Chemiluminescence determination of ferulic acid by flow-injection analysis using cerium(IV) sensitized by rhodamine 6G

Validated Stability-Indicating GC-MS Method for Characterization of Forced Degradation Products of Trans-Caffeic Acid and Trans-Ferulic Acid

When dealing with simple phenols such as caffeic acid (CA) and ferulic acid (FA), found in a variety of plants, it is very important to have control over the most important factors that accelerate their degradation reactions. This is the first report in which the stabilities of these two compounds have been systematically tested by exposure to various different factors. Forced degradation studies were performed on pure standards (trans-CA and trans-FA), dissolved in different solvents and exposed to different oxidative, photolytic and thermal stress conditions. Additionally, a rapid, sensitive, and selective stability-indicating gas chromatographic-mass spectrometric method was developed and validated for determination of trans-CA and trans-FA in the presence of their degradation products. Cis-CA and cis-FA were confirmed as the only degradation products in all the experiments performed. All the compounds were perfectly separated by gas chromatography (GC) and identified using mass spectrometry (MS), a method that additionally elucidated their structures. In general, more protic solvents, higher temperatures, UV radiation and longer storage times led to more significant degradation (isomerization) of both trans-isomers. The most progressive isomerization of both compounds (up to 43%) was observed when the polar solutions were exposed to daylight at room temperature for 1 month. The method was validated for linearity, precision as repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The method was confirmed as linear over tested concentration ranges from 1−100 mg L⁻¹ (r²s were above 0.999). The LOD and LOQ for trans-FA were 0.15 mg L⁻¹ and 0.50 mg L⁻¹, respectively. The LOD and LOQ for trans-CA were 0.23 mg L⁻¹ and 0.77 mg L⁻¹, respectively.

Enhanced chemiluminescence determination of paracetamol

Due to the severe consequences of potential overdoses of paracetamol (PCM) on the human body, the measurement of PCM in pharmaceutical and biological samples is essential.

QbD-steered development and validation of an RP-HPLC method for quantification of ferulic acid: Rational application of chemometric tools

The present work describes the systematic development of a simple, rapid, sensitive, robust, effective and cost-effective reversed-phase high performance liquid chromatographic method for quantitative analysis of ferulic acid using analytical quality by design paradigms. Initially, apt wavelength for the analysis of ferulic acid was selected employing principal component analysis as the chemometric tool. An Ishikawa fishbone diagram was constructed to delineate various plausible variables influencing analytical target profile, viz. peak area, theoretical plate count, retention time and peak tailing as the critical analytical attributes. Risk assessment using risk estimation matrix and factor screening studies employing Taguchi design aided in demarcating two critical method parameters, viz. mobile phase ratio and flow rate affecting critical analytical attributes. Subsequently, the optimum operational conditions of the liquid chromatographic method were delineated using face-centred composite design. Multicollinearity among the chosen factors for optimization was analyzed by the magnitude of variance inflation factor optimized analytical design space, providing optimum method performance, was earmarked using numerical and graphical optimization and corroborated using Monte Carlo simulations. Validation, as per the ICH Q2(R1) guidelines, ratified the efficiency and sensitivity of the developed novel analytical method of ferulic acid in the mobile phase and the human plasma matrix. The optimal method used a mobile phase, comprising of acetonitrile: water (47:53% v/v, pH adjusted to 3.0 with glacial acetic acid), at a flow rate of 0.8 mL·min^-1, at a λ_max of 322 nm using a C₁₈ column. Use of principal component analysis unearthed the suitable wavelength for analysis, while analytical quality by design approach, along with Monte Carlo simulations, facilitated the identification of influential variables in obtaining the "best plausible" validated chromatographic solution for efficient quantification of ferulic acid.

Simple and Rapid Determination of Ferulic Acid Levels in Food and Cosmetic Samples Using Paper-Based Platforms

Ferulic acid is an important phenolic antioxidant found in or added to diet supplements, beverages, and cosmetic creams. Two designs of paper-based platforms for the fast, simple and inexpensive evaluation of ferulic acid contents in food and pharmaceutical cosmetics were evaluated. The first, a paper-based electrochemical device, was developed for ferulic acid detection in uncomplicated matrix samples and was created by the photolithographic method. The second, a paper-based colorimetric device was preceded by thin layer chromatography (TLC) for the separation and detection of ferulic acid in complex samples using a silica plate stationary phase and an 85:15:1 (v/v/v) chloroform: methanol: formic acid mobile phase. After separation, ferulic acid containing section of the TLC plate was attached onto the patterned paper containing the colorimetric reagent and eluted with ethanol. The resulting color change was photographed and quantitatively converted to intensity. Under the optimal conditions, the limit of detection of ferulic acid was found to be 1 ppm and 7 ppm (S/N = 3) for first and second designs, respectively, with good agreement with the standard HPLC-UV detection method. Therefore, these methods can be used for the simple, rapid, inexpensive and sensitive quantification of ferulic acid in a variety of samples.

Synchronous fluorescence determination of ferulic acid with Ce(IV) and sodium tripolyphosphate

In this study, a synchronous fluorescence detection method for ferulic acid (FA) is proposed based on a redox reaction between FA and Ce(IV) sulfate in dilute sulfuric acid medium at room temperature. It was found that FA could reduce Ce(IV) to Ce(III) in acidic medium, and sodium tripolyphosphate could further enhance the intrinsic fluorescence of the Ce(III) produced. The enhanced extent of synchronous fluorescence intensity was in proportion to the concentration of FA over the range 3.0 × 10(-8) to 1.0 × 10(-5) mol/L. The corresponding limit of determination (S/N = 3) was 1.3 × 10(-8) mol/L. The proposed method was applied to the determination of sodium ferulate for injection sample with satisfactory results.

Determination of ferulic acid by flow injection chemiluminescence analysis based on enhancement of the N-bromobutanimide-eosin-CrCl3 system in alkaline solution

A simple and sensitive flow injection chemiluminescence method has been developed for the determination of ferulic acid (FA) based on the significant enhancement effect of FA on the CL signal of the N-bromobutanimide (NBS)-eosin-CrCl3 system in alkaline solution. Under optimum conditions, the enhanced CL intensity is linearly related to the concentration of FA in its pharmaceutical preparations and human plasma samples. The corresponding linear regression equations were established over the 4.0 × 10(-10)-1.0 × 10(-7) g/mL for FA tablets and 2.0 × 10(-10)-1.0 × 10(-7) g/mL for plasma samples. The limit of detection for FA tablets and limit of quantification for plasma samples were 2.8 × 10(-10) g/mL (3 σ) and 3.04 × 10(-10) g/mL (10 σ), respectively. A complete analysis could be performed within 40 s, including washing and sampling, giving a throughput of ≈90/h. The proposed method was successfully applied to the determination of FA in pharmaceutical preparations and human plasma samples with satisfactory results. The recoveries of pharmaceutical preparations and human plasma samples at three different concentrations were 97.8-102.6% and 96.7-104.0%, respectively. Furthermore, the possible mechanism of CL reactions was also discussed briefly.

Determination of the flavonoids/antioxidant levels in Cirsium oleraceum and Cirsium rivulare extracts with cerium(IV)-rhodamine 6G chemiluminescence detection

The determination of the sum of flavonoid compounds in extracts from inflorescences (expressed as mgL(-1) of apigenin) and leaves (expressed as mgL(-1) of linarin) of Cirsium oleraceum and Cirsium rivulare species by flow injection system with chemiluminescence detection (FI-CL) has been carried out. The method is based on the strong enhancement by polyphenols occurring in both plants of the CL signal generated by the reaction of cerium(IV) with rhodamine 6G in a sulfuric acid medium. Under the optimized conditions, the linear working ranges of 0.1-10 and 2.5-50μmolL(-1) were obtained for apigenin and linarin, respectively. The developed method is simple, sensitive with the detection limits of 38nmolL(-1) (apigenin) and 840nmolL(-1) (linarin) and offers high sample throughput (up to 300 samples per hour). The relative standard deviation was 0.62% and 3.75% for 10 measurements of 5μmolL(-1) apigenin and linarin, respectively. The proposed method has been successfully applied to determine the flavonoids/antioxidant levels in aqueous and methanolic extracts from inflorescences and leaves of C. oleraceum and C. rivulare. A possible mechanism of the enhancement of cerium(IV)-rhodamine 6G CL system by polyphenols was briefly discussed. For comparative studies, the antioxidant activity of C. oleraceum and C. rivulare extracts was also evaluated by spectrophotometric 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging method.

Chemiluminescence determination of cefotaxime sodium with flow-injection analysis of cerium (IV)-rhodamine 6G system and its application to the binding study of cefotaxime sodium to protein with on-line microdialysis sampling

A simple, sensitive and rapid flow-injection chemiluminescence (CL) method has been developed for the determination of cefotaxime sodium based on the chemiluminescence reaction of cefotaxime sodium with ceric sulfate and rhodamine 6G in nitric acid solution. The concentration of cefotaxime sodium was proportional with the CL intensity in the range of 4×10(-8)-8×10(-6) mol L(-1). The detection limit (signal-to-noise ratio=3) was 1×10(-8) mol L(-1). Coupled to the technique of on-line microdialysis sampling, this method was successfully applied to study cefotaxime sodium-protein interaction. The drug and protein were mixed in different molar ratios in Ringer's solution, pH 7.4, and incubated at 37°C in a water bath. The microdialysis probe was utilized to sample the mixed solution at a perfusion rate of 5 μL min(-1) and the recovery of cefotaxime sodium under experimental condition was 16.2%. The data obtained by the present Microdialysis-Flow Injection Analysis-CL method was analyzed with the Scatchard analysis and Klotz plot. The estimated association constant (K) and the number of the binding sites (n) on one of BSA molecule were 5.94×10(4) M(-1) and 1.29 (Klotz equation), respectively.

Molecular structure, spectroscopic studies and first-order molecular hyperpolarizabilities of ferulic acid by density functional study

Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of ferulic acid (FA) (4-hydroxy-3-methoxycinnamic acid) were carried out by using density functional (DFT/B3LYP/BLYP) method with 6-31 G(d,p) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment (micro) and the first hyperpolarizability (beta) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the FA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of FA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT-IR and FT-Raman spectra for the title molecule have been constructed.