Borate Buffer pH Research Articles

Determination of phenols in natural and waste waters by capillary electrophoresis after preconcentration on magnetic nanoparticles coated with aminated hypercrosslinked polystyrene.

An efficient sorbent for magnetic solid-phase extraction was developed from Fe3 O4 nanoparticles covered with aminated hypercrosslinked polystyrene. The sorbent has a saturation magnetization of 47 emu/g and a surface area of 509mg/g and was tested for the extraction of 11 phenols from aqueous media. The optimum conditions were as follows: pH 3; adsorbent mass, 20.0mg; adsorption time, 30min; eluent (acetone) volume, 0.5mL; and desorption time, 5min. The enrichment factor after desorption reached 1595-1716 and the maximum adsorption capacity was 501-909mg/g. Capillary electrophoresis was applied successively to separate 11 phenols after solid-phase extraction. The best separation was achieved using a fused silica capillary and borate buffer (pH 10.7) as a supporting electrolyte. After optimization, the linearity range was from 0.2 to 950 μg/L, and the limits of detection were 0.05-0.2 μg/L. The relative standard deviation varied from 6.1 to 8.7% (C=1 μg/L) and from 2.9 to 3.5% (C=500 μg/L). The determination of phenols is complicated in eutrophic water and spring water with a high content of humic and fulvic acids.

Optimization and validation of a liquid chromatography-tandem mass spectrometry method for the determination of glyphosate in human urine after pre-column derivatization with 9-fluorenylmethoxycarbonyl chloride

In 2015, glyphosate was classified as “Group 2A – probably carcinogenic to humans” by the International Agency for Research on Cancer (IARC). Therefore, public concerns about the environmental and health risks of this substance have rapidly increased. Considering its toxicokinetic characteristics, urinary levels of glyphosate could be a powerful tool for human biomonitoring. Nevertheless, the physicochemical properties of this molecule and the complexity of the matrix make this purpose particularly challenging. In order to solve this problem, the presented study describes a simple LC-MS/MS method for the quantification of glyphosate in human urine after pre-column derivatization with FMOC-Cl. Method development was focused on the optimization of the derivatization reaction in human urine, adjusting critical variables such as pH of borate buffer, FMOC-Cl concentration and derivatization time. Besides, chromatographic separation and spectrometric parameters were also established. The analytical method was fully validated according international guidelines for selectivity, carry over, linearity, accuracy, precision, lower limit of quantitation, matrix effect and stability under different conditions. All performance parameters were within the acceptance criteria. In addition, the method was successfully applied to 52 urine samples obtained from exposed subjects from northern Argentina, laying the foundation for future epidemiological studies.

Enantiomeric separation of panthenol by Capillary Electrophoresis. Analysis of commercial formulations and toxicity evaluation on non-target organisms

The first CE methodology enabling the enantiomeric separation of panthenol was developed in this work. Electrokinetic chromatography with cyclodextrins (CD-EKC) was the CE mode employed for this purpose. The effect of different experimental variables such as the nature and concentration of the cyclodextrin, the temperature and the separation voltage was investigated. The best enantiomeric separation was obtained with 25 mM (2-carboxyethyl)-β-CD (CE-β-CD) in 100 mM borate buffer (pH 9.0), with a separation voltage of 30 kV and a temperature of 30 °C. Under these conditions, an enantiomeric resolution of 2.0 in an analysis time of 4.2 min was obtained, being the biologically active enantiomer d-panthenol (dexpanthenol) the second-migrating enantiomer. The analytical characteristics of the method were evaluated in terms of precision, accuracy, selectivity, linearity, LOD, and LOQ, showing a good performance for the quantitation of dexpanthenol in cosmetic and pharmaceutical formulations. The enantiomeric impurity (L-panthenol) could be detected at a 0.1% level with respect to the majority enantiomer, allowing to accomplish the requirements of the ICH guidelines. The method was also successfully applied to study the stability of panthenol under abiotic and biotic conditions and its toxicity on non-target organisms (the aquatic plant Spirodela polyrhiza).

ВИДІЛЕННЯ ІНГІБІТОРА ТРИПСИНУ НАСІННЯ ЛЮЦЕРНИ З ДОПОМОГОЮ АФФІННОЇ ХРОМАТОГРАФІЇ

A protein inhibitor of trypsin of the cultivar Eva alfalfa seeds was isolated and characterized. It has significant antiproteolytic activity and is promising for the creation of compositions that are designed to correct nutrition in various conditions, accompanied by increased activation of proteolytic enzymes. The stages of purification of the trypsin inhibitor from alfalfa seeds included: extraction of 0.05 M borate buffer (pH 7.6), fractionation of the protein component of the extract with ammonium sulfate, followed by dialysis of the fraction between 75% and 100% saturation and affinity chromatography on a biospecific sorbent trypsin - sepharose 4B. Calculations showed that from 100 g of alfalfa seeds of the cultivar Eva, 67.14 mg of trypsin inhibitor was obtained, the inhibitory activity of which is 27.6 IU / mg protein. Experimental data show that the obtained inhibitor reduces trypsin activity by 63.05% with a weight ratio of inhibitor: enzyme of 1: 1. It is known from literature that a soybean trypsin inhibitor reduces trypsin activity by 30%. The isolated trypsin inhibitor has significant inhibitory activity, the value of which is higher than the inhibitory activity of the plant trypsin inhibitor from soybeans. Affinity chromatography allowed us to obtain a pure, homogeneous trypsin inhibitor, which has significant antiproteolytic activity, which can be compared with the antiproteolytic activity of known plant trypsin inhibitors. From the obtained experimental data, it follows that both, the obtained inhibitor and the inhibitor, which is part of a commercial preparation, effectively reduce trypsin activity, slightly inhibit chymotrypsin activity, and do not affect α-amylase and protease activity. The above data indicate that the trypsin inhibitor of alfalfa seeds of the cultivar Eva is not a bifunctional inhibitor, since it does not affect the activity of amilolytic enzymes. The isolated inhibitor belongs to proteins with a high degree of hydrophobicity. The composition of amino acids, the side chains of which can take part in the formation of hydrogen bonds, is 25% of the total number of amino acid residues of the alfalfa seed trypsin inhibitor. For STI, this value is 23%.

Final report on CCQM-K19.2018 key comparison on pH of an unknown borate buffer

Main textThis key comparison CCQM-K19.2018, as a repetition of the previous study CCQM-K19 from 2005, was performed to evaluate the degree of equivalence of measurement procedures of participating National Metrology Institutes (NMIs) and Designated Institutes (DIs) for the determination of pH of borate buffer solutions. The nominal pH value of the buffer was 9.2 at 25 °C and the suggested measurement temperatures were 5 °C, 15 °C, 25 °C, 37 °C and 50 °C. Good agreement of the results is demonstrated by most participants.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Micelle-Enhanced conventional and synchronous spectrofluorimetric methods for the simultaneous determination of lesinurad and febuxostat: Application to human plasma

A simple synchronous spectrofluorimetric method was developed for simultaneous determination of lesinurad and febuxostat. The investigated drugs were measured at 294 and 329 nm, respectively in the presence of each other without interference at Δλ of 50 nm (Method I). The different experimental parameters affecting the fluorescence intensities were carefully studied and optimized. The maximum synchronous fluorescence intensities were obtained at pH 6.5 using borate buffer and distilled water was used as a diluting solvent. Excellent linearity ranges were obtained using 20.0–500.0 ng mL−1 and 1.0–80.0 ng mL−1 for lesinurad and febuxostat, respectively. The method exhibited high sensitivity with detection limits down to 4.0 ng mL−1 and 0.01 ng mL−1 and quantitation limits down to 12.12 ng mL−1 and 0.02 ng mL−1, respectively. Recovery percentages ranged from 97.68 to 103.37% were obtained upon spiking of human plasma samples, indicating high bioanalytical applicability. Concerning Method II, methanolic solution of lesinurad was measured spectroflourimetrically with λexcitation at 290 nm and λemission at 341 nm with high sensitivity using borate buffer of pH 6.5 and methanol as a diluting solvent. A considerable enhancement of the fluorescence intensity was achieved by using 1.0% w/v cetremide as a micellar system. The method was rectilinear over the concentration range of 3.0–80.0 ng mL−1 with detection and quantitation limits down to 0.47 and 1.42 ng mL−1, respectively. The developed method was efficiently applied for the estimation of the cited drug in spiked human plasma with high recovery percentages (98.58–101.64%). The methods were validated according to the ICH guidelines and further applied to commercial tablets with good results.

Experimental design approach for development of spectrofluorimetric method for determination of favipiravir; a potential therapeutic agent against COVID-19 virus: Application to spiked human plasma

The present work describes development of rapid, robust, sensitive and green spectrofluorimetric method for determination of favipiravir (FAV). Different factors affecting fluorescence were carefully studied and Box Behnken Design was applied to optimize experimental parameters. The proposed method is based on measuring native fluorescence of FAV in 0.2 M borate buffer (pH 8.0) at 432 nm after excitation at 361 nm. There was a linear relationship between FAV concentration and relative fluorescence intensity over the range 40–280 ng/mL with limit of detection of 9.44 ng/mL and quantitation limit of 28.60 ng/mL. The method was successfully implemented for determination of FAV in its pharmaceutical formulation with mean % recovery of 99.26 ± 0.87. Moreover, the high sensitivity of the method allowed determination of FAV in spiked human plasma over a range of 48–192 ng/mL. The proposed spectrofluorimetric method was proved to be eco-friendly according to analytical eco-scale.

Use of choline chloride-D-sorbitol deep eutectic solvent as additive in cyclodextrin-electrokinetic chromatography for the enantiomeric separation of lacosamide

The potential of chiral deep eutectic solvents to enhance the chiral discrimination in Cyclodextrin-Electrokinetic Chromatography is demonstrated in this work. With this aim, a method enabling the enantiomeric separation of the antiepileptic drug lacosamide was developed. After a screening using 12 cyclodextrin derivatives, succinyl-β-CD was chosen due to its higher discrimination power to separate lacosamide enantiomers. The effect of different variables, such as cyclodextrin concentration, buffer concentration, temperature and separation voltage, on the enantiomeric separation of lacosamide, was studied. As the maximum enantiomeric resolution achieved under the optimized conditions was lower than 1.5, the effect of the addition of methanol or different deep eutectic solvents (choline chloride – ethylene glycol, choline chloride – urea, choline chloride – D-glucose, and choline chloride – D-sorbitol) as additives to the separation medium was investigated. The best results in terms of enantiomeric resolution and analysis time were obtained using choline chloride – D-sorbitol at a 0.5% (w/v) in a 100 mM borate buffer (pH 9.0) with 18 mM succinyl-β-CD. Under these conditions, lacosamide enantiomers were separated with a resolution value of 2.8. Analytical characteristics of the developed method were evaluated and demonstrated to be adequate to apply the methodology to the enantiomeric analysis of lacosamide in a pharmaceutical formulation.

Derivatization of tranexamic acid for its rapid spectrofluorimetric determination in pure form and pharmaceutical formulations: Application in human plasma.

An ingenious approach for determination of tranexamic acid spectrofluorimetrically has been developed. This experiment is very simple, sensitive and selective method for determination of tranexamic acid in pure form, pharmaceutical dosage forms and in spiked human plasma. All optimal conditions needed in our proposed experiment have been determined and validated precisely. This developed method based on the reaction between the primary amino group found in the chemical structure of tranexamic acid with the fluorescamine reagent in presence of borate buffer (pH 8.3) that result in the formation of fluorescence product measured at 473.5nm after excitation at 392nm. We notice that the linearity of the resulted calibration curve found to be (0.1-0.9μg/mL) with LOD and LOQ results were 0.0237 and 0.0719 respectively. The validation of the developed method is according to the international council for Harmonization (ICH) guidelines indicating good accuracy and precision. Finally, the developed method has been applied for in vitro study of tranexamic acid by making spiked human plasma with a mean percentage recovery 99.430±0.623 as well as in its pharmaceutical dosage forms tablets and ampoules.

Characterization and Optimization of Isotachophoresis Parameters for Pacific Blue Succinimidyl Ester Dye on a PDMS Microfluidic Chip.

Isotachophoresis (ITP) for Pacific Blue (PB) dye using a polydimethylsiloxane (PDMS) microfluidic chip is developed and characterized by determining the types and concentrations of electrolytes, the ITP duration, and the electric field density. Among candidate buffers for the trailing electrolyte (TE) and leading electrolyte (LE), 40 mM borate buffer (pH 9) and 200 mM trisaminomethane hydrochloride (Tris-HCl) (pH 8) were selected to obtain the maximum preconcentration and resolution of the PB bands, respectively. With the selected TE and LE buffers, further optimization was performed to determine the electric field (EF) density and the ITP duration. These ITP parameters showed a 20–170,000 preconcentration ratio from initial PB concentrations of 10 nM–100 fM. Further demonstration was implemented to preconcentrate PB-conjugated lactate dehydrogenase (LDH) using the PDMS microfluidic chip. By utilizing the quenching nature of PB-LDH conjugation, we were able to identify concentrations of LDH as low as 10 ng/mL. This simple PDMS microfluidic chip-based ITP for PB preconcentration enables highly sensitive biological and chemical analyses by coupling with various downstream detection systems.

Application of MEKC and UPLC with Fluorescence Detection for Simultaneous Determination of Amlodipine Besylate and Bisoprolol Fumarate.

Two chromatographic methods were described for simultaneous determination of the antihypertensive drugs amlodipine besylate (AML) and bisoprolol fumarate (BIS). Method I applies micellar electrokinetic capillary chromatography using a deactivated fused silica capillary (25 cm effective length × 50 μm internal diameter). The background electrolyte consisted of 0.01 M borate buffer (pH 9.2) containing 0.025 M sodium dodecyl sulphate and methanol in the ratio of 80:20 (v/v). Valsartan (VAL) was used as an internal standard. Diode array detector was set at 238, 224, and 210 nm for measuring AML, BIS, and VAL, respectively. Method II involves using ultra-performance liquid chromatography with fluorescence detection. Zorbax SB-C8 column (2.1 × 100 mm, 1.8 μm particle size) was used with isocratic elution of the mobile phase composed of 0.1% trifluoroacetic acid, acetonitrile, and methanol in the ratio of 55:35:10 (v/v) at a flow rate of 0.6 mL/min. Fluorescence detection was done using excitation wavelengths 230 and 370 nm and emission wavelengths 305 and 450 nm for BIS and AML, respectively. Validation parameters were carefully studied including linearity, ranges, precision, accuracy, robustness, detection, and quantification limits. Method I showed good linearity over the range 10-100 μg/mL for both dugs. Method II's linear ranges were 0.001-0.1 and 0.02-1 µg/mL for BIS and AML, respectively. The proposed methods were successfully validated and applied for assay of the studied drugs in their fixed-dose combination tablets. To the best of our knowledge, this study suggests the first electro-chromatographic and LC with fluorescence detection methods for simultaneous determination of amlodipine and bisoprolol.

Spectrophotometric methods for determination of ritodrine in bulk and in pharmaceutical dosage forms

Three simple and sensitive spectrophotometric methods are described for determination of ritodrine hydrochloride (RTH) either in pure form or dosage forms. The first method was based on the reaction with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazole (NBD-Cl) in borate buffer of pH 8.0 producing a yellow colored product measured at 392 nm. The second and third methods were based on RTH oxidation with either 1, 10-phenanthroline or Folin-Ciocalteu reagents producing red and blue chromogens which were measured at 510 and 760 nm, respectively. Beer's law was obeyed in the ranges of, 2-16, 0.2-2, 0.8-12 μg/mL with the minimum detectable values of 0.1, 0.05, 0.14 μg/mL for the three methods, respectively. Different experimental parameters affecting the development and stability of colored products were carefully studied and optimized. The effect of different foreign matters and sensitizers on the color development in the three proposed methods was also studied. The proposed methods were successfully applied to the determination of RTH in its dosage forms. The obtained percentage recoveries were 99.73±0.72, 99.88±1.2, 99.97±0.42 for the three proposed methods, respectively. The obtained results were statistically validated and compared with those obtained with a reference method. Proposals of the reactions mechanisms were presented.

Optimal conditions for extraction and simultaneous determination of sulfamethoxazole and trimethoprim in pharmaceuticals by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography was performed at 25°C and 30 kV (under pressure of 15 mbar), with 30 mM borate buffer (pH 9.0), 60 mM sodium dodecysulfate, and 10% (v/v) ethanol as background electrolyte for the determination of sulfamethoxazole and trimethoprim. UV detection was at 205 nm. Recoveries were optimal and acceptable after extraction with ethanol/deionized water (1:1, v/v) for both investigated compounds from laboratory mixtures of standards. The method was shown to be specific, accurate (recoveries were 99.9 ± 0.4% for sulfamethoxazole and 99.8 ± 0.3% for trimethoprim), linear over the tested ranges (correlation coefficients ≥ 0.9990) and precise (RSD below 0.6%). The method was applied to determine sulfamethoxazole and trimethoprim in tablets, powder for cutaneous use and solution for infusion.

Analysis of flavonoids in propolis by capillary electrophoresis

Flavonoid contents of nine raw and nine commercial propolis samples were analyzed by capillary electrophoresis. At first, 15 commercially available flavonoid standards including apigenin, chrysin, luteolin, galangin, kaempferol, morin, myricetin, quercetin, quercitrin, rutin, hesperetin, naringin, naringenin, daidzein and genistein were used to develop the electrophoretic conditions. At a running temperature of 25°C and detection wavelength at 214 nm, the separation of these standards was most satisfactorily achieved by a combination of capillary zone electrophoresis (CZE), utilizing 0.1 M borate buffer (pH 9.5) containing 5% methanol under a voltage of 18 kV, and micellar electrokinetic capillary electrophoresis (MECC), utilizing 0.03 M sodium borate (pH 8.5) containing 0.05 M SDS under a voltage of -15 kV. We found 12 out of the 15 flavonoids were identified in raw propolis, but only 11 were detected in commercial propolis products. The total contents of the identified flavonoids in raw and commercial propolis were 254 to 19147 ppm and 1228 to 7985 ppm, respectively, suggesting that both the origin and processing are important factors affecting the flavonoid content in propolis.

In vitro and in vivo evaluation of the neuroprotective activity of Uncaria hirsuta Haviland

Hyaluronic acid (HA), a multi-functional material, has a high dispersion in molecular weight, and the functions of HA are determined through the size. Nevertheless, hyaluronic acid mixtures are not easily separated due to their polydispersity. In this study, a capillary electrophoresis strategy was developed for resolution of different molecular-weight HA without enzymatic digestion. Here, hyaluronic acid mixtures with low molecular weight (380 kD; LHA) and high molecular weight (2180 kD; HHA) were successfully resolved by the SDS integrated with low molecular-weight polymer in capillary electrophoresis. By optimizing experimental conditions, the separation of LHA and HHA was completed within 14 min. The optimal conditions were as follows: the running buffer was 25 mM borate buffer (pH 9.75) containing 30 mM SDS and 10% polyethylene glycol (MW: 8000); applied voltage was 20 kV (detector at cathode side) and separation temperature was set at 25 °C. The data of method validation showed that calibration plots were linear (r ≥ 0.9977) over a range of 10–50 μg/mL for LHA, and 40–200 μg/mL for HHA. In the evaluation of precision and accuracy for this method, the RSD and RE values were all less than 4.2%. This fascinating technique was successfully applied to the quality control of cosmetic and pharmaceutical containing different ratios of LHA and HHA, and it was feasible for serving as a tool to quantitatively analyze different sizes of HA for clinical survey. © 2019

Simple and Rapid Micellar Electrokinetic Chromatography Method for Simultaneous Determination of Febuxostat and its Related Impurities

A micellar electrokinetic capillary chromatography (MEKC) method has been developed and validated for simultaneous analysis of febuxostat and its related substances in active pharmaceutical ingredients and pharmaceutical formulations. Analysis was performed in an uncoated fused silica capillary (34 cm effective length, 50 µm diameter). Method sensitivity was enhanced using an extended light path capillary, with an optical path 150 µm and the choice of 320 nm detector operating wavelength due to lower background noise and higher selectivity. BGE consisted of 20 mM borate buffer pH 9.3 and 50 mM SDS and 2% acetonitrile. Analysis was performed at 30 kV separation voltage and 32 °C capillary temperature. The method was linear over the range 1.0–10.0 µg mL−1 for each impurity corresponding to reporting limits regarding the ICH Q3A guidelines. The method has proven to be selective, precise, accurate and robust. Proposed MEKC method has been successfully applied for the quantitative determination of febuxostat and purity assay of active pharmaceutical ingredient and tablet dosage forms.

Spectrofluorimetric approach for determination of tranexamic acid in pure form and pharmaceutical formulations; Application in human plasma

Tranexamic acid (TXA) is an important antihemorrhagic drug that needs a simple, sensitive and low cost spectrofluorimetric method for its determination. This method depends on generation of a yellow product which produced from a nucleophilic substitution reaction of the lone pair of electrons on the amino group found in the TXA chemical structure and 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer PH 9.0. The product was measured at 536nm (λex=470.5nm). All variables that have an effect on the formation and stability of the product have been explored and optimized. The linear range was 20-100ngmL-1 with a limit of quantitation 12.4ngmL-1. This method has been applied for assurance of tranexamic acid in ampoules and tablets dosage forms without any interference from excipients present. Also, we study the drug in human plasma.

Determination of Kynurenine Enantiomers by Alpha-Cyclodextrin, Cationic-βeta-Cyclodextrin and Their Synergy Complemented with Stacking Enrichment in Capillary Electrophoresis

We present high resolution fast, cost-effective and sensitive Capillary zone electrophoresis (CZE) methods for determination of enantiomeric compounds of Kynurenine pathway, i.e. D, L-Kynurenine (KYN), in human serum and urine samples by cationic-β-CD and its synergistic dual chiral selector system (SD-CSs) with α-CD in 50 mM borax borate buffer (pH 9.0) as BGE. Acid-mediated stacking enrichment by HCl delivered 15 nM limit of detection (LOD) and 50 nM limit of quantification (LOQ). The methods gave advantages of linearity in the concentration range of 50 nM-1000 nM, reproducibility (RSD ≤ 3.35), selectivity against interfering amino acids, and remarkable recoveries. SD-CSs delivered resolution of D, L-KYN twice that of individual chiral selectors (CSs) under similar conditions. The binding constants (Kb) and electrophoretic mobilities (µeff) of D, L-KYN with different concentrations of CSs were calculated to find the migration order of enantiomers. The chiral recognition mechanism was investigated by molecular docking and molecular mechanics, which revealed strong hydrogen bonding between Kynurenine enantiomers and the SD-CSs as compared to individual CS as the key player in binding, formation of stable complexes which led to the ultimate separation.

New spectrophotometric methods for the determination of Trifluridine

Two new spectrophotometric techniques have been proposed for the quantification of Trifluridine in pharmaceutical dosage forms. Trifluridine is an antiviral drug. Double beam UV-VIS spectrophotometer (SHIMADZU Model UV-1800) was used for the present study. Zero-order and first-order spectrophotometric techniques have been developed for the determination of Trifluridine in methanol, water, phosphate buffer (pH: 2.0, 4.0, 7.0), NaOH and borate buffer (pH 9.0). Trifluridine has shown linearity over the concentration range 10–80 μg/ml for methanol, water, phosphate buffer pH 7.0 and 10–100 μg/ml for phosphate buffer (pH 2.0, 4.0), NaOH, borate buffer (pH 9.0) respectively and the methods were validated as per ICH guidelines. The proposed methods are simple, economical and can be successfully applied for the estimation of Trifluridine in pharmaceutical dosage forms.

Development and Validation of a New Derivative UV Spectrophotometric Method for Simultaneous Quantification of Tizanidine and Aceclofenac in Tablets

The present study deals with development and validation of a new derivative UV spectrophotometric method for simultaneous quantification of Tizanidine and Aceclofenac in tablets. Tizanidine and Aceclofenac were obtained as gift samples and a simple derivative method was developed in borate buffer pH 9.0 using double beam UV/Visible spectrophotometer. The absorbance of Tizanidine was measured at 250nm (zero crossing point of Aceclofenac) and for Aceclofenac, 308.92nm (zero crossing point of Tizanidine) was selected. The linearity of Tizanidine and Aceclofenac was found to be in the range of 0.1-40 µg/mL and 2-100 µg/mL respectively. The %RSD in precision study was found to be 0.014-1.92% (intraday) and 0.014-1.44% (inter day) indicating that the method was precise. The % recovery for both the drugs in combination was obtained in the range of 98 - 101.36 % and found no interference from excipients. The method was also found to be sensitive as observed from the LOD and LOQ values. The proposed method was validated as per ICH guidelines and can be conveniently used for quantification of Tizanidine and Aceclofenac in tablets.