Characterization and determination of stability constants of copper(II)-l-histidine complexation system by using multivariate curve resolution method of visible spectra and two hard modeling methods in aqueous solutions

Multivariate curve resolution, alternating least-squares is applied to spectra data obtained in the study of Cu(II) complexation by l-histidine. The combination of several chemometric techniques based on factor analysis (FA), singular value decomposition (SVD), evolving factor analysis (EFA), and multivariate curve resolution with constrained alternating least-squares (ALS) is used to determine the number of species and their distribution diagram. This multivariate analysis data treatment simultaneously reveals the species Cu, CuL, CuLH, CuL₂, CuL₂H, and CuLOH, through the calculated concentration profiles and allows the assignment of numerically obtained pure individual spectra. Formation constants of these species were calculated by hard-modeling methods applied potentiometric and spectrophotometric measurements.     

多元校正紫外光度法同时测定甲硝唑与维生素B6

本文报道多元校正紫外光度法同时测定甲硝唑和维生素B6。首先在0．1mol／LHCl溶液中对甲硝唑和维生素B6两组分混合溶液进行分光光度法测定,然后将所得的重叠光谱数据经计算机采集后,分别用化学计量学方法中的偏最小二乘法（PLS）和主成分回归法（PCR）进行处理,并用于药物样品的测定,获得了较好的定量分析结果。该法甲硝唑和维生素B6的线性范围分别为1．0～28．0mg／L和1．0～28．0mg／L,检出限分别为0．568mg／L和0．364mg／L。     

Electron impact mass spectral interpretation for some thiophosphoryl-p-acetylaminobenzenesulfonamides

This work discusses the synthesis and the fragmentation patterns for 2-(p-acetylaminosulfonamido)-2-thiono-(5,5-dimethyl-1,3,2-dioxaphosphorinane)(1) and for the p-acetylaminosulfonylamides of O,O-diethylthiophosphoric acid (2), O,O-diphenylthiophosphoric acid (3), dimethylaminocyclohexylthiophosphoric acid (4), and diethylaminophenylthiophosphoric acid (5). A thionamidic-thiolimidic structure was attributed to compounds 1-5, consistent with their IR and NMR spectra. EI mass spectra at 70 eV, high resolution (HR) mass measurements and metastable ion spectra were used to elucidate the fragmentation processes and to determine the kinetic energy release values associated with the metastable ion dissociations. HR accurate mass measurements were used to confirm the compositions of the more abundant ions.     

Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods

Three simple, rapid, and accurate methods, i.e., the derivative ratio spectra-zero-crossing method (method I), double divisor-ratio spectra derivative method (method II), and column reversed-phase high-performance liquid chromatographic (RP-HPLC) method (method III) were developed for the simultaneous determination of doxylamine succinate (DOX), pyridoxine hydrochloride (PYR), and folic acid (FA) in their ternary mixtures and in tablets. In methods I and II, the calibration graphs were linear in the range of 2.5-80, 1.0-40, and 1.0-30 microg/mL for DOX, PYR, and FA, respectively. In the HPLC method, the separation of these compounds was performed using mobile phase consisting of 0.05 M phosphate buffer (pH 6.3)-methanol-acetonitrile (50 + 20 + 30, v/v/v), and UV detection was performed at 263 nm. Linearity was observed between the concentrations of the analytes and peak areas [correlation coefficient (r) > or =0.9998] in the concentration range of 1.0-200, 4.0-600, and 4.0-600 microg/mL for DOX, PYR, and FA, respectively. The standard deviation of retention time in method III was 0.011, 0.015, and 0.016 for DOX, PYR, and FA, respectively. The precision studies for all of the methods gave relative standard deviation values of <2%. The results obtained from the methods were statistically compared by means of Student's t-test and the variance ratio F-test. It was concluded that all of the developed methods were equally accurate, sensitive, and precise. These methods could be applied to determine DOX, PYR, and FA in their combined dosage forms.     

Multivariate Analysis of Electron Detachment Dissociation and Infrared Multiphoton Dissociation Mass Spectra of Heparan Sulfate Tetrasaccharides Differing Only in Hexuronic acid Stereochemistry

The structural characterization of glycosaminoglycan (GAG) carbohydrates by mass spectrometry has been a long-standing analytical challenge due to the inherent heterogeneity of these biomolecules, specifically polydispersity, variability in sulfation, and hexuronic acid stereochemistry. Recent advances in tandem mass spectrometry methods employing threshold and electron-based ion activation have resulted in the ability to determine the location of the labile sulfate modification as well as assign the stereochemistry of hexuronic acid residues. To facilitate the analysis of complex electron detachment dissociation (EDD) spectra, principal component analysis (PCA) is employed to differentiate the hexuronic acid stereochemistry of four synthetic GAG epimers whose EDD spectra are nearly identical upon visual inspection. For comparison, PCA is also applied to infrared multiphoton dissociation spectra (IRMPD) of the examined epimers. To assess the applicability of multivariate methods in GAG mixture analysis, PCA is utilized to identify the relative content of two epimers in a binary mixture.     

Simultaneous fluorometric determination of nalidixic acid and 7-hydroxymethylnalidixic acid by partial least squares calibration

The resolution of binary mixtures of nalidixic acid (NA) and 7-hydroxymethylnalidixic acid (OH-NA) has been accomplished by partial least squares (PLS) and principal component regression (PCR) multivariate calibration. The method of determination is based on the fluorescence emission of these compounds in the presence of gamma-cyclodextrin (gamma-CD). The formation of the inclusion compounds gives rise to an increase of the fluorescence emission compared to aqueous solution. The total luminescence information of the compounds has been used to optimize the spectral data set to perform the calibration. A comparison between the predictive ability of three multivariate calibration methods, PLS-1, PLS-2 and PCR, on three spectral data sets, excitation, emission and synchronous spectra has been performed. The PLS-1 method, applied to the emission spectra, has been selected as optimum. The proposed method has been applied to the simultaneous determination of NA and OH-NA in urine. Recovery values from urine samples containing (NA) and (OH-NA) range from 91 to 103% (mean 97%), and from 92 to 105% (mean 99%), respectively.     

High-performance liquid chromatography--mass spectrometry and electron-capture dissociation tandem mass spectrometry of osteocalcin. Determination of gamma-carboxyglutamic acid residues

Two mass spectrometry methods, high-performance liquid chromatography combined on-line with electrospray ionization mass spectrometry (HPLC-ESI-MS) and electron-capture (EC) dissociation tandem mass spectrometry (MS-MS), were applied for structural analysis of bovine and human osteocalcins. Osteocalcin contains gamma-carboxyglutamic acid (Gla) residues, which bind metal ions, among its amino acids. Ethylenediaminetetraacetic acid (EDTA) was added to all samples in order to chelate bound metal ions. After elimination of interfering metal ions MS spectra became uncomplicated to interpret. EDTA is incompatible with ESI and it was removed from samples using either on-line HPLC or micropurification method. The number of Gla residues varies in osteocalcin. These subforms, which contain different amounts of Gla residues, were separated using the HPLC-ESI-MS method. In order to determine locations of Gla residues in human osteocalcin, which contained two Gla residues, dissociation MS-MS method was successfully applied.     

Simultaneous fluorimetric determination of acetylsalicylic acid metabolites in urine by partial least squares multivariate calibration

A method is described for the simultaneous determination of the main urinary acetylsalicylic acid (aspirin) metabolites, salicyclic, salicyluric and gentisic acids, based on their native fluorescence. The urine was extracted into diethyl ether in acid medium, and back-extracted with glycine/sodium hydroxide buffer solution at pH 9.4. A comparative study of the results found using the excitation, the emission and the combination of the excitation plus the emission spectral data, as analytical signals, was performed. The data set, composed of the excitation plus the emission spectra, was selected as the analytical signal. The optimum wavelengths to record the excitation (lambda(em)=444 nm) and the emission spectra (lambda(ex)=323 nm) were selected to maximize the contribution from gentisic acid, which is the minor urinary metabolite. Partial least squares (PLS-1) multivariate calibration was then applied for the determination. Recovery values from urine samples spiked with salicyclic, salicyluric and gentisic acids varied from 90.1 to 97.6% (mean 93.6%), from 90.0 to 110% (mean 97.9%) and from 89.9 to 104.7% (mean 98.5%), respectively.     

维生素B12与12-钨磷酸相互作用的双波长共振瑞利散射光谱及其分析应用

建立了一种双波长共振瑞利散射光谱测定维生素B12的新方法. 在pH=1.0的HCl介质中, 维生素B12(VB12)与12-钨磷酸(TP)形成摩尔比为3:1的离子缔合物, 导致双波长共振瑞利散射(DWO-RRS)、 二级散射(SOS)和倍频散射(FDS)光谱显著增强, 其最大散射波长分别位于330和370 nm(RRS), 608 nm(SOS)和386 nm(FDS). 在一定范围内, 3种散射增强(ΔIRRS, ΔISOS和ΔIFDS)均与VB12的浓度成线性关系. 该方法具有较高的灵敏度, RRS, SOS和FDS法对VB12的检出限(3σ)在2.0~7.6 ng/mL之间. 研究了反应条件和共存物质的影响, 结果表明, 该方法具有良好的选择性. 据此, 提出了简便、 快速、 准确且高灵敏测定痕量VB12的光散射新方法, 适用于片剂和尿样中VB12的测定. 还对反应机理和散射光谱增强的原因进行了讨论.     

Synthesis and vibrational study of some polydentate ligands

Sodium salts of iminodiacetic acid (IDA), ethylenediaminetetraacetic acid (EDTA), 1,2-propylenediaminetetraacetic acid (PDTA) and 1,2-diaminocyclohexanetetraacetic acid (DCTA) were prepared by modification of the literature methods and their i.r. and Raman spectra were studied. The results obtained by application of both techniques allowed a better characterization of these polydentate ligands. Raman spectroscopy was specially useful in elucidating structural aspects in compounds containing acetate groups.     

Simultaneous determination of diloxanide furoate and metronidazole in presence of diloxanide furoate degradation products

Three methods are presented for the simultaneous determination of diloxanide furoate (DLX) and metronidazole (MTR), used for their antiprotozoal and antiamoebic effect, in the presence of DLX alkaline degradates and in pharmaceutical formulations, without previous separation. The first method is chemometric-assisted spectrophotometry, in which principal component regression and partial least squares were applied. These two approaches were successfully applied to quantify each drug in the mixture using the information included in, the absorption spectra in the range of 225-320 nm. The second method is TLC-densitometry, in which the binary mixture and degradates were separated on silica gel plates using a chloroform-acetone-glacial acetic acid (9.5 + 0.5 + 0.07, v/v/v) mobile phase and the bands were scanned at 254 nm. The last method is HPLC, in which DLX, MTR, and degradates were separated using the mobile phase acetonitrile-0.05 M dibasic potassium phosphate (25 + 75, v/v), adjusted to pH 4 with orthophosphoric acid, at a flow rate of 1 mL/min, on a C18 analytical column. Detection was at 254 nm. The proposed methods were successfully applied for the analysis of DLX and MTR in pharmaceutical formulations, and the results were statistically compared with a reported spectrophotometric method.     

Simultaneous determination of pseudoephedrine sulfate, dexbrompheniramine maleate and loratadine in pharmaceutical preparations using derivative spectrophotometry and ratio spectra derivative spectrophotometry

Two new spectrophotometric methods are described for the simultaneous analysis of pseudoephedrine sulfate-dexbrompheniramine maleate (DBP) and pseudoephedrine sulfate-loratadine combinations. In the first, derivative spectrophotometry, dA/dlambda values were read at zero-crossing points. In the second, ratio spectra derivative spectrophotometry, analytical signals were measured at the wavelengths corresponding to either maxima or minima for these drugs in the first derivative spectra of their ratio spectra. The procedures do not require any separation step. Mean recoveries were found to be >99% in the methods for these compounds in their synthetic mixtures. All the spectrophotometric methods proposed were compared with each other and HPLC which was also developed by us and applied to the pharmaceutical preparations selected.     

Phthalocyanine polymers. I. Poly[2,2′-(4,4′,4″-,4‴-metal phthalocyanino)-5,5′-bibenzimidazoles] as new high temperature resistant polymers

A novel class of poly(metal phthalocyanino) benzimidazoles were prepared by the condensation reaction between metal (Cu, Co, and Zn), 4,4′,4″,4?-tetracarboxyphthalocyanine, and 3,3′-diaminobenzidine. The reaction was investigated by melt and solution condensation methods. These polymers showed excellent thermal and thermooxidative stability and are noteworthy for their high char yield (86–90%) at 800°C in an anerobic atmosphere. Elemental analyses, spectra, and TGA studies were used to characterize these materials. Isothermal gravimetric analyses were carried out to determine their long-term thermal stability.     

主成分回归用于分光光度法同时测定6种食品添加剂

山梨酸、苯甲酸钠、香兰素、NaNO2、NaNO3和糖精钠的紫外吸收光谱严重重叠,不经预先分离很难进行单一组分的直接测定.报道了一种同时测定上述6种食品添加剂的分光光度法,这种方法是基于在pH 2.85的Britton-Robinson(B-R)缓冲溶液中对该6种食品添加剂混合溶液进行光度测定,所得的重叠光谱数据用主成分回归(PCR)进行建模,并用该模型对未知样品浓度进行预报.该方法可以不经分离同时测定食品样品中的多种添加剂.     

Liquid chromatography and chemometric-assisted spectrophotometric methods for the analysis of two multicomponent mixtures containing cough suppressant drugs

Three methods were applied for the analysis of 2 multicomponent mixtures containing dextromethorphan hydrobromide, phenylephrine hydrochloride, chlorpheniramine maleate, methylparaben, and propylparaben, together with either sodium benzoate (Mix 1) or ephedrine hydrochloride and benzoic acid (Mix 2). In the first method, liquid chromatography was used for their simultaneous determination using an ODS column with a mobile phase consisting of acetonitrile-phosphate buffer, pH 2.7 (40 + 60, v/v), containing 5mM heptanesulfonic acid sodium salt and ultraviolet (UV) detection at 214 nm. Also, 2 chemometric methods, principal component regression, and partial least squares were used. For both chemometric calibrations, a concentration set of the mixture consisting of each compound in each mixture was prepared in distilled water. The absorbance data in the UV spectra were measured for the 76 or 71 wavelength points in the spectral region 210-240 or 210-224 nm considering the intervals of deltagamma = 0.4 or 0.2 nm for Mix 1 and Mix 2, respectively. The 2 chemometric methods did not require any separation step. These methods were successfully applied for the analysis of the 2 multicomponent combinations in synthetic mixtures and in commercial syrups, and the results were compared with each other.     

化学计量学-荧光分析法同时测定萘、1-萘酚和2-萘酚

根据正交信号校正(OSC)、小波包变换(WPT)及偏最小二乘法(PLS)的算法原理,编制了名为POSC-WPTPLS的程序,结合荧光分析法快速、灵敏、选择性较好的优点,将该程序用于同时测定荧光光谱严重重叠的萘、1-萘酚和2-萘酚多组分体系,并将3种化学计量学方法(OSC-WPT-PLS、WPT-PLS和PLS)进行比较...     

Determination of Cadmium(ii), Copper(ii), Mercury(ii), and Lead(ii) in Water Using Stochastic Sensors Based on Graphite and Diamond Paste Modified with 1H-Pyrrole-1-Hexanoic Acid

Graphite/diamond pastes modified with 1H-pyrrole-1-hexanoic acid were used for the design of stochastic sensors. The proposed stochastic sensors were used to determine four heavy metals, copper(II), cadmium(II), mercury(II), and lead(II), in water samples. The sensitivities of the stochastic sensors were high for all four metal ions, and their limits of determination were sufficiently low to enable detection at very minute concentrations; in some cases, unreachable using standard methods of analysis. The recoveries of copper(II), cadmium(II), mercury(II), and lead(II) in water samples were higher than 93.00%, with relative standard deviation values lower than 1.00%. The sensors were used to simultaneously determine copper(II), cadmium(II), mercury(II), and lead(II) in water samples. The obtained results were in agreement with those obtained using standard analytical methods.     

How to identify and discriminate between the methyl quinates of chlorogenic acids by liquid chromatography-tandem mass spectrometry

The methyl esters of chlorogenic acids, methyl quinates, are widely distributed in plant materials and frequently appear as extraction artifacts in plant samples. This is the first time when liquid chromatography-tandem mass spectrometry methods have been used for the identification and characterization of the methyl quinates. For this purpose, methyl quinates of mono caffeoylquinic acids and mono feruloylquinic acids were synthesized as authentic standards. The methyl quinates of mono and diacyl chlorogenic acids have shown characteristic fragmentation pattern in their tandem mass spectra. MS(n + 1) spectra of the methyl quinates of diacyl chlorogenic acids were identical to MS(n) spectra of mono acyl derivatives. These quinates do not produce any methyl quinate peak at m/z 205 if compared with quinic acid peak at m/z 191 in negative ion mode. In the MS(n) spectra of these quinates, cinnamic acid part or cinnamoyl part was detected as a base peak in negative ion mode. The retention time, order of elution and fragmentation pattern were completely different if compared with LC-MS(n) methods developed for chlorogenic acids. These LC-MS(n) methods have been applied for the identification and regioisomeric characterization of the methyl quinates of chlorogenic acids in maté tea and woodruff (Galium odoratum). Two methyl caffeoylquinates (2 and 4) were identified as methyl 3-caffeoylquinate and methyl 5-caffeoylquinate.     

缬氨酸阳离子型离子液体的实验与理论研究

以缬氨酸（Val）和氟硼酸、对甲苯磺酸、硝酸、盐酸、硫酸和磷酸为原料,通过混合适当摩尔比的缬氨酸和相应的强酸于水中,采用一步法在微波反应仪中合成缬氨酸阳离子型离子液体,得到了缬氨酸氟硼酸盐（ValBF4）、缬氨酸盐酸盐（ValCl）、缬氨酸硝酸盐（ValNO3）、缬氨酸对甲苯磺酸盐（ValTsO）、缬氨酸硫酸盐（Val2SO4）、缬氨酸磷酸盐（Val3PO4）共6种产物,并对其理化性质进行了表征,其中ValBF4、Val3PO4具有较低的熔点（低于100 ℃) ,但热稳定性较传统的离子液体差。此外研究了缬氨酸阳离子型离子液体在汽油脱硫中的应用,以正庚烷作溶剂、噻吩作含硫杂质组成模拟汽油体系,将缬氨酸硝酸盐作为脱硫剂加入模拟油中,在进行超声波振荡之后利用色谱仪检测不同振荡时间的脱硫效果。同时采用量子化学方法对合成的6种化合物的单个分子进行了理论研究,在B3LYP/6-11++G**水平下获得了最稳能量构型,并在此基础上进行了红外光谱、离子间相互作用、自然键轨道分析等,从理论上对上述实验结果进行验证及补充。     

Separation and determination of protocatechuic aldehyde and protocatechuic acid in Salivia miltorrhrza by capillary electrophoresis with amperometric detection

Capillary electrophoresis with amperometric detection was applied to separate and determine protocatechuic aldehyde and protocatechuic acid in Salivia miltorrhrza preparations. The electrode used was a 0.3 mm diameter carbon disk electrode fixed in a wall-jet with amperometric detection. Under the optimum conditions, the two analytes were separated completely within 8 min. Excellent linearity was obtained in the concentration ranges of 0.25-100.0 microg ml(-1) and 0.50-100.0 microg ml(-1) for protocatechuic aldehyde and protocatechuic acid, respectively. The detection limits were 0.10 microg ml(-1) of protocatechuic aldehyde and 0.25 microg ml(-1) of protocatechuic acid, which were found to be lower than those of other methods that determine protocatechuic aldehyde (3,4-dihydroxybenzaldehyde) and protocatechuic acid (3,4-dihydrobenzoic acid) simultaneously. The mean recoveries of protocatechuic aldehyde and protocatechuic acid were 97.4% and 103.3%. This method has been successfully applied to monitor these two components in real samples such as Salivia miltorrhrza and its two traditional Chinese medicinal preparations.