Comparison of infrared attenuated total reflection and Raman spectroscopy in the quantitative analysis of diclofenac sodium in tablets

The quantification of diclofenac sodium (DS) in tablets was performed using partial least squares (PLS) models based on FTIR ATR (Fourier transform infrared attenuated total reflection) and FT-Raman spectra. Separate calibration models were built for two groups of tablets, standard and sustained release, containing different excipients. To compare the predictive ability of these models the relative standard errors of prediction (RSEP) were calculated. In the case of DS determination from the Raman data, RSEP error values in the range of 2.4-2.8% (2.7-2.9%) for the calibration (validation) data sets were obtained. For ATR models constructed using spectra registered three times for each sample, RSEP errors in the range of 3.6-3.7% (4.2-4.3%) were found. These errors decreased to 2.8% (3.0%) when spectra collected six times were applied. Five commercial products containing 25, 50, 75 and 100 mg of DS per tablet were quantified. Concentrations derived from the elaborated models correlated strongly with the results of reference analyses and gave recoveries of 99.1-101.3% and 99.1-101.7% for the ATR and Raman data, respectively. Although both spectroscopic techniques can be used as fast and convenient alternatives to the standard pharmacopeial methods of DS quantification in solid dosage forms, in the case of the ATR technique, it is necessary to repeat measurements at least a few times to obtain acceptable quantification errors.     

Selective Spectrophotometric Determination of Oxyphenbutazone Using a Chelate Forming Reaction

Abstract

A selective spectrophotometric method for the determination of oxyphenbutazone is described. The method is based on nitrosation reaction and simultaneous formation of copper(II) or cobalt (II) chelate of the nitrosoderivative. The formed chelates are extractable with organic solvents giving yellow solutions whose absorbance are proportional to the concentration of oxyphenbutazone. In addition, the chelate extracts, upon treatment with diethyldithiocarbomate develop an additional indirect method of high selectivity for determining oxyphenbutazone. The developed methods are highly accurate and comparable with an official method.     

Spectropolarimetric Assay of Codeine Tablets and Cocaine Hydrochloride

Abstract

A rapid, simple and specific procedure for the simultaneous assay and determination of enantiomeric purity of pharmaceutical grade cocaine hydrochloride and codeine tablets is described. The procedure is as accurate, faster and more specific than the U. S. P. or N. F. methods.     

An HPLC Procedure for the Analysis of Furosemide in Pharmaceuticals-Analysis of Furosemide Tablets and Furosemide Injection

Abstract

A simple and specific procedure was developed for the analysis of furosemide from tablets and injections. The procedure consists of extracting furosemide into aqueous sodium hydroxide, addition of the internal standard, appropriate dilution and injection onto a u Bondapak C₁₈ reversed phase column. The mobile phase consisted of a solvent containing acetonitrile and aqueous sodium acetate and the eluate was monitored by either U.V. absorption or spectrofluorimetry. A standard linear calibration curve was obtained for direct standard solutions containing 75 ng to 500 ng on column. This procedure was successfully used to analyze furosemide tablets (individual assay) and injections.     

Fluorometric and Derivative Spectrophotometric Determination of Norfloxacin

The method for the direct determination of norfloxacin, without prior separation, in serum and pharmaceutical formulations, by means of fluorometry and second derivative u.v. spectrophotometry, was developed. Fluorometric assay of norfloxacin in serum was carried in 0.1 M HCl, with the adition of sodium-dodecylsulphate, at emission wavelength 450 nm (excitation 320 nm). Linear calibration curve was obtained in the concentration range 20 – 320 μg/L with the detection limit 2μg/L. The second derivative spectrophotometry was used for the determination of the norfloxacin in tablets at 337 nm using 0.05 M NaOH as solvent. Detection limit was 30μg/L.     

毛细管电泳法测定复方鱼腥草片中的绿原酸和槲皮素

建立了毛细管电泳法分析复方鱼腥草片中绿原酸和槲皮素的方法,通过研究缓冲溶液酸度和浓度、工作电压和进样时间的影响优化了分析条件。在优化的条件下,15min内实现了两种分析物质的良好分离。绿原酸和槲皮素峰高和质量浓度分别在0．05～0．80g／L和0．05～1．00g／L范围内成良好线性。基于迁移时间和峰高的重复性(RSD)分别为：绿原酸,1．91％和4．32％;槲皮素,2．30％和3．18％。绿原酸和槲皮素的检出限(S／N=3)分别为0．014g／L和0．015g／L。通过分析实际样品并做加样回收实验进一步验证了该方法的可行性。     

KPCA-聚类分析法和用便携式拉曼仪快速鉴别降糖药

对不同种类的降糖药片进行拉曼光谱的核主成分分析(KPCA)-聚类分析,实现快速、简便的鉴别。KPCA可以有效地避免主成分分析(PCA)只能处理线性问题和降维效果不明显的弊端。它通过一个非线性变换,首先将原变量空间映射到高维特征空间,然后在这个高维特征空间中进行线性主成分分析。采集得到的药片拉曼光谱的KPCA-聚类分析结果表明,采用KPCA提取特征变量的聚类结果比采用PCA提取特征变量后进行聚类分析的效果好,并且未经刮除表面包膜的降糖药片识别准确率为96.5%,经过刮除表面包膜处理的降糖药片的识别准确率为100%。便携式拉曼光谱仪结合该方法以其检测速度快、准确率高、使用简便、无样品前处理等显著优势,为药品的快速检验技术提供一种新的有效的鉴别手段。     

Spectrofluorimetric determination of levofloxacin in tablets, human urine and serum

A spectrofluorimetric method to determine levofloxacin is proposed and applied to determine the substance in tablets and spiked human urine and serum. The fluorimetric method allow the determination of 20–3000 ng ml⁻¹ of levofloxacin in aqueous solution containing acetic acid–sodium acetate buffer (pH 4) with λ_exc=292 and λ_em=494 nm, respectively. Micelle enhanced fluorescence improves the sensibility and allows levofloxacin direct measurement in spiked Human serum (5 μg ml⁻¹) and urine (420 μg ml⁻¹), in 8 mM sodium dodecyl sulphate solutions at pH 5.     

Study on the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug-delivery systems and tablets in rabbits by liquid chromatography-mass spectrometry

To evaluate the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug delivery systems (SMEDDS) and Yufengningxin tablets, a rapid and specific liquid chromatography--mass spectrometric method was developed and validated to determine puerarin in rabbit serum. The analyte was extracted from serum samples by precipitating the serum proteins, separated on a Diamonsil C(18) column and detected by mass spectrometry with an electrospray ionization interface. 4-Hydroxybenzaldehyde was used as the internal standard. The method has a limit of quantitation of 10 ng/mL using 200 microL serum. The intra-day relative standard deviations (RSDs) ranged from 3.7 to 6.9% and inter-day RSDs were within 6.5%. After administration of SMEDDS and tablets to rabbits, a significant difference was observed in main pharmacokinetic parameters of t(max), C(max) and AUC(0--infinity) between SMEDDS and tablets, and a 2.2-fold increase in the relative bioavailability of puerarin was observed with the SMEDDS compared with Yufengningxin tablets. It was concluded that the absorption of puerarin from Pueraria lobata isoflavone SMEDDS was enhanced.     

Capillary Electrophoretic Determination of Citalopram in Pharmaceutical Tablets and Serum

Determination of citalopram by capillary electrophoresis is described. Compounds were separated at 28 kV in 75 μm i.d. fused silica capillary tubing (total length 85 cm, effective length 65 cm) with 10 mM borate buffer, pH 8.5, containing 10% (v/v) methanol as running buffer. Citalopram and propylparaben (IS) appeared at 3.5 and 5.5 min, respectively. Repeatable linear results were obtained. The limits of detection and quantification were 5.73 × 10⁻⁶ and 1.72 × 10⁻⁵ M, respectively. When citalopram was determined in a pharmaceutical tablet by capillary electrophoresis and by a UV-spectrophotometric method differences between the results were not significant. The citalopram content of tablets was 100.8 ± 2.95% of the label claim. The amount found in serum was 26.7 ± 0.1% of the free drug, indicating that 73.3% of the drug was bound to protein.