Determination of the design space of the HPLC analysis of water‐soluble vitamins

Analysis of water‐soluble vitamins has been tremendously approached through the last decades. A multitude of HPLC methods have been reported with a variety of advantages/shortcomings, yet, the design space of HPLC analysis of these vitamins was not defined in any of these reports. As per the food and drug administration (FDA), implementing the quality by design approach for the analysis of commercially available mixtures is hypothesized to enhance the pharmaceutical industry via facilitating the process of analytical method development and approval. This work illustrates a multifactorial optimization of three measured plus seven calculated influential HPLC parameters on the analysis of a mixture containing seven common water‐soluble vitamins (B₁, B₂, B₆, B_12, C, PABA, and PP). These three measured parameters are gradient time, temperature, and ternary eluent composition (B1/B2) and the seven calculated parameters are flow rate, column length, column internal diameter, dwell volume, extracolumn volume, %B (start), and %B (end). The design is based on 12 experiments in which, examining of the multifactorial effects of these 3 + 7 parameters on the critical resolution and selectivity, was carried out by systematical variation of all these parameters simultaneously. The 12 basic runs were based on two different gradient time each at two different temperatures, repeated at three different ternary eluent compositions (methanol or acetonitrile or a mixture of both). Multidimensional robust regions of high critical R_s were defined and graphically verified. The optimum method was selected based on the best resolution separation in the shortest run time for a synthetic mixture, followed by application on two pharmaceutical preparations available in the market. The predicted retention times of all peaks were found to be in good match with the virtual ones. In conclusion, the presented report offers an accurate determination of the design space for critical resolution in the analysis of water‐soluble vitamins by HPLC, which would help the regulatory authorities to judge the validity of presented analytical methods for approval.     

A novel indirect inhibitive immunoassay for sulfamethoxazole

<正>A new indirect inhibitive immunoassay using surface plasmon resonance(SPR) coupled with molecularly imprinted polymer(MIP) was developed.A sulfamethoxazole(SMX) MIP coating capillary was produced and used as an in-tube solid phase extraction(SPE) device.The MIP coating formed a nanometer film on the inner wall of the capillary.The anti-SMX mono-antibody was inhibited by SMX extracted by the MIP coating in a dose-dependent manner.The calibration curve was generated by linear fit over the range of 0.04-10.00 ng/mL.The limit of detection was 0.01 ng/mL.This method has high sensitivity and can be performed automatically.     

On the duality between the profit and the indirect distance functions in production theory

Färe and Primont [3] stated, without proofs, duality results between the profit and the indirect distance functions in production theory. The aim of this note is to state these duality results in precise terms and to prove them.     

Simultaneous Determination of Micro Bromide and Iodide by Kinetic Spectrophotometric Method

ABSTRACT

ABSTRACTA new kinetic spectrophotometric method for the simultaneous determination of concentrations of micro bromide and iodide has been proposed. It is based on their catalytic effects on the reaction of m-cresol purple oxidized by potassium periodate in hydrochloride acid medium. The reaction rate was monitored by measuring the decrease in absorbance at 528nm and the increase in absorbance at 455nm. The total difference in absorbance of the sum of bromide and iodide is identical with determination of bromide was carried out after Cr(VI) oxidized I? to I₂, and I₂ was removed by extraction with CCI₄, and the amount of iodide was measured by subtracting the absorbance change of bromide from the total absorbance change in the presence of bromine and iodide. The optimum conditions influencing the reaction rate were studied. The linear range of determination is 0～4.0μg/ml for Br? and 0～3.0 μg/ml for I?. The detection limits are 0.032μg/ml for Br? and 0.059 μ/ml for I?. The method was successfully applied to the determination of micro amounts of bromide and iodide in food and life samples.     

Analysis of Bilirubin (Total or “Direct”) with an Automated Michaelsson Method on the Dsa-560 Autoanalyzera

Abstract

A method for the determination of Bilirubin, total or “direct”, is presented. It is a fully automated version of the Michaels son method, comprising the introduction of the sample at the beginning and at the end of the reaction sequence. Reference values are proposed based on the Gaussiam distributions of the square roots of values measured in blood donors, 99 men and 97 women.     

Indirect AAS Determination of Cationic Surfactants in Waste Effluents and Shampoos

Abstract

An indirect atomic absorption spectro-metric (AAS) method using electrothermal atomization (ETAAS) for the determination of cationic surfactants has been proposed. The method involves ion-pair formation between cationic surfactant and sodium hexanitro-cobaltate(III), extraction of the ion-pair into 1, 2-dichloroethane and determination of cobalt con centration in organic phase by ETAAS and hence indirectly relating to the cationic surfactant concentrations. Surfactants of the anionic and nonionic group do not interfere to a great extent, and matrix inter ferences from many other cations, anions and organics are also not observed. The method has been success fully applied to cationic surfactant determination in waste water and hair rinsers. Relative standard deviation values (RSD) of 3.2% for waste water samples and 4.3% for shampoo were observed in these analyses.     

A Spectrophotometric Method for the Determination of Propoxur

A simple spectrophotometric technique is reported for the determination of propoxur using the coupling complexing agents namely 2-amino, 4-nitrophenol and 2,4-dimethoxy aniline. The u max observed for these coloured complexes were at 402 and 460 nm respectively. The recoveries of propoxur pesticides obtained using the above procedure were reported in their formulations, water and food grains.     

确定光子晶体光纤轴向方位角的侧视光强特征法

光子晶体光纤轴向方位角的确定在光纤器件的加工制作中具有重要的意义.采用平行光侧向照射光子晶体光纤,研究了六边形结构、混合结构以及大模场结构这三种光子晶体光纤,获取其在不同轴向方位角时的侧视光强图像.随着光纤绕轴向旋转,其光强图像出现特定的亮纹光强特征,通过分析得到亮纹光强特征值随光纤轴向旋转之间的变化关系,发现其透射光强图像的光强特征值呈现周期性变化,并与光纤空气孔结构有一定对应关系.采用Tracepro仿真模拟三类光子晶体光纤的侧视光强图像特征,在模拟侧视光强图像中,也出现随轴向旋转变化而变化的亮纹特征,模拟侧视光强亮纹变化特征与实验亮纹特征具有相似的变化规律.对比光子晶体光纤亮纹光强特征值随轴向方位角变化关系的实验曲线与模拟曲线,发现当光源平行于光纤空气孔构成的近似六边形结构的顶角连线照射时,其亮纹光强特征值出现极大值,可以实现光子晶体在特定轴向方位角的定位.     

金属纳米柱天线的快速电磁分析

基于分段正弦基函数和矩量法,通过求解离散电流节点格林函数的封闭解得到金属纳米柱天线激发表面等离子体的阻抗矩阵.与使用其它基函数矩量法相比,该方法可以减少矩阵方程的维数.仿真结果表明:使用此方法只需求解很小的矩阵方程就可以求解出纳米天线表面极化电流,从而实现对纳米天线的散射特征及谐振模式的快速分析;其结果与时域有限差分仿真结果吻合良好且速度具有显著的优势,尤其在计算斜入射问题时计算优势更加明显.本文的方法对文中计算的模型有效,同样为其他形状纳米柱天线和碳纳米管器件散射特性仿真提供了快速有效的电磁分析方法.