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Anwar Z, Sheraz MA, Ahmed S, Mustaan N, Khurshid A, Gul W, Khattak SUR, Ahmad I. Photolysis of thiochrome in aqueous solution: A kinetic study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2020; 203:111766. [PMID: 31927488 DOI: 10.1016/j.jphotobiol.2019.111766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 12/19/2019] [Accepted: 12/27/2019] [Indexed: 06/10/2023]
Abstract
The photolysis of thiochrome (THC), an oxidation product of thiamine (vitamin B1) (THE), used for its fluorimetric assay, has been studied in the pH range 7.0-12.0. THC undergoes photooxidation to oxodihydrothiochrome (ODTHC) which is oxidized to a non-fluorescent compound (OP1) on UV irradiation. The kinetics of the consecutive first-order reactions: THC→k1ODTHC→k2OP1, has been evaluated and the values of first-order rate constants, k1 (0.58-4.20 × 10-5, s-1) and k2 (0.05-2.03 × 10-5, s-1), at pH 7.0-12.0 have been determined. The rates of degradation of THC and ODTHC are enhanced with pH and the second-order rate constants k1' and k2' for the OH- ion-catalyzed reaction are in the range of 0.002-58.3 M-1 s-1. The quantum yields of the photolysis of THC and ODTHC in the pH range 7.0-12.0 have been determined. THC, ODTHC and OP1 have been identified by chromatographic, spectrometric and fluorimetric methods. THC and ODTHC have similar fluorescence characteristics and emit at 450 and 445 nm, respectively. THC, ODTHC and OP1 with distinct absorption maxima (370, 344 and 290 nm, respectively) have been determined by a newly developed and validated multicomponent spectrometric method during the photolysis reactions. The on-line formation of THC by the photooxidation of THE may lead to the degradation of THC and give erroneous results in the fluorimetric assay of THE. A scheme for the photolysis reactions of THC in aqueous solution is presented.
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Affiliation(s)
- Zubair Anwar
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan.
| | - Muhammad Ali Sheraz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan
| | - Sofia Ahmed
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan
| | - Nafeesa Mustaan
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan
| | - Adeela Khurshid
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan
| | - Wajiha Gul
- Department of Pharmaceutical Chemistry, Dow College of Pharmacy, Dow University of Health Sciences, Karachi 74200, Pakistan
| | - Saif-Ur-Rehman Khattak
- Central Drug Laboratories, Ministry of Health, DRAP, Block-B, S.M.C.H., Karachi 74400, Pakistan
| | - Iqbal Ahmad
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Super Highway, Gadap Road, near Toll Plaza, Karachi 74600, Pakistan
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Alizadeh T, Akhoundian M, Ganjali MR. A ferrocene/imprinted polymer nanomaterial-modified carbon paste electrode as a new generation of gate effect-based voltammetric sensor. NEW J CHEM 2018. [DOI: 10.1039/c7nj03396f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, a carbon paste electrode, concurrently incorporated with ferrocene and a molecularly imprinted polymer nanomaterial (Fc-MIP-CP electrode), is introduced as an innovative sensing platform for the detection of thiamine.
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Affiliation(s)
- Taher Alizadeh
- Department of Analytical Chemistry
- Faculty of Chemistry
- University College of Science
- University of Tehran
- Tehran
| | - Maedeh Akhoundian
- Department of Analytical Chemistry
- Faculty of Chemistry
- University College of Science
- University of Tehran
- Tehran
| | - Mohammad Reza Ganjali
- Department of Analytical Chemistry
- Faculty of Chemistry
- University College of Science
- University of Tehran
- Tehran
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Stability-Indicating Photochemical Method for the Assay of Riboflavin: Lumichrome Method. J CHEM-NY 2015. [DOI: 10.1155/2015/256087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A stability-indicating photochemical method for the assay of riboflavin (RF) in photodegraded samples and aged vitamin preparations has been developed. It is based on photochemical conversion of RF to lumichrome (LC) in alkaline solution under controlled conditions of light intensity, temperature, pH, time of exposure, and distance. Under these conditions about two-thirds of RF is converted to LC and on the basis of the RF : LC ratio the concentration of RF can be determined in degraded solutions. The method involves the extraction of photolyzed solutions of RF (pH 2.0) with chloroform and determination of LC along with lumiflavin (LF) by a two-component spectrometric method at 356 and 445 nm. The method has been validated and the results of the assay of RF in photodegraded solutions compare well with those of the standard USP fluorimetric method. The recovery of the method is 99–101% and the precision is within 2%. The method is stability-indicating and can be applied to the assay of RF in photodegraded solutions and aged vitamin preparations. The method is specific compared to that of the USP fluorimetric method in which the degraded LC may interfere with the fluorescence emission of RF.
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Analytical applications of photoinduced chemiluminescence in flow systems—A review. Anal Chim Acta 2010; 679:17-30. [DOI: 10.1016/j.aca.2010.09.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/27/2010] [Accepted: 09/02/2010] [Indexed: 11/24/2022]
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Pérez-Ruiz T, Martínez-Lozano C, García-Martínez MD. Simultaneous determination of thiamine and its phosphate esters by a liquid chromatographic method based on post-column photolysis and chemiluminescence detection. J Pharm Biomed Anal 2009; 50:315-9. [DOI: 10.1016/j.jpba.2009.04.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 04/27/2009] [Accepted: 04/29/2009] [Indexed: 11/29/2022]
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Adcock JL, Francis PS, Barnett NW. Acidic potassium permanganate as a chemiluminescence reagent—A review. Anal Chim Acta 2007; 601:36-67. [PMID: 17904470 DOI: 10.1016/j.aca.2007.08.027] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/20/2007] [Accepted: 08/20/2007] [Indexed: 11/21/2022]
Abstract
A critical and comprehensive review of acidic potassium permanganate chemiluminescence is presented. This includes discussion on reaction conditions, the influence of enhancers such as polyphosphates, formaldehyde and sulfite, the relationship between analyte structure and chemiluminescence intensity, and the application of this chemistry to determine a wide variety of compounds, such as pharmaceuticals, biomolecules, antioxidants, illicit drugs, pesticides and pollutants. Previous proposals for the nature of the emitting species are re-evaluated in light of recent evidence.
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Affiliation(s)
- Jacqui L Adcock
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217, Australia
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