HPLC determination of antithyroid drugs

An HPLC procedure was developed for determining 1-methylimidazoline-2-thione (MMI), 6-n-propyl-2-thiouracil (PTU), and 3-carbethoxy-1-methylimidazoline-2-thione (Carb) using a 150±4.0 mm column packed with Diasfer-110-C18 (5μm) in the elution with a mixture of acetonitrile and a phosphate buffer solution with pH 6.86 (25: 75). The substances were detected at the maximum absorbance: MMI, 254; PTU, 275; and Carb, 292 nm. The calibration curves were linear in concentration ranges of 0.34–114.17, 0.51–170.23, and 0.56–186.24 mg/L, and the detection limits were 0.29, 0.26, and 0.24 mg/L for MMI, PTU, and Carb, respectively. The procedure was tested in the analysis of a urine sample from a healthy human with additions of PTU and Carb. The analytes were pre-extracted from urine with ethyl acetate. The recovery of PTU and Carb was 70±2%; the detection limits in urine were 0.38 mg/L PTU and 0.35 mg/L Carb.     

HPLC determination of plasma taurine

Summary The taurine content in plasma was determined by high performance liquid chromatographic analysis of its dansyl derivative with fluorometric detection. After the reaction with dansyl chloride, the derivative was extracted from an aqueous mixture by using tetrabutylammonium as a counter-ion. The influences of different tetrabutylammonium salts and of the eluent mixture composition were studied. Omotaurine, added as the internal standard to the plasma samples, assured good reproducibility. The procedure was applied to the determination of taurine in specimens from different mammalian species.     

Improved HPLC determination of urinary neopterin

In order to improve the urinary neopterin measurement, the reversed-phase HPLC method has been reevaluated. The parameters which influence the chromatographic behavior of 12 pteridines were studied: nature of buffer, pH, ionic strength, addition of organic modifier to the mobile phase. Accordingly, an isocratic HPLC method is described which offers a good compromise between specificity and analysis time. This method is well-suited to automation in routine clinical laboratory use. Using this HPLC method, urinary neopterin related to creatinine was determined in lung diseases (neoplasm, sarco?dosis and bronchial asthma) and in kidney allografts. This method was shown to be useful in the diagnosis and in the monitoring of treatment of rejection episodes.     

Urinary phenylacetic acid determination by HPLC

Summary A high-performance liquid chromatographic method for urinary total phenylacetic acid (PAA) determination is reported for clinical diagnostic purpose in depressed patients.The urine samples are hydrolized in 6N HCl at 100°C. The hydrolized samples are then adsorbed on a C₈ reversed-phase extraction cartridge and eluted with 0.05 N NaOH. This solution is extracted on an anionexchange extraction cartridge and eluted with 0.1 M phosforic acid; the eluate is injected into HPLC and separated by reversed-phase liquid chromatography with ultraviolet detection at 225 nm. The extraction recovery is 93±2.8%, the retention time is 3.7 min and the PAA minimum detectable level is 4 mg/l.The normal value determined on 10 healthy subjects was 151.3±19.1 mg/day. Ten depressed subjects were investigated, and no difference in PAA excretion between normal and depressed subjects was observed. Also, the expected PAA enhancement in depressed subjects after treatment did not occur.     

HPLC determination of volatile phenols in wines

Summary An alternative to the traditional solvent extraction method used to extract and rapidly quantify ethyl-and vinylphenol and ethyl-and vinylgaiacol from wine is presented. The method is based on retention of volatile phenols on adsorbants. Among the tested resins, the most efficient, AG 2-X8 (anion exchange resin), worked as well with a synthetic solution as with wines. The percolation of clarified wine adjusted to pH 9 on this resin permits, in particular, the elimination of organic acids. Phenols are not eluted after rinsing the column with 1N HCl, but are eluted with methanol after this treatment. Good recovery (91 %) and good repeatability are observed. The eluate is directly analysed by HPLC on an RP18 column after two-fold dilution in water. The four volatile phenols were completely separated and detected by UV at 280 nm with high sensitivity (20–40 ppb). No interference with other compounds were noted in the different wines analysed.     

HPLC determination of majdine in Vinca herbacea

A reliable HPLC method coupled with DAD detection was developed and validated for determination of majdine in Vinca herbacea. The chromatographic separation was carried out on a Symmetry C18 column (250 mm x 4.6 mm, 5 microm, Waters) with an isocratic solvent system of 25 mM potassium phosphate buffer (pH = 3.0)-acetonitrile. UV detection was performed at 225 nm. Good linear behavior over the investigated concentration range was observed with the value of r2 > 0.9978. The method was reproducible with intra- and inter-day variations of less than 4.38%. The proposed method was linear, accurate, precise and specific. The validated method was successfully applied to quantify majdine in various parts of V. herbacea, which was collected during the flowering months of April and May. The results indicated that the developed HPLC method could be used for the quality control of V. herbacea and for the standardization of its extracts in majdine.     

HPLC determination and antihypertensive effect of metipamide

Summary Metipamide was monitored during a two month cap period of treatment to determine whether the wholeblood levels estimated by HPLC provide a relevant indicator of the possible accumulation of the drug., We also analysed antihypertensive activity and biochemical changes in blood of twenty hypertonic patients. Result showed that metipamide is an effective, first-line antihypertensive agent, combining statisfactory blood pressure reduction with low frequency of side effects and a simple once-daily dosage regime.     

Limits of determination and calibration in HPLC

Summary In HPLC calibration the expressions lowest calibration limit and determination limit are defined in statistical terms. The lowest calibration limit is the minimum mass in the measured series of calibration points. It is calculated from the confidence interval of the inverse of the calibration function as the lowest mass limit that may be differentiated from zero mass with a preset probability of error. If the calculated lowest calibration limit is lower than the actual data, points at lower concentration may be measured. The determination limit is the smallest concentration of an analysis that is differentiated from the concentration zero or an apparent blind value in the calibration curve with a given probability of error.Using two different UV-detectors (variable wavelength and photodiode-array) the lowest calibration limit is experimentally evaluated and compared with specific data for the detectors.Dedicated to Prof. Dr. E. Bayer, Tübingen on ocassion of his 60th birthday.     

反相高效液相色谱法测定兔血浆中的灯盏乙素

建立一种测定兔血浆中灯盏乙素浓度的高效液相色谱法.以芦丁为内标,采用甲醇沉淀蛋白法对血浆样品进行预处理.HPLC色谱柱为Kromasil C18柱(4.6 mm×250 mm,5 μn),流动相为水(用醋酸调pH 3.0)-乙腈(7822),检测波长335 nm,流速1.0 mL/min,柱温为室温;本法的线性范围为0.025～4μg/mL,最低定量浓度为0.025 μg/mL;方法回收率为95.9%～104.8%,日内RSD为1.9%～7.3%,日间RSD为1.9%～8.9%.方法学评价结果表明本方法灵敏、准确,操作简便,可用于深入研究灯盏乙素在动物体内的药代动力学过程.     

HPLC determination of the aromatic fraction of gasoline

Summary This work reports a rapid and easy procedure for the analysis of the aromatic fraction in gasoline. No sample pretreatment is required, since the gasoline is diluted in methanol and directly injected into a liquid chromatograph. A spectrophotometer detector and a spectrofluorimeter detector are used in series. The procedure has been applied to a large number of Italian and European refined gasoline samples.Dedicated to Prof. Dr. A. Liberti on the occasion of his 70th birthday.     

HPLC determination of ferrochelatase activity in human liver

A method utilizing HPLC to estimate ferrochelatase activity in human liver cells is presented. A partially purified homogenate of liver cells is incubated with mesoporphyrin IX and cobalt(II)ion. The ferrochelatase in the homogenate incorporates the cobalt(II)ion into the mesoporphyrin. After a fixed time (90 min) the porphyrins are extracted into an ethyl acetate-acetic acid mixture. The porphyrins are then separated using reversed phase HPLC with a mobile phase of methanol-acetonitrile-phosphate buffer pH 3.0 (200:60:30 v/v). The enzyme activity is estimated by measuring the rate of utilization of mesoporphyrin. The optimum pH and substrate concentration for the reaction have been determined.     

HPLC determination of polyamines in the femtomole range

A new method for the chromatographic determination of polyamines is presented. The procedure consists of the reaction of 9-fluorenylmethyl chloroformate (FMOC-Cl) with polyamines at 50 +/- 1 degrees C for 10 min, followed by stepwise elution chromatography. The reaction is simple and the derivatives are stable. All the polyamine-FMOC derivatives can be separated within 13 min. The linearity of this method is satisfactory in the range of 0.5-100 pmol. The detection limits for putrescine, cadaverine, spermidine and spermine are 83.3 fmol, 109 fmol, 25.5 fmol and 22.7 fmol respectively.     

有机脱模剂中多环芳烃的高效液相色谱测定

建立了有机硅类和金属皂类脱模剂中多环芳烃的高效液相色谱测定方法。方法所用色谱柱为多聚C18(LC-PAH)柱,流动相为乙腈/水,采用梯度淋洗方式,开始时为体积分数40%乙腈,28min后变为82%乙腈,48min后变成100%乙腈,保持8min。方法的线性范围为0.10~200mg/L,线性相关系数为0.9993~1.0000,平均回收率分别为68.55%~101.2%(有机硅类)和75.29%~99.89%(金属皂类),精密度RSD分别为1.6%~8.1%(有机硅类)和1.8%~6.8%(金属皂类),检出限(S/N=3)分别为0.05~0.10mg/L(有机硅类)和0.05~0.20mg/L(金属皂类)。该方法可以满足有机硅类和金属皂类脱模剂中多环芳烃的检测要求。     

HPLC method for determination of cefuroxime in plasma

Summary This paper describes an HPLC method for the determination of cefuroxime in human plasma. The method uses solid phase extraction (SPE) and has acceptable sensitivity, precision and accuracy. The limit of quantification in plasma samples is 0.1 μg mL⁻¹. Calibration curves were linear within 0.1–20 μg mL⁻¹, with mean correlation coefficient of 0.9982. Mean inter day precision and accuracy were 7.8% and 6.4%, respectively. The method was applied to determine cefuroxime levels in patients receiving cefuroxime, 3 time per day.     

HPLC法测定虎舌红药物中的去氢飞廉碱

建立了测定虎舌红药物中喹唑酮类生物碱的HPLC方法。色谱柱为Diamonsil C18柱(250 mm×4.6 mm i.d.,5μm),流动相为V(0.2%三乙胺溶液)∶V(乙腈)=35∶65;检测波长:345 nm;流速:1.0 mL/min。结果表明,喹唑酮类生物碱可以得到有效的分离,去氢飞廉碱在0.02~0.15μg间呈线性关系(r=0.9995)。     

HPLC determination of phenylpropanolamine in pharmaceutical OTC preparations

A convenient HPLC method to determine phenylpropanolamine (PPA) in addition to phenylephrine (PE) and chlorpheniramine (CPA) in commercially available over-the-counter (OTC) preparations has been developed. Sample solutions were prepared by dilution with water or methanol followed by filtration and direct injection into the HPLC system. The mobile phase was a mixture of methanol-acetonitrile-acetic acid (0.1 M)-triethylamine (20:20:60:0.6, v/v/v/v) containing sodium heptanesulfonate (0.5 mM) as an ion pair. The separation was achieved on a reversed-phase ODS column with detection wavelength set at 254 nm. The compounds showed good linearity in the range 2.5-1000 micro M with detection limits ranged from 0.13 to 0.48 micro M. PE, caffeine and CPA were well separated when present together with PPA. The method was applied to the determination of PPA in pharmaceutical preparations including hard and soft capsules.     

HPLC determination of clenbuterol in pharmaceutical gel formulations

A quick, accurate, reproducible high performance liquid chromatographic (HPLC) method for the determination of clenbuterol in the presence of some common pharmaceutical preservatives (i.e., methyl and propyl paraben) is described. The method is specific enough to separate and determine clenbuterol in the presence of degradation products of the formulation components. Extraction of interfering formulation components provides the necessary clean-up to determine clenbuterol via HPLC.