scholarly journals Influence of the composition of the stationary and mobile phase on the retention factors and solvent strength parameters in RP chromatographic systems in which the Everett equation is valid

2001 ◽  
Vol 66 (10) ◽  
pp. 671-683 ◽  
Author(s):  
T.J. Janjic ◽  
G. Vuckovic ◽  
M.B. Celap
Keyword(s):  
Phase Equilibrium ◽  
Equilibrium Constant ◽  
Mole Fraction ◽  
Linear Dependence ◽  
Mobile Phase ◽  
Strength Parameters ◽  
Retention Factors ◽  
Mobile Phases ◽  
Solvent Strength

It is shown how in RP chromatography the Everett equation for ideal phase equilibriums can be used to estimate SP values (SP = log xs/x1, xs and x1 denoting the modifier mole fractions in the stationary and mobile phases, respectively) which are in a linear dependence with the log k values. The described procedure includes the determination of the approximate phase equilibrium constant K. By analysis of the Everett equation it was found that in the field of x1/K there are regions of linear dependence of the SP parameter or log k values and the mole fraction of modifiers or its logarithm. Consequently, only in these regions it is possible for two different chromatographic systems to have the same solvent strength scale: x1 or log x1.

scholarly journals Therapeutic Drug Monitoring of Anticonvulsant Drugs by Micellar HPLC with Direct Injection of Serum Samples

2002 ◽  
Vol 48 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
Adrián Martinavarro-Domínguez ◽  
Maria-Elisa Capella-Peiró ◽  
Mayte Gil-Agustí ◽  
José V Marcos-Tomás ◽  
Josep Esteve-Romero
Keyword(s):  
Mobile Phase ◽  
Direct Injection ◽  
Sodium Dodecyl ◽  
Chromatographic Determination ◽  
Therapeutic Drug ◽  
Organic Modifiers ◽  
Serum Samples ◽  
Drug Concentrations ◽  
Mobile Phases

Abstract Background: We developed a micellar liquid chromatographic (MLC) procedure for the determination of three extensively monitored antiepileptics in serum samples: carbamazepine, phenobarbital, and phenytoin. Methods: We determined the composition of the mobile phase after modeling the elution behavior of the antiepileptics in hybrid micellar mobile phases of sodium dodecyl sulfate (SDS) with different organic modifiers (propanol, butanol, or pentanol) in an experimental design that used five mobile phases, a C18 column, and ultraviolet detection. In the micellar chromatographic system, the serum samples can be injected directly. Results: The optimum mobile phase was 70 mL/L butanol in 0.05 mol/L SDS, pH 7, in which the three antiepileptics were resolved in <10 min. Intra- and interday precision was evaluated at four different drug concentrations within the therapeutic range (n =10); CVs were <2.1%. The method was applied to the analysis of 120 serum samples, and results were similar to those obtained by the TDx® method. Conclusions: The MLC method allows chromatographic determination of three antiepileptics, using an interpretative strategy of optimization, without pretreatment of the serum samples and with direct injection in a hybrid micellar mobile phase of SDS–butanol. The method provides complete resolution and quantification of mixtures of two and three antiepileptics.

Determination of Reserpine, Hydralazine HCl, and Hydrochlorothiazide in Tablets by Liquid Chromatography on a Short, Normal-Phase Column

1994 ◽  
Vol 77 (5) ◽  
pp. 1104-1108 ◽  
Author(s):  
Ugo R Cieri
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Normal Phase ◽  
Uv Absorbance ◽  
Commercial Sample ◽  
Second Stage ◽  
Mobile Phases ◽  
Acid Sodium Salt ◽  
Phase Column

Abstract A procedure is presented for the determination of reserpine, hydralazine HCI, and hydrochlorothiazide in tablets by liquid chromatography. The sample is extracted with methanol, and the extract is filtered through paper. Chromatography is performed in 2 stages, each using a 7.5 cm-long normal-phase column but different mobile phases. In the first stage, intended exclusively for reserpine, the mobile phase consists of methanol containing 2% aqueous 1-pentanesulfonic acid sodium salt at 4 parts/1000. Detection and quantitation of reserpine was by fluorescence at 280 nm (excitation) and 360 nm (emission). In the second stage, the amount of the salt solution in the mobile phase was increased to 5%. Detection and quantitation of hydrochlorothiazide and hydralazine HCI was by UV absorbance at 260 nm. One commercial sample of tablets was analyzed by the proposed method. Two determination of each ingredient were made on a ground composite. Ten individual tablets also were examined.

scholarly journals Development of Micellar HPLC-UV Method for Determination of Pharmaceuticals in Water Samples

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Danielle Cristina da Silva ◽  
Cláudio Celestino Oliveira
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Solid Phase ◽  
Sodium Dodecyl ◽  
Micellar Liquid Chromatography ◽  
Phase Extraction ◽  
Mobile Phases ◽  
Concentration Factors ◽  
Better Than

Method for extraction and determination of amoxicillin, caffeine, ciprofloxacin, norfloxacin, tetracycline, diclofenac, ibuprofen, nimesulide, levonorgestrel, and 17α-ethynylestradiol exploiting micellar liquid chromatography with PDA detector and solid-phase extraction was proposed. The usage of toxic solvents was low; the chromatographic separation of the medicaments was performed using a C18 column and mobile phases A and B containing 15.0% (v/v) ethanol, 3.0% (m/v) sodium dodecyl sulfate (SDS), and 0.02 mol·L−1 phosphate at pHs 7.0 and 8.0, respectively. The method is simple, selective, and fast, and the analytes were separated in 23.0 min. For extraction, 1000 mL of sample containing 2.0% (v/v) ethanol and 0.002 mol·L−1 citric acid at pH 2.50 was loaded through a 1000 mg of C18 cartridge. The analytes were eluted using 3.0 mL of ethanol, which were evaporated and redissolved in 0.5 mL of mobile phase. Concentration factors better than 1200, except amoxicillin (224), were obtained. The analytical curves were linear (R2 better than 0.992); LOD and LOQ n=10 presented values in the range of 0.019–0.247 and 0.058–0.752 mg·L−1, respectively. Recoveries of 99% were obtained, and the results are in agreement with those obtained by the comparative methods.

scholarly journals Pharmacokinetics study of potential anti-CML drug Cyclobentinib (CB1107) by HPLC–MS/MS

2021 ◽  
Vol 3 (1) ◽  
pp. 169-175
Author(s):  
Xinghua Zhao ◽  
◽  
Jiaojiao Zhang ◽  
Yutong Liang ◽  
Jie Li ◽  
...  
Keyword(s):  
Formic Acid ◽  
Mobile Phase ◽  
Time Curve ◽  
Column Temperature ◽  
Mobile Phases ◽  
Ionization Reaction ◽  
Liquid Chromatography Tandem Mass ◽  
Different Doses

Purpose: A simple, sensitive and specific HPLC–MS/MS method was established to analysis the pharmacokinetics of CB1107 in mouses. Methods: A simple, selective, and sensitive high-throughput liquid chromatography-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for quantitative determination of CB1107 in rat serum.Chromatographic separation was achieved on a Zorbax Extend C18 Rapid Resolution HD column (4.6 mm × 50 mm, 1.8 μm). The column temperature was maintained at 35℃ and at flow rate of 0.6 mL/min. Injection volume was 20 μL. The mobile phases consisted of 0.1% formic acid in water (mobile phase A)and 0.1% formic acid in acetonitrile (mobile phase B), and total run time was 30min. MS-MS detection was performed in the selected monitoring mode of electrospray positive ionization reaction. Results: The pharmacokinetic characteristics of CB1107 in mice belong to the two-compartment model.When the doses were 400 mg/kg, 600 mg/kg and 800 mg/kg, corresponding area under the plasma concentration-time curve (AUC) respectively were 20.011±1.24 mg/h/L, 26.778±2.19 mg/h/L, 38.82±1.44 mg/h/L, suggesting that CB1107 have a good absorption in the body.And the AUC of three doses are proportional, indicating that CB1107 conforms to linear pharmacokinetics in vivo. Conclusion: This method was successfully applied to study the pharmacokinetics at three different doses of CB1107 after oral administration in mouses. In this study, the bioactivity mechanism of CB1107, by the pharmacokinetic investigation of CB1107 in vivo.

scholarly journals Application of the log k pair linearity rule and proportionality rule to the RPP mobile phase scales estimation on cyano-silica column

2001 ◽  
Vol 66 (3) ◽  
pp. 173-178
Author(s):  
Tomislav Janjic ◽  
Gordana Vuckovic ◽  
Milenko Celap
Keyword(s):  
Linear Relationship ◽  
Satisfactory Agreement ◽  
Linear Dependence ◽  
Mobile Phase ◽  
Silica Column ◽  
Good Linear ◽  
Good Linear Relationship ◽  
Solvent Strength ◽  
Proportionality Rule

On the basis of literature-reported log k values, the Log k pair linearity rule and the Proportionality rule were found to be also valid in the case of cyano-silica sorbent, whenmethanol, acetonitrile or propane-2-olwere used as modifiers. The RPPscales, reflecting the solvent strength, are in good linear relationship with the experimentally determined log k values. Furthermore, in the case of methanol and acetonitrile, the linear dependence: log k = f(mol%of modifier) was also established. In the function obtained in a such way, the intercept and the slope exhibit an approximate linear dependence. Finally, in the case of methanol, the experimentally obtained log k values are in a satisfactory agreement with the values calculated by the above equation.

scholarly journals Development and validation of an LC-MS/MS method for the determination of adapalene in pharmaceutical forms for skin application

2016 ◽  
Vol 81 (10) ◽  
pp. 1171-1181 ◽  
Author(s):  
Vladimir Dobricic ◽  
Natasa Bubic-Pajic ◽  
Bojan Markovic ◽  
Sote Vladimirov ◽  
Snezana Savic ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Ammonium Acetate ◽  
Intermediate Precision ◽  
Column Temperature ◽  
Mobile Phases ◽  
Relative Standard ◽  
Liquid Chromatography Tandem Mass ◽  
Chromatographic Parameters ◽  
Development And Validation

Development and validation of a liquid chromatography - tandem mass spectrometry (LC-MS/MS) method for the determination of adapalene in pharmaceutical forms for skin application were presented. The MS/MS analysis of adapalene was performed by use of three mobile phases, consisted of acetonitrile and (a) 0.1 % formic acid, (b) 0.1 % trifluoroacetic acid and (c) 20 mM ammonium acetate. The strongest signals of parent ion and dominant product ion were obtained in negative mode by use of the mobile phase (c). Validation of this method was performed according to the ICH guidelines. Small variations of selected chromatographic parameters (concentration of ammonium acetate, mobile phase composition, column temperature and flow rate) did not affect qualitative and quantitative system responses significantly, which proved method?s robustness. The method is specific for the determination of adapalene. Linearity was proved in the concentration range 6.7 - 700.0 ng mL-1 (r = 0.9990), with limits of detection and quantification 2.0 ng mL-1 and 6.7 ng mL-1, respectively. Accuracy was confirmed by calculated recoveries (98.4 % - 101.5 %). Precision was tested at three levels: injection repeatability, analysis repeatability and intermediate precision. Calculated relative standard deviations were less than 1, 2 and 3 %, respectively.

scholarly journals Application of TLC for Evaluation of the Lipophilicity of Newly Synthetized Esters: Betulin Derivatives

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Katarzyna Bober ◽  
Ewa Bębenek ◽  
Stanisław Boryczka
Keyword(s):  
Cluster Analysis ◽  
Mobile Phase ◽  
Correlation Equation ◽  
Retardation Factor ◽  
Similarity Analysis ◽  
Correlation Equations ◽  
Mobile Phases ◽  
Layer Chromatography ◽  
Betulin Derivatives

The problem of designing a new drug is nowadays very important for researches representing many branches of science. This work considers the usefulness of the analytical method such as thin-layer chromatography for the lipophilicity of newly synthesized compounds, betulin derivatives, which could be potential drugs with anticancer activity. The two mobile phases were used for the purpose of experimental determination of lipophilicity for mono- and diesters investigated. The first mobile phase consists of acetate and Tris buffer, whilst the second consists of 1,4-dioxane and acetate buffer. The value of the retardation factor was recalculation into the RM value, and then RM0 values were obtained by extrapolating acetone or 1,4-dioxane concentration to zero. The chromatographic data of lipophilicity were correlated with theoretically obtained values of ALOGPS, AClogP, miLogP, ALOGP, MLOGP, XLOGP2, and XLOGP3. The particular correlation equations were obtained. The cluster analysis was also used to find similarity between the esters investigated on the basis of the experimental or theoretical value of lipophilicity obtained. The good correlation between experimentally and theoretically calculated lipophilicity gives the possibility of prediction of this value on the basis of the correlation equation. On the basis of similarity analysis was stated strong connections between the structure and the value of lipophilicity, for both experimental and theoretical values.

Sign in / Sign up

Export Citation Format

Share Document