Solvent Effect on the Photolysis of Riboflavin

Ahmad, Iqbal; Anwar, Zubair; Ahmed, Sofia; Sheraz, Muhammad Ali; Bano, Raheela; Hafeez, Amtul

doi:10.1208/s12249-015-0304-2

Cited by 27 publications

(32 citation statements)

References 54 publications

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“…RF is known to degrade to FMF and LC in acid solution and to FMF, LC and LF in alkaline solution on exposure to light . FMF is an intermediate product leading to the formation of LC and LF in these reactions . In the present study the formation of FMF and LC in the photolysis of RF in acid solution and FMF, LC and LF in alkaline solution has been confirmed by TLC using solvent systems (a) and (b) by comparison of their R f value and fluorescence color (RF, FMF, LF yellow‐green; LC sky blue) with those of the reference compounds.…”

Section: Resultssupporting

confidence: 64%

Stability‐indicating spectrofluorimetric method for the assay of riboflavin and photoproducts: Kinetic applications

et al. 2018

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A stability-indicating spectrofluorimetric method has been developed for the simultaneous assay of riboflavin (RF) and photoproducts, formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF) in aqueous solution. The method is based on the extraction of LC formed in acid solution and LC and LF formed in alkaline solution with chloroform at pH 2.0 and their assay by fluorescence measurements at 478 and 530 nm, respectively. The aqueous phase, on readjustment of the pH to 6.5, is used to extract FMF with chloroform and its assay is carried out at 530 nm. The aqueous phase is then used for the assay of RF at 530 nm. The proposed method gives more accurate results for the assay of RF compared to those of the United States Pharmacopeia (USP) spectrofluorimetric method which does not take into account the presence of RF photoproducts having similar fluorescence characteristics. The proposed method along with the USP method has been applied to the study of the kinetics of photolysis of RF, assay of stored commercial vitamin preparations and their radiated samples. The results show that the USP method does not distinguish between the fluorescence of RF and its photoproducts, and, therefore, gives erroneous results with about 11% excess in the quantity of the vitamin compared to that of the proposed method. This is due to the interference of the fluorescence of photoproducts in the assay of RF. The method has been validated for various analytical parameters according to the guideline of the International Council for Harmonization (ICH).

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Section: Resultssupporting

confidence: 64%

Stability‐indicating spectrofluorimetric method for the assay of riboflavin and photoproducts: Kinetic applications

et al. 2018

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“…Since the reaction rate for the photocatalytic degradation of any organic compound is a strong function of catalyst concentration, two kinetic experiments were carried out to investigate the effect of the initial ZnO/TiO 2 concentration on the reaction rate. Based on the data in the literature, it was assumed that the investigated photochemical processes were pseudo‐first‐order reactions (Ahmad et al, ; Khodja, Sehili, Pilichowski, & Boule, ). Therefore, the Langmuir–Hinshelwood kinetic model was used to describe the photocatalytic degradation rate of BIF by plotting the graph of ln( C / C 0 ) vs time.…”

Section: Resultsmentioning

confidence: 99%

“…Organic solvents could scavenge hydroxyl radicals (Khodja et al, ). The degree of photodegradation is influenced by solvent physical characteristics such as dielectric constants and viscosity (Ahmad et al, ). Therefore, research is needed to examine the effect of methanol reduction or replacement by other organic solvent on the rate of BIF photodegradation and on qualitative and quantitative composition of its photoproducts.…”

Section: Resultsmentioning

confidence: 99%

Determination of bifonazole and identification of its photocatalytic degradation products using UPLC‐MS/MS

Kryczyk

Żmudzki

Hubicka

2017

Biomedical Chromatography

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The main goal of the presented work was to investigate the effect of ZnO or/and TiO on the stability of bifonazole in solutions under UVA irradiation. To this end, a simple and reproducible UPLC method for the determination of bifonazole in the presence of its photocatalytic degradation products was developed. Linearity was studied in the range of 0.0046-0.15 mg mL with a determination coefficient of 0.9996. Bifonazole underwent a photocatalytic degradation process under the experimental conditions used. Comparative studies showed that combination of TiO /ZnO (1:1 w/w) was a more effective catalyst than TiO or ZnO with a degradation rate of up to 67.57% after 24 h of irradiation. Further, kinetic analyses indicated that the photocatalytic degradation of bifonazole in the mixture of TiO /ZnO can be described by a pseudo-first order reaction. Statistical comparison clearly indicated that the presence of TiO /ZnO also affected the stability of bifonazole from a cream preparation after 15 h of UVA exposure (p < 0.05). Ten photodegradation products of bifonazole were identified for the first time and their plausible fragmentation pathways, derived from MS/MS data, were proposed. The main pathway in the photocatalytic transformation of bifonazole in the presence of ZnO or/and TiO involves hydroxylation of the methanetriyl group and/or adjacent phenyl rings and cleavage of the imidazole moiety.

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“…[1][2][3][4][5][6][7][8] It is photodegraded to several products in aqueous and organic solvents to yield for-mylmethylavin (FMF) (2) as a major intermediate in the reaction. [9][10][11][12][13][14][15][16] FMF undergoes hydrolysis [17][18][19] and photolysis to form lumichrome (LC) (3) and lumiavin (LF) (4) in aqueous solution 20,21 and LC in organic solvents. 20 It is photooxidized to carboxymethylavin (CMF) (5) in aqueous and organic solvents.…”

Section: Introductionmentioning

confidence: 99%

“…20 It is photooxidized to carboxymethylavin (CMF) (5) in aqueous and organic solvents. 12,13,16,21,22 CMF has also been suggested to act as an intermediate in the formation of LC and LF during the photolysis of RF in aqueous solution. 23 It is an isoalloxazine derivative like RF, FMF and LF 1,24,25 and is susceptible to hydrolytic degradation in alkaline solution by the cleavage of the isoalloxazine ring to give 1,2-dihydro-1-methyl-2-keto-3quinoxaline carboxylic acid (KA) (6) and 1,2,3,4-tetrahydro-1methyl-2,3-dioxoquinoxaline (DQ) (7).…”

Section: Introductionmentioning

confidence: 99%

Photolysis of carboxymethylflavin in aqueous and organic solvent: a kinetic study

et al. 2019

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Solvent Effect on the Photolysis of Riboflavin

Cited by 27 publications

References 54 publications

Stability‐indicating spectrofluorimetric method for the assay of riboflavin and photoproducts: Kinetic applications

Stability‐indicating spectrofluorimetric method for the assay of riboflavin and photoproducts: Kinetic applications

Determination of bifonazole and identification of its photocatalytic degradation products using UPLC‐MS/MS

Photolysis of carboxymethylflavin in aqueous and organic solvent: a kinetic study

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