Derivative spectrophotometry-assisted determination of tryptophan metabolites emerges host and intestinal flora dysregulations during sepsis.

Sepsis is a life-threatening condition characterized by organ dysfunction resulting from a dysregulated host response to infection. Dysregulated tryptophan (TRP) metabolites serve as significant indicators for endogenous immune turnovers and abnormal metabolism in the intestinal microbiota during sepsis. Therefore, a high coverage determination of TRP and its metabolites in sepsis is beneficial for the diagnosis and prognosis of sepsis, as well as for understanding the underlying mechanism of sepsis development. However, similar structures in TRP metabolites make it challenging for separation and metabolite identification. Here, high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was developed to determine TRP metabolites in rat serum. The first-order derivative spectrophotometry of targeted metabolites in the serum was investigated and proved to be promising for chromatographic peak annotation across different columns and systems. The established method separating the targeted metabolites was optimized and validated to be sensitive and accurate. Application of the method revealed dysregulated TRP metabolites, associated with immune disorders and NAD+ metabolism in both the host and gut flora in septic rats. Our findings indicate that the derivative spectrophotometry-assisted method enhances metabolite identifications for the chromatographic systems based on DAD detectors and holds promise for precision medicine in sepsis.

A nonionic microemulsion co-loaded with atorvastatin and quercetin: Simultaneous spectroscopic analysis and payload release kinetics.

In this study, we have co-loadedatorvastatin (ATR) and quercetin (QCT) in a nonionic microemulsion. After developing a derivative ratio spectrophotometric technique for simultaneous analysis of ATR and QCT, pseudoternary phase diagram was constructed utilizing1:4 d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and ethanol as surfactant and cosurfactant, respectively. Oleic acid was used as oil phase. Structural characterization of the formulation was carried out along a water dilution line created in monophasic region. Characterizations at these dilution points were performed using dynamic light scattering and polarized light microscopy. The average hydrodynamic size of the optimized formulation was found to be 18.9 nm and it did not change upon loading of ATR and QCT. In vitro release was assessed for the formulations loaded with different ratios of ATR and QCT, and the data were fitted to different mathematical models. Interestingly, we noticed differences in release kinetics during changes in dose ratios, particularly for QCT. Higuchi kinetics, observed at equal dose, shifted to Korsmeyer-Peppas model at higher QCT-ATR ratio (2:1 and 4:1). This difference is attributable to the ability of QCT molecules of overwhelming the interface at higher concentrations. Altogether, our observations highlight that the ratio of payloads should be selected carefully in order to avoid unpredictable release patterns.

Smart green spectrophotometric assay of the ternary mixture of drotaverine, caffeine and paracetamol in their pharmaceutical dosage form.

Three green and facile spectrophotometric methods were developed for the assay of Petro® components; drotaverine HCl (DRT), caffeine (CAFF), and paracetamol (PAR). The three methods depend on measuring the absorbance of the studied drugs through their ethanolic solution. The first derivative spectrophotometry (FDS) at (Δλ = 10) were good parameters for DRT and CAFF resolution; DRT and CAFF could be well calibrated using FDS at 320 and 285 nm, respectively. PAR could be estimated at 308 nm utilizing the second derivative spectrophotometry (SDS). Method II relies on the double divisor ratio derivative spectroscopy (DDRDS). The first derivative was applied on each drug where they would be assayed at 309, 288, and 255 nm for DRT, CAFF, and PAR, respectively. Method III depends on the mean centering (MCR) technique. DRT, CAFF, and PAR could be determined at 309, 214, and 248 nm, respectively. The concentrations were rectilinear in the ranges of 2-20 µg/mL for DRT, 1.5-15 µg/mL for CAFF, and 2-40 µg/mL for PAR in double devisor and mean centering but PAR from 5 to 40 µg/mL in derivative method. Method validation was performed according to ICH guidelines assured by the agreement with the comparison method. In addition, greenness assessment of the proposed methods was investigated. The application of the proposed method was extended to analyse tablet dosage form and performing invitro dissolution testing.

Continuous wavelet transform for solving the problem of minor components in quantitation of pharmaceuticals: a case study on the mixture of ibuprofen and phenylephrine with its degradation products.

The presence of minor components represents a challenging problem in spectrophotometric analysis of pharmaceuticals. If one component has a low absorptivity or present in a low concentration compared to the other components, this will hinder its quantitation by spectrophotometric methods. Continuous Wavelet Transform (CWT) as a signal processing technique was utilized to figure out a solution to such a problem. A comparative study was established between traditional derivative spectrophotometry (Numerical Differentiation, ND) and CWT to indicate the advantages and limitations of each technique and possibility of solving the problem of minor components. A mixture of ibuprofen (IBU) and phenylephrine (PHE) with its degradation products forming a ternary mixture was used for comparing the two techniques. The two techniques were applied on raw spectral data and on ratio spectra data resulting in four methods, namely ND, CWT, Derivative Ratio-Zero Crossing (DRZC) and Continuous Wavelet Transform Ratio-Zero Crossing (CWTR-ZC) methods. By comparing the results in laboratory prepared mixtures, CWT technique showed advantages in analysis of mixtures with minor components than ND. The proposed methods were validated according to the ICH guideline Q2(R1), where their linearity was established with correlation coefficient ranging from 0.9995 to 0.9999. The linearity was in the range 3-40 µg/mL for PHE in all methods, while for IBU it was 20-180 and 30-180 µg/mL in CWT and ND methods, respectively. The CWT methods were applied for quantitative determination of the drugs in their dosage form showing the ability of the methods to quantitate minor components in pharmaceutical formulations.

Detection and identification of a mixed cyanobacteria and microalgae culture using derivative spectrophotometry.

Early detection and monitoring of algal blooms and potentially toxic cyanobacteria in source waters are becoming increasingly important with rising climate change and industrialization. There is a growing need to measure the mixed microalgae cultures sensitively and accurately, as multiple algae species are present in natural source waters. This study investigated the detection of an equal concentration, mixed-culture of cyanobacteria (Microcystis aeruginosa) and a common green algae (Chlorella vulgaris) in water using UV-Vis spectrophotometry while employing longer pathlengths and derivative spectrophotometry to improve the detection limit. A strong linear relationship (R2 > 0.99) was found between the concentration and absorbance of the mixed-culture at 682 nm using 50 and 100 mm pathlengths. This study showed that the cyanobacterial (phycocyanin) peak could be separately identified in mixed-culture setting, while the chlorophyll peaks of both algae overlapped each other. The lowest detection limit of the mixed algal culture using traditional spectrophotometry and derivative spectrophotometry was calculated to be 25,997 cells/mL and 5505 cells/mL using a 100 mm cuvette pathlength. Lastly, the performance of mixed-culture and individual algal cultures were compared, and analyses were carried out to evaluate differences in slopes which can be used for quantification purposes. The results indicate that derivative spectrophotometry significantly improved the detection limit making the method potentially viable for the early detection of mixed algal cultures.

Simultaneous determination of ofloxacin and bromfenac in combined dosage form using four different spectrophotometric methods.

Four simple, precise, accurate and validated spectrophotometric methods have been developed for the simultaneous determination of ofloxacin (OFL) and bromfenac sodium (BROM). Firstly, first and second derivative spectrophotometric methods (1D &2D) using a zero-crossing technique utilizing 309.3 and 257.5 nm for OFL and 290.7 and 246.5 nm for BROM as optimum working wavelengths in a binary mixture, respectively. Secondly, the first derivative ratio spectrophotometric method (1DD) in which peak amplitudes at 297.3 nm and 260.7 nm were chosen to simultaneously estimate OFL and BROM, respectively. Thirdly, dual wavelength (DW) method based on two selected wavelengths for each drug in such a way that the difference in absorbance is zero for the second one. At wavelengths 296.4, 348.4 nm BROM has equal absorbance values, therefore, these two wavelengths have been used to determine OFL. Similarly, 271.7 nm and 313.1 nm were selected to determine BROM in the combined formulation. Finally, the fourth method depends on ratio difference spectrophotometry (RDSM), in which the difference between amplitudes at 305.6 nm and 326.5 nm on the ratio spectrum of the mixture was directly proportional to the concentration of OFL; independent of the interfering components. Similarly, the difference between amplitudes at 265.1 nm and 275.4 nm on the ratio spectrum was used for the determination of BROM. The linearity was confirmed in the range of 4 - 18 µg/ml for OFL and BROM for the four methods. The proposed methods were used to determine both drugs in their laboratory prepared mixture and combined formulation with mean percentage recoveries of 99.41 ± 1.35% for OFL and 99.98 ± 1.30 % for BROM in method (A). In method (B), the mean percentage recoveries were 101.70 ± 1.61% for OFL and 101.90 ± 1.45% for BROM. In method (C) OFL was 99.57 ± 1.61% and 100.90 ± 1.62% for BROM. Finally, in method (D) the mean percentage recoveries were 99.37 ± 1.67% for OFL and 100.70 ± 1.59% for BROM. The developed methods were successfully employed for determination of OFL and BROM in laboratory prepared mixtures and combined formulation showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results conformed to the accepted ranges of recovery, precision and repeatability.

Development of three ecological spectroscopic methods for analysis of betrixaban either alone or in mixture with lercanidipine: greenness assessment.

Three eco-friendly spectrophotometric methods were developed for determination of the novel anticoagulant drug, betrixaban (BTX). The first method (method A) was based on direct analysis of BTX at 229.4 nm on the zero-order spectrum using methanol as the optimum solvent. While the second method (method B) was based on measuring difference absorption value (ΔA) of BTX at 335 nm, which was obtained from pH-induced spectral difference (difference spectra of BTX in 0.1 M NaOH versus 0.1 M HCl). The third method (method C) was based on measurement of the first-derivative amplitudes of BTX and its co-administered Ca channel blocker lercanidipine (LER) at 304 and 229 nm for simultaneous assay of BTX and LER, respectively. All methods were linear over concentration ranges of 1.0-20.0 and 8.0-80.0 µg ml-1 for BTX in methods A and B, respectively, and of 1.0-20.0 and 1.0-25.0 µg ml-1 for BTX and LER, respectively, in method C. The three methods were fully validated and assessed for greenness by three metrics: analytical eco-scale, green analytical procedure index and Analytical GREEnness metrics. The results indicated the validity and greenness of the proposed methods. Moreover, the methods were applied to assay the studied analytes in their dosage forms with high percentage of recovery and low percentage of relative s.d. values.

Four chemometric spectrophotometric methods for simultaneous estimation of amlodipine besylate and olmesartan medoxomil in their combined dosage form.

For determination of amlodipine besylate (AML) and olmesartan medoxomil (OLM) at the same time, four UV chemometric spectrophotometric techniques were created and tested in accordance with ICH standards. Method (I) was absorption subtraction method (ASM) using two wavelengths, one of which was of AML at 365 nm and the other was the isoabsorptive point of both drugs at 237 nm. Method (II) was ratio subtraction method (RSM) for determination of OLM at λmax = 254 nm by taking the ratio spectrum and subtracting the constant values using 10 µg/mL of AML as a divisor in combination with extended ratio subtraction method (ERSM) to determine AML at λmax = 239 nm using 10 µg/mL OLM as a divisor. Method (III) was dual wavelength method; the wavelengths used to determine OLM were 221 nm and 235 nm, while those used to determine AML were 246 nm and 259 nm. Method (IV) was the second order derivative (2D) spectrophotometric method at 219 nm for OLM and 227 nm for AML. The proposed approaches were used to achieve linearity in the concentration range of 2-25 µg/mL for both drugs. The approaches were found to be uncomplicated, reproducible, efficient, and cost-effective as well as they were successfully used to determine the cited drugs in both laboratory samples and commercial pharmaceutical formulations.

Innovative derivative/zero ratio spectrophotometric method for simultaneous determination of sofosbuvir and ledipasvir: Application to average content and uniformity of dosage units.

An innovative simple, rapid and sensitive spectrophotometric method was developed for the simultaneous analysis of sofosbuvir (SOF) and ledipasvir (LED) in their combined dosage forms. Sofosbuvir with ledipasvir (SOF/LED) as a combined dosage form was tried at the pandemic COVID 19 crisis. This technique has the advantages of both zero order and first order spectrophotometry. The zero and first derivative amplitudes were measured at 274.2 nm for SOF (zero crossing point of LED in first derivative spectrum) and 314 nm for LED (zero crossing point of SOF in first derivative spectrum) over the concentration range of 2.0-50.0 µg mL-1 with coefficients of determination (R2) > 0.9999 for both drugs and mean percentage recoveries of 100.25 ± 1.61 and 99.85 ± 0.99 for SOF and LED; respectively. This original method was validated according to ICH requirements and statistically compared to published comparison methods. This method was applied to estimate the average content and the uniformity of dosage units of SOF/LED combined dosage form according to British Pharmacopeia requirements.

Development of Ecofriendly Derivative Spectrophotometric Methods for the Simultaneous Quantitative Analysis of Remogliflozin and Vildagliptin from Formulation.

Three rapid, accurate, and ecofriendly processed spectrophotometric methods were validated for the concurrent quantification of remogliflozin (RGE) and vildagliptin (VGN) from formulations using water as dilution solvent. The three methods developed were based on the calculation of the peak height of the first derivative absorption spectra at zero-crossing points, the peak amplitude difference at selected wavelengths of the peak and valley of the ratio spectra, and the peak height of the ratio first derivative spectra. All three methods were validated adapting the ICH regulations. Both the analytes showed a worthy linearity in the concentration of 1 to 60 µg/mL and 2 to 90 µg/mL for VGN and RGE, respectively, with an exceptional regression coefficient (r2 ≥ 0.999). The developed methods demonstrated an excellent recovery (98.00% to 102%), a lower percent relative standard deviation, and a relative error (less than ±2%), confirming the specificity, precision, and accuracy of the proposed methods. In addition, validated spectrophotometric methods were commendably employed for the simultaneous determination of VGN and RGE from solutions prepared in the laboratory and the formulation. Hence, these methods can be utilized for the routine quality control study of the pharmaceutical preparations of VGN and RGE in pharmaceutical industries and laboratories. The ecofriendly nature of the anticipated spectrophotometric procedures was confirmed by the evaluation of the greenness profile by a semi-quantitative method and the quantitative and qualitative green analytical procedure index (GAPI) method.

Fe3O4@PDA@PANI core-shell nanocomposites as a new adsorbent for simultaneous preconcentration of Tartrazine and Sunset Yellow by ultrasonic-assisted dispersive micro solid-phase extraction.

In this research, novel magnetic Fe3O4@PDA@PANI core-shell nanoparticles were designed and fabricated as an efficient adsorbent in the service of ultrasound-assisted dispersive micro-solid phase extraction for simultaneous preconcentration of Sunset Yellow (SY) and Tartrazine (Tar) before UV-Vis spectrophotometric detection. This adsorbent was fully characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray (EDX) analysis. To overcome the spectral overlapping of SY and Tar dyes, the derivative spectrophotometric method was successfully used for the simultaneous detection of dyes in their binary solutions. The operating parameters affecting preconcentration efficiency and spectrophotometric determination were optimized. Under optimal conditions, the limit of detections (LOD) was obtained 0.2 and 0.5 ng mL-1 for SY and Tar, respectively. The adsorption capacity and reusability of core-shell nanoparticles were significant. The satisfactory results of analysis of a few real samples indicate that the method is very favored in the analysis of various complex matrices.

Advanced eco-friendly UV spectrophotometric approach for resolving overlapped spectral signals of antihypertensive agents in their binary and tertiary pharmaceutical dosage form.

Cardiovascular disorders are among the foremost causes of death worldwide, especially hypertension, a silent killer syndrome that requires multiple drug therapy for proper management. This work presents novel and green spectrophotometric methods for the concurrent analysis of Amlodipine (AML), Telmisartan (TEL), Hydrochlorothiazide (HCTZ), and Chlorthalidone (CLO) in their pharmaceutical dosage form. The suggested methods were Fourier-self deconvolution, amplitude factor, and first derivative methods developed and validated for the simultaneous determination of a tertiary mixture of AML, TEL, and HCTZ in TELVAS 3D 80 mg tablet and a binary mixture of TEL and CLO in TELMIKIND-CT 40 tablets. The investigated methods revealed limits of detection 0.7283 µg/ml for AML and ranging from 0.0121 to 0.0433, 0.1547 to 0.1767 µg/ml and 0.0578 to 0.1262 µg/ml for TEL, HCTZ, and CLO, respectively.The greenness of the suggested techniques was examined by an eco-scale scoring method called the penalty points, which revealed that the methods were excellent green regarding several parameters as reagents, instrument, and waste safety. The introduced methods' validity was investigated by resolving prepared laboratory mixtures containing different AML, TEL, HCTZ, or TEL and CLO ratios. Furthermore, the introduced methods were ensured by the standard addition technique. Finally, the obtained results were statistically compared by the reported spectrophotometric methods, showing no significant difference concerning precision and accuracy.

Spectrophotometric evaluation of hemolysis in plasma by quantification of free oxyhemoglobin, methemoglobin, and methemalbumin in presence of bilirubin.

Severe intravascular hemolysis leads to the simultaneous presence of free heme pigments (oxyhemoglobin, methemoglobin, and methemalbumin) and bilirubin in human plasma. Standard spectrophotometric methods used to assess in vivo hemolysis inadequately address this complex analytical situation. Thus, we propose a novel quantification algorithm to ensure the highest analytical specificity. A corresponding second-derivative fitting algorithm was validated according to the guideline of bioanalytical method validation from the European Medicines Agency using plasma specimens (n = 1759) spiked with different concentrations of oxyhemoglobin and methemoglobin. The results were compared to standard spectrophotometric quantification methods described by Harboe, Noe, and Fairbanks. Based on the second-derivative method, simultaneous quantification of oxyhemoglobin and methemoglobin/methemalbumin in samples with total bilirubin concentrations ≤4.9 mg/dL (83.8 µmol/L) provided robust results (inaccuracy ≤20%, imprecision ≤16%). Analyzing UV/VIS spectra of plasma from patients with confirmed severe intravascular hemolysis evidenced an underestimation of up to 33% for the combined free heme pigment content. The employed second-derivative algorithm allows for automated and highly specific quantification of the free heme pigment content in diluted human plasma, which cannot be realized with standard spectrophotometric evaluation methods. An Excel-based tool readily applicable to clinical datasets accompanies this manuscript.

Investigation of some univariate and multivariate spectrophotometric methods for concurrent estimation of Vancomycin and Ciprofloxacin in their laboratory prepared mixture and application to biological fluids.

Four simple, rapid, accurate and precise spectrophotometric methods were established and validated in accordance with ICH Q2 (R1) guidelines for the simultaneous determination of Vancomycin (VNC) and Ciprofloxacin (CPR) in their raw materials, laboratory prepared mixtures and pharmaceutics. Method A depends on using first derivative spectrophotometry (D1) where VNC and CPR were resolved at 243.6 and 262.0 nm, respectively. Concerning method B, it is based on utilizing first derivative of ratio spectra (DD1) where determination was performed at the peak maxima at 244.0 nm and 258.0 nm for VNC and CPR, respectively. Two chemometric models were applied for the quantitative analysis of both drugs in their laboratory prepared mixtures, namely, partial least squares (PLS) (method C) and artificial neural network (ANN) (method D). For univariate methods linearity range for both drugs was in the range of 3-30 and 1-10 µg/mL for VNC and CPR, respectively. Multivariate calibration methods using five level, two factor calibration model for the development of 25 mixtures were also applied for the simultaneous estimation of the two drugs in their laboratory prepared mixture using spectral region from 200.0 to 300.0 nm using interval 1 nm. The suggested methods have been successfully extended to the assay of the two studied drugs in laboratory-prepared mixtures and pharmaceuticals with excellent recovery. First derivative spectrophotometry (D1) was also applied for the assay of both analytes in spiked human plasma with good recovery. No interaction with common pharmaceutical additives has been observed which indicate the selectivity of the method. The results obtained were favourably compared with those obtained applying the reported methods. The methods are validated in compliance with the ICH Q2 (R1) guidelines and the measured accuracy and precision are assessed to be within the accepted limits.

Improved spectral resolution for the rapid simultaneous spectrophotometric determination of sofosbuvir and daclatasvir as anti hepatitis C virus drugs in pharmaceutical formulation and biological fluid using continuous wavelet and derivative transform.

In this study, the simultaneous spectrophotometric estimation of Sofosbuvir (SOF) and Daclatasvir (DAC) in synthetic mixtures and tablet formulation in the presence of overlapping spectra was performed based on continuous wavelet transform (CWT) and derivative spectrophotometry (DS) methods without any separation process. The Coiflet (Coif2) and Daubechies (Db3) wavelet families with wavelength of 256 nm and 218 nm were obtained as the best families for the simultaneous determination of SOF and DAC, respectively. Also, the first derivative absorption spectra revealed the best results corresponding to the analysis of SOF and DAC at 237 nm and 291 nm, respectively. The ranges of limit of detection (LOD) and limit of quantitation (LOQ) related to the CWT and DS methods were 2.45 × 10-3 to 0.5054 and 6.91 × 10-3 to 0.6027, respectively. Mean recovery values of SOF and DAC in synthetic mixtures for CWT approach were 98.55%, 98.09% and in DS method were 98.78% and 95.83%, respectively. Real samples, including Sovodak tablet and urine was used for accurate simultaneous determination of the mentioned components. Analyzing Sovodak tablet was implemented using high-performance liquid chromatography (HPLC) as a reference method that the results were near to the CWT and DS methods. In order to investigate the existence of significant differences between the methods, analysis of variance (ANOVA) test at the 95% confidence level was performed but no significant differences were observed. In addition, the amounts of SOF and DAC in the complex matrix of biological sample were well predicted by the proposed methods.

The Development of Spectrophotometric and Validated Stability- Indicating RP-HPLC Methods for Simultaneous Determination of Ephedrine HCL, Naphazoline HCL, Antazoline HCL, and Chlorobutanol in Pharmaceutical Pomade Form.

BACKGROUND: Allergic rhinitis, acute nasal congestion and sinusitis are one of the most common health problems and have a major effect on the quality of life. Several medications are used to improve the symptoms of such diseases in humans. Pharmaceutical pomade form containing Ephedrine (EPD) HCl, Naphazoline (NPZ) HCl, Antazoline (ANT) HCl, and Chlorobutanol (CLO) is one of them. OBJECTIVE: For these reasons, this study includes the development of spectrophotometric and chromatographic methods for the determination of EPD HCl, NPZ HCl, ANT HCl, and CLO active agents in the pharmaceutical pomade. METHOD: In the spectrophotometric method, third-order derivative of the amplitudes at 218 nm n=5 and the first-order derivative of the amplitudes 254 nm n=13 was selected for the determination of EPD, ANT, respectively while NPZ was determined by the second derivative at 234 nm and n=21. Colorimetric detection was applied for assay analysis of CLO at 540 nm. Furthermore, a reverse phase high performance liquid chromatographic (RP- HPLC) method has been developed and optimized by using Agilent Zorbax Eclipse XDB C18 (75 mm x 3.0 mm, 3.5µm) column. The column temperature was 40°C, binary gradient elution was used and the mobile phase consisted of 15 mM phosphate buffer in distilled water (pH 3.0) and methanol, and the flow rate was 0.6 mL min-1 and the UV detector was detected at 210 nm. The linear operating range was obtained as 11.97-70, 0.59-3, 2.79-30, and 2.92-200 µg mL-1 for EPD HCl, NPZ HCl, ANT HCl, and CLO respectively. RESULTS: The LOD values were found to be 3.95, 0.19, 0.92 and 0.96 µg mL-1 for EPD HCl, NPZ HCl, ANT HCl, and CLO in the spectrophotometric method, respectively. The linear ranges in the RP-HPLC method were 8.2-24.36 µg mL-1, 0.083 - 0.75 µg/mL, 2.01-7.5 µg mL-1 and 2.89-24.4 µg mL-1 for EPD HCl, NPZ HCl, ANT HCl, and CLO, respectively. The LOD values in the validation studies were 2.7, 0.025, 0.66 and 0.86 µg mL-1 for EPD HCl, NPZ HCl, ANT HCl, and CLO in RP-HPLC method respectively. CONCLUSION: The results of the spectrophotometric and chromatographic methods were compared and no differences were found between the two methods.

Chitosan-based molecular imprinted polymer for extraction and spectrophotometric determination of ketorolac in human plasma.

A selective chitosan-based ion exchange molecular imprinted polymer (MIP) was prepared for ketorolac (KET) using the sol-gel method and glutaraldehyde as a crosslinker. The nonimprinted polymer (NIP) was prepared and used as a control, during the whole experiment. The chemical and morphological characteristics of the prepared polymers were investigated using FTIR and SEM, respectively. The prepared MIP was applied to determine the optimum operational conditions for KET extraction from dilute aqueous solutions. The adsorption step was performed at pH 5 and a contact time of 20 min, using 0.1 N HCl as an elution solvent for 30 min. The specificity of the prepared polymer was indicated by an imprinting factor of 1.45. The prepared MIP was successfully applied for selective solid phase extraction and subsequent determination of KET in spiked human plasma samples over a range of 2-20 µg/mL, with a mean % recovery of 94.62% using derivative spectroscopy.

Fourier convolution versus derivative spectrophotometry: Application to the analysis of two binary mixtures containing tamsulosin hydrochloride as a minor component.

Simple and rapid spectrophotometric methods are described for determination of two mixtures of tamsulosin (TM), as minor component, with either solifenacin (SL) or tolterodine (TL). The proposed methods involve treatment of the absorbance ratio spectra or zero order spectra by derivative or discrete Fourier function. TM and TL mixture could not be resolved by manipulation of their zero order spectra due to the strong overlap between both spectra and only derivative or Fourier function coefficients of ratio spectra could resolve their spectra. TM and SL mixture was fully resolved by the manipulation of both ratio and zero order spectra. The values of the derivative or the Fourier function coefficients of ratio spectra and/or zero order spectra, at either peak or trough points, were correlated to the concentration of each drug in each mixture. Calibration graphs were linear in ranges 2.5-40 and 30-500µg.mL-1 using derivative ratio and Fourier function ratio, 5-40 and 80-600µg.mL-1 using direct derivative and 2.5-40 and 30-300µg.mL-1 using direct Fourier function for TM and SL, respectively. The plots of derivative ratio amplitude and the Fourier function ratio coefficient versus concentration were linear over ranges 2.5-20 and 25-250µg.mL-1 for TM and TL, respectively. Higher sensitivity as indicated by lower values of detection and quantitation limits were obtained using Fourier convoluted spectra (ratio or zero order) compared to derivative methods. All validation aspects per ICH guidelines are included. The proposed methods were also applied for the studied drugs assay in their tablets and capsules.

Quantitative determination of Dapoxetine Hydrochloride and Tadalafil using different validated spectrophotometric methods.

Three rapid, simple and selective spectrophotometric methods were developed for determination of Dapoxetine Hydrochloride (DAP) and Tadalafil (TAD) in bulk and pharmaceutical dosage forms. Method (A) is simultaneous first derivative (1D) spectrophotometric method in which the peak amplitudes of the first derivative spectra (1D) were measured for both DAP and TAD at 322.4 nm and 230 nm, respectively with no interference from each other. Method (B) is the area under curve (AUC) spectrophotometric method in which the areas under curve in the wavelength ranges 228-240 nm and 242-254 nm are used for determination of DAP and TAD respectively. Method (C) is ratio subtraction combined with extended ratio subtraction spectrophotometry (EXRS) in which TAD was determined by dividing the mixture spectra by the spectrum of 15 µg/mL solution of DAP, while DAP was be determined by dividing the mixture spectra by the spectrum of 30 µg/mL solution of TAD. The developed methods were applied to different laboratory prepared mixtures of DAP and TAD. These methods were validated according to the ICH guidelines with respect to linearity, accuracy, precision, selectivity and specificity, and can be used for routine quality control analysis of DAP and TAD in their dosage forms.

Multiple analytical methods for determination of formoterol and glycopyrronium simultaneously in their novel combined metered dose inhaler.

One of the major causes of mortality all over the world is chronic obstructive pulmonary disease (COPD). Recently approved combined inhaler of formoterol fumarate (FF) and glycopyrronium bromide (GLY) has been used in very low concentrations (µg level/actuation) doses in COPD patients. The first spectrophotometric and advanced highly sensitive liquid chromatography has been achieved successfully throughout this study, permitting validated analysis of dual combined inhaler in raw material as well as pharmaceutical inhaled dosage form. Three sensitive analytical methods were carried out for the simultaneous assay of FF and GLY in their novel combined Metered dose inhaler (MDI). The first method depends on measuring the first derivative amplitudes at 208.27 nm for FF and at 213.27 nm and 239.86 nm for GLY, respectively. The second method depends on measurement of the first derivative of the ratio spectra at 214 or 229 nm for FF and 240 or 259 nm for GLY, respectively. For the spectrophotometric methods, the linearity ranges were 0.48-9.6 µg/mL for FF and 0.9-18 µg/mL for GLY. For the third method, valid ion-pairing chromatographic method was carried out applying C18 column and isocratic mobile phase of 60% v/v acetonitrile and 40% v/v deionized waster (pH 3.0) enclosing 0.025% sodium dodecyl sulfate, using UV detection adjusted to 210 nm and flow rate of 1.2 mL/min. For the ion-pairing chromatographic method, the linearity ranges were 0.048-4.8 µg/mL for FF and 0.09-9.0 µg/mL for GLY. The developed methods are reproducible, valid and offer efficient resolution between formoterol and glycopyrronium using spectrophotometric methods and highly sensitive and precise chromatographic method. The percent recoveries of the inhaled drugs in their MDI were good. The method was successfully established for the quantitative analysis of FF and GLY in their combined pharmaceutical inhaler capsules to validate the therapeutic efficiency of the combined drugs in quality control labs.