Transforming microbial pigment into therapeutic revelation: extraction and characterization of pyocyanin from Pseudomonas aeruginosa and its therapeutic potential as an antibacterial and anticancer agent.

BACKGROUND: The objectives of the current study were to extract pyocyanin from Pseudomonas aeruginosa clinical isolates, characterize its chemical nature, and assess its biological activity against different bacteria and cancer cells. Due to its diverse bioactive properties, pyocyanin, being one of the virulence factors of P. aeruginosa, holds a promising, safe, and available therapeutic potential. METHODS: 30 clinical P. aeruginosa isolates were collected from different sources of infections and identified by routine methods, the VITEK 2 compact system, and 16 S rRNA. The phenazine-modifying genes (phzM, phzS) were identified using polymerase chain reaction (PCR). Pyocyanin chemical characterization included UV-Vis spectrophotometry, Fourier Transform Infra-Red spectroscopy (FTIR), Gas Chromatography-Mass Spectrometry (GC-MS), and Liquid Chromatography-Mass Spectrometry (LC-MS). The biological activity of pyocyanin was explored by determining the MIC values against different clinical bacterial strains and assessing its anticancer activity against A549, MDA-MB-231, and Caco-2 cancer cell lines using cytotoxicity, wound healing and colony forming assays. RESULTS: All identified isolates harboured at least one of the phzM or phzS genes. The co-presence of both genes was demonstrated in 13 isolates. The UV-VIS absorbance peaks were maxima at 215, 265, 385, and 520 nm. FTIR could identify the characteristic pyocyanin functional groups, whereas both GC-MS and LC-MS elucidated the chemical formula C11H18N2O2, with a molecular weight 210. The quadri-technical analytical approaches confirmed the chemical nature of the extracted pyocyanin. The extract showed broad-spectrum antibacterial activity, with the greatest activity against Bacillus, Staphylococcus, and Streptococcus species (MICs 31.25-125 µg/mL), followed by E. coli isolates (MICs 250-1000 µg/mL). Regarding the anticancer activity, the pyocyanin extract showed IC50 values against A549, MDA-MB-231, and Caco-2 cancer cell lines of 130, 105, and 187.9 µg/mL, respectively. Furthermore, pyocyanin has markedly suppressed colony formation and migratory abilities in these cells. CONCLUSIONS: The extracted pyocyanin has demonstrated to be a potentially effective candidate against various bacterial infections and cancers. Hence, the current findings could contribute to producing this natural compound easily through an affordable method. Nonetheless, future studies are required to investigate pyocyanin's effects in vivo and analyse the results of combining it with other traditional antibiotics or anticancer drugs.

RGB Trichromatic Whiteness Assessment of Bio Analytical Chromatographic Tool Using Fluorescence for Quantitation of Semaglutide: Application to Pharmaceutical Preparations and Spiked Plasma.

Semaglutide (SEMG) is one of the most widely used and trending medications to treat type II diabetes and obesity. This work aimed to develop a liquid chromatography with spectroflourimetric detection (HPLC-flourimetry) analysis of SEMG in both its tablet dosage form and plasma. The power of fluorescence detection coupled with HPLC proved its capability as a bioanalytical tool to assay SEMG in plasma samples owing to its simplicity and sensitivity which reached below the Cmax of SEMG. Separation was done using a C18 column with mobile phase of acetonitrile and water acidified with orthophosphoric acid (pH 3.5) (1.41 × 10-5 M) in isocratic mode in ratio 57:43 and 1 mL/min flow rate after extraction using protein precipitation. Detection was carried out at λ excitation of 238 nm and λ emission of 416 and 307 nm for SEMG and the internal standard, respectively. Evaluation of greenness of the proposed method was done using AGREE (Analytical GREEnness Metric Approach), ComplexGAPI (Complementary Green Analytical Procedure Index) & the new algorithm RGB 12 model (Red-Green-Blue). They showed that these methods can be a greener alternative with acceptable sensitivity for analysis of SEMG. The developed seven min-assay was validated per ICH as well as FDA bio analytical methods' guidelines to prove its applicability for routine sample analysis and future pharmacokinetic studies.

Quantification of 16 cephalosporins in the aquatic environment by liquid chromatography-tandem mass spectrometry.

Antimicrobial agents are essential to protect human and animal health. During the coronavirus disease 2019 pandemic, antimicrobials such as cephalosporins were widely used as prophylactics and to prevent bacterial co-infection. Undoubtedly, the prevalence of antibiotics in the aquatic environment will ultimately affect the degree of resistance against these bacteria in animals and the environmental systems. In order to monitor 16 cephalosporins in the aquatic environment, we developed a new liquid chromatography-tandem mass spectrometry method that functioned simultaneously under positive and negative electrospray ionization switching modes. The chromatographic separation has been implemented using a pentafluorophenyl propyl column kept at 40°C. The limits of detection and quantitation for the studied cephalosporins ranged from (8 × 10-4 ) to (7.11 × 10-2 ) ng/ml and from (2.61 × 10-3 ) to (2.37 × 10-1 ) ng/ml, respectively. The percent extraction efficiency (apparent recovery) and relative standard deviations for the analyzed cephalosporins ranged from 61.69% to 167.67% and 2.45% to 13.48%, respectively. The overall findings showed that the effluent from the wastewater treatment plants that receive wastewater from pharmaceutical factories had a higher detected amount of cephalosporins than that of domestic sewage. Moreover, seven cephalosporins, including cefuroxime, ceftazidime, cefradine, cefprozil, cefixime, cefalexin, and cefadroxil (0.68-105.45 ng/L) were determined in the aquatic environment.

Accelerated stability study of the ester prodrug remdesivir: Recently FDA-approved Covid-19 antiviral using reversed-phase-HPLC with fluorimetric and diode array detection.

Remdesivir (RDV) is the first antiviral drug, approved by the Food and Drug Administration, to treat severe acute respiratory syndrome coronavirus 2. RDV is a relatively new chemical entity, 'ester prodrug', with no reported stability profile. Due to the urgency of its use and thus fast production, it is important to develop a stability-indicating method for its assay. Chromatographic separation was carried out on a C18 column (250 × 4.6 mm, 5 µm) with dual detection: diode array at 240 nm and fluorescence at λex/em 245/390 nm. Isocratic elution of acetonitrile and distilled water (acidified with phosphoric acid, pH 4) in the ratio of 55:45 (v/v), respectively, was used. The linearity range using HPLC-diode array detection was 0.1-15 µg/mL, whereas that using fluorimetric detection was 0.05-15 µg/mL. As per the International Conference on Harmonization guidelines, RDV has been degraded by accelerated alkaline, acidic, neutral hydrolysis, oxidative, heat, and photolytic stress conditions. Possible degradation hypothesis of the parent molecule has been suggested and illustrated. The proposed methods have achieved selective determination of the intact drug with no peaks overlapping in all assumptions. Extensive degradation confirms threatened drug stability at thermal and basic hydrolytic stressing. The developed methods were fully validated and proved suitable for quality control routine analysis of RDV in raw material and pharmaceutical dosage forms.

Least median of squares and iteratively re-weighted least squares as robust linear regression methods for fluorimetric determination of α-lipoic acid in capsules in ideal and non-ideal cases of linearity.

This study outlines two robust regression approaches, namely least median of squares (LMS) and iteratively re-weighted least squares (IRLS) to investigate their application in instrument analysis of nutraceuticals (that is, fluorescence quenching of merbromin reagent upon lipoic acid addition). These robust regression methods were used to calculate calibration data from the fluorescence quenching reaction (∆F and F-ratio) under ideal or non-ideal linearity conditions. For each condition, data were treated using three regression fittings: Ordinary Least Squares (OLS), LMS and IRLS. Assessment of linearity, limits of detection (LOD) and quantitation (LOQ), accuracy and precision were carefully studied for each condition. LMS and IRLS regression line fittings showed significant improvement in correlation coefficients and all regression parameters for both methods and both conditions. In the ideal linearity condition, the intercept and slope changed insignificantly, but a dramatic change was observed for the non-ideal condition and linearity intercept. Under both linearity conditions, LOD and LOQ values after the robust regression line fitting of data were lower than those obtained before data treatment. The results obtained after statistical treatment indicated that the linearity ranges for drug determination could be expanded to lower limits of quantitation by enhancing the regression equation parameters after data treatment. Analysis results for lipoic acid in capsules, using both fluorimetric methods, treated by parametric OLS and after treatment by robust LMS and IRLS were compared for both linearity conditions.

Development and validation of spectrophotometric and HPTLC methods for simultaneous determination of rosiglitazone maleate and metformin hydrochloride in the presence of interfering matrix excipients.

Two simple methods have been developed and validated for the simultaneous determination of rosiglitazone maleate (ROS) and metformin hydrochloride (MET) in synthetic mixtures and coated tablets in a ratio of 1:250 (ROS:MET). The first method was a spectrophotometric one. The minor component, ROS was determined by measuring the values of absorbance at λmax 312 nm and the D1 amplitudes at 331 nm where MET shows no absorption contribution. However, absorbance interferences from tablet excipients were successfully corrected by D1 at 331 nm zero-crossing technique. Study of spectral interference from tablet excipients was included in the text. Standard curves for Amax and D1 methods were in the concentration range 20.0-80.0 µg mL(-1). The major component, MET was determined both in binary mixtures and tablets by measuring its Amax at 236 nm. Extensive dilution eliminated any absorption contribution from the coexisting ROS or tablet matrix. Standard curves showed linearity in the concentration range 4.0-12.8 µg mL(-1). The second method was based on high performance thin layer chromatography (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 230 nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using methanol:water:NH4Cl 1% w/v (5:4:1 v/v/v) as the mobile phase. Linear calibration graphs of peak area values were obtained versus concentrations in the range of 0.4-2.0 µg band(-1) and 20.0-100.0 µg band(-1) for ROS and MET, respectively. According to International Conference on Harmonisation (ICH) guidelines, different validation parameters were verified for the two methods and presented.

Penalization and Color Code Technical Approaches for Method Greenness and Whiteness Appraisal in Veterinary Medication: Assay of Toltrazuril Suspension.

BACKGROUND: Intestinal coccidiosis is a debilitating disease in poultry and livestock, leading to economic impact worldwide. Coccidiosis is prevented and treated in broilers by the inclusion of anticoccidials in feed. Toltrazuril is administered in potable water to treat coccidiosis. OBJECTIVE: Three robust analytical methods for the quantitation of toltrazuril in pure and pharmaceutical formulations are developed. Furthermore, ecological metrics, either penalization- or color-code-based techniques, are applied for the appraisal of assays. METHODS: First, second-derivative (Δλ; 5 nm) spectrophotometric method is used. Toltrazuril is measured from peak to peak at 244-260 nm within a linearity range of 5-25 µg/mL. The second method is an HPTLC analysis performed on an aluminum sheet of silica gel using ethyl acetate-methanol-ammonium chloride buffer-water (8:1:0.5:0.5, by volume respectively) as the elution phase. Toltrazuril, at a retardation factor of 0.66 ± 0.01, is linearly determined in the range of 1-9 µg/spot at 243 nm. The third method is reversed-phase HPLC with diode array detection, using an Agilent C18 column (5 µm, 4.6 × 150 mm) in isocratic elution mode at 1 mL/min flow rate with a mobile phase of acetonitrile and water in a ratio of 80:20 (v/v). Toltrazuril elutes at a retention time of 2.58 ± 0.1 min and is linearly determined at 243 nm in the range of 0.25-25 µg/mL. RESULTS: Calculated 2D-values and peak areas are highly correlated to their corresponding drug concentrations at coefficients: r > 0.999. All methods were International Council of Harmonization (ICH) validated and applied to the dosage form with satisfactory % recoveries (97-103%). Statistical comparisons versus reported one using t-test and F-test disclose insignificant variation. In examining greenness and whiteness norms, the proposed methods were evaluated and ranked alongside four different reported methods. CONCLUSIONS: The proposed methods are green, accurate, and can be applied in routine QC for the determination of toltrazuril in pharmaceutical formulations. HIGHLIGHTS: Intestinal coccidiosis substantially affects the chicken intestinal tract leading to reduced growth. Toltrazuril is used for the treatment and prevention of intestinal coccidiosis. Three robust, accurate, and precise analytical methods are developed for toltrazuril determination in pure and pharmaceutical formulations. All proposed methods were ecologically assessed and compared with published ones.

In-lab synthesized turn-off fluorescence sensor for estimation of Gemigliptin and Rosuvastatin polypill appraised by Spider diagram, AGREE and whiteness metrics.

Gemigliptin-Rosuvastatin single-pill combination is a promising therapeutic tool in the effective control of hyperglycemia and hypercholesterolemia. Organic sensors with high quantum yields have profoundly significant applications in the pharmaceutical industry, such as routine quality control of marketed formulations. Herein, the fluorescence sensor, 2-Morpholino-4,6-dimethyl nicotinonitrile 3, (λex; 226 nm, λem; 406 nm), was synthesized with a fluorescence quantum yield of 56.86% and fully characterized in our laboratory. This sensor showed high efficiency for the determination of Gemigliptin (GEM) and Rosuvastatin (RSV) traces through their stoichiometric interactions and simultaneously fractionated by selective solvation. The interaction between the stated analytes and sensor 3 was a quenching effect. Various experimental parameters and the turn-off mechanism were addressed. The adopted approach fulfilled the ICH validation criteria and showed linear satisfactory ranges, 0.2-2 and 0.1-1 µg/mL for GEM and RSV, respectively with nano-limits of detection less than 30 ng/mL for both analytes. The synthesized sensor has been successfully applied for GEM and RSV co-assessment in their synthetic polypill with excellent % recoveries of 98.83 ± 0.86 and 100.19 ± 0.64, respectively. No statistically significant difference between the results of the proposed and reported spectrophotometric methods in terms of the F- and t-tests. Ecological and whiteness appraisals of the proposed study were conducted via three novel approaches: the Greenness Index via Spider Diagram, the Analytical Greenness Metric, and the Red-Green-Blue 12 model. The aforementioned metrics proved the superiority of the adopted approach over the previously published one regarding eco-friendliness and sustainability. Our devised fluorimetric turn-off sensing method showed high sensitivity, selectivity, feasibility, and rapidity with minimal cost and environmental burden over other sophisticated techniques, making it reliable in quality control labs.

Carbon dots as fluorescent nanoprobes for assay of some non-fluorophoric nitrogenous compounds of high pharmaceutical interest.

Background: Carbon dots, CDs, have excellent photoluminescence properties, good biocompatibility, low toxicity and good light stability. The optical, magnetic and electronic properties of CDs make them a hugely relevant tool to be used in pharmaceutical analysis, bioimaging, drug delivery, and other fields. The fluorescence of carbon nanodots makes it suitable for assay of some nitrogenous compounds of high pharmaceutical interest. In this work, we develop simple, fast and green spectrophotometric methods for quantification of Azithromycin and Rasagiline mesilate using synthesized fluorescent CDs from garlic peels. Results: The spectrometric methods depend on stoichiometric reactions of both drugs with fluorescent CDs. Carbon dots exhibit a declared absorption peak λmax at 238 nm and potent fluorimetric emission at λem 528 nm, upon excitation at λex 376 nm. Drugs' concentrations in ppm are efficiently calculated using Stern-Volmer Equation. Decrease in fluorescence (ΔF = F o - F) and the F-ratio values are linearly correlated to molar concentration of each quencher (drug). A significant linear diminish in the dots' measured absorbance and fluorimetric emission values was observed. Validation of all the developed methods was according to the ICH guidelines. Conclusions: In a new way, this work successfully indicates, spectrometric methods for rapid detection of two non-fluorophoric nitrogenous compounds using potent carbon nanodots. Consequently, these green developed methods offer several benefits as simplicity, ease of quantification, accuracy and precision that encourage the application of the developed methods in routine analysis of Azithromycin and Rasagiline mesilate in quality control laboratories as analytical tool. Supplementary Information: The online version contains supplementary material available at 10.1186/s43088-023-00346-z.

Green and Smart Quantitative Quality Control for Veterinary Mixture of Ivermectin and Clorsulon: Ecological Evaluation of Spectral Analyses via Analytical Eco-Scale, Green Analytical Procedure Index, and Analytical GREEnness Metric Approaches.

BACKGROUND: The global financial market is still highly threatened by bovine fasciolosis, a parasitic infection that targets cattle, mainly in tropical regions. Binary combination of ivermectin (IVER) and clorsulon (CLO), in challenging concentration ratios, is typically indicated for treatment and control of fasciolosis. OBJECTIVE: The present study aims at smart simultaneous spectrophotometric assay of both compounds at their high ratio in marketed formulation and synthetic mixtures, without any prior separation. Furthermore, their greenness profile was evaluated and compared with previous reported assay methods, including the official one. METHODS: Mathematical-based proposed methods are the dual-wavelength, induced dual-wavelength, and first derivative ratio methods. Each is developed, optimized, and applied to determine simultaneously IVER and CLO at linear ranges of 1-30 and 5-40 µg/mL, respectively. They have been validated according to ICH guidelines. Statistical Student t-tests and F-tests compared the proposed methods with a USP chromatographic technique. Ecological appraisal is accomplished using three independent metrics: Analytical Eco-Scale (AES), Green Analytical Procedure Index (GAPI), and Analytical GREEnness Metric Approach (AGREE). RESULTS: Satisfactory recoveries, ICH compliance, and adherence of proposed methods to the ecological safety margin are achieved. CONCLUSIONS: Developed methods are eco-friendly and cost-effective and can accomplish a routine quantitative quality control for concurrent determination of both drugs. HIGHLIGHTS: Veterinary antimicrobials need analytical quality control using safer and green methodologies. Data manipulated spectral analyses of IVER and CLO, in a ratio of 1:10% (v/v), are developed and optimized. AES, GAPI, and AGREE approaches illustrate the high green compliance in respect to assays reported in the literature. Furthermore, the United States Pharmacopeia (USP) assay for IVER and CLO in injectable dosage form depends on analysis of each drug separately in the presence of the other drug, but it cannot determine both drugs simultaneously.

Comparative Greenness Metric Estimates for Content Uniformity Testing of Anti-Cov-2, GS-5734 in Commercial Vials: Validated Micellar Electrokinetic Chromatographic Assay.

BACKGROUND: The antiviral drug GS-5734 remdesivir is a new phosphoramidate prodrug developed initially as a treatment for Ebola virus which then proved to have antiviral properties against other viruses. After clinical trials, it was the first antiviral to be approved by the U.S. Food and Drug Administration in 2020 to treat severe coronavirus (COVID-19) cases. The widespread current pandemic gave an urge to its fast production and marketing. Thus, new analytical methods must be available for its analysis in a fast and easy manner with low cost to be applicable in all laboratories. OBJECTIVE: In the current study, a green and economic micellar electrokinetic chromatographic (MEKC) method is proposed for remdesivir analysis. METHODS: A fused-silica capillary (58.5 cm × 50 µm id, 50 cm effective length) with 20 mM borate buffer (pH 9) and 25 mM sodium dodecyl sulfate was used under a positive potential of 30 kV at 25°C with detection at 245 nm. RESULTS: Remdesivir analysis was achieved in approximately 5 min. The method proved to be linear in range of 1-50 µg/mL with correlation coefficient, r > 0.999. CONCLUSION: The MEKC method proposed was applied to the analysis of remdesivir in its commercial vials. The method was validated per International Conference on Harmonization guidelines. HIGHLIGHTS: Green chemistry has been the focus of the analytical community in the past few years. This method is considered green due to its low energy and solvent consumption without sacrificing the method's sensitivity or selectivity. The method's green profile has been assessed by different greenness assessment scales to ensure the method is eco-friendly and can be used in the pharmaceutical industry.

Novel Siprulina platensis Bilosomes for Combating UVB Induced Skin Damage.

The recent interest in bioactive compounds from natural sources has led to the evolution of the skin care industry. Efforts to develop biologically active ingredients from natural sources have resulted in the emergence of enhanced skin care products. Spirulina (SPR), a nutritionally enriched cyanobacteria-type microalga, is rich in nutrients and phytochemicals. SPR possesses antioxidant, immunomodulatory, and anti-inflammatory activities. Spirulina-loaded bilosomes (SPR-BS), a novel antiaging drug delivery system, were designed for the first time by incorporation in a lecithin−bile salt-integrated system for bypassing skin delivery obstacles. The optimized BS had good entrapment efficiency, small particle size, optimal zeta potential, and sustained drug release pattern. Blank and SPR-loaded BS formulations were safe, with a primary irritancy index of <2 based on the Draize test. In vivo tests were conducted, and photoprotective antiaging effects were evaluated visually and biochemically by analyzing antioxidant, anti-inflammatory, and anti-wrinkling markers following ultraviolet (UV) B irradiation. Results of biochemical marker analysis and histopathological examination confirmed the superior antiaging effect of SPR-BS compared with SPR. Thus, SPR-loaded BS is a promising nanoplatform for SPR delivery, can be used for treating UV-induced skin damage, and offers maximum therapeutic outcomes.

Second-derivative synchronous fluorimetry and time-programmed HPLC-fluorescence detection for simultaneous estimation of flibanserin and sitagliptin phosphate in synthetic mixtures and human plasma samples.

Diabetes Mellitus is directly related to female anaphrodesia. Female Viagra or Flibanserin (FLB), U.S. FDA approved in 2015, is specifically indicated for premenopausal Hypoactive Sexual Desire Disorder, HSDD, which is one of the primary consequences of Diabetes Mellitus. Simultaneous analysis of the concomitantly administered, FLB and oral antidiabetics, as Sitagliptin phosphate (STG), is a crucial demand to investigate mutual drug-drug interaction. The latter is responsible for uncontrolled glycaemia and higher risk of sudden hypoglycemia. Two simple, sensitive, economical and direct analytical methods, namely, Second-Derivative Synchronous Fluorimetric Spectroscopy, D2-SFS, and High Performance Liquid Chromatography with fluorimetric detection, HPLC-FD, are established for simultaneous determination of FLB and STG in their binary mixtures. First method relies on measuring D2-SFS spectra of both drugs, at Δλ = 25 nm, along linearity ranges of 0.05-1 µg/mL for both drugs. The second method is a chromatographic one with gradient elution of FLB and STG on RP-ZORBAX Eclipse C18 column (5 µm, 4.6 × 150 mm). Mobile phase; phosphate buffer: acetonitrile, pH 4.5, with a flow rate of 1 mL/min at room temperature has been used. Time programmed fluorimetric detection is optimized at λem = 305 nm for STG (0.0-5.9 min), at λem = 375 nm for FLB (6-9 min) after both excitation at λex = 257 nm, in the linear ranges of 1-40 µg/mL and 5-60 µg/mL for FLB and STG, respectively. Proposed methods have been validated according to ICH guidelines, then applied for simultaneous quantitation of FLB and STG in their laboratory-prepared mixtures and in spiked human plasma samples. Satisfactory Student's t-value and F-variance ratio have been obtained upon comparing the results of both methods.

Analysis of Closely Related Antioxidant Nutraceuticals Using the Green Analytical Methodology of ANN and Smart Spectrophotometric Methods.

Two new, simple, and specific green analytical methods are proposed: zero-crossing first-derivative and chemometric-based spectrophotometric artificial neural network (ANN). The proposed methods were used for the simultaneous estimation of two closely related antioxidant nutraceuticals, coenzyme Q10 (Q10) and vitamin E, in their mixtures and pharmaceutical preparations. The first method is based on the handling of spectrophotometric data with the first-derivative technique, in which both nutraceuticals were determined in ethanol, each at the zero crossing of the other. The amplitudes of the first-derivative spectra for Q10 and vitamin E were recorded at 285 and 235 nm respectively, and correlated with their concentrations. The linearity ranges of Q10 and vitamin E were 10-60 and 5.6-70 µg⋅mL-1, respectively. The second method, ANN, is a multivariate calibration method and it was developed and applied for the simultaneous determination of both analytes. A training set of 90 different synthetic mixtures containing Q10 and vitamin E in the ranges of 0-100 and 0-556 µg⋅mL-1, respectively, was prepared in ethanol. The absorption spectra of the training set were recorded in the spectral region of 230-300 nm. By relating the concentration sets (x-block) with their corresponding absorption data (y-block), gradient-descent back-propagation ANN calibration could be computed. To validate the proposed network, a set of 45 synthetic mixtures of the two drugs was used. Both proposed methods were successfully applied for the assay of Q10 and vitamin E in their laboratory-prepared mixtures and in their pharmaceutical tablets with excellent recovery. These methods offer advantages over other methods because of low-cost equipment, time-saving measures, and environmentally friendly materials. In addition, no chemical separation prior to analysis was needed. The ANN method was superior to the derivative technique because ANN can determine both drugs under nonlinear experimental conditions. Consequently, ANN would be the method of choice in the routine analysis of Q10 and vitamin E tablets. No interference from common pharmaceutical additives was observed. Student's t-test and the F-test were used to compare the two methods. No significant difference was recorded.

Kinetic spectrophotometric methods for the determination of artificial sweetener (sucralose) in tablets.

Two simple and sensitive kinetic spectrophotometric methods for the determination of sucralose are described. The first method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 30 min. The absorbance of the green coloured manganate ions produced was measured at 610 nm. The second method is based on the reaction of sucralose with cerium (IV) ammonium sulfate in the presence of perchloric acid with the subsequent measurement of the excess unreacted cerium (IV) ammonium sulfate at 320 nm at a fixed time of 30 min in a thermostated water bath at 60 ± 1 °C. This principle is adopted to develop a kinetic method for sucralose determination. The absorbance concentration plots in both methods were rectilinear over the range 4-16 and 10-30 µg ml(-1) , for the first and second methods, respectively. The different experimental parameters affecting the development and stability of the colours were carefully studied and optimized. The determination of sucralose by rate constant method, fixed concentration method, and fixed-time method was also feasible with calibration equations obtained but the latter method was found to be more applicable. The two methods have been applied successfully to commercial tablets.