Simultaneous Derivative Spectrophotometric Quantification of Diethylamine Salicylate and Methyl Nicotinate in Ointments

A direct derivative, D1 i.e. dA/dλ, spectrophotometric procedure for simultaneous determination of diethylamine salicylate and methyl nicotinate in their binary mixtures and in ointments has been investigated. Good percent mean recoveries, 99.68 ± 0.58 & 99.71 ± 0.27 and 100.85 ± 0.21, could be obtained for diethylamine salicylate at 303 nm & 236 nm and methyl nicotinate at 224 nm, in order, added to ointment. The band overlapping in the first order due to the coexisting parabens, main additive, and the water-washable ointment base occurs sufficient away from those wavelengths chosen for the direct D1-measurement of both drug substances.     

毛细管电泳法分离测定潮汕凉果中的山梨酸、苯甲酸、糖精钠

采用毛细管电泳-PDA检测法,考察了pH、缓冲介质、波长、电压对山梨酸、苯甲酸、糖精钠分离测定的影响,得到优化的实验条件.以20mmol/乙磷酸盐(pH=7.4)为运行缓冲液,12kV为分离电压,检测通道波长为:192、202、254nm的电泳条件下,进样时间5s,山梨酸、苯甲酸、糖精钠可在15min内实现分离.山梨酸在0.250-100mg/L,苯甲酸在0.100-50.0mg/L,糖精钠在0.100-50.0mg/L范围内呈良好的线性关系,迁移时间、峰面积相对标准偏差均小于1.41%(n=5).用上述方法对实际样品进行测定,回收率在90.9%以上.     

液相色谱法检测化妆品中3种防腐剂

建立了化妆品中防腐剂水杨酸、苯甲酸和山梨酸的高效液相色谱检测方法.试样经乙醇和硫酸处理后,由C18反相色谱柱进行分离,紫外检测器进行检测,用外标法定量.实验结果表明,该方法简便、高效,测定结果准确,适用于化妆品中水杨酸、苯甲酸和山梨酸含量的同时检测.     

Radiosensitivities of parabens and characterization of the radical species induced in this class of antimicrobial agents after gamma irradiation

Radiosensitivities of methyl, ethyl, propyl and butyl parabens and sodium salts of methyl and propyl parabens (hereafter, MP, EP, PP, BP, SMP and SPP, respectively) were investigated by monitoring, through electron spin resonance (ESR) spectroscopy, the evolution under different experimental conditions of characteristic features of the radicalic species produced upon irradiation by gamma radiation. While ESR spectra of the studied parabens consisted of the sum of broad and narrow resonance lines of different microwave saturation and thermal characteristics, those of sodium salts appeared to consist of the sum of two overlapping narrow resonance lines. Radical species presented different room and high-temperature decay characteristics, depending on the extent of the cage effect created by the lattice networks on these species. A model based on the presence of two radical species presenting different spectroscopic and kinetic features described best the experimental data collected for parabens and their sodium salts. Radiation yields of the studied parabens towards gamma radiation were calculated to be low (G≤10^?2), providing the opportunity of using these antimicrobial agents in food, cosmetics and drugs to be sterilized by radiation without much loss from their antimicrobial activities.     

Stability-Indicating Method for the Determination of Meloxicam and Tetracaine Hydrochloride in the Presence of their Degradation Products

Abstract

Sensitive, spectrophotometric and densitometric methdos are described for the determination of meloxicam I and tetracaine hydrochloride II in the presence of their degradation products.

Meloxicam was determined in the presence of its degradation products (5-methyl-2-aminothiazole) III and benzothiazine carboxylic acid IV by two methods. These methods are the first derivative Spectrophotometry at 338 nm and TLC densitometric method at 365nm. The methods were applicable over the concentration range of 5–20μg.m^?1 and 2–10μg with mean accuracies of 99.66±0.91% and 99.99±0.70% respectively.     

Stability-Indicating Methods for the Determination of Cimetidine Using Derivative and Fourier-Transform Infrared Spectrophotometry

Abstract

Two different techniques, that is, second (D₂) and third (D₃) derivative spectrophotometry and fourier transform infrared (FTIR) Spectrophotometry, are investigated for the selective determination of the intact cimetidine in presence of up to 25% and 75% of its degradates, respectively. The procedures determine 2–10 jag ml^?1 at 224 nm and 217.5 nm by D₂ and D₃, respectively, and 1–6 mg per 250 mg in K Br by the FTIR with mean accuracies of 100.0 ± 1.07%, 100.5 ± 0.87% and 100.3 ± 1.16%, respectively. The drug is successfully analysed in its pharmaceutical formulations.

     

卡尔曼滤波紫外光度法同时测定酱油、食醋中的山梨酸和苯甲酸

在酸性条件下，采用乙酸乙酯萃取、Na2HPO4溶液反萃取分离酱汪、食醋中的山梨酸、苯甲酸，卡尔曼滤波法计算结果，并与比值导数波谱法进行比较。结果表明，卡尔曼滤波法较地数波谱法有较高准确度和精密度，并能监测干扰物质存在与否。用于实际样品分析有更高的可靠性。     

UV-Spectroscopic Determination of Mixtures of Tetramethrin and Piperonyl Butoxide in Pharmaceutical Formulations

Abstract

A simple rapid and accurate UV-spectroscopic method have been developed for determination of tetramethrin in presence of piperonyl butoxide, which are present in Licid^R, a newly introduced pharmaceutical drug in Egypt used as antilice, and antiscopis. The method is applicable in the concentration range of 1–12 μg.ml^?1 and 1–50 μg.ml^?1 for tetramethrin and piperonylbutoxide respectively. Average recoveries for tetramethrin and piperonyl butoxide in Licid^R spray and Licid^R lotion are 98.14 ± 0.3 – 103.88 ± 1.88 (Tetra), 103.78 ± 1.23 (piperonyl) and 100.62 ± 0.89 – 100.94 ± 1.10 (Tetra), 102.38 ± 1.02 (piperonyl) for the spray and lotion, respectively.     

Selective Determination of Itraconazole in the Presence of Its Oxidative Degradation Product by A New Spectrophotometric Method

A simple, specific, accurate and precise spectrophotometric stability indicating method is developed for determination of itraconazole in the presence of its oxidative degradation product and in pharmaceutical formulations. A newly developed spectrophotometric method called ratio difference method by measuring the difference in amplitudes between 230 and 265 nm of ratio spectra. The calibration curve is linear over the concentration range of 5～25 μg·mL-1 with mean percentage recovery of 99.81±1.002. Selective quantification of itraconazole, singly in bulk form, pharmaceutical formulations and in the presence of its oxidative degradation product is demonstrated. The results have been statistically compared with a pharmacopeial method.     

高效液相色谱-质谱联用法测定饮料中的苯甲酸含量

建立了高效液相色谱-质谱联用法检测饮料中的苯甲酸.选用ZORBAX XDB-C18柱(50mm×2.1mm,3.5μm)为分析柱,流动相为乙腈-水,梯度洗脱,流速为200μL·min-1;质谱条件选用气动辅助电喷雾离子源(ESI),检测方式为负离子多离子反应检测(MRM);苯甲酸校准曲线线性范围为1-500μg/L;方...     

Sonochemical degradation of ethyl paraben in environmental samples: Statistically important parameters determining kinetics,by-products and pathways

The sonochemical degradation of ethyl paraben (EP), a representative of the parabens family, was investigated. Experiments were conducted at constant ultrasound frequency of 20 kHz and liquid bulk temperature of 30 °C in the following range of experimental conditions: EP concentration 250–1250 μg/L, ultrasound (US) density 20–60 W/L, reaction time up to 120 min, initial pH 3–8 and sodium persulfate 0–100 mg/L, either in ultrapure water or secondary treated wastewater.A factorial design methodology was adopted to elucidate the statistically important effects and their interactions and a full empirical model comprising seventeen terms was originally developed. Omitting several terms of lower significance, a reduced model that can reliably simulate the process was finally proposed; this includes EP concentration, reaction time, power density and initial pH, as well as the interactions (EP concentration) × (US density), (EP concentration) × (pH_o) and (EP concentration) × (time).Experiments at an increased EP concentration of 3.5 mg/L were also performed to identify degradation by-products. LC–TOF–MS analysis revealed that EP sonochemical degradation occurs through dealkylation of the ethyl chain to form methyl paraben, while successive hydroxylation of the aromatic ring yields 4-hydroxybenzoic, 2,4-dihydroxybenzoic and 3,4-dihydroxybenzoic acids. By-products are less toxic to bacterium V. fischeri than the parent compound.     

A multiple function sonar rangefinder for divers

The rangefinder described here is a self-contained instrument for hand-held operation by a diver for searching, tracking, navigation and surveying applications. It has four modes: 1 — to measure range to a passive target directly to ± 1 m; 2 — to measure range to a passive target indirectly to ± 0.1 m; 3 — to measure range to a coded transponder to either ± 1 m or ± 0.1 m; 4 — to indicate the presence of multiple targets downrange where each target occurs in a selected range interval. The pulse echo principle is employed, with pulses typically 250 μs long. The carrier frequency of 300 kHz can be altered easily if required by changing the transducer array.     

Spectrophotometric determination of sparfloxacin in pharmaceutical formulations and urine samples

A simple and sensitive spectrophotometric method has been developed for the determination of sparfloxacin in bulk and pharmaceutical formulations, and in artificial urine. Sparfloxacin was oxidized into a red colored product using ammonium monovanadate in acidic media. The proposed method was successfully applied to the determination of sparfloxacin in different pharmaceutical formulations (tablets) and in a spiked urine sample. The influence of commonly used excipients on the determination of sparfloxacin was studied. Percentage recoveries in the range of 98.0 ± 0.14 % to 100.0 ± 0.20 % were obtained. The observed data have been evaluated statistically which showed high accuracy and precision.     

MgF2:Mn2+光谱、超精细常数和局部结构的关联

基于电子顺磁共振(EPR)超精细常数A_s确定键长的新方法和半自洽场d轨道理论，对MgF₂:Mn²⁺光谱和EPR超精细常数作出了统一解释.得到室温下MgF₂:Mn²⁺晶体中杂质中心Mn—F的键长为0.2124±0.0010nm. 关键词： 晶体场 电子顺磁共振 光学和磁学性质     

柱前衍生-反相高效液相色谱法快速测定食品中的甜蜜素

样品溶于水,在酸性条件下,以次氯酸钠柱前衍生。在C18柱上用乙腈:水(体积比为70:30)为流动相,在314nm处测定,外标法反相高效液相色谱法快速测定食品中的甜蜜素,加标回收率为96.1%-101.8%之间,食品中共存的苯甲酸、山梨酸、安赛蜜、色素等不影响测定,方法简捷、准确。     

系数倍率紫外光谱法同时测定复方苯甲酸软膏中的苯甲酸和水杨酸的研究

本文用系数倍率紫外光谱法同时测定了复方苯甲酸软膏中苯甲酸和水杨酸的含量,取得了满意的结果,苯甲酸测定回收率为99．33％－101．80％,水杨酸测定回收率100．92％－105．46％。     

RP-HPLC同时测定饮料中安赛蜜、阿斯巴甜及苯甲酸

建立了一种同时检测几种饮料中安赛蜜、阿斯巴甜及苯甲酸的高效液相色谱检测方法。确定了最佳色谱条件:色谱柱:Diamonsil-C₁₈（250mm×4.6mm,5μm）;流动相:0.02mol/L硫酸铵:乙腈:磷酸=80:20:0.02（V/V/V）;流速:1.0mL/min;紫外检测器检测波长:210nm。该方法加标回收率在94.5%—101.5%之间,精密度小于3%。实现了对碳酸饮料、茶饮料及橙汁中的安赛蜜、阿斯巴甜及苯甲酸的同时测定。     

1kHz窄脉宽高峰值功率MgO∶LN电光腔倒空Nd∶YAG激光器

报道了一种1kHz窄脉冲宽度、高峰值功率的电光腔倒空1 064nm全固态激光器.该激光器采用808nm脉冲LD侧面泵浦Nd:YAG晶体棒的双凹型折叠谐振腔结构和同步延迟MgO∶LN晶体横向加压式电光腔倒空技术,通过优化设计谐振腔结构,在脉冲重复频率200Hz时,获得了最大单脉冲能量46.7mJ、脉冲宽度4.06ns、峰值功率11.50MW的1 064nm脉冲激光稳定输出,脉冲宽度和能量的峰峰值不稳定度分别为±1.52%和±2.02%;在1kHz时,最大单脉冲能量达到18.3mJ,脉冲宽度5.02ns,峰值功率3.69MW,脉冲宽度和能量的峰峰值不稳定度分别为±2.75%和±3.52%,激光束因子为3.849和3.868,远场发散角为3.46mrad和3.55mrad,束腰直径为1 508.84μm和1 477.30μm.     

Compartmental Approach for Evaluation of Plasma Kinetics and 13Co2-Exhalation after Oral Loading with L-[1-13C]Leucine

Abstract

A seven compartment model was applied for evaluation of oral L-[1-¹³C]leucine loading tests (38 μmol/kg body wt.) in healthy volunteers. The model comprises transport and absorption in stomach and gut into a central L-leucine-compartment which is connected to a protein compartment and to the compartment of the corresponding 2-oxo acid. CO₂ release from the latter occurs in a fast and a slow compartment into the central CO₂ compartment for exhalation. Using the fmins routine of MATLAB for parameter estimation, a good agreement was obtained between calculated and actually measured kinetics of ¹³C-labelled metabolites and a mean in vivo L-leucine oxidation of 0.365 ± 0.071 μmol/kg per min (n = 5) was computed. Plausibility of the model was checked by predicting in vivo leucine oxidation rates from primed continuous infusion tests (priming: L-[1-¹³C]leucine, 5 μmol/kg; NaH¹³CO₂, 1.2 μmol/kg; infusion: L-[1-¹³C]leucine, 5 μmol/kg per h). In 5 tested volunteers, the experimental L-leucine oxidation rate amounted to 0.358 ± 0.105 μmol/kg per min versus predicted 0.324±0.099 μmol/kg per min. Possible causes for some observed intraindividual variations are discussed.     

基于LS-SVM和THz光谱技术的面粉中苯甲酸检测研究

面粉（小麦粉）是中国北方大部分地区的主食,苯甲酸是重要的酸型食品防腐剂,为了便于食品长期保存,往往会添加苯甲酸以便延长食品保存时间。但食用添加苯甲酸过量的小麦粉会对身体健康产生严重危害。太赫兹技术是一种新兴的检测技术,由于处于特殊的0.1～10 THz的太赫兹频段,在食品安全检测方面体现出了很强的应用潜力。主要致力于探索太赫兹光谱技术检测苯甲酸的合理性、可行性,利用太赫兹时域光谱技术对面粉中的食品添加剂苯甲酸进行实验研究。实验获取了面粉和苯甲酸的太赫兹时域光谱和频域光谱,其吸收系数显示苯甲酸的特征吸收峰在1.94 THz波段,面粉的太赫兹吸收系数几乎以一定的斜率增加,说明可以用THz-TDS（Terahertz time domain spectrum）技术对面粉中的苯甲酸进行特征识别。为建立面粉中添加剂苯甲酸的定量检测模型,实验获取了面粉中掺杂不同百分比（质量分数）苯甲酸的太赫兹时域光谱,计算得到吸收系数谱。实验发现吸收峰幅度的变化是与苯甲酸的含量成正比的,苯甲酸含量增加吸收峰幅度变大。首先探索了不同光谱预处理方法对太赫兹光谱的影响,采用如平滑校正、多元散射校正、基线校正和归一化等方法对原始光谱进行校正处理。校正之后,建立相应的PLS (partial least squares)模型以选择最优预处理方法。然后分别建立苯甲酸浓度和太赫兹吸收系数的MLR (multiple linear regression)、PLS和LS-SVM（partial least squares support vector machines）回归模型,并对比分析不同模型的优劣。将光谱数据归一化后建立的PLS模型更具有优势,预测相关系数R_p为0.979,预测均方根误差RMSEP为1.30%。LS-SVM与PLS和MLR模型相比,LS-SVM模型可以获得更好的建模结果,LS-SVM的预测相关系数R_p为0.987,预测均方根误差RMSEP为1.10%。利用MLR方法仅使用1.946和1.869 THz两个波段点进行建模,建模效果预测相关系数R_p为0.955,预测均方根误差RMSEP为1.90%。通过该研究为面粉中苯甲酸添加剂的无损检测提供了新的解决方案,也为其他类型的添加剂的检测提供了方法指导,对促进面粉行业的健康发展具有重要的意义。