Development of coupled ultrasound-assisted and reversed-phase dispersive liquid-liquid microextraction before high-performance liquid chromatography for the sensitive determination of vitamin A and vitamin E in oil samples

Simultaneous Determination of Estradiol Cypionate and Medroxyprogesterone Acetate Hormones in Injectable Suspension by UV Spectrophotometry Based on Least-Squares Support Vector Machine and Fuzzy Inference System: Comparison with HPLC

BACKGROUND

The combination of estradiol cypionate (ECA) and medroxyprogesterone acetate (MPA) is used to prevent pregnancy in women. The analysis of the ECA and MPA combination reveals a challenge due to the strong overlap of the spectra of these compounds.

OBJECTIVE

Spectrophotometry techniques along with chemometrics methods are simple, fast, precise, and low-cost for the simultaneous determination of ECA and MPA in a combined pharmaceutical dosage form.

METHODS

Two developed approaches, the least-squares support vector machine (LSSVM) and fuzzy inference system (FIS), along with a spectrophotometric method were proposed to solve such a challenging overlap.

RESULTS

Based on the cross-validation method, the regularization parameter (γ) and width of the function (σ) in the LSSVM model were optimized and the root mean square error (RMSE) values were found to be 0.3957 and 0.2839 for ECA and MDA, respectively. The mean recovery values were 99.87 and 99.63% for ECA and MDA, respectively. The FIS coupled with principal component analysis (PCA) showed mean recovery percentages equal to 99.05 and 99.50% for ECA and MDA, respectively. Also, the RMSE of both components was lower than 0.3.

CONCLUSION

The analysis results of a real sample (injection suspension) using the proposed methods were compared with HPLC by a one-way analysis of variance (ANOVA) test, and no significant differences were found in the results.

HIGHLIGHTS

Intelligent methods were proposed for the simultaneous determination of ECA and MPA. The least-squares support vector machine and fuzzy inference system along with spectrophotometry were used. HPLC as a reference method was performed and compared with chemometrics methods. The benefits of the proposed approaches are that they are rapid, simple, low-cost, and accurate.

Comparative Study of Continuous Wavelet Transform and Multivariate Calibration for the Simultaneous Spectrophotometric Determination of Tamsulosin and Solifenacin in Pharmaceutical Formulation and Biological Sample

BACKGROUND

Spectrophotometry alone is not applicable for the simultaneous determination of drugs in a multicomponent pharmaceutical formulation owing to their overlap.

OBJECTIVE

In this study, the combination of UV-Vis spectrophotometry and chemometric methods, including continuous wavelet transform (CWT) and partial least-squares (PLS) was presented for the simultaneous estimation of tamsulosin (TAM) and solifenacin (SOL) in synthetic mixtures, commercial formulations, and a biological sample.

METHODS

The simultaneous spectrophotometric determination of TAM and SOL in binary mixtures, a real sample, and a biological sample was performed by applying CWT and PLS approaches.

RESULTS

In the CWT method, two various wavelet families named Daubechies (db2) at wavelength 223 nm and Biorthogonal (bior1.3) at wavelength 227 nm based on the appropriate zero-crossing point were selected for TAM and SOL, respectively. The linear ranges of TAM and SOL were 0.25-4 μg/mL and 10-30 μg/mL, respectively. The LODs were 0.0459 μg/mL and 0.2085 μg/mL, while the LOQs were 0.3208 μg/mL and 0.6495 μg/mL for TAM and SOL, respectively. The average recovery values of 18 mixtures were 98.28% and 97.79% for TAM and SOL, respectively. Also, the root mean square error (RMSE) of both components was lower than 2.3. Based on the k-fold cross-validation in the PLS approach, the optimum number of components related to TAM and SOL were 9 and 5 with a mean square error prediction (MSEP) of 0.0153 and 0.0370, respectively. The mean recovery values of the test set were found to be 100.09% for TAM and 99.95% for SOL where RMSE values were 0.0064 and 0.0169 for TAM and SOL, respectively.

CONCLUSION

Analysis of variance (ANOVA) was applied to the results of the real sample and there was no significant difference between the proposed methods and HPLC as a reference technique. The result obtained revealed that the proposed methods were found to be fast, facile, economical, and precise, and provide a suitable alternative to the HPLC technique for the concurrent determination of TAM and SOL in QC laboratories.

HIGHLIGHTS

UV-Vis spectrophotometry combined with CWT and PLS was developed. Simultaneous analysis of TAM and SOL was performed using the proposed approaches. These methods were implemented on synthetic mixtures, commercial formulations, and a biological sample. ANOVA test was used to compare the suggested methods and the HPLC technique.

Reversed-phase dispersive liquid-liquid microextraction based on decomposition of deep eutectic solvent for the determination of lead and cadmium in vegetable oil

In this work, a reversed-phase dispersive liquid-liquid microextraction procedure based on the decomposition of deep eutectic solvent was suggested for the first time. The procedure was utilized for fast and simple separation of lead and cadmium from vegetable oil samples. The procedure assumed mixing of oil sample and DES based on menthol, formic acid and water. Water as component of DES promoted its decomposition in sample matrix resulting menthol dissolution in the sample phase and dispersion of aqueous formic acid solution. In this procedure menthol acted as a dispersive solvent during DES decomposition for dispersion of aqueous formic acid solution. The metals were determined by the square-wave anodic stripping voltammetry. The limits of detection, were 0.01 µg kg^-1 for lead and 0.006 µg kg^-1 for cadmium. The RSD was less then 6% for both analytes. The enrichment factor was 36 and 39 for lead and cadmium, respectively.

Development of highly hydrophobic fabric phase sorptive extraction membranes and exploring their applications for the rapid determination of tocopherols in edible oils analyzed by high pressure liquid chromatography-diode array detection

Α novel, green, and facile fabric phase sorptive extraction (FPSE) prior to high pressure liquid chromatography with diode array detection (HPLC-DAD) methodology was developed for the efficient extraction and quantitative determination of tocopherols (α-, sum of (β+γ), and δ-) in edible oils. Among several highly hydrophobic FPSE membranes, sol-gel polycaprolactone-polydimethylsiloxane-polycaprolactone (sol-gel PCAP-PDMS-PCAP) coated polyester FPSE membrane was found as the most efficient in extracting tocopherol homologues from edible oil samples. To maximize the extraction efficiency of FPSE membrane, major parameters of FPSE including the membrane size, sample loading time, the choice of the appropriate elution solvent and the elution solvent volume, desorption time, and the influence of stirring were systematically optimized. The developed FPSE-HPLC-DAD methodology was validated and presented adequately low limits of detection (LODs) and limits of quantification (LOQs) over the ranges 0.05-0.10 μg/g, and 0.17-0.33 μg/g, respectively. The RSD% of the within-day and between-day assays were lower than 1.3, and 11.8, respectively, demonstrating good method precision. The trueness of the method was assessed by means of relative percentage of recovery and ranged between 90.8 and 95.1% for within-day assay, and between 88.7-92.8% for between-day assay. The developed methodology was applied in the analysis of edible oils.

Application of Tandem Dispersive Liquid-Liquid Microextraction as an Efficient Method for Preconcentration of Two Antidepressant Drugs in Real Samples Combined with High Performance Liquid Chromatography

In the present work, tandem dispersive liquid-liquid microextraction (TDLLME) coupled with liquid chromatography was used for the determination of the two antidepressant drugs citalopram (CIT) and sertraline (SER) in complicated matrices. Indeed, the present approach was used to improve the suitability and appropriateness of the dispersive liquid-liquid microextraction (DLLME) method in complicated matrices. Firstly, 10 mL of the sample solution containing the two understudied drugs was extracted into an organic solvent (200 μL of 1,2-dichloromethane) using the DLLME method. Then the extracted analytes were back-extracted into 100 μL of an aqueous acceptor phase. The total extraction time of this method is about 6 min. To achieve the best efficiency for this method, efficient parameters like the kind and volume of the organic solvent and the effect of the ionic strength on the effectiveness of extraction were reviewed and improved. Under the optimized experimental conditions, TDLLME showed good linearity in the range of 100.0-7000.0 ng mL-1. The limits of detection were found to be 10.0 ng mL-1 for CIT and 2.0 ng mL-1 for SER. The relative standard deviation (RSD) is obtained in the range of 0.7-4.1%.

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 application of continuous wavelet transform based on spectrophotometric method and high-performance liquid chromatography for simultaneous determination of anti-glaucoma drugs in eye drop

In this study, a fast, low-cost, accurate, and precise spectrophotometric method based on the continuous wavelet transform (CWT) was assayed to determine dorzolamide (DOR) and timolol (TIM) in an eye drop sample simultaneously. Different wavelet families were investigated to select the best family for analyzing the DOR and TIM. The Mexican hat wavelet (MHW) family with the wavelength of 281 nm and Gaussian wavelet family (gaus2) in the wavelength of 267 nm were found for the simultaneous analysis of DOR and TIM, respectively. Mean recovery values of synthetic mixtures were found 97.44%±2.63 and 99.18%±4.00 for DOR and TIM, respectively. The root mean square errors (RMSE) of DOR and TIM were achieved 0.5550 and 0.3306, respectively. Eye drop as a real sample was analyzed by spectrophotometry coupled with the CWT technique, as well as high-performance liquid chromatography (HPLC) as a reference method. The obtained results were compared with each other by the one-way analysis of variance (ANOVA) test and there was no significant difference between them.

A Novel Ionic Liquid-Based Liquid-Liquid Microextraction Combined with High Performance Liquid Chromatography for Simultaneous Determination of Eight Vitamin E Isomers in Human Serum

BACKGROUND

Vitamin E deficiencies are prevalent around the world and have become one of the major public health issues. It is necessary to determine their levels in human serum for routine clinical practice.

OBJECTIVE

In this study, a simple and green ionic liquid-based (IL)vortex-assisted (VA) liquid-liquid microextraction (LLME) combined with HPLC was developed for simultaneous determination of eight vitamin E isomers in human serum.

METHODS

The IL, 1-octyl-methylimidazolium trifluoromethanesulfonate ([OMIM]OTf), was added into the diluted sample and vortexed to form a cloudy solution. After centrifugation, the IL phase was collected for HPLC analysis. The separation was accomplished on a Phenomenex Luna-C18 column (250 mm × 4.6 mm, 5 μm) and the column temperature was 30°C. The mobile phase was methanol/acetonitrile (80 + 20, v/v) and the flow rate was 0.7 mL/min. A fluorescence detector was used for the simultaneous detection of eight vitamin E isomers, and the detection wavelength was set at 290/327 nm. The LLME procedure can be completed within 10 min without using any organic solvent. The parameters affecting the extraction efficiencies were optimized, including the type and volume of the ILs, dispersive solvent, vortex time, and salt addition.

RESULTS

Under the optimal conditions, limits of detection were 0.857-4.16 ng/mL. Acceptable recoveries ranging from 80.1% to 103% were achieved, with relative standard deviations less than 13.0%. The proposed method was successfully applied to the detection of eight vitamin E isomers in human serum samples.

CONCLUSIONS

This method is simple, fast, environment-friendly, cheap, and has similar linear ranges, sensitivities, accuracy, and precision as those reported chromatographic methods.

HIGHLIGHTS

The IL, [OMIM]OTf, was chosen as the green extractant of LLME for vitamin E extraction because of its strong adsorption property for vitamin E isomers. An IL-VA-LLME method has been developed for the analysis of 8 vitamin E isomers. The established method was successfully applied to the analysis of 8 vitamin E isomers in human serum samples.

Flotation/ultrasound-assisted microextraction followed by HPLC for determination of fat-soluble vitamins in multivitamin pharmaceutical preparations

Dissolved carbon dioxide flotation-emulsification microextraction technique coupled with high-performance liquid chromatography was developed for separation and determination of fat-soluble vitamins (A, D₃ , E, and K₃ ) in multivitamin pharmaceutical preparations. Dissolved carbon dioxide flotation was used to break up the emulsion of extraction solvent in water and to collect the extraction solvent on the surface of aqueous sample in narrowed capillary part of extraction cell. Carbon dioxide bubbles were generated in situ through the addition of 300 μL of concentrated hydrochloric acid into the alkaline sample solution at pH = 11.5 (1% w/v sodium carbonate), which was sonicated to intensify the carbon dioxide bubble generation. Several factors affecting the extraction process were optimized. Under the optimal conditions, the limits of detection were 0.11, 0.47, 0.20 and 0.35 μg/L for A, E, D₃ , and K₃ vitamins in water samples, respectively. The inter-day and intra-day precision of the proposed method were evaluated in terms of the relative standard deviation and were <10.5%.

Simultaneous determination of furfural and its degradation products, furoic acid and maleic acid, in transformer oil by the reversed-phase vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography

To explore why the use of furfural as a transformer oil-paper insulation aging characteristic is problematic in real world application, we developed a method for the simultaneous determination of furfural, furoic acid, and maleic acid in transformer oil by reversed-phase vortex-assisted liquid-liquid microextraction combined with high-performance liquid chromatography. The conditions for the proposed method were optimized, and the obtained extract can be directly analyzed by high-performance liquid chromatography. The detection limits (signal-to-noise ratio = 3) of the method ranged from 1.0 to 4.6 μg/L, the enrichment factors for furfural, furoic acid, maleic acid, and fumaric acid were 4.6, 25.1, 15.6, and 17.5, respectively, and the recovery rates for three analytes (fumaric acid was undetected) range from 82.1 to 106.2%. The contents of furfural, furoic acid, and maleic acid resulted from accelerated aging of transformer insulation oil-paper were measured using the present method for the first time, and the aging samples were analyzed by liquid chromatography with mass spectrometry for the identification of furoic acid and maleic acid in the aging transformer oil samples. Using the optimal method, the target products of samples at different aging time were tracked and measured.