Simultaneous determination of albiflorin and paeoniflorin in rat urine by solid-phase extraction and high-performance liquid chromatography following oral administration of Si-Wu decoction

A high performance liquid chromatographic method (HPLC), together with solid phase extraction (SPE), was developed for simultaneous determination of albiflorin and paeoniflorin in rat urine after oral administration of Si-Wu decoction. The samples were pretreated with solid phase extraction using Extract-Cleantrade mark cartridges. Analysis of the extract was performed on a reversed-phase C18 column and a mobile phase made up of acetonitrile and 0.03% formic acid (17:83, v/v). UV detection was set at 230 nm. The assay was linear over the range 2.625-52.50 mg/mL for albiflorin and 3.875-77.50 microg/mL for paeoniflorin. The average percentage recoveries of three spiked urines were 97.01 +/- 3.32 and 102.32 +/- 6.97 for albiflorin and paeoniflorin, respectively. The intra-day precision (RSD) ranged from 0.21 to 1.79% at concentrations of 4.20, 10.50, 26.25 and 39.375 microg/mL of albiflorin and 0.12 to 2.92% at concentrations of 3.875, 10.85, 23.25 and 58.125 microg/mL of paeoniflorin, and inter-day precision (RSD) was from 1.02 to 1.86% for albiflorin and 0.94 to 3.30% for paeoniflorin, at the same four concentrations. This method was applied in order to analyze albiflorin and paeoniflorin in rat urine following oral administration of traditional Chinese medicinal preparation of Si-Wu decoction.     

Determination of picroside II in dog plasma by HPLC and its application in a pharmacokinetics study

A sensitive and simple high-performance liquid chromatography method with UV detection was developed and validated for determining picroside II in dog plasma. Paeoniflorin was employed as internal standard and the sample pre-treatment procedure consists of deproteinization by addition of acetonitrile. Chromatographic separations were performed on a Shimadzu VP-ODS column (250 x 4.6 mm i.d., 5 microm). The mobile phase consisted of acetonitrile-0.1% acetic acid aqueous (v/v), 23:77, v/v, at a rate of 1 mL/min. Detection was carried out at a wavelength of 266 nm. Calibration standards ranged from 0.25 to 500 microg/mL in dog plasma and the mean correlation coefficient of 0.9981 was found for the linear calibration curves (n = 6). The limit of quantification (LOQ) was 0.25 microg/mL. Intra- and inter-assay RSD ranged from 0.70 to 7.5%. Accuracy (%bias) ranged from -6.3 to 6.0%. This method was applied to the pharmacokinetic study of picroside II in dogs. The study demonstrated the plasma picroside II concentration-time curves were fitted to the two-compartment open model and showed linear pharmacokinetics.     

A validated method for analysis of chromium picolinate in nutraceuticals by reversed phase high performance liquid chromatography

A validated high performance liquid chromatographic method was developed for the determination of chromium picolinate in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed-phase Supelcosil LC-18 (250 x 4.6 mm, 5 microm) column. The mobile phase consisted of acetonitrile:water (40:60 v/v) at a fl ow rate of 0.8 mL/min. The UV-detector was set at 264 nm. The developed method showed a good linear relationship in the concentration range from 0.125 to 12.5 microg/mL with a correlation coefficient from 0.999. The limit of detection and limit of quanti fi cation were 0.091 and 0.181 microg/mL, respectively.     

Simultaneous determination of rifampicin and sulbactam in mouse plasma by high-performance liquid chromatography

A simple and rapid high-performance liquid chromatographic (HPLC) method with ultraviolet detection has been developed and validated for the simultaneous determination of rifampicin and sulbactam in mouse plasma. Plasma samples were deproteinized with acetonitrile and separated by HPLC on a RP-18 (125 x 4 mm, 5 microm) column and gradient elution with potassium dihydrogen phosphate solution (pH 4.5; 50 mm) and acetonitrile at a flow-rate of 1.0 mL/min. Rifampicin and sulbactam were monitored at 230 nm and confirmed by means of their UV spectra using a diode-array detector. The method was linear at plasma levels from 1 to 100 microg/mL for rifampicin and from 5 to 200 microg/mL for sulbactam. The limits of quantification were 0.6 microg/mL for rifampicin and 4.2 microg/mL for sulbactam. The intra- and inter-day precisions of the method (RSD) were lower than 5% for both compounds. Average recoveries of rifampicin and sulbactam from mice plasma were 98.2 and 89.3%, respectively. The developed method was successfully applied to the determination of the pharmacokinetic profile of both compounds in mice.     

An improved high-performance liquid chromatographic method with a solid-phase extraction for the determination of piperacillin and tazobactam: application to pharmacokinetic study of different dosage in Chinese healthy volunteers

An improved HPLC method was developed for the determination of piperacillin and tazobactam in human plasma and pharmacokinetic study in Chinese healthy volunteers. Piperacillin and tazobactam in human plasma were extracted by solid-phase extraction and separated on a C(18) column and detected at 220 nm. The mobile phase for piepracillin consisted of 0.01 mol/L sodium dihydrogen phosphate (pH = 4.65) and acetonitrile (71:29, v/v), and that for tazobactam was 0.05 mol/L sodium dihydrogen phosphate (pH = 4.45) and methanol (90:10, v/v). The method was linear in the range 0.25-320.00 microg/mL for piperacillin (r(2) = 0.995) and 0.25-64.00 microg/mL for tazobactam (r(2) = 0.994). The lower limit of quantification of both compounds was 0.25 microg/mL. The intra- and inter-day precisions of piperacillin and tazobactam at three concentrations were all less than 9.2% and accuracies were within the range 97.0-108.0%. The method was used to investigate the pharmacokinetics of piperacillin and tazobactam in 12 volunteers who were intravenously given a dosage of 1.25, 2.50 and 3.75 g in three periods. The results showed that piperacillin sodium-tazobactom sodium (4:1) for injection in Chinese people fits linear dynamics, and the administred dosage can be adjusted with therapeutic effect.     

High performance liquid chromatographic method for the determination and pharmacokinetic studies of oxyresveratrol and resveratrol in rat plasma after oral administration of Smilax china extract

A sensitive and simple HPLC method has been developed and validated for the determination of oxyresveratrol (trans-2,4,3',5'-tetrahydroxystilbene, OXY) and resveratrol (trans-3,5,4'-trihydroxystilbene, RES) in rat plasma. The plasma samples were extracted with ethyl acetate and analyzed using HPLC on an Aglient Zorbax SB-C(18) column (250 x 4.6 mm, 5 microm) at a wavelength 320 nm, with a linear gradient of (A) acetonitrile and (B) 0.5% aqueous acetic acid (v/v), at a flow rate of 1.0 mL/min. The method was linear over the range of 0.1265-25.3 microg/mL for OXY and 0.117-23.4 microg/mL for RES. The extraction recovery for OXY, RES and internal standard ranged from 71.1 to 88.3%. The intra- and inter-day precisions were better than 10%, and the accuracy ranged from 89 to 108%. The validated method was used to study the pharmacokinetic profiles of OXY and RES in rat plasma after oral administration of Smilax china root extract.     

Stress degradation studies and kinetic determinations of duloxetine enteric-coated pellets by HPLC

A stability-indicating HPLC assay method was developed for the quantitative determination of duloxetine (DLX) in a pharmaceutical dosage form in the presence of its degradation products, and kinetic determinations were evaluated in acid conditions and UV-C radiation exposure. Chromatographic separation was achieved by use of an ACE C18 column (250 x 4.0 mm id, 5 microm particle size). The mobile phase was prepared by mixing aqueous 50 mM potassium phosphate buffer (pH 6.0 containing 0.3% triethylamine) and acetonitrile (60 + 40, v/v). DLX was rapidly degraded in an acid medium and in the presence of hydrogen peroxide and UV-C radiation; it was more stable in alkaline medium. The described method was linear over a range of 4.0-14.0 microg/mL for determination of DLX (r = 0.9998). The precision was demonstrated by the RSD of intraday (0.79-1.07%) and interday (0.85%) studies. The mean recovery was found to be 100.56%. The acid degradation of DLX in 0.1 M HCI solution showed an apparent zero-order kinetics (k = 0.177 microg/mL/min), and the photodegradation demonstrated an apparent first-order kinetics (k = 0.082 microg/mL/min). The developed method was found to be simple, specific, robust, linear, precise, and accurate for the determination of DLX in enteric-coated pellets.     

Simultaneous determination of glucose, 1,5-anhydro-d-glucitol and related sugar alcohols in serum by high-performance liquid chromatography with benzoic acid derivatization

A new, simple and sensitive pre-column high-performance chromatographic method for the determination of diabetes marker d-glucose, 1,5-anhydro-d-glucitol and related compounds is reported. Sugars (d-glucose, d-galactose, d-mannose, sucrose and arabinose) were derivatized with benzoic acid (BA) at 80 degrees C for 60 min. l-Fucose, fructose, d-lactose, l-rhamnose, arabinose and ascorbic acid were not reacted. Sugar alcohols (xylitol, erythritol, mannitol, sorbitol myo-inositol) were also derivatized with BA at 80 degrees C for 60 min. The fluorescence derivatives were separated on a TSK amide 80 column (4.6 mm i.d. x 250 mm, 5 microm) with acetonitrile-50 mm acetate buffer (pH 5.6; 4:96, v/v) as the mobile phase. The detection wavelength of beizoic acid derivatives was lambda(ex) 275 nm and lambda(em) 315 nm. The detection limits of sugars were 10-80 microg/mL. The calibration graphs were linear up to 10 mg/mL. The relative standard deviations of 500 microg/mL sugars were 7.0-7.3%. The proposed method was compared with the enzymatic photometric glucose analysis method (Glucose B-Test II Wako). The correlation coefficient was 0.83 (n = 20) and y = 0.82x + 5.91, where y and x are concentrations in microg/mL obtained by the proposed pre-column HPLC and enzyme-photometric method, respectively. The detection limits of sugar alcohols were 100-1000 ng/mL. The calibration graphs were linear to 50 microg/mL and relative standard deviations of 10 microg/mL were 7.2-8.2%. The 1,5-AG data by the proposed method was also compared with the enzymatic photometric 1,5-AG analysis method (Rana AG 1,5-AG determination kit, Nihon Kayaku) and good correlation (r = 0.91, n = 20) was also obtained. The proposed method was applied to the simultaneous determination of d-glucose, 1,5-AG and related sugar alcohols in serum from healthy males.     

Simultaneous quantification of chlorogenic acid and caffeic acid in rat plasma after an intravenous administration of mailuoning injection using liquid chromatography/mass spectrometry

A simple, rapid and sensitive method was developed for the simultaneous quantification of chlorogenic acid (CGA) and caffeic acid (CA) in rat plasma using a high-performance liquid chromatography system coupled to a negative ion electrospray mass spectrometric analysis. The plasma sample preparation was a simple deproteinization by the addition of two volumes of acetonitrile followed by centrifugation. The analytes and internal standard ferulic acid were separated on an Intersil C8-3 column (5 mm; 250 x 2.1 mm) with acetonitrile/0.05% triethylamine solution (70:30, v/v) as mobile phase at a flow rate of 0.2 mL/min with an operating temperature of 30 degrees C. Detection was performed on a quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operated in selected ion monitoring (SIM) mode. Negative ion ESI was used to form deprotonated molecules at m/z 353 for chlorogenic acid, m/z 179 for caffeic acid, and m/z 193 for the internal standard ferulic acid. Linear detection responses were obtained for CGA concentrations ranging from 0.005 to 2.0 microg/mL and for CA concentrations ranging from 0.010 to 2.0 microg/mL and the lower limits of quantitation (LLOQs) for CGA and CA were 0.005 and 0.01 microg/mL, respectively. The intra- and inter-day precisions (RSD%) were within 9.0% for both analytes. Deviation of the assay accuracies was within +/-10.0% for both analytes. Their average recoveries were greater than 88.0%. Both analytes were proved to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to the pharmacokinetic study of CGA and CA following an intravenous dose of 5 mL/kg mailuoning injection to rats.     

Simultaneous determination of phenytoin and dextromethorphan in urine by solid-phase extraction and HPLC-DAD

A rapid and simple high-performance liquid chromatographic method with photodiode array detection was developed for the separation and the simultaneous determination of phenytoin and dextromethorphan in human urine. Analysis was performed in less than 4.5 min in isocratic mode on a reversed-phase C18 column (5 microm; 150 x 4.6 mm) using a mobile phase composed of acetonitrile-buffer phosphate 0.01 M (60:40, v/v) adjusted to pH 6.0, at 1 mL/min flow rate and UV absorbance at 210 nm. The elution order of analytes was dextromethorphan (DXM), Internal Standard (IS), and phenytoin (PHT). Calibration curves were linear in the 7.5-25 microg/mL range for PHT and in the 10-30 microg/mL range for DXM. Spike recoveries for urine samples prepared at three spiking levels ranged from 97.8 to 102.3% for PHT and from 94.8 to 100.4% for DXM. The detection limit (LOD) values ranged from 0.08 microg/mL for PHT to 0.5 microg/mL for DXM. The quantitation limit (LOQ) values ranged from 0.3 microg/mL for PHT to 1.6 microg/mL for DXM. The sample preparation method involves a rapid and simple procedure based on solid-phase extraction using a C18 reversed-phase column. Validation of the optimised method was carried out according to the ICH guidelines. The method developed in this study allows the reliable simultaneous analysis of PHT and DXM, drugs that were never quantified together in previously reported analytical methods. The described method has the advantage of being rapid and easy and it could be applied in therapeutic monitoring of these drugs in human urine of epileptic patients.     

反相高效液相色谱法分离测定墨旱莲中的鳢肠醛

对墨旱莲中的有效成分鳢肠醛进行了分离和结构鉴定,并对其含量进行了分析。色谱条件:Kromasil C18柱(200 mm×4.6 mm,5 μm),流动相为乙腈-0.1%磷酸水溶液(体积比为65∶35),流速为1.0 mL/min,柱温为30 ℃,检测波长为365 nm,进样量为10 μL。结果表明,鳢肠醛的峰面积与其质量浓度有良好的线性关系(r=0.9993)。方法的加样回收率为96.7%～100.0%。该方法简便、快速、准确,可作为墨旱莲质量控制的一个有效方法。     

AQC柱前衍生化RP-HPLC法测定蒜氨酸及其有关物质的含量

采用6-氨基喹啉-N-(羟基琥珀酰亚胺基)氨基甲酸酯(6-aminoquinolyl -N- Hydroxysuccinimide Carbamate ,AQC)为柱前衍生化试剂,建立了AQC柱前衍生化RP-HPLC法测定蒜氨酸及其有关物质的含量。该衍生化方法反应瞬间完成,衍生化产物稳定。色谱条件为：Kromasil C18柱（250mm×4.6mm,5mm）,流动相A为0.1%乙酸铵(含0.03%乙酸),流动相B为水-乙腈（40∶60）,线性梯度洗脱,流速1.0ml/min,检测波长248nm。蒜氨酸在1.1719~1500μg /ml浓度范围内线性关系良好（r=0.9998）, 日内、日间精密度良好(RSD <1.8%,n=5), 加样回收率为99.1%（RSD1.9%,n=5）,检测限为3ng,该方法准确、方便、快速。     

Biological assay and liquid chromatographic method for analysis of moxifloxacin in tablets

A microbiological assay and a liquid chromatographic method were validated for quantitation of moxifloxacin in tablets. The microbiological method consisted of a cylinder-plate agar diffusion assay using Micrococcus luteus ATCC 9341 as the test microorganism and phosphate buffer (0.1M, pH 8.0) as the diluent solution. The response graphs for standard and sample solutions were linear (r = 0.9479), and no parallelism deviations were detected in the tested levels of concentration (4.0, 8.0, and 16.0 microg/mL). The interday precision was 2.73%. Recovery values were between 96.25 and 100.5%. The chromatographic analyses were performed using a Shim-pack CLC-ODS column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of (A) a mixture of phosphoric acid (0.17%, v/v) with tetramethylammonium hydroxide (0.05M) and acetonitrile (95 + 5, v/v) and (B) methanol (55 + 45, v/v) adjusted to pH 3.0. The flow rate was 1.0 mL/min, and detection was made at 294 nm. The method was linear in a range from 12.0 to 42 microg/mL (r = 0.9999), and the interday precision was 1.39%. Recovery ranged between 101.9 and 103.81%. Both validated methods were used to quantify the moxifloxacin content in tablets exposed to ultraviolet radiation, and similar results were obtained.     

Development and validation of a rapid reversed-phase HPLC method for the determination of insulin from nanoparticulate systems

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of insulin in nanoparticulate dosage forms. Its application for the development and characterization of insulin-loaded nanoparticulates composed of polyelectrolytes has also been carried out. A reversed-phase (RP) C18 column and gradient elution with a mobile phase composed of acetonitrile (ACN) and 0.1% aqueous trifluoroacetic acid (TFA) solution at a flow rate of 1 mL/min was used. Protein identification was made by UV detection at 214 nm. The gradient changed from 30:70 (ACN:TFA, v/v) to 40:60 (v/v) in 5 min followed by isocratic elution at 40:60 (v/v) for a further five minutes. The method was linear in the range of 1-100 microg/mL (R2 = 0.9996), specific with a good inter-day and intra-day precision based on relative standard deviation values (less than 3.80%). The recovery was between 98.86 and 100.88% and the detection and quantitation limits were 0.24 and 0.72 microg/mL, respectively. The method was further tested for the determination of the association efficiency of insulin to nanoparticulate carriers composed of alginate and chitosan, as well as its loading capacity for this protein. Encapsulant release under simulated gastrointestinal fluids was evaluated. The method can be used for development and characterization of insulin-loaded nanoparticles made from cross-linked chitosan-alginate.     

Simultaneous determination of the bioactive components in rat plasma by UPLC‐MS/MS and application in pharmacokinetic studies after oral administration of radix Scutellariae extract

A highly sensitive and rapid ultraperformance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method has been developed and validated for simultaneous quantification of the four main bioactive compounds, i.e. baicalin, baicalein, wogonoside and wogonin, in rat plasma after oral administration of Radix Scutellariae extract. Clarithromycin was used as an internal standard (IS). Plasma samples were processed by protein precipitation with methanol. The separation was performed on an Acquity BEH C₁₈ column (100 × 2.1 mm, 1.7 μm) at a flow rate of 0.4 mL/min, using 0.1% formic acid–acetonitrile as mobile phase. The MS/MS ion transit ions monitored were 447.5 → 270.1 for baicalin, 270.1 → 168.1 for baicalein, 461.2 → 284.0 for wogonoside, 284.2 → 168.1 for wogonin and 748.5 → 158.1 for IS. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantification (LLOQ) achieved was 1.13 ng/mL for baicalin, 1.23 ng/mL for baicalein, 0.82 ng/mL for wogonoside and 0.36 ng/mL for wogonin. The calibration curves obtained were linear (r > 0.99) over the concentration range ~ 1–1000 ng/mL. The intra‐ and inter‐day precision was <15% and the accuracy was within ±14.7%. After validation, this method was successfully applied to a pharmacokinetic study of Radix Scutellariae extract.     

Monitoring of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine by high-performance liquid chromatography after pre-column derivatization with glyoxal reagents

A new, simple and sensitive pre-column fluorescence derivatization high-performance liquid chromatographic method for the determination of the oxidative DNA stress marker, 8-oxo-7,8-dihydro-2'-deoxyguanosine, was developed. Solid-phase extraction using an Oasis HLB cartridge avoided troublesome sample preparation steps, interference from charged species and frequent and essential electrode maintenance in electrochemical procedures. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and other guanine compounds were selectively derivatized with glyoxal reagents (phenylglyoxal, 3,4-methylenedioxyglyoxal, 2-naphtylglyoxal and 6-methoxynaphthylglyoxal) at 40-60 degrees C. Derivatization with 6-methoxynaphthylglyoxal at 40 degrees C for 30 min gave the strongest fluorescence product. The fluorescence derivatives from reaction with 6-methoxynaphthylglyoxal were separated on a Capcell Pak C18 SG 120A column (4.6 mm i.d. x 150 mm, 5 microm) with acetonitrile-5 mM phosphate buffer (pH 6.0; 3:7, v/v) as mobile phase. The detection wavelength of the fluorescence derivative of 8-oxo-7,8-dihydro-2'-deoxyguanosine was lambda(ex) 400 nm and lambda(em) 510 nm. The detection limit of 8-oxo-7,8-dihydro-2'-deoxyguanosine was 1 ng/mL using 50 mL of urine. The calibration graphs were linear up to 30 microg/mL for 8-oxo-7,8-dihydro-2'-deoxyguanosine. The relative standard deviation of 20 ng/mL of 8-oxo-7,8-dihydro-2'-deoxyguanosine was 7.0%. The proposed method was compared with the enzymatic ELISA 8-oxo-7,8-dihydro-2'-deoxyguanosine analysis method (8-OH-dG Check, JaICA, Shizuoka, Japan). The correlation coefficient was 0.79 (n = 20) and y = 0.85x + 5.34. The proposed method was applied to the monitoring of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine from male heavy smokers.     

HPLC method for the determination and pharmacokinetic studies on geniposide in rat serum after oral administration of traditional Chinese medicinal preparation Yin-Zhi-Ku decoction

A new HPLC method for the determination of geniposide in rat serum with solid-phase extraction (SPE) for preconcentration is described. Geniposide and an internal standard (paeoniflorin) were extracted from serum by SPE using C18 cartridges. Analysis of the extract was then performed on a reversed-phase C18 column using acetonitrile-water (16:84, v/v) as the eluting solvent system, and UV detection at 238 nm was used to measure the analyte with a limit of quantitation about 0.1 microg/mL. The calibration curve for geniposide was linear (r = 0.9993) in the concentration range 0.1-16.0 microg/mL. The intra- and inter-day precision of the geniposide were determined and their RSD did not exceed 10%. The validated method has been successfully applied for pharmacokinetic studies of geniposide from rat serum after oral administration of Yin-Zhi-Ku decoction.     

Quantification of myrislignan in rat plasma by solid-phase extraction and reversed-phase high-performance liquid chromatography

A rapid and simple reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for determination of myrislignan in rat plasma after intravenous administration. The analytes extracted from plasma samples by solid-phase extraction were successfully carried out on a Diamonsiltrade mark ODS C(18) column (250 x 4.6 mm i.d., 5 microm) with an RP(18) guard column (8 x 4.6 mm i.d., 5 microm) and a mobile phase of MeOH-H(2)O (4:1, v/v). The UV detector was set at a single wavelength of 270 nm. The linear ranges of the standard curves were 0.5-30.0 microg/mL with the correlation coefficients greater than 0.9992. The lower limits of detection and quantification were 0.1 and 0.3 microg/mL for myrislignan. Intra- and inter-day precisions were 2.4-7.5 and 1.3-5.7%, respectively. The extraction recovery from plasma was more than 90%. This assay method has been successfully used to study the pharmacokinetics of myrislignan in rats.     

Simultaneous determination of hydroxysafflor yellow A and ferulic acid in rat plasma after oral administration of the co-extractum of Rhizoma chuanxiong and Flos Carthami by HPLC-diode array detector

A simple, rapid and accurate HPLC method has been developed for simultaneous determination of hydroxysafflor yellow A and ferulic acid in rat plasma after oral administration of the co-extractum of Rhizoma chuanxiong and Flos Carthami. Plasma samples were deproteinized with 6% perchloric acid, and riboflavin was used as internal standard. The supernatant after centrifuge was injected into a Shimadzu C(18) (150 x 4.6 mm, i.d. 5 microm) column. Gradient elution for A:B (0 min, 90:10; 25 min, 70:30; 27 min, stop) was applied. The mobile phase was composed of 0.022 mol/L potassium dihydrogen phosphate solutions, adjusted to pH 3.0 with phosphoric acid for pump A, and 90% (v/v) acetonitrile for pump B. The assay was shown to be linear over the range 0.046-4.6 microg/mL (r(2) = 0.9995) for hydroxysafflor yellow A and 0.037-3.7 microg/mL (r(2) = 0.9998) for ferulic acid. Mean recovery was 97.5% for hydroxysafflor yellow A and 83.6% for ferulic acid. Both of the intra-day and inter-day precisions were 相似文献