Rapid and Sensitive Hplc Determination of Ranitidine in Plasma. Application to Pharmacokinetics Study

Abstract

A rapid and sensitive reversed-phase high-performance liquid chrormatography (RP-HPLC) method for the separation and quantification of the H₂-receptor antagonist drug ranitidine in human plasma is described.

The extraction of ranitidine from plasma by an organic solvent was eliminated in this method. Instead, the pre-chromatography isolation of the drug was done by adding approximately 50 mg of zinc sulfate and 200 μL of acetonitrile in 1.0 mL of plasma. A short column packed with pH-stable (1–13) reversed phase PLRP-S^TM particles was used with an isocratic elution of 5.0mM dibasic potassium phosphate plus 0.50mM tetraethyl ammonium hydroxide/ acetonitrile, 80:20 (v/v). The ranitidine was monitored at 315 nm and 0.20 to 0.002 absorption units full scale (AUFS). The completion time of the assay was less than 15 minutes and had a limit of detection of 1.0 ng/mL for a 100-μL injection volume.

After an oral dose of 150 mg of ranitidine, plasma samples were collected at several time points and were analyzed by using this method to determine various pharmacokinetic parameters.     

Rapid analysis of pyrethroids in whole urine by high-performance liquid chromatography using a monolithic column and off-line preconcentration in a restricted access material cartridge

A rapid high-performance liquid chromatography (HPLC) method using a monolithic column with UV detection at 238 nm was developed for the determination of fenpropathrin, betacyfluthrin, deltamethrin, and permethrin (cis and trans isomers) in whole urine. The method is based on the use of a monolithic chromatographic column and a restricted access material (RAM) cartridge for sample preparation. The mobile phase was water/acetonitrile (42:58 v/v), the flow rate was 3 mL min^–1, and chromatographic separation was carried out in 10 min. The separation of cis and trans isomers of permethrin was also possible under the above-mentioned conditions. Detection limits in reconstituted whole urine samples were between 0.9 g L^–1 for betacyfluthrin and 4.4 g L^–1 for fenpropathrin and trans-permethrin. Recoveries for urine samples spiked with different amounts of pyrethroids (between 19 g L^–1 and 75 g L^–1) were in the 70±6 to 90±7% range.     

Hplc Assay for Phenelzine Sulfate Drug Substance and the Decomposition Product Phenethyl Alcohol Using Short Wavelength UV Detection

Abstract

An HPLC procedure for the determination of phenelzine sulfate in the presence of its oxidation decomposition products expressed as phenethyl alcohol has been developed. The method uses a mobile phase consisting of 20:80 acetonitrile - 0.05 M sodium dihydrogen phosphate (pH 2.5) containing 0.02 M heptane sulfonic acid sodium salt, pumped at a flow rate of 1.0 mL/min. through a 100 mm × 4.6 mm i. d. octadecylsilane column (5 um) with UV detection at 209 nm. As little as 0.005% decomposition of phenelzine, expressed as phenethyl alcohol (134.5 pg on column), can also be detected at 209 nm. Peak height or area versus concentration of phenelzine base is linear over the range of 7.5 to 22.5 mg (r²=0.9982 for height and 0.9991 for area; n=5). Analysis of spiked samples of phenelzine gave mean percent recoveries of 101.31 ± 0.78%. Precision of the method ranged from 0.33 ? 1.42% and 0.53 ? 0.85% using peak height and peak area data, respectively.     

Development and validation of a high performance liquid chromatographic method for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets

A simple, sensitive and rapid high performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefadroxil in synthetically prepared tablets. Chromatographic separation and detection was carried out on a C-18 column using 0.05 M potassium dihydrogen phosphate buffer (pH 5.0) and acetonitrile in the ratio of 94: 06 (v/v) as mobile phase at wavelength of 225 nm. The method was linear in the concentration range of 3.75–22.5 μg/mL for potassium clavulanate and 15–90 μg/mL for cefadroxil. The flow rate was 1.0 mL/min and the total analysis time was less than 10 min. The mean recoveries was found to be greater than 99% with RSD less than 1.0%. The proposed method was validated by performing linearity, recovery, specificity, robustness, LOD/LOQ and within-day and between-day precision. The chromatographic results obtained from the synthetically prepared tablets show that the method is highly precise and accurate for the simultaneous quantitation of clavulanate potassium and cefadroxil.     

Trace determination of peptides in water samples using packed capillary liquid chromatography with UV and MS detection and characterization of peptide oxidation products by MS

A capillary liquid chromatographic column switching method has been developed for fast and sensitive determination of peptides in water samples. Sample volumes of 1 mL were loaded onto a (320 m I.D. ×30 mm) 10 m Kromasil C₁₈ pre-column, providing on-line analyte enrichment, prior to back-flushed elution onto a (320 m I.D. ×150 mm) 3.5 m Kromasil C₁₈ analytical column. Loading flow rates of 250 L/min and a mobile phase composition of acetonitrile/water/trifluoroacetic acid (22/77.9/0.1, v/v) provided a total analysis time of less than 25 minutes for the test peptides angiotensin II, bombesin, bradykinin, corazonin, neurotensin and substance P, using temperature programmed elution. In addition, solvent gradient elution and combined solvent gradient elution and temperature programming were explored. Using on-capillary UV detection at 210 nm resulted in a concentration limit of detection (cLOD) of about 1 ng/mL. The method was validated over the concentration range 1–100 ng/mL, yielding a coefficient of correlation of 0.997 or better. The within-assay (n=6) and between-assay (n=6) precisions of peak areas were on average 6% RSD and 5% RSD, respectively.When the method was applied to spiked chlorinated tap water samples, it was found that peptides containing methionine, tryptophan and cystine were oxidized. Identification of the oxidation products of the peptides in hypochlorite-treated water was done with positive electrospray ionization time-of-flight mass spectrometric detection.     

Evaluation and validation of an HPLC procedure for the determination of the positional isomeric impurity in 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid

A high-performance liquid chromatographic (HPLC) procedure was evaluated for the determination of a positional isomeric impurity in bulk 2-[4-(1-hydroxy-4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl)-phenyl]-2-methylpropionic acid HCl drug substance. The use of a β-cyclodextrin bonded-phase column with a mobile phase of 20/80 (v/v) acetonitrile/water containing an ammonium acetate buffer at apparent pH 4.0 and a flow rate of 0.45 mL/min resulted in an excellent separation of the isomers. Ultraviolet detection was used at 220 nm. A recovery study of known spike levels (0.1 to 1.5% w/w) showed that the procedure was accurate. A two-day, two-column repeatability study showed consistent results with the test batch of the bulk compound. The level of impurity in the tested lot of the compound had a mean level of 0.32% (w/w) and a standard deviation of 0.038% (w/w, n = 5). The text was submitted by the author in English.     

Surface modification by calcium ions—Effect on chromatographic properties of silica

Summary A liquid chromatographic method incorporating column-switching and fluorimetric detection for the determination of triamterene in untreated urine, is described. The urine samples (5 L) were directly introduced onto an Hypersil ODS-C18, 30 m (20 mm×2.1 mm I.D.) pre-column. Polar urinary compounds were removed by flushing the pre-column with water for 1 min, and the analyte was then switched onto an HP-LiChrospher RP C18,5 m (125 mm×4mm ID) analytical column using an acetonitrile/phosphate buffer gradient elution. Fluorescence detection was performed at 230 nm excitation and 430 nm emission wavelengths. The recovery of drug was 102±2% in the 0.10–20.0 g/mL concentration range, the limit of detection being 5 ng/mL. A validation of the usefulness of this procedure was accomplished by analysing urine extracts obtained from real samples.Hypersil ODS is not a product of Merck, Germany. Please give supplier (p. 5).     

Lithium isotope separation by chemical exchange with polymer-bound azacrown compounds

The chromatographic separation of lithium isotopes was investigated by chemical exchange with the recently synthesized polymer-bound dibenzo pyridino diamide azacrown (DBPDA) and reduced dibenzo pyridino diamide azacrown (RDBPDA). Column chromatography was employed for the determination of the effect of solvents and ligand conformation on the separation coefficients. The maximum separation coefficients, , for the DBPDA and RDBPDA at 20.0±0.02°C with acetonitrile as eluent, were found to be 0.034±0.002 and 0.035±0.002, respectively. The isotope separation coefficient and adsorption capability of the lithium ion on the DBPDA and RDBPDA were only slightly dependent on ligand structure, but strongly dependent on the solvent. DBPDA and RDBPDA appeared to have almost the same value for the isotope separation coefficient of lithium.     

Gas chromatographic analysis of C1–C4 nitroparaffins. Separation and identification

Summary The separation of C₁–C₄ nitroparaffins on SE-30, PEGA and Porapak R stationary phases was investigated. The nitroparaffin mixture was obtained from a real technological process. The best separation was achieved on Porapak R at 190°C. The fact that each peak obtained from this column corresponded to a single compound was checked by utilizing the linear relationship between the peak widths and the adjusted retention times (t _R ). Peak identification was carried out using the chromatographic data only, with help of plots of log t _R vs. carbon number and log t _R vs. boiling point; some of the results were also confirmed with comparing the retention times with those of pure substances and IR investigation of the collected chromatographic fraction.     

A Comparison of Radially-Compressed and Stainless Steel Columns for the Reversed-Phase Ion-Pair Separation of Phencyclidine Synthetic Mixtures

Abstract

The reversed-phase ion-pair HPLC separation of phencyclidine synthetic mixtures was optimized utilizing Radial-Pak radially compressed columns. Variables examined in the optimization included column type (C-18, C-8, or CN), pairing ion (methane-, pentane-, hexane-, or octane sulfonates) and mobile phase composition (varying concentrations of methanol or acetonitrile in water). The chromatographic behavior of the phencyclidine mixtures in the various systems utilizing radially compressed columns is compared and contrasted to a similar previous study which examined similar variables on stainless steel columns. The optimum system for radially compressed columns was found to consist of a Radial-Pak C-18 column and a mobile phase of 85:15 MeOH:H₂O, 2.5% acetic acid, 1% triethylamine and 5mM sodium hexane sulfonate.     

Separation of Fatty Acids as Their p-Bromophenacyl Esters on a C30-Bonded Silica Column by High Performance Liquid Chromatography

Abstract

A new C₃₀-bonded silica column was developed for high performance liquid chromatography. This column was tested for the fractionation of fatty acids as their p-bromophenacyl esters by the reverse-phase mode. Certain pairs of fatty acid esters that are very difficult to separate on a C₁₈-bonded silica column, i. e., arachidonic (C₂₀:4)-palmitoleic (C₁₆:1); elaidic (trans C₁₈:1)-vaccinic (cis C₁₈:1); behenic (C₂₂:0)-nervonic (C₂₄:1); and arachidonic (C₂₀:0)-erucic (C₂₂:1) esters, were completely resolved on the C₃₀-bonded column using solvent gradients of acetonitrile: water and acetonitrile: p-dioxane. A solvent system of methylene chloride: acetonitrile (2:1, v/v) was developed for this column to achieve good separation of a homologous series of extremely nonpolar C₇₆ to C₈₂ α-mycolic acid esters from Mycobacterium tuberculosis H37Ra.     

Artenolide — A new disesquiterpenoid fromArtemisia absinthium

A new steroid glycoside — alliospiroside B (I) — has been isolated from the collective fruit ofAllium cepa L. On the basis of chemical transformations and with the aid of physicochemical measurements it has been established that compound (I) has the structure of (25S)spirost-5-ene-1,3-diol 1-O-[O--L-rhamnopyranosyl-(1 2)--D-galactopyranoside. Compound (I) C₃₉H₆₂O₃, mp 200–202°C (from ethanol). [] _D ²⁰ –110.9±2° (c 1.01; pyridine) was obtained by extracting the collective fruit ofA. cepa with ethanol folowed by the column chromatographic separation of the combined glycosides on silica gel. The acid hydrolysis of (I) gave (25S)-ruscogenin (II), C₂₇H₄₂O₄, mp 189–191°C, [] _D ²³ –104.1±2° (c 0.98; pyridine). The¹H and¹³C NMR spectra are given for both compounds and the IR spectrum for compound (I).Institute of the Chemistry of Plant Substances of the Uzbek SSR, Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 589–592, September–October, 1986.     

Simple Determination of 1-Deoxynojirimycin in a New Dietary Supplement by Liquid Chromatography

A simple and fast chromatographic method using ultraviolet diode-array detector (UV-DAD) was developed for the high performance liquid chromatography determination of the content of 1-deoxynojirimycin (DNJ) in a new dietary supplement in the form of granules for oral solution preparation. The derivatization reaction was carried out at room temperature for 15 min at pH 7. The reaction reached completeness at a reagent to analyte molar ratio of about 60. The chromatographic separations were performed on a C18 Phenomenex Synergi Fusion stainless steel column (250 mm?×?4.6 mm; 4 µm) with detection at λ?=?254 nm. The mobile phase consisted of triethylammonium (TEA) phosphate buffer (0.05 M; pH 3) and acetonitrile under gradient conditions at a flow-rate ramping from 1 to 1.2 mL/min. The validation parameters (linearity, sensitivity, accuracy, precision, specificity and stability) were satisfactory. Intra-day precision (relative standard deviation, RSD) was ≤?2.23% for peak area and retention time without significant differences between intra- and inter-day data. Recovery studies gave good results (93.59%; n?=?15) with a RSD of 2.64%. The developed method is suitable for the quality control of DNJ in raw material and industrial products. The method can be applied in any analytical laboratory and does not require sophisticated instrumentation.     

Simultaneous determination of trimethoprim,enrofloxacin, and ciprofloxacin in blood serum of poultry

A method is proposed for the simultaneous determination of trimethoprim, enrofloxacin, and ciprofloxacin in blood serum of poultry using HPLC. Samples were prepared using protein precipitation. The chromatographic separation of substances was attained on a C18 column using a mixture of a 50 mM acetate buffer solution (pH 3.0) with acetonitrile (86: 14) as a mobile phase. Detection was performed at 278 nm. Linearity was observed in the concentration range 50–5000 ng/mL for trimethoprim and 10–5000 ng/mL for ciprofloxacin and enrofloxacin. Precision was ≤2.1% for enrofloxacin, ≤1.6% for ciprofloxacin, and ≤14% for trimethoprim. Accuracy was ≤10.2% for enrofloxacin, ≤9.9% for ciprofloxacin, and ≤11.9% for trimethoprim. The method was applied to pharmacokinetic studies of complex antibacterial drugs containing trimethoprim and enrofloxacin as active substances.     

Development of a validated liquid chromatographic method for the determination of related substances and assay of tenofovir disoproxil fumarate

The present study describes the development and validation of a selective liquid chromatographic (LC) method for the analysis of tenofovir disoproxil fumarate (TDF) and its related substances. The gradient method uses a base deactivated C18 column (Hypersil BDS column; 25 cm×4.6 mm I.D.) maintained at a temperature of 30°C. The mobile phases consist of acetonitrile, tetrabutylammonium/phosphate buffer pH 6.0 and water: (A; 2:20:78 v/v/v) and (B; 65:20:15 v/v/v). The flow rate is 1.0 mL/min and UV detection is performed at 260 nm. Good separation of TDF and 21 impurities was achieved. A system suitability test (SST) to check the quality of separation is also specified. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. The method is proved to be robust, precise, sensitive and linear between 0.1 μg/mL and 0.15 mg/mL. The limit of detection and limit of quantification are 0.03 and 0.1 μg/mL, respectively. The method was successfully applied to the quantification of related substances and assay of commercial TDF samples (bulk substances and tablets).     

Lithium isotope separation on a monobenzo-15-crown-5 resin

A study on the separation of Li isotopes was carried out with a resin having monobenzo-15-crown-5 as a functional group, synthesized by substitution reaction of chloromethylated styrene-DVB copolymer with 4-aminobenzo-15-crown-5. Adsorption properties of the resin for Li⁺ were invesgated with batch method in various solvents and counter anions. Upon column chromatography [0.9 cm (I. D.)×25 cm (height)] using 5% (v/v) H₂O in acetonitrile as an eluent, single separation factor, , 1.053 (±0.005), (⁶Li/⁷Li)resin/ (⁶Li/⁷Li) solution was obtained by the GLUECKAUF method from the elution curve and isotope ratios.     

反相离子对色谱-直接电导检测法分析六氟磷酸根离子液体阴离子

建立了反相离子对色谱-直接电导检测六氟磷酸根(PF6-)离子液体阴离子的分析方法。用DiamonsilC18反相色谱柱为分离柱,以离子对试剂-柠檬酸-乙腈混合水溶液为流动相,考察了离子对试剂、乙腈含量、pH值及色谱柱温度对六氟磷酸根保留的影响,并讨论了相关保留机理。在优化的色谱条件下,即流动相为0.05 mmol/L氢氧化四丁铵-0.038 mmol/L柠檬酸-35%乙腈(pH 5.5),流速1.0 mL/min,色谱柱温度40℃时,PF6-与其它常见阴离子(F-、Cl-、Br-、NO3-、SO24-、BF4-)达到基线分离且保留时间在15 min内。方法检出限(S/N=3)为0.25 mg/L,标准曲线的线性范围为0.5～100.0 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.17%和0.15%。该法用于1-丁基-3-甲基咪唑六氟磷酸盐和1-丙基-2,3-二甲基咪唑六氟磷酸盐两种离子液体中PF6-的测定,加标回收率分别为99%和104%。该方法简单、准确、可靠,实用性好。     

Simultaneous determination of thirteen main components and identification of eight major metabolites in Xuebijing Injection by UPLC/Q-TOF

An ultra performance liquid chromatographic method was used for the simultaneous identification and quantification of thirteen main components in Xuebijing Injection, including uridine, gallic acid, guanosine, danshensu, protocatechualdehyde, oxypaeoniflorin, hydroxysafflor yellow A, paeoniflorin, ferulic acid, safflor yellow A, senkyunolide I, senkyunolide H and salvianolic acid B. The chromatographic separation was performed on an Acquity UPLC BEH C₁₈ column (1.7-μm, 2.1 × 100 mm, i.d.) with a gradient elution of acetonitrile and 0.2% acetic acid at a flow rate of 0.4 mL/min. The method was validated for linearity (r ² > 0.9990), intra- and inter-day precision (RSD < 1.94%), accuracy (91.8–99.7%), recovery (96.8–103.8%), limits of detection (0.16–8.0 ng), and limits of quantification (0.54–26.8 ng). At least eight metabolites in prototype were found in rat plasma and urine after intravenous injection of 4 mL/kg doses of Xuebijing Injection. The proposed method could be utilized to qualify and control Xuebijing Injection to ensure its safety and efficacy in application.     

Quantification of mephenytoin and its metabolites 4'-hydroxymephenytoin and nirvanol in human urine using a simple sample processing method

A reliable and easy to use liquid chromatography/tandem mass spectrometry (LC/MS/MS) method without the use of sample extraction was developed for the simultaneous quantification of urinary concentrations of mephenytoin, a standard phenotyping substrate for the cytochrome P450 enzyme CYP2C19, and its phase I metabolites 4'-hydroxymephenytoin and nirvanol. Fifty microL of urine were diluted with a buffered beta-glucuronidase solution and incubated at 37 degrees C for 6 h followed by addition of methanol, containing the internal standard 4'-methoxymephenytoin. The chromatographic separation was achieved using a 100 x 3 mm, 5 micro Thermo Electron Aquasil C18 column with a gradient flow, increasing the organic fraction (acetonitrile/methanol 50:50) of the mobile phase from 10 to 90%. Quantification by triple-stage mass spectrometry (TSQ Quantum, Thermo Electron) was accomplished by negative electrospray ionization in the selected reaction monitoring mode. Linearity was observed for all substances in the concentration range 15-10 000 ng/mL. The lower limit of quantification (LLOQ) was 20 ng/mL for 4'-hydroxymephenytoin and 30 ng/mL for nirvanol and mephenytoin, respectively. Intra- and inter-day inaccuracy did not exceed 9.5% for all substances from LLOQ to 10 000 ng/mL. Intra- and inter-day precision were in the range of 0.8-10.5%. The method was validated according to international ICH and FDA guidelines and successfully applied for phenotyping of Caucasian male volunteers who received an oral dose of 50 mg mephenytoin.     

高效液相色谱-双波长检测-梯度洗脱法同时测定小儿氨酚烷胺颗粒中的3种有效组分

建立了高效液相色谱(HPLC)-双波长检测-梯度洗脱同时测定小儿氨酚烷胺颗粒中对乙酰氨基酚、咖啡因和马来酸氯苯那敏含量的分析方法。采用的色谱条件: 以Diamonsil C18色谱柱(4.6×200 mm, 5 μm)为分离柱,以乙腈和0.1%三乙胺水溶液(用磷酸调pH至3.7±0.5)为流动相进行梯度洗脱,流速1.0 mL/min,检测波长为280 nm和210 nm,柱温为30 ℃,进样量为5 μL。结果表明,对乙酰氨基酚、咖啡因和马来酸氯苯那敏的线性范围均比较宽(依次为2.4～60、0.14～3.6、0.019～0.48 μg),平均加标回收率均不低于99.0%,而且方法操作简单,重现性好,测定结果准确,可用于更好地控制该制剂的质量。