly used herbal remedies for asthma in Sri Lanka to identify the presence of Prednisolone. A tailored LC-MS/MS method was developed and validated for this purpose. An optimized ultrasound-assisted extraction procedure was established using a reference standard, achieving a recovery rate of 100.45% by adjusting the extraction solvent and sonication time. The LC-MS/MS method utilised a biphenyl column (100 mm × 2.1 mm, 2.7 μm) with a mobile phase of acetonitrile and water acidified with 0.1% formic acid. Chromatographic conditions were optimized for a column; oven temperature of 50 °C, an initial acetonitrile concentration of 5%, a dwell time of 0.200 secs, and a run time of 10 min. Validation of the method followed EuraChem guidelines and was done using a Prednisolone reference standard, demonstrating high precision, accuracy, sensitivity, and specificity. Extraction recoveries showed relative standard deviation (%RSD) ≤ 10% and calibration linearities had R2 ≥ 0.988. The detection limits were 0.03 μg/g for powdered and 0.003 μg/mL for liquid herbal matrices. The study screened 27 different over-the-counter brands and prescription anti-asthmatic herbal products collected randomly from suburban areas of Colombo. The validated LC-MS/MS method identified that 25 products were below the detection limit, while two prescribed products were flagged as doubtful. In conclusion, the developed LC-MS/MS method successfully detected prednisolone in complex herbal matrices with high specificity and precision, providing valuable insights into the prevalence and extent of prednisolone adulteration in herbal remedies.