Derivative Spectrofluorimetric Method Research Articles

An eco-friendly first and second derivative synchronous spectrofluorimetry for quantification of florfenicol in presence of its different degradation products. Application to kinetic stability study.

Two rapid, simple, sensitive and selective derivative spectrofluorimetric methods (first and second derivative synchronous spectrofluorimetric (FDSFS and SDSFS) procedures) have been developed for the analysis of florfenicol in the presence of its various degradation products. FDSFS was applied to assay the drug in the presence of its alkaline, oxidative and photolytic degradation products while SDSFS was used to quantify it in the presence of its acidic degradation product. These methods permitted quantification of florfenicol at corresponding λ Em of 288, 287, 279 and 284 nm without interferences from any of its degradation products. Full validation procedures were applied to the suggested method according to International Conference of Harmonization guidelines. Moreover, different degradation kinetic parameters were calculated such as half-life (t 1/2), degradation rate constant (K) and activation energy (E a). Using the analytical eco-scale, green analytical procedure index and analytical greenness metric approach AGREE as greenness assessment tools, the proposed method was found to be environmentally friendly.

Development and validation of a novel Spectrofluorimetric method of oral anticoagulant Edoxaban via derivatization with 9-fluorenyl methyl chloroformate: green assessment of the method by Eco-Scale and ComplexGAPI

A precise, sensitive eco-friendly, simple, rapid, and derivative spectrofluorimetric method was developed to quantify edoxaban tosylate monohydrate in pure form and pharmaceutical dosage form. Sudden death due to pulmonary embolism as a consequence of coronavirus infection (covid-19) is an emerging problem. As a result, the world health organization introduced new guidelines to treat patients with COVID-19 with oral anticoagulants. Edoxaban tosylate monohydrate is an oral anticoagulant that doesn’t require hospitalization after dose adjustment. This spectrofluorimetric method relies on the derivatization by 9-fluorenyl methyl chloroformate at room temperature in borate buffer pH 9.0. After excitation at 265 nm, the product is highly fluorescent at 309 nm. Many experimental factors influencing the reaction's stability and development were thoroughly investigated and optimized. The method validation was evaluated by using ICH guidelines and showed high precision and accuracy with an average percent recovery of 101.46% ± 1.02. The linear range was 5.0–50.0 ng/mL with a correlation coefficient of 0.9999, the LOD was 1.5 ng/mL, and the LOQ was 4.5 ng/mL. The green assessment of the method was achieved utilizing the eco-scale and the Green Analytical Procedure Index. There was no significant difference between the results of the suggested method and those of the reported method according to Statistical analysis.

FIRST- DERIVATIVE SPECTROFLUORIMETRIC DETERMINATION OF ENROFLOXACIN AND CIPROFLOXACIN IN COW MILK USING ROTATING SORPTIVE EXTRACTION

A derivative spectrofluorimetric method for simultaneous determination of enrofloxacin (EFX) and ciprofloxacin (CFX) in cow milk was developed. The sample preparation was based on rotating disk sorptive extraction (RDSE) using Oasis HLB® as extraction phase and followed by desorption of the analytes with methanol. The final extracts were evaluated by derivative spectrofluorimetry. An analyte-free cow milk was used as blank sample which was spiked with a known amount of analytes for the study of variables. The sample was treated with trichloroacetic acid in order to precipitate proteins. Furthermore, the extraction was carried out in the presence of Mc Ilvaine-EDTA 0.3M buffer to avoid any type of interference from the calcium ion. The variables involved in the RDSE process were pH and extraction time. Spectral variables were also optimized and analytical signals were evaluated at 417nm and 438nm for EFX and CFX, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 2.98 - 9.04 µg · L-1 and 2.56 - 7.75 µg · L-1, for EFX and CFX respectively. The precision levels, expressed as relative standard deviation, for EFX and CFX were 3.2% and 3.0%, respectively. The recoveries were between 98.8% to 100.5%. Commercial milks were analyzed and both antibiotics shown concentrations below to LOD in the batches analyzed. Finally, the proposed method offers advantages in terms of simplicity, efficiency and cost. Besides being friendly with the environment.

D-optimal design as a useful tool response surface methodology for the optimization of signals from synchronous fluorescence prior to simultaneous determination of avanafil and tadalafil.

A rapid, smart and sensitive first derivative spectrofluorimetric method has been carried out for the simultaneous estimation of avanafil and tadalafil either in their pure form, tablet dosage form or spiked human plasma. The measurements of normal emission spectra or synchronous fluorescence intensity of both drugs show severe overlap which hindered their determination using normal fluorescence or synchronous intensity. Therefore, a highly sensitive first derivative synchronous fluorescence procedure was used to resolve this overlap. The method is based upon measurement of the amplitude of the first derivative of synchronous fluorescence intensity of both drugs at Δλ=70nm and at suitable wavelength of 396nm and 364nm for avanafil and tadalafil, respectively. Under the optimum conditions, the linear determination ranges are 50-1800 and 5-400ngmL-1 with a detection limit of 12.93 and 1.46ngmL-1 for avanafil and tadalafil, respectively. A response surface methodology was used for optimization using D-optimal design which can be used for determination of the exact optimum parameters specifically designed for this method. In addition; it is a good way to graphically clarify the relationship between various experimental variables and the synchronous fluorescence intensity.

First derivative emission spectrofluorimetric method for the determination of LCZ696, a newly approved FDA supramolecular complex of valsartan and sacubitril in tablets.

LCZ696 (sacubitril/valsartan, Entresto™) is a therapy lately approved by United States Food and Drug Administration (US FDA) as a heart failure therapy. It is claimed to decrease the mortality rate and hospitalization for patients with chronic heart failure. This study is considered as the first report to investigate the fluorimetric behavior of sacubitril in addition to pursuing all the different conditions that may affect its fluorescence. Various conditions were studied, for example studying the effects of organized media, solvents and pH, which may affect the fluorescence behavior of sacubitril. For the simultaneous determination of the newly approved supramolecular complex of valsartan (VAL) and sacubitril (SAC) in their tablets, a sensitive and simple first derivative spectrofluorimetric method was developed. The method involved the measurement of native fluorescence at 416nm and 314nm (λex 249nm) for VAL and SAC, respectively. The first (D1) derivative technique was applied to the emission data to resolve a partial overlap that appeared in their emission spectra. The proposed method was successfully applied for the assay of the two drugs in their supramolecular complex LCZ696 with no interference from common pharmaceutical additives. International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines were followed in order to validate the proposed method.

First derivative spectrofluorimetric determination of zopiclone and its degradation product, 2-amino-5-chloropyridine, in pharmaceutical formulations with preliminary tool in biological fluids for clinical evidence of zopiclone intake

A simple, fast, sensitive and stability-indicating derivative spectrofluorimetric method is presented for the assay of zopiclone (ZOP), a drug with hypnotic effect, and its main degradation product and major contaminant, 2-amino-5-chloropyridine (ACP). The method is based on measuring the inherent fluorescence intensity of both drugs at λex=300nm in methanol, then differentiation using D1 (first derivative technique). The developed method was found to be rectilinear over a range of 0.2–4μg/mL of ZOP and 4–100ng/mL of ACP. The limits of detection were 0.05μg/mL of ZOP and 0.2ng/mL of ACP with the limit of quantitation of 0.17μg/mL of ZOP and 0.7ng/mL of ACP. The outcoming results of the proposed method were compared to those obtained by a reference method showing no significant statistical difference between them concerning precision and accuracy. Additionally, the developed method was applied for detecting ACP in spiked human urine and plasma specimens as a tool of clinical evidence of zopiclone intake that can be easily implemented in forensic laboratories. The proposed method was validated as per ICH guidelines.

Development and validation of spectrofluorimetric method for determination of diflunisal and its impurity

A new sensitive, simple, rapid, accurate and precise spectrofluorimetric method for determination of diflunisal and its impurity is developed. Determination of diflunisal is based on first derivative spectrofluorimetric method, while its impurity can be determined by zero order spectrofluorimetric method. Diflunisal was measured at zero-crossing wavelength 394nm (zero crossing point with its impurity) which was selected for quantification of diflunisal. The impurity was measured directly at 334 nm, using 0.05 M phosphate buffer (pH = 9) as solvent. The analytical signal resulting from first derivative and zero order spectra were measured for diflunisal and its impurity, respectively. Linearity was over the range of 0.1-0.9 μg/mL for both with detection limit of 0.02 and 0.03 μg/mL and quantitation limit of 0.07 and 0.09 μg/mL for diflunisal and its impurity, respectively. The proposed method was validated as per ICH guidelines.The accuracy was checked by applying the proposed method for the determination of the drug and its impurity, the mean percentage recoveries were found to be 99.61±0.911 and 100.41±1.373 for diflunisal and its impurity, respectively. RSD values for repeatability testing were 0.268 and 0.569 and for intermediate precision were 0.224 and 0.259 for diflunisal and its impurity, respectively. The proposed method was effectively applied to analysis of studied drug in its tablet formulation. The results obtained by it were statistically compared with the reported method revealing high accuracy and good precision.

Development of dissolution test method for a telmisartan/amlodipine besylate combination using synchronous derivative spectrofluorimetry

The dissolution process is considered an important in vitro tool to evaluate product quality and drug release behavior. Single dissolution methods for the analysis of combined dosage forms are preferred to simplify quality control testing. The objective of the present work was to develop and validate a single dissolution test for a telmisartan (TEL) and amlodipine besylate (AML) combined tablet dosage form. The sink conditions, stability and specificity of both drugs in different dissolution media were tested to choose a discriminatory dissolution method, which uses an USP type-II apparatus with a paddle rotating at 75 rpm, with 900 mL of simulated gastric fluid (SGF without enzymes) as the dissolution medium. This dissolution methodology provided good dissolution profiles for both TEL and AML and was able to discriminate changes in the composition and manufacturing process. To quantify both drugs simultaneously, a synchronous first derivative spectrofluorimetric method was developed and validated. Drug release was analyzed by a fluorimetric method at 458 nm and 675 nm for AML and TEL, respectively. The dissolution method was validated as per ICH guidance.

New spectrofluorimetric methods for determination of melatonin in the presence of N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]- ethyl}acetamide: a contaminant in commercial melatonin preparations

BackgroundMelatonin (MLT) has many health implications, therefore it is of valuable importance to develop specific analytical methods for determination of MLT in the presence of its main contaminant, N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]ethyl}acetamide (10). For development of these analytical methods, compound 10 had to be prepared in an adequate amount.ResultsCompound 10 was synthesized in six steps starting from 5-methoxyindole-2-carboxylic acid (1). Analytical performance of the proposed spectrofluorimetric methods was statistically validated with respect to linearity, accuracy, precision and specificity. The proposed methods were successfully applied for the assay of MLT in laboratory prepared mixtures containing up to 60 % of compound 10 and in commercial MLT tablets with recoveries not less than 99.00 %. No interference was observed from common pharmaceutical additives and the results were favorably compared with those obtained by a reference method.ConclusionsThis work describes simple, sensitive, and reliable second derivative spectrofluorimetric method in addition to two multivariate calibration methods, principal component regression (PCR) and partial least square (PLS), for the determination of MLT in the presence of compound 10.

Spectrofluorimetric determination of serotonin and 5-hydroxyindoleacetic acid in urine with different cyclodextrin media

Alternative and sensitive spectrofluorimetric methods for the determination of hydroxyindoles, such as serotonin ( 5HT) and 5-hydroxyindoleacetic acid ( 5HIA), were developed on the basis of supramolecular interaction with cyclodextrin ( CD) nanocavities ( βCD and hydroxypropyl- βCD, HPCD) at different pH values. Both substrates and receptors have acidic protons, therefore the interactions produced in different systems were considered. The effects of neutral CD at pH 2.00 and 6.994, and of anionic CD at pH 13.00 on the specific acid-base species of the compounds at each pH were determined. In all the conditions studied, the fluorescence of the substrates in the presence of CD increased. The association constants ( K A, mol −1 L) between the substrates and CD were determined (30–300) and interpreted. A zero-crossing first-derivative spectrofluorimetric method with and without HPCD was developed for the simultaneous determination of 5HT and 5HIA. The limits of detection ( L D , ng mL −1) for the best conditions were 0.37 for 5HT and 0.50 for 5HIA at pH 2.00 with HPCD. These L D proved to be better than others reported. The applicability of the direct and derivative spectrofluorimetric methods to urine samples was demonstrated with good recoveries 92–110% and R.S.D. 1–10%.

Determination of mirtazapine in spiked human plasma and tablets by first derivative spectrofluorimetric method

A sensitive first derivative spectrofluorimetric method ( 1D-spectrofluorimetry) was developed for the determination of mirtazapine. Calibration graph for mirtazapine determination was established using the first derivative amplitudes of the mirtazapine emission spectrum ( λ ex = 314 nm) in 0.1 M sulphuric acid measured at 375–435 nm from peak to peak, as the analytical signals. Moreover, the ratio of 1D-spectrophotometric peak amplitudes at these wavelengths was calculated and used for the detection of the presence of interferences. Linearity range was found to be between 1 and 40 ng ml −1 with correlation coefficient ( r) = 0.9999. The limit of quantitation (LOQ) was 1.0 ng ml −1 and the limit of detection (LOD) was 0.2 ng ml −1. The proposed method was validated according to ICH; and it has been applied for the drug determination in human plasma without prior extraction and in tablets. The proposed method’s accuracy, reproducibility, selectivity and simplicity suggest its application in quality control analysis of the drug.

Hydroxypropyl-β-cyclodextrin effect on the fluorescence of auxin and skatole and on the simultaneous determination of binary mixtures of indole compounds in urine by first derivative spectrofluorimetry

The effect of hydroxypropyl-β-cyclodextrin (HPβCD, β-cyclodextrin (βCD) derivative) was determined on the fluorescence emission spectra of skatole (3-methylindole, MI) and auxin (indole 3-acetic acid, IA). The experiments were conducted at excitation wavelength ( λ ex) = 280 nm, in aqueous solutions at different pH values, with and without HPβCD as receptor. The enhanced fluorescence in the presence of the receptor showed a 1:1 host–guest interaction and the values of the association constants K A were between 100 and 200 mol −1 L. The effects of methanol and propanol with and without receptor were also studied. The limit of detection ( L D) for the HPβCD enhanced fluorimetric method at pH = 7.00 were 0.279 and 0.765 ng mL −1 for MI and IA, respectively. For the determination of indole compounds with closely overlapping spectral bands a zero-crossing first derivative spectrofluorimetric method with or without HPβCD is described. Binary mixtures of MI or IA with melatonin ( N-acetyl-5-methoxytryptamine, M) or 5-methoxytryptamine (5-methoxy-3-(2-aminoethyl)indole, 5M) were analysed in the presence of HPβCD. In the absence of receptor, binary mixtures of MI with IA and M with 5M were determined. The matrix effect was evaluated in urine samples by the method of standard addition. Good apparent recoveries were found for each indolic compound by the direct method (98–105% with R.S.D. 0.5–5%) and for mixtures of them by the first derivative method (90–105% with R.S.D. 1–5%) indicating the applicability of them with the advantage of their simplicity, low cost in materials, no time consuming and no requirement of the use of a sophisticate calibration program.

Fluorimetric determination of aluminium and beryllium in mixtures by synchronous derivative spectrometry

Morin (2′,3,4′,5,7-pentahydroxyflavone) has been used as a ligand in the fluorimetric determination of beryllium and aluminium in binary mixtures. A synchronous derivative spectrofluorimetric method has been developed for the determination of beryllium and aluminium at ng ml–1 levels. The precision of the method, expressed as relative standard deviation, is better than 5%. This paper reports the testing of a graphical model used to measure derivative amplitudes. The method is based on the interference-free character of the isodifferential points in the derivative calibration graphs.