Simultaneous Determination of Mepyramine Maleate,Lidocaine Hydrochloride,and Dexpanthenol in Pharmaceutical Preparations by Partial Least‐Squares Multivariate Calibration

Abstract

A partial least‐squares calibration (PLS) method has been developed for simultaneous quantitative determination of mepyramine maleate (MAM), lidocaine hydrochloride (LIH), and dexpanthenol (DPA) in pharmaceutical preparations. The resolution of these mixtures has been accomplished by using partial least‐squares (PLS‐2) regression analysis of electronic absorption spectral data without prior separation or derivatization. The experimental calibration matrix was constructed with 27 samples. The concentration ranges considered were 2, 3, 4 µg mL^?1 for MAM, 2, 3, 4 µg mL^?1 for LIH, and 8, 10, 12 µg mL^?1 for DPA. The absorbances were recorded between 190 and 340 nm every 5 nm. The results show that PLS‐2 is a simple, rapid, and accurate method applied to the determination of these compounds in pharmaceuticals.     

Simultaneous Spectrofluorimetric Determination of Paracetamol and Caffeine in Pharmaceutical Preparations in Solid‐Phase Using Partial Least Squares Multivariate Calibration

Abstract

Partial least‐squares algorithm (PLS)‐1 was used for the solid‐phase spectrofluorimetric determination of paracetamol (PA) and caffeine (CF) in pharmaceutical formulations. In despite of the closely overlapping spectral bands, the method allows the simultaneous quantification and sample preparation prior to analysis is not required. The calibration set consisted of 96 samples with 100–400 mg/g^?1 PA plus 10–65 mg/g^?1 CF; another set of 25 samples was used for external validation. Agreement between predicted and experimental concentrations was fair (r=0.993 and 0.964 for PA and CF models). Prediction performance was evaluated in terms of the coefficient of variability (CV), relative predictive determination (RPD), and ratio error range (RER). The PLS‐1 model was used for the determination of PA and CF in pharmaceutical formulations.     

A Partial Least Squares‐Based Consensus Regression Method for the Analysis of Near‐Infrared Complex Spectral Data of Plant Samples

Abstract

A consensus regression approach based on partial least square (PLS) regression, named as cPLS, for calibrating the NIR data was investigated. In this approach, multiple independent PLS models were developed and integrated into a single consensus model. The utility and merits of the cPLS method were demonstrated by comparing its results with those from a regular PLS method in predicting moisture, oil, protein, and starch contents of corn samples using the NIR spectral data. It was found that cPLS was superior to regular PLS with respect to prediction accuracy and robustness.     

Determination of Quercetin in Extracts of Ginkgo biloba L. Leaves by Near‐Infrared Reflectance Spectroscopy Based on Interval Partial Least‐Squares (iPLS) Model

Abstract

This paper developed a multivariate method of analysis of quercetin in Ginkgo biloba leaf extracts, based on reflectance NIR measurements and partial least squares regression. In order to give a better correlation with the results obtained by HPLC, multiplicative scatter correction (MSC) was utilized to correct scattering effect and interval partial least squares (iPLS) to select optimum wavelength region. In general, good calibration statistics were obtained for the prediction of quercetin content, as demonstrated by some figures of merit, namely linearity, repeatability, and accuracy. And the iPLS model was more reliable than the full model.     

Stereospecific Synthesis of (2E,13Z)‐2,13‐Octadecadienyl Acetate,the Sex Pheromone Component of the Lepidoptera Species

The main component of the sex pheromone of many lepidopteran pests, (2E,13Z)‐2,13‐octadecadienyl acetate (1), has been synthesized following a simple route using 12‐(2‐tetrahydropyranyloxy)‐1‐dodecyne (2) as the starting material.     

Mild Oxidation of Alcohols with o‐Iodoxybenzoic Acid (IBX) in a Water/CH2Cl2 Mixture in the Presence of Phase‐Transfer Catalyst

A mild oxidation of alcohols to the respective carbonyl compounds with o‐iodoxybenzoic acid (IBX) catalyzed by n‐Bu₄NBr in a water/dichloromethane (1:1) mixture is described. The method offers the advantage of a simple, inexpensive catalyst and the diminution of organic solvent employed in the reaction.     

Alternative,High‐Yield Synthesis of (E)‐4‐Oxonon‐2‐enoic Acid from 2‐Methoxyfuran

Alkylation of 2‐methoxyfuran, followed by in situ TPP‐sensitized photooxygenation of 2‐methoxy‐5‐pentylfuran in the presence of Me₂S, gave methyl (Z)‐4‐oxonon‐2‐enoate. Hydrolysis of methyl (Z)‐4‐oxonon‐2‐enoate afforded (E)‐4‐oxonon‐2‐enoic acid in three steps and in 79% overall yield.     

Effect of Triton‐X‐100 Solvent in the Micellar Catalysis of the Aquation of Tris(2‐nitroso‐1‐naphtholate) Ferrate (II)

The effect of triton‐X‐100 micelles on the aquation of Fe(C₁₀H₆N₂O)₃ ²⁺ has been investigated with triton‐X‐100 as solvent. In liquid triton‐X‐100, over a range of [H₂O] _T (0.0–3 M), significant rate enhancement factors of 50–150 are observe. Acid inhibits the rate of aquation at fixed [H₂O] _T . A mechanism based on effective solvent participation in a chemical environment similar to that in reversed micelles is proposed in liquid triton‐X‐100 with dispersed water pockets. This mechanism predicts direct H₂O substitution into the coordination sphere of Fe(C₁₀H₆N₂O)₃ ²⁺ in the highly polar water pockets or cavities where the Fe (II) complex molecules are solubilized. Changes in the tumbling rate, structure, and activity of water are suggested to account for the observed changes in the rate of aquation as a function OH [H₂O] _T . All k _ψ–[H₂O] _T profiles are structured and exhibit maxima with k _ψ(max) shifted to progressively higher [H₂O] _T as the fixed concentration [H⁺] _T is increased.     

Application of Sulfinyl bis(2,4‐dihydroxythiobenzoyl) in the Synthesis of N‐Substituted 2‐Amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles

One‐stage synthesis of N‐substituted 2‐amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles is described. The compounds were prepared by the reaction of the sulfinyl bis(2,4‐dihydroxythiobenzoyl) (STB) with 4‐substituted 3‐thiosemicarbazides. STB was obtained from 2,4‐dihydroxybenzenecarbodithioic acid and thionyl dichloride. The structure of compounds was confirmed by IR, ¹H NMR, ¹³C NMR, and EI‐MS data.     

Vibrational analysis of the S—trans conformation of (E,E), (Z,E) and (Z,Z)-2,4-hexadienes in the gaseous and solid states

The infrared (IR) spectra of liquid, gaseous and solid states as well as the liquid and solid phases Raman ones of the pure (Z,Z)-2, 4-hexadiene are recorded for the first time between 3100–50 cm⁻¹. Furthermore, the IR spectra of the gaseous and solid states and the solid Raman ones have been obtained (3100-50 cm⁻¹) for the (E,E) and (Z,E) isomers. A comparison between the present and our previous results for the liquid phase have enabled us to complete and confirm our previous assignment and to conclude that the planar s-trans conformation is prevailing in the three physical states under conditions used in this work.     

Stereoselective Synthesis of (2E, 6E, 10E)‐ Geranylgeraniol from Geranyllinalyl Acetate via Palladium‐Catalyzed Amination

Amination of geranyllinalyl acetate 1 with diethylamine and Pd(OAc)₂ · 2PPh₃ as catalyst gave N,N‐diethylgeranylgeranylamine 3 (E/Z=91/9) in 85% yield. Amine 3 was treated by ethyl chloroformate followed by KOAc to give geranylgeranyl acetate 2 in 82% yield. Then 2 was hydrolyzed to afford geranylgeraniol 4 in 94% yield.     

Synthesis,Crystal Structure,and Conversion of the Polycyclic Tris‐Anhydrotetramer of O‐Aminobenzaldehyde to Cu(TAAB)2+

Abstract

Polycyclic tris‐anhydrotetramer 6 of o‐aminobenzaldehyde was synthesized directly from reduction of o‐nitrobenzaldehyde and its structure was determined by X‐ray crystallography. This provides a practical synthesis of 6, as opposed to starting from the unstable o‐aminobenzaldehyde. The tris‐anhydrotetramer 6 is useful for the synthesis of a variety of TAAB‐metal complexes.     

Headspace Solid‐Phase Microextraction (HS‐SPME) for the Determination of Benzene,Toluene, Ethylbenzene,and Xylenes (BTEX) in Foundry Molding Sand

Abstract

The use of headspace solid‐phase microextraction (HS‐SPME) to determine benzene, toluene, ethylbenzene, and xylenes (BTEX) in foundry molding sand, specifically a “green sand” (clay‐bonded sand) was investigated. The BTEX extraction was conducted using a 75 µM Carboxen‐polydimethylsiloxane (CAR‐PDMS) fiber, which was suspended above 10 g of sample. The SPME fiber was desorbed in a gas chromatograph injector port (280°C for 1 min) and the analytes were characterized by mass spectrometry. The effects of extraction time and temperature, water content, and clay and bituminous coal percentage on HS‐SPME of BTEX were investigated. Because green sands contain bentonite clay and carbonaceous material such as crushed bituminous coal, a matrix effect was observed. The detection limits for BTEX were determined to be ≤0.18 ng g^?1 of green sand.     

Analysis of pigments and coverings by X-ray diffraction (XRD) and micro Raman spectroscopy (MRS) in the cemetery of Tutugi (Galera, Granada, Spain) and the settlement convento 2 (Montemayor, Córdoba, Spain)

This paper focuses on the identification of the composition of the coverings and pigments of two archaeological sites. The sites researched here lie in Andalusia and show two contexts, which have a highly symbolic and ritual meaning. The first, Convento 2 (Montemayor, Córdoba), dates back to the period of formation of the Iberian Culture (VIIth century b.c.). The second is the cemetery of Tutugi (Galera, Granada), of the mid-Iberian period (IVth century b.c.). The analytical procedure consisted in combined and complementary use of XRD and MRS. This allowed to identify the materials used, namely hematite, goethite, coal, gypsum and calcite. Identification of these materials proves essential for the restoration and musealization of both archaeological sites.     

Synthesis of the Potassium Channel Opener (3S,4R)‐3,4‐Dihydro‐4‐(2,3‐dihydro‐2‐methyl‐3‐oxo‐pyridazin‐6‐Yl)oxy‐3‐hydroxy‐6‐(3‐hydroxyphenyl)sulphonyl‐2,2,3‐trimethyl‐2H‐benzo[b]pyran

The preparation of the potassium channel opener (3S,4R)‐3,4‐dihydro‐4‐(2,3‐dihydro‐2‐methyl‐3‐oxo‐pyridazin‐6‐yl)oxy‐3‐hydroxy‐6‐(3‐hydroxyphenyl)sulphonyl‐2,2,3‐trimethyl‐2H‐benzo[b]pyran (1) as a single enantiomer is reported. Considerable improvements have been implemented with respect to the original synthesis that allow for the preparation of multigram quantities of the final target compound. The optimized synthesis consists of a six‐step linear sequence whose key step is an asymmetric epoxidation protocol through the use of Jacobsen's (S,S)‐(+)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) chloride catalyst.     

Application of Organolithium and Related Reagents in Synthesis,Part 31: Effective Conversion of 3‐Arylphthalides into 2‐(1‐Aryl‐3‐oxo‐4‐alkoxycarbonyl‐butyl)benzoic Acids

A convenient three‐step protocol preparation of the ortho‐alkylated (long‐chain substituent with terminal methylcarbonyl or acetoacetate moiety) aromatic carboxylic acids 15 or 16 from benzoic acids anilides 10 was developed, which exploited the reductive alkylation of phthalides 13 with dimethyl‐6‐methylene‐4‐(trimethoxysiloxy)‐1,3‐diox‐4‐ene (9) as a key step.     

Synthesis of a Blocked Tetrasaccharide Related to the Repeating Unit of the Antigen from Shigella dysenteriae Type 9 in the Form of Its Methyl (R)‐Pyruvate Ester and 2‐(Trimethylsilyl)Ethyl Glycoside

Starting from d‐mannose, d‐galactose and d‐glucosamine hydrochloride, two disaccharide blocks were synthesized. Schmidt's inverse addition technique of trichloroacetimidate was utilized for the construction of a disaccharide with a β‐mannosidic linkage in good yield. The other disaccharide had a methyl 4,6‐(R)‐pyruvate ester. The two disaccharides in the appropriate form were then allowed to react in the presence of N‐iodosuccinimide (NIS) and trifluoromethanesulfonic acid (TfOH) to give the desired tetrasaccharide derivative, 2‐(trimethylsilyl)ethyl 2‐acetamido‐3,4,6‐tri‐O‐benzoyl‐2‐deoxy‐β‐d‐glucopyranosyl‐(1→3)‐2‐O‐benzoyl‐4,6‐O‐[(R)‐1‐methoxycarbonylethylidene]‐β‐d‐galactopyranosyl‐(l→4)‐2,3,6‐tri‐O‐benzyl‐β‐d‐mannopyranosyl‐(1→4)‐2,6‐di‐O‐benzyl‐3‐O‐(4‐methoxybenzyl)‐β‐d‐galactopyranoside.     

Source Rocks of the Caledonian-Age Granitoid Rocks in Wanyanshan-Zhuguangshan, Southeast China (Ⅱ)——Topological Analysis in Isotopic Multispace

Topological analysis in Sr-Nd-O-Pb_3 six-dimensional isotopic space suggests that the source rocks of the Caledonian-age granitoid rocks in Wanyangshan-Zhuguangshan, southeast China, comprise three end-member components. Isotopic mixing model discrimination indicates that the granitoid rocks were produced through mixing of the three componentsin varying proportions. Comprehensive study of multiple isotopic systems and geochemistry of the granitoid rocks suggests that the three end-member components were crustal rocks which are continent-derived sediments, geosycline sediments and altered basic volcanic rocks.     

Quantitative TLC Analysis of Sterol (24β-Ethylcholesta-5,22E,25-triene-3β-ol) in Agnimantha (Clerodendrum phlomidis Linn)

A quantitative method using silica gel 60F₂₅₄ high performance thin layer chromatography plates, automated bandwise sample application, and automated visible mode densitometric method has been developed for the determination of 24β-ethylcholesta-5,22E,25-triene-3β-ol (ECTO) in the aerial part of Clerodendrum phlomidis. ECTO was used as a chemical marker for the standardization of C. phlomidis plant extracts. The separation was performed on silica gel 60F₂₅₄ TLC plates using chloroform-methanol (98.5: 1.5, v/v) as mobile phase. The quantitation of ECTO was carried out using the densitometric reflection/absorption mode at 650 nm after post chromatographic derivatization with anisaldehyde reagent. A precise and accurate quantification can be performed in the linear working concentration range of 150–400 ng band⁻¹ with good correlation (r ² = 0.996). The method was validated for peak purities, precision, robustness, limit of detection (LOD) and quantitation (LOQ), etc. as per ICH guidelines.