In this study, a new liquid chromatographic method with pre-column derivatization was developed and validated for the simultaneous quantification of acetylcarnitine taurinate, asparagine, potassium aspartate, asparagine and carnosine in new and commercial alimentary supplements. The effect of complex matrices was evaluated by the study of the amino acid derivatization reaction with 2,5-dimethyl-1H-pyrrole-3,4-dicarbaldehyde in placebo solutions (DPD). Experimental parameters affecting the derivatization and chromatographic separation were investigated. The reaction was carried out at room temperature for 10 min. The adducts were separated on a Synergi Hydro-RP 80 Å column using a mobile phase consisting of 11 mM aqueous tetrapropylammonium bromide (pH 3.5)/methanol by gradient elution conditions at a flow rate of 0.8 mL/min. UV absorbance detection was set at λ = 320 nm. The validation parameters such as linearity, sensitivity, accuracy, precision, specificity and ruggedness were highly satisfactory. Linear responses were obtained by placebo solutions (determination coefficient ≤ 0.9994). Intra-day precision (RSD) was ≤1.06 % for corrected peak area and ≤1.14 % for retention times (t R) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 97.72 to 101.5 %) with RSD ≤1.30 %.
相似文献A rapid, simple and sensitive liquid chromatographic method has been developed to assay ciclopirox olamine in raw material and topical solution. The analysis used a reversed-phase C18 end-capped column, with UV detection at 305 nm and pre-column derivatization with dimethyl sulphate. A linear response (r 2 > 0.999) was observed in the range of 0.4–200 μg mL−1. The method showed good recoveries for the raw material and topical solution and the relative standard deviation intra and inter-day were ≤2.00%. Validation parameters such as specificity and robustness were also determined. The proposed method provided an accurate and precise analysis of ciclopirox olamine in raw material and topical solution.
相似文献A simple liquid chromatographic method was developed for the separation and simultaneous determination of cobalt and nickel as chelates with 1-(2-pyridylazo)-2-naphthol (PAN). The method, using a switching column technique for the on-line purification and separation, enables to reach the sub-microgram per litre concentration level excluding off-line sample treatment with the exception of the derivatization reaction. Two small-sized columns packed with CN- and C4-bonded stationary phases were selected and used considering their complementary behaviour with respect to chelated Co and Ni ions. The analysis was performed within 10 min using an optimised eluent (water–acetonitrile–methanol–tetrahydrofuran, 40:45:10:5, v/v/v/v) containing Tween 40 (10−3 M) and acetate buffer (5 × 10−3 M, pH 4.8). Detection was performed by UV-vis spectrophotometry (λ = 565 nm) permitting to reach quantification limits of 0.9 and 0.5 μg L−1 for Co and Ni, respectively.
相似文献Two chromatographic methods have been described for the simultaneous determination of metronidazole (MET) and spiramycin (SPY) in their mixtures. The first method was based on a high performance thin layer chromatographic (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 240 nm. The separation was carried out on Merck TLC aluminum sheets of silica gel 60 F254 using methanol: chloroform (9:1, v/v) as a mobile phase. Analysis data was used for the linear regression line in the range of 1.0–2.0 and 0.8–2.0 μg band−1 for MET and SPY, respectively. The second method was based on a reversed-phase liquid chromatographic separation of the cited drugs on a C-18 column (5 μm, 250 × 4.6 mm, i.d.). The mobile phase consisted of a mixture of phosphate buffer of pH 2.4 and acetonitrile (70:30, v/v). The separation was carried out at ambient temperature with a flow rate of 1.0 mL min−1. Quantitation was achieved with UV detection at 232 nm based on peak area with linear calibration curves at concentration ranges 0.4–50.0 and 0.5–50.0 μg mL−1 for MET and SPY, respectively. The proposed chromatographic methods were successfully applied to the determination of the investigated drugs in pharmaceutical preparations. Both methods were validated in compliance with ICH guidelines; in terms of linearity, accuracy, precision, robustness, limits of detection and quantitation and other aspects of analytical validation.
相似文献A simple, reliable, and rapid RP-LC method has been developed for the determination of some anticancer drugs (daunorubicin, doxorubicin and vincristine sulfate) in their dosage forms and human urine. These compounds are well separated on a C18 column using the mobile phase consisting of a mixture of acetonitrile (50:50; v/v) at a flow rate of 1.5 mL min−1. The analyte peaks were detected at 235 nm for doxorubicin and daunorubicin, and 220 nm for vincristine. Linearity was obtained in different concentration ranges between 0.10 and 12 μg mL−1 for all compounds. Good sensitivity for all analytes was observed with DAD detection. LOD and LOQ of the method were found satisfying. The proposed method has been extensively validated in accordance with ICH guidelines and obtained results proved that the proposed method was precise, accurate, selective, and sensitive for simultaneous analysis of studied compounds. All analytical procedures including sample preparation, flow rate, and run time were at low levels. Also, pK a values were determined using the dependence of the retention factor on the pH of the mobile phase. The effect of the mobile phase composition on the ionization constant was studied by measuring the pK a at different methanol–water mixtures, ranging between 45 and 60 % (v/v).
相似文献Two new, rapid, precise, accurate and specific chromatographic methods were described for the simultaneous determination of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage forms. The first method was based on reversed phase liquid chromatography using an Eurosphere 100 RP C18 column (250 × 4.6 mm ID, 5 μm). The mobile phase was methanol–0.05% o-phosphoric acid (60:40 v/v) at a flow rate of 1.0 mL min−1. Commercially available tablets and laboratory mixtures containing both drugs were assayed and detected using a UV detector at 270 nm. The second method involved silica gel 60 F254 high performance thin layer chromatography and densitometric detection at 254 nm using acetonitrile–ethyl acetate–glacial acid (7:3:0.4 v/v/v) as the mobile phase. Calibration curves ranged between 200–600 and 125–375 ng spot−1 for olmesartan and hydrochlorothiazide, respectively.
相似文献Simple, sensitive, selective, precise, and stability-indicating thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) methods for the determination of mosapride and pantoprazole in pharmaceutical tablets were developed and validated as per the International Conference on Harmonization guidelines. The TLC method employs aluminum TLC plates precoated with silica gel 60F254 as the stationary phase and ethyl acetate/methanol/toluene (4:1:2, v/v/v) as the mobile phase to give compact spots for mosapride (R f 0.73) and pantoprazole (R f 0.45) separated from their degradation products; the chromatogram was scanned at 276 nm. The HPLC method utilizes a C18 column and a mobile phase consisting of acetonitrile/methanol/20 mM ammonium acetate (4:2:4, v/v/v) at a flow rate of 1.0 mL min−1 for the separation of mosapride (t R 11.4) and pantoprazole (t R 4.4) from their degradation products. Quantitation was achieved with UV detection at 280 nm. The same HPLC method was successfully used in performing calibrations in lower concentration ranges for both drugs in human plasma using ezetimibe as internal standard. The methods were validated in terms of accuracy, precision, linearity, limits of detection, and limits of quantification. Mosapride and pantoprazole were exposed to acid hydrolysis and then analyzed by the proposed methods. As the methods could effectively separate the drugs from their degradation products, these techniques can be employed as stability-indicating methods that have been successively applied to pharmaceutical formulations without interference from the excipients. Moreover the HPLC method was successfully used in the determination of both drugs in spiked human plasma.
相似文献A sensitive and simple HPLC method with fluorimetric detection has been developed for determination of droperidol in pharmaceutical tablets, human serum, and human milk. Chromatography was performed on a 100 mm × 3 mm i.d. C18 column with methanol–water, 30:70 (v/v), pH 3.5, as mobile phase at a flow-rate of 0.8 mL min−1. The injection volume was 5 μL and detection was by monitoring emission at 324 nm after excitation at 283 nm. Droperidol and p-hydroxybenzoic acid (internal standard) eluted after 5.3 and 6.1 min, respectively. The method was validated over the concentration range 1.14 × 10−7 to 9.12 × 10−6 M. Selectivity was good and the limits of detection and quantitation of the method were approximately 3.54 × 10−8 and 1.07 × 10−7 M, respectively, corresponding to 13 and 40 ng mL−1. The applicability of the method to determination of droperidol in pharmaceuticals, human serum, and human milk was demonstrated.
相似文献The present paper describes the synthesis, characterization, and utilization of multi-functional magnetic conjugates that integrate optical and magnetic properties in a single structure for use in many biomedical applications. Spontaneous interaction with eukaryotic cell membrane (HEK-239 cell culture) was determined using fluorescence microscopy, and fluorescence analyses. Both, differences in excitation, and emission wavelength were observed, caused by glutathione intake by cells, resulting in disintegration of core–shell structure of quantum dots, as well as adhesion of conjugate onto cell surface. When compared with quantum dots fluorescent properties, HEK-239 cells with incorporated nanoconjugate exhibited two excitation maxima (λ ex = 430 and 390 nm). Simultaneously, application of ideal λ ex for quantum dots (λ ex = 430 nm), resulted in two emission maxima (λ = 740 and 750 nm). This nanoconjugate fulfills the requirements of term theranostics, because it can be further functionalized with biomolecules as DNA, proteins, peptides or antibodies, and thus serves as a tool for therapy in combination with simultaneous treatment.
相似文献A simple stability-indicating reversed-phase liquid chromatographic method with diode-array detection was developed and validated for the quantitative determination of ebastine in tablets and syrup. The LC method was carried out on a C18 column with acetonitrile:phosphoric acid 0.1% pH 3.0 (55:45, v/v) as mobile phase, at a flow rate of 1.2 mL min−1. Ultraviolet detection of ebastine was at 254 nm. A linear response (r = 0.9999) was observed in the range of 10–80 μg mL−1. The RSD values for intra- and inter-day precision studies showed good results (RSD < 2%) and accuracy was greater than 98%. Validation parameters such as specificity and robustness were also determined. The method was found to be stability-indicating and can be applied to quantitative determination of ebastine in tablets and syrup.
相似文献A new, sensitive, stability indicating gradient RP-LC related substances and assay method has been developed for the quantitative determination of entacapone in bulk drugs. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination of buffer and acetonitrile. Buffer consisted of 0.1% orthophosphoric acid, delivered in a gradient mode and quantitation was carried out using ultraviolet detection at 220 nm with a flow rate of 1.5 mL min−1. In the developed LC method the resolution (R s ) between entacapone and its three potential process impurities were found to be >2.0. Regression analysis showed an r 2 value (correlation coefficient) >0.99 for entacapone and its three potential impurities. This method was capable to detect all three process impurities of entacapone at a level of 0.003% with respect to test concentration of 0.5 mg mL−1 for a 20 μL injection volume. The inter- and intra-day precision values for all three impurities and for entacapone was found to be within 2.0% RSD. The method has shown good and consistent recoveries for entacapone in bulk drugs (99.2–101.5%) and its three impurities (99.5–102.2%). The test solution was found to be stable in diluent for 48 h. The drug substances were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in acid stress, base stress and oxidative conditions. The stressed test solutions were assayed against the qualified working standard of entacapone and the mass balance in each case was close to 99.7% indicating that the developed method was stability-indicating. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.
相似文献A simple, sensitive and specific liquid chromatographic method with UV detection (228 nm) was developed for the simultaneous estimation of rosiglitazone and glimepride in human plasma. Rosiglitazone and glimepride were extracted from plasma using liquid–liquid extraction. Separation was achieved with an RP C18 Column using a mixture of phosphate buffer (50 mM) with octane sulfonic acid (10 mM), methanol and acetonitrile as a mobile phase (55:10:35, v/v). pH was adjusted to 7.0. Amlodipine was used as an internal standard (IS). LOD of the method was found to be 20 ng mL−1 for both drugs. Results were linear over the studied range 40.994–2007.556 ng mL−1 for rosiglitazone (r 2 ≥ 0.99) and 41.066–2094.84 ng mL−1 for glimepride( r 2 ≥ 0.99). The method was found to be simple, selective, precise and reproducible for the estimation of both drugs from spiked human plasma.
相似文献An LC method was developed for determination of mangiferin in rat plasma and tissues after oral administration of Rhizoma Anemarrhenae extract. Analysis was performed on a Gemini C18 analytical column (250 × 4.6 mm, i.d.) with mobile phase consisting of acetonitrile–water (23:77, v/v) with 1% acetic acid and 1% tetrahydrofuran at a flow rate of 0.7 mL min−1. Spinosin was used as internal standard and UV detector was set at 320 nm. The calibration curve of mangiferin in rat plasma and tissues showed excellent linear behaviors over the investigated concentration ranges with the value of R 2 higher than 0.994. The within-day and between-day precisions for all samples were measured to be below 11.0%. The limit of quantitation was low enough for determination of mangiferin in all samples. After Rhizoma Anemarrhenae extract was orally administered to rats, the main pharmacokinetic parameters of mangiferin T max, C max, T 0.5α , T 0.5β , AUC0 − T and Vc were 4.20 h, 9.52 μg mL−1, 1.21 h, 1.71 h, 29.9 mg h L−1 and 0.18 L kg−1, respectively. Mangiferin was extensively distributed in most of the main tissues of rats. This validated method has been successfully applied to preliminary pharmacokinetics and tissue distribution study of mangiferin in rats.
相似文献A short ionic liquids-based monolithic cartridge was prepared and used as the selective extraction sorbent. Characteristic and evaluation are investigated by field emission scanning electron microscopy (FE-SEM), and a new approach was developed for the extraction and determination of β-sitosterol from Salicornia herbacea L. using the ionic liquids-based monolithic cartridge. Chromatographic analysis was conducted on a C18 column with UV detection at 210 nm, and an eluting solution consisting of acetonitrile–water (60/40, v/v) was used as the mobile phase at a flow rate of 0.8 mL min−1. The linearity was confirmed in the concentration range of 0.50–100.00 μg mL−1, with RSDs within 4.20%, and a recovery of β-sitosterol ranging from 97.20 to 102.93%. This method effectively removed the impurities without any tedious pretreatment, and it provided a fast, economic and effective way to assay trace drugs from natural plants.
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