http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/51 2026-04-20T13:52:39Z 2026-04-20T13:52:39Z Natarajan, Ramesh Babu Kakkasery, Joby Thomas Arimboor, Ranjith Jacob, Joby Thankan, Binumol http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/424 2025-01-29T09:54:05Z 2022-05-13T00:00:00Z

Development and validation of a GC-MS method for analysis of Dithiocarbamate Fungicide residues in the Spices Cardamom (Elettaria cardamomom) and black pepper (Piper nigrum) Natarajan, Ramesh Babu; Kakkasery, Joby Thomas; Arimboor, Ranjith; Jacob, Joby; Thankan, Binumol Dithiocarbamates constitute an important class of broad-spectrum antifungal compounds used extensively in agriculture, including in the cultivation of spices. Maximum residue limits for these compounds have been enforced by several importing countries in international food trade. Validation of analytical methods for dithiocarbamates in spices have not been reported previously. A quick and sensitive method for estimation of total dithiocarbamates as carbon disulphide (CS2) using GC-MS in two major spices, viz. small cardamom (Elettaria cardamomom) and black pepper (Piper nigrum) was optimized and validated. Dithiocarbamate residues in these spice matrices were extracted and subjected to acid hydrolysis followed by reduction to CS2, which was then quantitatively absorbed into isooctane and analysed using GC-MS, employing selected ion monitoring and post-run mid-column backflush technique. For fortification levels from 0.1 to 1.0 mg kg- 1 , recoveries obtained ranged from 75 to 98% in cardamom and 76–98% in black pepper, with intraday precision (RSDr) \12% and inter-day precision (RSDR) \15% in all cases. Limit of Quantification of 0.05 mg kg- 1 was achieved in both spices. It was found that there was negligible interference in quantitative accuracy due to essential oils present in the two spices studied. Matrix effect was seen to be suppressive in the two spices studied, and sufficiently low to exclude the use of matrix-matched calibration in routine quantitative analysis. The optimized analytical method was found to be suitable for evaluation of compliance of real samples against the Codex maximum residue limits for cardamom and black pepper. Safety evaluation for human consumption, based on the incidence of Dithiocarbamate residues, was performed in real samples of cardamom and black pepper. This method offers the possibility of extending applicability to other spices also.

2022-05-13T00:00:00Z Deena, P. L. Selvaraj, Savariraj Joseph Thomas, K. Joby http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/420 2025-01-28T06:13:30Z 2023-11-01T00:00:00Z

Chitosan – hydrogen iodide salt supported graphite electrode: A simple and novel electrode for the reduction of nitro group under electrochemical condition Deena, P. L.; Selvaraj, Savariraj Joseph; Thomas, K. Joby The present investigation provides a unique, simple, selective and efficient method for the electrochemical reduction of aromatic nitro groups into amines using chitosan-hydrogen iodide salt supported graphite electrode. 3:1 tetrabutyl ammonium chloride and acetic acid mixture was used as the medium for electrolytic process and a constant voltage of 5 V applied between the modified electrodes. The reaction was found to be selective and further reduction of amines was not observed. The purity of the products was checked with HPLC and characterized using spectroscopic tools. The electrochemical synthesis resulted in moderate to good yields of amino compounds which were higher than the reduction using conventional graphite electrodes. Quaternary ammonium chloride behaved as supporting electrolyte during synthesis and the reaction did not progress in the absence of acetic acid. The redox characteristic of the process was studied by cyclic voltammetry of the reaction mixture.

2023-11-01T00:00:00Z Vidhya Thomas K Joby Thomas K Vinod Rapheal P Sabu AS Ragi K Reeja Johnson http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/231 2024-02-20T04:21:09Z 2021-09-01T00:00:00Z

Tinospora cordifolia extract as an environmentally benign green corrosion inhibitor in acid media: electrochemical, surface morphological, quantum chemical, and statistical investigations Vidhya Thomas K; Joby Thomas K; Vinod Rapheal P; Sabu AS; Ragi K; Reeja Johnson The inhibiting capacity of Tinospora cordifolia extract (TCE) was evaluated on mild steel in 1 M HCl and 0.5 M H2SO4 by physicochemical and electrochemical techniques and by utilizing statistical tools such as response surface methodology and the Box-Behnken design (BBD). Surface properties were ascertained by scanning electron microscopy and atomic force microscopy to confirm the adsorption performance of the inhibitor molecules on the surface of the metal. Experimental results were found to agree with quantum chemical calculations of the active principle of TCE, Tinosponone. Weight loss measurements exhibited extreme inhibition power of TCE as 94.73% and 82.53% in 1 M HCl and 0.5 M H2SO4, respectively, at 5 v/v% concentration at 303 K. Electrochemical impedance spectroscopy (EIS) studies were agreed with weight loss measurements as EIS showed an inhibition efficiency of 93.51% in 1 M HCl and 88.68% in 0.5 M H2SO4 solutions. Electrochemical studies were evident that TCE can hinder reactions of the cathode and anode of mild steel. Kinetic and thermodynamic studies indicated the mixed-type adsorption behavior of TCE on mild steel by following the Langmuir adsorption isotherm in both acid media. The BBD method was applied to verify the impact of three test factors, temperature, TCE concentration, and acid concentration, on inhibition efficiency of mild steel in HCl medium. Experimental and theoretical results confirmed the anticorrosion potential of the environment-friendly inhibitor TCE.

2021-09-01T00:00:00Z Binsi, M Paulson Joby, Thomas K Ragi, K Sini, Varghese C Reeja, Johnson http://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/214 2022-03-05T06:26:05Z 2020-01-01T00:00:00Z

Interaction of two heterocyclic Schiff bases derived from 2-acetyl pyridine on mild steel in hydrochloric acid: Physicochemical and corrosion inhibition investigations Binsi, M Paulson; Joby, Thomas K; Ragi, K; Sini, Varghese C; Reeja, Johnson Two heterocyclic Schiff bases namely (E)-2-(1-(2-phenylhydrazono)ethyl)pyridine (or 2- acetyl pyridine phenyl hydrazone) (2APPH) and (E)-2-(1-triazylidineethyl)pyridine (or 2-acetyl pyridine semicarbazone) (2APSC) were synthesized, characterized and their corrosion inhibition behaviour as well as mechanism of inhibition were investigated by different techniques. Structural characterization includes NMR, Mass, IR and UV-visible spectroscopy and elemental analysis. Corrosion inhibition behaviour of aforesaid compounds on mild steel in 1M hydrochloric acid was examined by electrochemical methods including potentiodynamic polarization analysis and electrochemical impedance spectroscopic techniques. The mechanism of corrosion inhibition was explored and supplemented by adsorption and surface morphological studies. Quantum mechanical investigations on corrosion behaviour of compounds were also conducted and satisfying correlation was noticed between the results of corrosion measurement methods and quantum mechanical evaluations.

2020-01-01T00:00:00Z