Simultaneous spectrophotometric determination of ethinylestradiol and levonorgestrel by partial least squares and principal component regression multivariate calibration

Two spectrophotometric methods for the determination of Ethinylestradiol (ETE) and Levonorgestrel (LEV) by using the multivariate calibration technique of partial least square (PLS) and principal component regression (PCR) are presented. In this study the PLS and PCR are successfully applied to quantify both hormones using the information contained in the absorption spectra of appropriate solutions. In order to do this, a calibration set of standard samples composed of different mixtures of both compounds has been designed. The results found by application of the PLS and PCR methods to the simultaneous determination of mixtures, containing 4–11 μg ml⁻¹ of ETE and 2–23 μg ml⁻¹ of LEV, are reported. Five different oral contraceptives were analyzed and the results were very similar to that obtained by a reference liquid Chromatographic method.     

Simultaneous Kinetic‐Spectrophotometric Determination of Hydrazine and its Derivatives by Partial Least Squares and Principle Component Regression Methods

Simultaneous kinetic‐spectrophotometric determination of a ternary mixture of hydrazine (HZ) and its derivatives by principal component regression (PCR) and partial least squares (PLS) calibration is described. The methods were based on the difference observed in the reduction rate of iron(III) with HZ, thiosemicarbazide (TSCZ) and phenylhydrazine (PHZ) in the presence of 2,2′‐bipyridine (Bpy). The colored complex of [Fe(Bpy)₃]²⁺ was formed in sodium dodecyl sulfate (SDS) as micellar media, and then monitored at 520 nm. The results showed that simultaneous determination of HZ, TSCZ and PHZ could be performed in their concentration ranges of 1.0–70.0, 0.2–6.0 and 0.1–10.0 μg mL^?1, respectively. The root mean squares errors of prediction (RMSEP) of HZ, TSCZ and PHZ were 0.719, 0.164 and 0.105 (for PLS) 0.788, 0.166 and 0.993 (for PCR), respectively. Both methods (PCR and PLS) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ, TSCZ and PHZ in water samples.     

Multivariate calibration techniques applied to the spectrophotometric analysis of one-to-four component systems

The UV spectrophotometric analysis of a multicomponent mixture containing paracetamol, caffeine, tripelenamine and salicylamide by using multivariate calibration methods, such as principal component regression (PCR) and partial least-squares regression (PLS), was described. The calibration set was based on 47 reference samples, consisting of quaternary, ternary, binary and single-component mixtures, with the aim to develop models able to predict the concentrations of unknown samples containing as many as one-to-four components. The calibration models were optimized by an appropriate selection of the number of factors as well as wavelength ranges to be used for building up the data matrix and excluding any information about the interfering excipients included in pharmaceutics. The PCR and PLS models were compared and their predictive performance was inferred by a successful application to the assays of synthetic mixtures and pharmaceutical formulations.     

Analysis and Protection of One Thousand Hand Buddha in Dazu Stone Sculptures

The components of the rock, the pigments, the gold foils and the adhesive of One Thousand Hand Buddha in Dazu stone sculptures, Chongqing, China, have been analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF), infrared spectroscopy (IR), energy dispersive X-ray analysis (EDX) and fiber optics reflectance spectroscopy (FORS). Furthermore, the weathering and degeneration of One Thousand Hand Buddha have been discussed and the protective methods have been provided. In this work some useful information to study on conservation of stone relics is given.     

Chemical Composition of the Essential Oil of Rosmarinus officinalis Cultivated in the Algerian Sahara

The volatile compounds obtained by hydrodistillation of the aerial parts of Rosmarinus officinalis cultivated at the Algerian Sahara were analyzed by GC/MS. Thirty compounds were characterized representing 98.2% of the essential oil with 1,8-cineole (29.5%), 2-ethyl-4,5-dimethylphenol (12.0%) and camphor (11.5%) as the major components.     

Essential Oil and Antimicrobial Evaluation of the Pistacia eurycarpa

The compositions of microdistilled and hydrodistilled essential oils of the mastix ofPistacia eurycarpaYalt. (Anacardiaceae) were compared. The essential oils were analyzed by GC/MS:- andbeta;-pinenes were found as the major constituents. The antimicrobial activity of the hydrodistilled oil was determined due to the ethnomedical uses of the oleo-gum resin on skin diseases.     

Effect of surface treatment on the Hamaker constant of intermediate modulus carbon fibers

The Hamaker constant of unsized intermediate modulus carbon fibers was evaluated by contact angle measurement following the Fowkes theory of interfacial energetics. The effects of a surface treatment (performed by the manufacturer) and an oxygen plasma treatment (performed by us), both of oxidizing nature, proved to slightly increase the value of the Hamaker constant to a level that enhanced by about 9% the Lifshitz-van der Waals contribution to the theoretical adhesion force between the fiber and an epoxy matrix. A possible explanation of the observed increase of the Hamaker constant is the higher contribution to the overall Lifshitz-van der Waals interaction of Keesom (orientation) and Debye (induction) forces.     

GC/MS法分析油松节挥发油化学成分

用气相色谱-质谱法对山东昆嵛山产油松节挥发油进行化学成分的分析。采用水蒸气蒸馏法从油松节中提取挥发油。采用不同类型的毛细管柱进行分析，找出最佳分析条件，用归一化法测定其含量，并用气相色谱-质谱法对化学成分进行鉴定。共鉴定了48个成分，占挥发油总成分的84％以上。结果表明，此方法稳定可靠，重现性好，适用于中药挥发油的化学成分分析。     

Components of <Emphasis Type="Italic">Artemisia pontica</Emphasis>

Chemical components from the aerial part of the Kazakhstan population of Artemisia pontica, from which the rarely encountered flavonoids 7-O-methyl- and 4′,7-di-O-methyl-esters of apigenin were isolated for the first time, were identified. The complete chemical composition of the essential oil was established using GC-MS.__________Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 143–145, March–April, 2005.     

气相色谱-质谱法分析木奶果挥发油的化学成分

采用水蒸汽蒸馏法从大戟科木奶果中提取挥发油,用气相色谱-质谱对挥发油的化学成分进行了分析。鉴定出19种化合物,占总油量的100%,用面积归一化法测定了各成分的相对百分含量。木奶果挥发油主要成分为正十六碳酸、丁基甲氧基苯、9,12-十八碳二烯酸,分别占挥发油总量的29.53%、17.47%和11.59%,三者占其总量的58.59%。