Variation in likelihood ratios for forensic evidence evaluation of XTC tablets comparison

In forensic comparison casework, where it is investigated whether items are from the same source, the likelihood ratio (LR) is a measure for evaluating the strength of evidence of the observed (dis)similarity between these items. The paper concentrates on evaluation of various LR models for comparison of XTC tablets from different production batches. Starting from a two‐level random effect model, where means are considered random, the distribution of these means may be assumed normal or approximated by kernel density estimations (KDEs), and variation in the data may or may not be allowed to differ per batch. It is investigated what effect the corresponding model and estimation choices have on the distribution of LRs for same‐ and different‐batch comparisons. Copyright © 2010 John Wiley & Sons, Ltd.     

高效液相色谱法同时测定多维元素片中9种水溶性维生素

采用更简便的流动相体系,建立了高效液相色谱法同时测定多维元素片中9种水溶性维生素的快速分析方法。以酸水解与离心的方法处理样品,用C8柱分离,流动相A为0.1%三氟乙酸的水溶液,B为甲醇,梯度洗脱,二极管阵列检测器(DAD)检测。28min内实现了9种水溶性维生素的同时分离测定。各维生素线性关系、精密度、回收率均良好。并使用美国国家标准技术研究院(NIST)的SRM3280多维元素片标准物质对方法进行了确认,运用此法测定了市售多维元素片中的水溶性维生素含量。该法可作为维生素片剂中水溶性维生素分离测定的质控方法。     

Pharmaceutical polymorphs quantified with transmission Raman spectroscopy

The quantification of polymorphs in dosage forms is important in the pharmaceutical industry. Conventional Raman spectroscopy of solid‐state pharmaceuticals may be used for this, but it has some limitations such as sub‐sampling and fluorescence. These problems can be mitigated through the use of transmission Raman spectroscopy (TRS). The efficacy of TRS measurements for the prediction of polymorph content was evaluated using a ranitidine hydrochloride test system. Four groups of ranitidine hydrochloride‐based samples were prepared: three containing form I and II ranitidine hydrochloride and microcrystalline cellulose (spanning the ranges 0–10%, 90–100% and 0–100% form I fraction of total ranitidine hydrochloride), and a fourth group comprising form I ranitidine hydrochloride (0–10%) spiked commercial formulation. Transmission and conventional Raman spectroscopic measurements were recorded from both capsules and tablets of the four sample groups. Prediction models for polymorph and total ranitidine hydrochloride content were more accurate for the tablet than for the capsule systems. TRS was found to be superior to conventional backscattering Raman spectroscopy in the prediction of polymorph and total ranitidine hydrochloride content. The prediction model calculated for form I content across the 0–100% range was appropriate for process control [ratio of prediction to deviation (RPD) equal to 14.62 and 7.42 for tablets and capsules, respectively]. The 10% range calibrations for both form I and total ranitidine hydrochloride content were sufficient for screening (RPDs greater than 2.6). TRS is an effective tool for polymorph process control within the pharmaceutical industry. Copyright © 2011 John Wiley & Sons, Ltd.     

Cyclodextrin polymers in the pharmaceutical industry

The potential applications of cyclodextrin polymers (soluble and insoluble ones) in the pharmaceutical industry are reviewed. The soluble polymers are good solubilizers of drugs thus enhancing their bioavailability. When applied topically the insoluble bead polymer accelerates the healing of burns and ulcers. It can also be used for chromatography and to remove certain components from mixtures. The insoluble ground polymer is an effective tablet disintegrant in direct compression systems as well as in formulations made by wet granulation.Lecture, presented at the meeting Anwendungsmöglichkeiten von Cyclodextrin in der pharmazeutischen Industries, Berlin, 21/22 September 1987.     

Resolution of overlapping capillary electrophoresis peaks by using chemometric analysis: quantification of the components in compound reserpine tablets

The application of multivariate curve resolution with alternating least squares (MCR-ALS) methods to second-order data from capillary electrophoresis with diode array detector (CE-DAD) is reported. Initial qualitative solutions obtained by evolving factor analysis (EFA) and pure-variable detection method can be further optimized by a simultaneous analysis of multiple electrophoresis run data with ALS regression. While unknown samples are analyzed simultaneously against the corresponding standards in different composition ratios, the exact amounts of common components in different CE runs can be determined by the traditional calibration curve method, and quantification can thus be achieved. The above methods are applied to the determination of the components in compound reserpine tablets in overlapping peaks from CE. The quantification results are compared with those of the first derivative of the electropherogram method and artificial neural network (ANN) method.     

Rapid titrimetric and spectrophotometric assay methods for the determination of lamivudine in pharmaceuticals using iodate and two dyes

One titrimetric and two spectrophotometric methods, which are simple, sensitive and rapid, are described for the assay of lamivudine in bulk drug and in tablet dosage forms using potassium iodate and two dyes, methyl orange and indigocarmine, as reagents. In titrimetry, an aqueous solution of lamivudine is titrated directly with iodate in an acidic medium, and in the presence of an excess of bromide using methyl orange as an indicator. After the decoloration of the red color of methyl orange, the residual bromine is titrated iodometrically to a starch endpoint. Spectrophotometric methods involve the addition of a known excess of iodate in an acidic medium and in the presence of an excess of bromide followed by the determination of residual bromine by the reaction with a fixed amount of either methyl orange and measuring the absorbance at 520 nm (method A), or indigo carmine and measuring the absorbance at 610 nm (method B). In all methods, the amount of iodate which reacted corresponds to the amount of lamivudine content. The titrimetric method is applicable over the 1.5–8.0 mg range. The systems obey Beer’s law for 0.5–5.0 μg/mL (method A) and 1.25–12.5 μg/mL (method B). The calculated apparent molar absorptivity values are found to be 3.3 × 10⁴ and 9.3 × 10³ L mol⁻¹ cm⁻¹, for method A and method B, respectively, and the corresponding Sandell sensitivity values are 6.94 and 24.62 ng/cm². The limits of detection and quantification are also reported for both spectrophotometric methods. Intra-and interday precision and accuracy for the developed methods have been evaluated. The methods were successfully applied to the assay of lamivudine in tablet form and the results were compared with those of a reference method by applying the Student’s t-test and F-test. No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by recovery experiments using the standard addition technique. The text was submitted by the authors in English.     

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.     

Forced-degradation study of valdecoxib as bulk drug and in tablet formulation by HPTLC

A stability-indicating forced-degradation study of valdecoxib was conducted using high performance thin layer chromatography (HPTLC). It was used to analyze valdecoxib as bulk drug and as tablets. Undegraded valdecoxib was eluted with a retardation factor, Rf, of 0.56. Valdecoxib was forcibly degraded by exposure to alkali, acid, oxidation, and light, the greatest degradation occurring under basic conditions. Base-degraded valdecoxib gave an additional peak with an Rf value of 0.76. The calibration curve was linear in the range of 0.2-1 microg/microL with a correlation coefficient of 0.9952. Complete validation was carried out for precision (inter-day, intra-day, repeatability), accuracy, and robustness. All the data were analyzed statistically. This HPTLC procedure shows the reliability needed for use as a stability-indicating method. It can quantify valdecoxib in bulk and in tablets and also resolves the degraded peak of valdecoxib. This method is also useful for studying the degradation pattern and degradation mechanism of valdecoxib.     

pH/溶剂双梯度反相高效液相色谱法同时测定氨酚曲麻片中的5种有效成分

建立了一种pH/溶剂双梯度反相高效液相色谱(HPLC)同时测定氨酚曲麻片中对乙酰氨基酚、咖啡因、水杨酰胺、盐酸伪麻黄碱、盐酸曲普利啶5种有效成分的方法。通过对溶剂梯度和pH/溶剂双梯度体系的优化,得到分离5种成分的最佳色谱体系。采用Diamonsiol C18色谱柱(250 mm×4.6 mm, 5 μm),以甲醇、0.05 mol/L醋酸铵水溶液和0.08 mol/L醋酸水溶液组成三元流动相体系,pH/溶剂双梯度洗脱,流速为1.0 mL/min;柱温为30 ℃。采用分段变波长检测: 0～6 min, 280 nm; 6～7 min, 257 nm; 7～14 min, 280 nm; 14 min, 233 nm。片剂中的5种成分在25.5 min内能达到基线分离,对乙酰氨基酚、盐酸伪麻黄碱、咖啡因、水杨酰胺、盐酸曲普利啶5种成分的线性范围分别为0.055～0.998 g/L、0.053～0.946 g/L、0.007～0.129 g/L、0.035～0.622 g/L和0.002～0.039 g/L,相关系数r均大于0.9990;检出限(以信噪比为3(S/N=3)计)分别为0.09、6、0.02、0.128和0.02 mg/L,回收率为97.9%～102.8%。该方法能在短时间内同时分离酸性、中性和碱性化合物,能提高被测物的柱效,减少半峰宽和拖尾,可应用于氨酚曲麻片中5种成分的含量分析。     

偏最小二乘法测定复方乙酰水杨酸片中的有效成分

将偏最小二乘法(PLS)与近红外漫反射光谱法相结合,对复方乙酰水杨酸片进行无损非破坏定量分析．建立了最佳的数学校正模型,比较了样品中3种有效成分(乙酰水杨酸、非那西丁和咖啡因)同时测定和单独测定时的主成分数对PLS定量预测能力的影响,预测了未知样品。3种有效成分同时测定和单独测定建立的PLS模型具有相同的主成分数,PLS预报浓度与参考浓度具有相近的标准偏差,说明用PLS法同时测定3种组分的含量是可行的。