Chemical stability of haloperidol injection by high performance thin-layer chromatography

The chemical stability of haloperidol lactate injection was studied under different storage conditions by high performance thin-layer chromatography (HPTLC). The study was performed at 25 +/- 2 degrees C and at refrigeration temperature (8 +/- 1 degrees C) in original glass ampoules over 15 days after being opened. The samples tested at 25 +/- 2 degrees C were stored with exposure to and protection from light. Chromatographic separation was achieved on precoated silica gel F 254 HPTLC plates using a mixture of acetone/chloroform/n-butanol/glacial acetic acid/water (5:10:10:2.5:2.5, v/v/v/v/v) as a mobile phase. Quantitative analyses were carried out at a wavelength of 254 nm. The method exhibited adequate linearity (r = 0.999), selectivity, precision (RSD = 1.92%), and accuracy (recoveries from 98.59 to 101.90%). The concentrations of all samples remained greater than or 90% of the original concentration. Haloperidol lactate injection was chemically stable under all conditions studied over 15 days.     

Simultaneous determination of nicotinamide,pyridoxine hydrochloride,thiamine mononitrate and riboflavin in multivitamin with minerals tablets by reversed-phase ion-pair high performance liquid chromatography

A reversed-phase ion-pair high performance liquid chromatographic method (HPLC) has been developed and validated for the routine analysis of nicotinamide, pyridoxine hydrochloride, thiamine mononitrate and riboflavin in multivitamin with minerals tablets. HPLC separation of the vitamins was performed on a Hypersil C(18) column and detected by ultraviolet absorbance at 280 nm. The use of methanol-aqueous 0.5% acetic acid solution (18:82, v/v; containing 2.5 mM sodium hexanesulfonate, pH = 2.8) as the mobile phase at a flow-rate of 1.2 mL/min enables the baseline separation of the four analytes free from interferences with isocratic elution at 30 degrees C. The analysis time was 17 min per injection. The method was linear in the ranges of 5-90, 2.5-90, 5-95 and 25-450 micro g/mL for thiamine mononitrate, riboflavin, pyridoxine hydrochloride and nicotinamide, respectively. The average coefficients of variation of within- and between-day assays were 2.2 and 3.6% for thiamine mononitrate, 1.8 and 2.4% for riboflavin, 1.3 and 1.7% for pyridoxine hydrochloride and 1.0 and 1.5% for nicotinamide, respectively. The average recoveries of thiamine mononitrate, riboflavin, pyridoxine hydrochloride and nicotinamide were 97.0, 97.2, 98.9 and 100.4% for the tablets, respectively. The method has been successfully applied to the simultaneous determination of nicotinamide, pyridoxine hydrochloride, thiamine mononitrate and riboflavin in multivitamin with minerals tablets.     

Simultaneous determination of manganese and selenium in serum by electrothermal atomic absorption spectrometry

A method for determination of manganese and selenium in serum by simultaneous atomic absorption spectrometry (SIMAAS) is proposed. The samples (30 mul) were diluted (1+3) to 1.0% v/v HNO(3)+0.10% w/v Triton X-100 directly in the autosampler cups. A total of 20 mug Pd+10 mug Mg(NO(3))(2) was used as chemical modifier. The pyrolysis and atomization temperatures for the simultaneous heating program were 1200 and 2300 degrees C, respectively. The addition of an oxidant mixture (15% w/w H(2)O(2)+1.0% v/v HNO(3)) and the inclusion of a low temperature pyrolysis step (400 degrees C) attenuated the build-up of carbonaceous residues onto the integrated platform. An aliquot of 15 mul of the reference or sample solution was introduced into the graphite tube and heated at 80 degrees C; subsequently, 10 mul of oxidant mixture+10 mul of chemical modifier was introduced over that aliquot and the remaining heating program steps were executed. This strategy allowed at least 250 heating cycles for each THGA tube without analytical signal deterioration. The characteristic masses for manganese (6 pg) and selenium (46 pg) were estimated from the analytical curves. The detection limits were 6.5 pg (n=20, 3delta) for manganese and 50 pg (n=20, 3delta) for selenium. The reliability of the entire procedure was checked with the analysis of serum from Seronormtrade mark Trace Elements in Serum (Sero AS) and by addition and recovery tests (97+/-9% for manganese and 96+/-7% for selenium) using five serum samples.     

Determination of 1-(2-methoxyphenyl)piperazine derivatives of isocyanates at low concentrations by temperature-programmed miniaturized liquid chromatography

A temperature-programmed packed capillary LC method with large-volume injection on-column focusing has been developed for screening and determination of 1-(2-methoxyphenyl)piperazine derivatives of airborne toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylenediisocyanate and methylenebisphenyl-4,4-diisocyanate, based on sampling methods described in MDHS 25/3. Injection volumes up to 100 microl were successfully loaded onto the 250x0.32 mm I.D. capillary column packed with 3 microm Hypersil ODS particles. The isocyanate derivatives were loaded at 10 degrees C and eluted by a three-step temperature program starting at 10 degrees C for 10 min, followed by a temperature ramp of 2.5 degrees C min(-1) to 45 degrees C and then 9.9 degrees C min(-1) to 90 degrees C. The mobile phase consisted of acetonitrile-acetate buffer (3% triethylamine, pH 4.5) (45:55, v/v). The isocyanate derivatives were dissolved in acetonitrile-acetate buffer (3% triethylamine, pH 4.5) (30:70, v/v) to achieve sufficient focusing. The concentration limit of detection of the individual derivatives utilizing an "U" shaped flow cell with a 8.0 mm light path and an injection volume of 100 microl was 44, 87, 43 and 210 pg ml(-1) for toluene-2,6-diisocyanate, hexamethylenediisocyanate, toluene-2,4-diisocyanate and methylenebisphenyl-4,4-diisocyanate, respectively. Within the investigated concentration range, 10-500 ng ml(-1), the linear calibration curves gave correlation coefficients ranging from 0.994 to 0.998. The repeatability of the method with regard to retention time and peak height ranged from 0.3 to 1.1% and 1.1 to 2.3% (n=9) relative standard deviation, respectively. The average recovery of the method, with regard to toluene-2,4-diisocyanate, was 97.7+/-1.6% (n=9).     

Determination of ethambutol hydrochloride in the combination tablets by precolumn derivatization

A new high-performance liquid chromatography method for the quantitative determination of ethambutol hydrochloride in combination tablets is presented. Ethambutol is derivatized with phenylethylisocyanatate at room temperature (22 +/- 2 degrees C) for 5 min. Separation is performed by a C(18) column using methanol-water-glacial acetic acid (70:30:0.2, v/v/v) as the mobile phase. The method is linear for drug concentrations in the range of 20-120 microg/mL (r=0.9995). The intra- and inter-day precisions are lower than 1.46% and 2.22%, respectively. The average recovery of the samples at three levels is 99.8%. The results show that derivatization of ethambutol is stable at 30 degrees C for 24 h. This method is simple, rapid, and stable in the presence of common excipients and antituberculosis drugs in the tablets.     

Evaluation of the pH- and thermal stability of the recombinant green fluorescent protein (GFP) in the presence of sodium chloride

The thermal stability of recombinant green fluorescent protein (GFP) in sodium chloride (NaCl) solutions at different concentrations, pH, and temperatures was evaluated by assaying the loss of fluorescence intensity as a measure of denaturation. GFP, extracted from Escherichia coli cells by the three-phase partitioning method and purified through a butyl hydrophobic interaction chromatography (HIC) column, was diluted in water for injection (WFI) (pH 6.0-7.0) and in 10 mM buffer solutions (acetate, pH 5.0; phosphate, pH 7.0; and Tris-EDTA, pH 8.0) with 0.9-30% NaCl or without and incubated at 80-95 degrees C. The extent of protein denaturation was expressed as a percentage of the calculated decimal reduction time (D-value). In acetate buffer (pH 4.84+/-0.12), the mean D-values for 90% reduction in GFP fluorescence ranged from 2.3 to 3.6 min, independent of NaCl concentration and temperature. GFP thermal stability diluted in WFI (pH 5.94+/-0.60) was half that observed in phosphate buffer (pH 6.08+/-0.60); but in both systems, D-values decreased linearly with increasing NaCl concentration, with D-values (at 80 degrees C) ranging from 3.44, min (WFI) to 6.1 min (phosphate buffer), both with 30% NaCl. However, D-values in Tris-EDTA (pH 7.65+/-0.17) were directly dependent on the NaCl concentration and 5-10 times higher than D-values for GFP in WFI at 80 degrees C. GFP pH- and thermal stability can be easily monitored by the convenient measure of fluorescence intensity and potentially be used as an indicator to monitor that processing times and temperatures were attained.     

Rapid determination of lead and cadmium in sewage sludge samples using electrothermal atomic absorption spectrometry with slurry sample introduction

Lead and cadmium concentrations in sewage sludge samples are determined by suspending the ground samples in a solution containing 10% (v/v) concentrated hydrofluoric acid, 1% (v/v) concentrated nitric acid, 0.5% (m/v) dihydrogen ammonium phosphate and 0.1% (m/v) sodium hexametaphosphate. Aliquots of 20 microL of these suspensions (4 mg/mL) are diluted to 1000 microL with the same solution and then injected into the electrothermal atomizer. The drying stage is performed by programming a 400 degrees C temperature, a ramp time of 20 s and a hold time of 15 s on the power supply of the atomizer. No ashing step is used. Platform atomization is carried out at 1600 and 1800 degrees C for Pb and Cd, respectively. Calibration is performed using aqueous standards in the 5-75 and 0.2-5 microg/L Pb and Cd ranges, respectively. Results obtained for three certified reference materials and four samples demonstrate the reliability of the procedures described.     

衍生化气相色谱法测定盐酸芬氟拉明片的纯度

 应用衍生化气相色谱法测定盐酸芬氟拉明片的纯度。样品溶解后经碱化乙酸乙酯提取 ,以盐酸美西律作内标 ,提取液用三氟乙酸酐进行酰化衍生化 ,衍生化产物在 5 %SE 30的色谱柱上分析 ,用氢火焰离子化检测器 (FID)检测。实验结果表明 ,芬氟拉明的质量浓度在 0 1g/L～ 0 5 g/L范围内线性良好 (r =0 9996 ) ;芬氟拉明与内标美西律的分离度大于 4;理论塔板数以芬氟拉明峰计大于 2 0 0 0 ;方法的精密度好 ,相对标准偏差 (RSD)为 1 4% (n=7) ;平均回收率为 (10 0 2± 2 2 ) % (n =6 ) ;检测限为 8ng。用该方法得到的结果灵敏、准确、重复性好。     

Determination of beryllium and selenium in human urine and of selenium in human serum by graphite-furnace atomic absorption spectrophotometry.

For human urine beryllium (Be), each sample (500 microl) was diluted (1+1) with Nash reagent (containing 0.2% (v/v) acetylacetone and 2.0 M ammonium acetate buffer at pH 6.0) and then a 20-microl volume of Triton X-100 (0.4%, v/v) aqueous solution was added. An aliquot (10 microl) of the diluted urine mixture was introduced into a graphite cuvette and was atomized according to a temperature program. The method detection limit (MDL, 3sigma) for Be was 0.37 microg/l in the undiluted urine sample and the calibration graph was linear up to 65.0 microg/l. Calibration graphs were prepared by the standard addition method. Accuracies of 98.6-102% were obtained when testing standard reference material (SRM 2670) freeze dried human urine samples. Precision (relative standard deviation, RSD) for urine Be was < or = 2.3% (withinrun, n = 5) and was < or = 3.0% (between-run, n = 3). For human urine and serum selenium (Se), samples (100 microl) were diluted with HNO3 (0.2%, v/v) to make a (1+1) dilution for urine analysis or a (1+4) dilution for serum analysis. An additional aliquot (10 microl) of Triton X-100 (0.1%, v/v) was added to each 200 microl of (1+1) diluted urine (or 20 microl of the Triton X-100 was added to each 500 microl of (1+4) diluted serum) sample. After the diluted sample mixture (10 microl) was introduced into a graphite cuvette, the corresponding chemical modifier (10 microl, containing Ni2+ + Pd + NH4NO3 in HNO3 (0.2%, v/v)) was added to it and the mixture was atomized. The MDL (3sigma) for Se in urine and in serum was 4.4 and 21.4 microg/l in undiluted sample, respectively, and the calibration graphs were linear up to 150 and 400 microg/l. Accuracies of urine Se were 98.9 - 99.4% by testing SRM 2670 (NIST) urine standards with RSD (between-run, n = 3) within 2.9%; and that of serum Se was 97.2% when testing a certified second-generation human serum (No. 29, #664) with RSD (between-run, n = 3) of 1.4%. The proposed method can be applied easily, directly, and accurately to the measurement of Be and Se in real samples (including six urine Se and four serum Se from patients of Blackfoot Disease in Taiwan).     

Determination of phenylephrine hydrochloride by flow injection analysis with chemiluminescence detection

A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80 degrees C. The calibration graph is linear over the range 0.03-8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.     

Simultaneous determination of midazolam and 1'-hydroxymidazolam in human plasma by liquid chromatography with tandem mass spectrometry

A sensitive and simple liquid chromatography-tandem mass spectrometry method for the determination of midazolam and 1'-hydroxymidazolam in human plasma has been developed and validated with a dynamic range of 0.1-250 ng/mL. The analysis was based on semi-automated liquid-liquid extraction followed by evaporation of the extraction solvent, reconstitution and chromatography on a reversed-phase C(18) column. The mobile phase consists of 5 mm ammonium acetate and methanol and runs in gradient at a flow rate of 0.25 mL/min with column temperature of approximately 20 degrees C. The entire column effluent was transferred into the LC-MS/MS interface operated in positive electrospray ionization mode. The chromatographic run time was 4.3 min per injection, with retention times for midazolam, 1'-hydroxymidazolaml and the internal standard, triazolam, of 2.5, 2.3 and 2.1 min, respectively. The intra-day and inter-day precision (RSD %) and accuracy (bias %) of the quality control samples were <15.0% and within +/-13%, respectively. The current method has been applied to a clinical drug-drug interaction study in human.     

Validation of a high-performance liquid chromatographic method for the simultaneous determination of tramadol and its impurities in oral drops as a pharmaceutical formulation

The novel, rapid high performance liquid chromatographic method for the determination of tramadol hydrochloride and its three impurities was developed and validated. The method can simultaneously assay potassium sorbate, used as preservative, and saccharin sodium, used as sweetener in tramadol pharmaceutical formulation. The separation was carried out on a C(18) XTerra (150 mm x 4.6 mm, 5 mm) column using acetonitrile-0.015 M Na(2)HPO(4) buffer (2:8, v/v) as mobile phase (pH value 3.0 was adjusted with orthophosphoric acid) at a flow rate 1.0 ml min(-1), temperature of the column 20 degrees C and UV detection at 218 nm. The method was found to be linear (r > 0.999) in the range of 0.05-0.8 mg ml(-1) for tramadol hydrochloride, 0.1-1.2 mg ml(-1) for impurities B and C and for impurity A (r > 0.995) in the range 0.15-2.4 mg ml(-1). The low RSD values indicate good precision and high recovery values indicate excellent accuracy of the HPLC method. Developed method was successfully applied to the determination of tramadol hydrochloride, its investigated impurities and potassium sorbate in commercial formulation. The recovery of tramadol hydrochloride was 98.25% and RSD was 1.80%. The method is rapid and sensitive enough to be used to analyse Trodon oral drops.     

反相高效液相色谱法测定苹果中槲皮素的含量

采用反相高效液相色谱法测定了苹果肉和苹果皮中槲皮素的含量。将样品于-80 ℃冷冻24 h后,在2,6-二叔丁基对 甲酚的保护下加入6 mol/L盐酸制成匀浆,于90 ℃恒温水浴中回流水解2 h。水解液在反相ODS柱上分离,以甲醇-水(体积 比为55∶45,乙酸调pH值为3.3)为流动相,在波长370 nm处进行测定。结果表明:苹果肉中槲皮素的平均含量为3.11～10.78 μg/g;苹果皮中槲皮素的平均含量为253.57～744.59 μg/g;苹果肉中槲皮素的平均加标回收率为100.4%。该法操作简 便易行、结果准确可靠。     

Simultaneous estimation of metformin hydrochloride, pioglitazone hydrochloride, and glimepiride by RP-HPLC in tablet formulation

A simple, precise, rapid, and reproducible reversed-phase high-performance liquid chromatography method is developed for the simultaneous estimation of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO), and glimepiride (GLP) present in multicomponent dosage forms. Chromatography is carried out isocratically at 25 degrees C +/- 0.5 degrees C on an Inertsil-ODS-3 (C-18) Column (250 x 4.60 mm, 5 microm) with a mobile phase composed of methanol-phosphate buffer (pH 4.3) in the ratio of 75:25 v/v at a flow rate of 1 mL/min. Detection is carried out using a UV-PDA detector at 258 nm. Parameters such as linearity, precision, accuracy, recovery, specificity, and ruggedness are studied as reported in the International Conference on Harmonization guidelines. The retention times for MET, PIO, and GLP are 2.66 + 0.5 min, 7.12 + 0.5 min, and 10.17 + 0.5 min, respectively. The linearity range and percentage recoveries for MET, PIO, and GLP are 10-5000, 10-150, and 1-10 microg/mL and 100.4%, 100.06%, and 100.2%, respectively. The correlation coefficients for all components are close to 1. The relative standard deviations for three replicate measurements in three concentrations of samples in tablets are always less than 2%.     

HPLC determination of diltiazem in human plasma and its application to pharmacokinetics in humans

A simple and sensitive reversed-phase high performance liquid chromatographic method (HPLC) has been developed and validated for the routine analysis of diltiazem in human plasma and the study of the pharmacokinetics of the drug in the human body. Diltiazem and diazepa (internal standard) were extracted with a mixed organic solution of hexane, chloroform and isopropanol (60:40:5, v/v/v), and then HPLC separation of the drugs was performed on an Spherisorb C(18) column and detected by ultraviolet absorbance at 239 nm. The use of methanol-water solution (containing 2.8 mm triethylamine, 80:20, v/v) as the mobile phase at a fl ow-rate of 1.2 mL/min enables the baseline separation of the drugs free from interferences with isocratic elution. The method was linear in the clinical range 0-300 ng/mL and the lower limit of detection of diltiazem in plasma was 3 ng/mL. The range of percentage of relative standard deviation (%RSD) was from 3.5 to 6.8% for within-day analyses and from 6.2 to 8.4% for between-day analyses, respectively. The extraction recoveries of diltiazem from spiked human plasma (n = 5) at three concentrations were 91.4-104.0%. The method has been used to determine diltiazem in human plasma samples from eight volunteers who had taken diltiazem hydrochloride slow release tables and the data obtained was fitted with a program on computer to study the pharmacokinetics. The results showed that the peak level in plasma approximately averaged 118.5 +/- 14.3 ng/mL at 3.1 +/- 0.4 h, and the areas under the drug concentration curves (AUC) was 793.1 +/- 83.1 ng.h/mL.     

Thermostability testing and degradation profiles of doxycycline in bulk, tablets, and capsules by HPLC

A high-performance liquid chromatography (HPLC) method for the quantitation of doxycycline in bulk, tablets, and capsules after storage at -20, 5, 25, 40, 50, 60, and 70 degrees C, has been developed and validated. The samples are eluted from a micro-Bondapak C8 column (4.6x150-mm, i.d., 5-microm particle size) at 27 degrees C, with a mobile phase of acetonitrile-water-THF (29.5:70:0.5, v/v/v), adjusted to pH 2.5 with 1.0M HCl. The flow rate is 1.0 mL/min and detection by UV is at 350 nm. The stability of doxycycline in bulk and in pharmaceuticals is checked over 90 days. Doxycycline shows thermo-degradation after exposure to high temperature; tablets are more stable than capsules. The shelf lives (t90%) are determined to be 1.00, 2.84, and 5.26 years in bulk, capsules, and tablets, respectively, at 25 degrees C. Metacycline and 6-epidoxycyline are identified as degradation products at high temperatures. Amounts of doxycycline, metacycline, and 6-epidoxycycline in all samples are determined by HPLC, and the results compare with those from micellar electrokinetic capillary chromatography. After 90 days, metacycline and 6-epidoxycyline are almost equal in test samples from standard bulk form, tablets, and capsules. It is 27.8+/-0.3%, 13.7+/-0.1%, and 18.8+/-0.2%, respectively.     

高效液相色谱法同时测定快安抗感冒液中5种组分的含量

 采用高效液相色谱法（HPLC）同时测定快安抗感冒液中对乙酰氨基酚、咖啡因、盐酸甲基麻黄碱、马来酸氯苯那敏和愈创木酚甘油醚的含量。色谱柱为NOVA－PAKC_18柱,流动相为V（已腈）：V（0．03mol／L磷酸氢二铵）：V（0．004mol／L庚烷磺酸钠）：V（三乙胺）=12：44：43．5：0．5,并用磷酸调节pH值至3．0;检测波长220nm,柱温35℃。在此色谱条件下,各组分均获得良好分离。平均回收率为98．0％～100．3％,相对标准偏差小于1．8％。     

Rapid identification and quantification of chlorpheniramine maleate or pheniramine maleate in pharmaceutical preparations by thin-layer chromatography-densitometry

Thin-layer chromatography (TLC)-densitometry was used to separate, identify, and quantitate chlorpheniramine maleate (CPM) and pheniramine maleate (PM) when present in combination with other drugs in pharmaceutical preparations of tablets, syrups, eye and ear drops, etc. CPM or PM was extracted (tablets, capsules, etc.) or diluted (liquid preparations, if needed) with 80% ethanol and isolated from other ingredients by TLC on silica gel G using cyclohexane-chloroform-methanol-diethylamine (4.5 + 4.0 + 0.5 + 1.0, v/v) as the mobile phase. Separated CPM and PM were detected under shortwave ultraviolet light and quantitated by scanning densitometry at 260 nm. Recoveries of CPM and PM were 100.09+/-0.77% and 100.09+/-0.87%, respectively.     

Cloud point extraction and simultaneous determination of zirconium and hafnium using ICP-OES

In the present study a simple versatile separation method using cloud point procedure for extraction of trace levels of zirconium and hafnium is proposed. The extraction of analytes from aqueous samples was performed in the presence of quinalizarine as chelating agent and Triton X-114 as a non-ionic surfactant. After phase separation, the surfactant-rich phase was diluted with 30% (v/v) propanol solution containing 1 mol l(-1) HNO3. Then, the enriched analytes in the surfactant-rich phase were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 3.4 x 10(-5) mol l(-1) quinalizarine, 0.1% (w/v) Triton X-114, 55 degrees C equilibrium temperature) the calibration graphs were linear in the range of 0.5-1000 mug l(-1) with detection limits (DLs) of 0.26 and 0.31 microg l(-1) for Zr and Hf, respectively. Under the presence of foreign ions no significant interference was observed. The precision (%RSD) for 8 replicate determinations at 200 microg l(-1) of Zr and Hf was better than 2.9% and the enrichment factors were obtained as 38.9 and 35.8 for Zr and Hf, respectively. Finally, the proposed method was successfully utilized for the determination of these cations in water and alloy samples.     

Complex formation of p-nitrocalix[6]arene with rare earth metal ions.

p-Nitrocalix[6]arene (CALX-N6, L) formed a 1:1 metal complex, ML, with light rare earth metal ions (M3+), such as La3+, Pr3+ and Nd3+ except Ce3+, but formed a 1:2 (M(3+):L) complex, ML2 (the charge of the complex is omitted) with heavy rare earth metal ions, such as Sm(3+)-Lu3+ including Y3+. The conditional stability constants of these 1:1 and 1:2 complexes, KML and KML2, were measured by a ligand displacement method using absorption spectrophotometry in 4% (v/v) acetone aqueous solution at pH 9.65 +/- 0.15 and 25 degrees C.