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Multicomponent spectrofluorimetric method for the assay of formylmethylflavin and its hydrolytic products: Kinetic applications
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy ( IF 4.3 ) Pub Date : 2018-07-25 , DOI: 10.1016/j.saa.2018.07.066
Iqbal Ahmad , Tania Mirza , Zubair Anwar , Muhammad Ahsan Ejaz , Muhammad Ali Sheraz , Sofia Ahmed

A multicomponent spectrofluorimetric method has been developed for the simultaneous assay of formylmethylflavin (FMF), an intermediate product in the photolysis of riboflavin (vitamin B2), and its side-chain hydrolytic products, lumichrome (LC) in acidic solution and LC and lumiflavin (LF) in the alkaline solution as well as its ring cleavage products, 1,2-dihydro-1-methyl-2-keto-3-quinoxaline carboxylic acid (KA) and 1,2,3,4-tetrahydro-1-methyl-2,3-dioxo-quinoxaline (DQ) in alkaline solution. The assay method also takes into account an oxidation product of FMF, i.e. carboxymethylflavin (CMF), in both acid and alkaline solutions. The method involves adjustment of the pH of hydrolysed solution to 2.0 to convert FMF to its protonated form, extraction of LC (acid solution) or LC and LF (alkaline solution) with chloroform and their simultaneous assay by fluorescence measurement at 478 and 530 nm, respectively. The aqueous phase is readjusted to pH 6.5, extracted with chloroform to remove undegraded FMF and used for the assay of CMF, KA and DQ at 530, 443 and 420 nm, respectively. The chloroform extract is used for the assay of FMF at 530 nm. The proposed method has been validated and applied to the study of the kinetics of a hydrolysis reaction of FMF at pH 11.0. The calibration curves for FMF and degradation products are linear in the range of 0.1–1.0 × 10−6 M. The limit of detection (LOD) and limit of quantification (LOQ) range from 2.54–5.75 × 10−8 M and 0.78–1.74 × 10−7 M, respectively, for these compounds. The mean recovery ranges from 99.3–102.1% with a RSD of 0.14–0.35%. Judging from the molar balance of FMF and the hydrolytic products, uniformity of analytical data during the reactions and linearity of kinetic plot, the method gives accurate results for the assay of FMF and all of its degradation products. It can be conveniently used for the assay of these compounds and for the kinetics and stability studies of FMF.



中文翻译:

多组分光谱荧光法测定甲酰基甲基黄素及其水解产物的动力学应用

已开发出一种多组分光谱荧光法,用于同时测定核黄素(维生素B 2)的中间产物甲酰甲基黄素(FMF)。)及其侧链水解产物,酸性溶液中的Luminchrome(LC)和碱性溶液中的LC和Lumiflavin(LF),以及其环裂解产物1,2-二氢-1-甲基-2-酮-碱性溶液中的3-喹喔啉羧酸(KA)和1,2,3,4-四氢-1-甲基-2,3-二氧代喹喔啉(DQ)。该测定方法还考虑了在酸性和碱性溶液中FMF的氧化产物,即羧甲基黄素(CMF)。该方法包括将水解溶液的pH值调节至2.0以将FMF转化为其质子化形式,用氯仿萃取LC(酸性溶液)或LC和LF(碱性溶液),并通过在478和530 nm处的荧光测量同时进行测定,分别。将水相重新调节至pH 6.5,用氯仿萃取以去除未降解的FMF,并用于CMF的测定,分别在530、443和420 nm处的KA和DQ。氯仿提取物用于在530 nm处测定FMF。所提出的方法已经过验证,并用于研究FMF在pH 11.0时的水解反应动力学。FMF和降解产物的校准曲线在0.1–1.0×10范围内呈线性-6  M.检测(LOD)和定量限(LOQ)范围限制地从2.54-5.75×10限-8  M和0.78-1.74×10 -7 分别用M,对于这些化合物。平均回收率范围为99.3–102.1%,RSD为0.14–0.35%。从FMF和水解产物的摩尔平衡,反应过程中分析数据的均一性和动力学图的线性来看,该方法为测定FMF及其所有降解产物提供了准确的结果。它可以方便地用于这些化合物的测定以及FMF的动力学和稳定性研究。

更新日期:2018-07-25
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