Static–dynamic sequential superheated liquid extraction of phenols and fatty acids from alperujo

Superheated liquids of different polarity have been used for sequential extraction of fatty acids and phenols from alperujo. Multivariate methodology has been used to optimise the static–dynamic extraction. Forty-two minutes are required to complete extraction (20 mg/kg of fatty acids and up to 2,200 mg/kg of hydroxytyrosol in the raw material used). The efficacy of the extraction has been demonstrated and compared with that of conventional methods (Folch and stirring-based methods for fatty acids and phenols, respectively), which needed 4.5 and 24 h for the extraction of fatty acids and phenols, respectively. The non-polar and polar extracts were injected into GC–MS and HPLC–MS–MS equipment, respectively, for individual separation–quantification of the target compounds. The simplicity of the experimental setup and the low costs of the raw material make the proposed method advisable when extraction of both fractions is required.     

Certification of butyltins and phenyltins in marine sediment certified reference material by species-specific isotope-dilution mass spectrometric analysis using synthesized <Superscript>118</Superscript>Sn-enriched organotin compounds

A new marine sediment certified reference material, NMIJ CRM 7306-a, for butyltin and phenyltin analysis has been prepared and certified by the National Metrological Institute of Japan at the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). Candidate sediment material was collected at a bay near industrial activity in Japan. After air-drying, sieving, and mixing the material was sterilized with γ-ray irradiation. The material was re-mixed and packaged into 250 glass bottles (15 g each) and these were stored in a freezer at −30 °C. Certification was performed by use of three different types of species-specific isotope-dilution mass spectrometry (SSID–MS)—SSID–GC–ICP–MS, SSID–GC–MS, and SSID–LC–ICP–MS, with ¹¹⁸Sn-enriched organotin compounds synthesized from ¹¹⁸Sn-enriched metal used as a spike. The ¹¹⁸Sn-enriched mono-butyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were synthesized as a mixture whereas the ¹¹⁸Sn-enriched di-phenyltin (DPhT) and triphenyltin (TPhT) were synthesized individually. Four different extraction methods, mechanical shaking, ultrasonic, microwave-assisted, and pressurized liquid extraction, were adopted to avoid possible analytical bias caused by non-quantitative extraction and degradation or inter-conversion of analytes in sample preparations. Tropolone was used as chelating agent in all the extraction methods. Certified values are given for TBT 44±3 μg kg⁻¹ as Sn, DBT 51 ± 2 μg kg⁻¹ as Sn, MBT 67 ± 3 μg kg⁻¹ as Sn, TPhT 6.9 ± 1.2 μg kg⁻¹ as Sn, and DPhT 3.4 ± 1.2 μg kg⁻¹ as Sn. These levels are lower than in other sediment CRMs currently available for analysis of organotin compounds.     

Determination of volatile oak compounds in aged wines by multiple headspace solid-phase microextraction and gas chromatography–mass spectrometry (MHS-SPME–GC–MS)

Multiple headspace solid-phase microextraction (MHS-SPME) with gas chromatography–mass spectrometry is proposed for quantification of nine volatile oak compounds in aged wines. These compounds are formed and extracted by wine when it is matured in oak barrels and are responsible for particular organoleptic properties and the high quality of these wines. Some important variables of the extraction process, for example volume of sample and extraction time, were studied. Extraction of 50 μL wine was performed with a divinylbenzene–Carboxen–polydimethylsiloxane fibre at 55 °C for 60 min. For calibration the same conditions were used, except that the wine was substituted by 50 μL of a standard solution in synthetic wine. The linearity, detection limits, and repeatability of the method were determined by use of standard solutions in synthetic wine. Detection limits were between 0.01 and 10 μg L⁻¹ (for eugenol and furfural, respectively) and repeatability, expressed as relative standard deviation, was from 2 to 6%. The method was used to analyse six red wines and the concentrations obtained were statistically compared with those obtained by the standard addition method for the same wines.     

Detection of small RNA molecules by a combination of branched rolling circle amplification and bioluminescent pyrophosphate assay

Polyfluorinated compounds (PFCs) are a relatively new and diverse set of compounds analyzed as contaminants in food. Their unique physical-chemical properties dictate the methods used for their analysis. Current analyses of the more volatile PFCs involve gas chromatography–mass spectrometry; liquid chromatography–tandem mass spectrometry is generally used for the less volatile PFCs. Considerations in the analysis of PFCs in foods include contamination from the widespread presence of materials that contain various PFCs, endogenous interfering compounds, and matrix effects. Future opportunities for research on PFCs in food exist, particularly in the areas of biological molecule–PFC interactions and the effects of food processing on these interactions. Future research will be facilitated by the synthesis of a wider variety of analytical standards.     

DFT-PCM Study of the Bond Dissociation Energies of N-nitrosoindole Compounds in Acetonitrile

Quantum chemical calculations are used to estimate the equilibrium N–NO bond dissociation energies (BDEs) in acetonitrile (MeCN) for seven N-nitrosoindole compounds. These compounds are studied by employing the hybrid density functional theory (B3LYP, B3P86 and B3PW91) methods together with 6-31G^∗∗ basis sets. The obtained results are compared with the available experimental results. It is demonstrated that the B3PW91 method is the best of these methods to compute the bond dissociation energies of N-nitrosoindole compounds. The solvent effects on the BDEs of the N–NO bond are analyzed and it is shown that the N–NO BDEs in a vacuum, computed by the B3LYP method, are the closest to the computed values in MeCN and the average solvent effect is 4.0 kJ⋅mol⁻¹. The substituent effects on the N–NO BDEs were further analyzed and it is found that the N–NO BDE increases with increments of the Hammett constants of substituent groups on the benzene ring for N-nitrosoindole compounds, except the compound with 5-NO₂−C₈H₅N–NO. Finally, N-nitrosoindole compounds and the other NO-donors (N-nitroso compounds) are compared.     

Identification by GC—MS of cymene isomers and 3,7,7-trimethylcyclohepta-1,3,5-triene in essential oils

Retention indices of cymene isomers published in popular GC—MS atlases were found to be erroneous by analyzing synthetic samples. The following retention indices (RI) were found using a nonpolar phase (diphenyl: dimethylpolysiloxane, 5:95) for four essential-oil components with indistinguishable mass spectra: 3,7,7-trimethylcyclohepta-1,3,5-triene (RI = 970), m-cymene (RI = 1022), p-cymene (RI = 1024), and o-cymene (RI = 1039). The relative distributions of these compounds were evaluated based on the analysis of about 1000 essential oils. Simple methods were given for preparing standard mixtures of isomeric compounds for identification by GC—MS. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 569–571, November–December, 2006.     

A rapid synthetic method of pyridobenzodiazepines

A new one-pot Bischler–Napeiralski type cyclization reaction between pyridine-1,2-diamines and various carboxylic acids with PPA as catalyst to prepare pyridobenzodiazepines is proposed. In the new synthetic route, the reaction time is only one-third of the methods reported. The synthetic strategy provides an efficient way to prepare novel structurally diversified heterocyclic compounds of pyridobenzodiazepine family with potential pharmaceutical or biological activities.     

Liquid chromatographic determination of the species composition of membrane lipids and their derivatives

This review gives quantitative results of the separation of individual classes of polar glycerolipids of natural and synthetic origin into their individual species. Universal quantitative criteria calculated from the fatty-acid composition of the species obtained or of their mixtures are proposed for determining the degree of reliability of these results. The fractionation of the initial acyl-containing glycerolipids, their N- and O-derivatives with high hydrophobicity, the products of the enzymatic hydrolysis of the native lipids (diacylglycerols, phosphatidic acids) and also the lipophilic O-derivatives of these products is considered. For all these compounds, the results of their separation by the methods of TLC and HPLC both in the form of the adsorption chromatography of the coordination complexes with silver and also in the form of reversed-phase chromatography are discussed. Institute of Plant Physiology of the USSR Academy of Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 453–477, July–August, 1989.     

Synthesis of heterocycles with polyfluoroalkyl substituents from unsaturated compounds containing polyfluoroalkyl groups. (Review)

Methods for the construction of heterocyclic systems containing polyfluoroalkyl substituents from derivatives of ethylene and acetylene are discussed. It is shown that various compounds with polyfluoroalkyl groups can be used as building blocks: α,β-unsaturated carbonyl compounds, their synthetic organosilicon equivalents (silyl-substituted alcohols, silyl ethers of enols), and also sulfones, nitriles, polyfluoroalkenes (in reactions at the double bond), acetylenecarboxylic acids, their esters, and polyfluoroalkynes. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 323–360, March, 2006.     

Preparation of benzoate esters of morphine and its derivatives

Abstract  

Sustained analgesia is crucial for patients suffering from long-acting pain. Ester derivatives of morphine could enhance the lipophilicity of morphine; consequently its transdermal delivery as well as its duration of action are also increased. Therefore, twenty-one 3-O-, 6-O-, and 14-O-benzoate esters of morphine and their derivatives were synthesized in order to elaborate different synthetic methods suitable for esterification of these widely used compounds. Schotten–Baumann reaction was applied with sodium hydrogen carbonate, triethylamine, or pyridine in methylene chloride or 1,2-dichloroethane as solvents. The presence of 4-dimethylaminopyridine catalyst was also successfully utilized mainly in the case of tertiary alcohols. A novel synthesis of dihydromorphine via diacetyl morphine free of by-products is also presented. Structures of all synthesized compounds were elucidated by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, high-resolution mass spectrometry (HRMS), and electron ionization mass spectrometry (EI-MS). The log D (pH 7.4) values of the synthesized compounds were determined by a reversed-phase high-performance liquid chromatography (HPLC)–MS-based method, and calculated hydrolysis rate constants are also provided. The synthesized benzoate esters are potential prodrugs of the parent morphine with enhanced lipophilicity, derivatives which can also be used in transdermal drug delivery as prospective long-acting narcotic analgesics.     

PLS and first derivative of ratio spectra methods for determination of hydrochlorothiazide and propranolol hydrochloride in tablets

Two new analytical methods have been developed as convenient and useful alternatives for simultaneous determination of hydrochlorothiazide (HCT) and propranolol hydrochloride (PRO) in pharmaceutical formulations. The methods are based on the first derivative of ratio spectra (DRS) and on partial least squares (PLS) analysis of the ultraviolet absorption spectra of the samples in the 250–350-nm region. The methods were calibrated between 8.7 and 16.0 mg L⁻¹ for HCT and between 14.0 and 51.5 mg L⁻¹ for PRO. An asymmetric full-factorial design and wavelength selection (277–294 nm for HCT and 297–319 for PRO) were used for the PLS method and signal intensities at 276 and 322 nm were used in the DRS method for HCT and PRO, respectively. Performance characteristics of the analytical methods were evaluated by use of validation samples and both methods showed to be accurate and precise, furnishing near quantitative analyte recoveries (100.4 and 99.3% for HCT and PRO by use of PLS) and relative standard deviations below 2%. For PLS the lower limits of quantification were 0.37 and 0.66 mg L⁻¹ for HCT and PRO, respectively, whereas for DRS they were 1.15 and 3.05 mg L⁻¹ for HCT and PRO, respectively. The methods were used for quantification of HCT and PRO in synthetic mixtures and in two commercial tablet preparations containing different proportions of the analytes. The results of the drug content assay and the tablet dissolution test were in statistical agreement (p < 0.05) with those furnished by the official procedures of the USP 29. Preparation of dissolution profiles of the combined tablet formulations was also performed with the aid of the proposed methods. The methods are easy to apply, use relatively simple equipment, require minimum sample pre-treatment, enable high sample throughput, and generate less solvent waste than other procedures. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

EDTA assisted sol–gel synthesis of ZrW2O8

A novel sol–gel synthetic route using water-soluble precursor salts is presented as a synthetic path for a high-purity negative thermal expansion material, ZrW₂O₈. This synthetic route involves a sol–gel method with the use of EDTA as complexing agent. The aqueous solution is transformed into a ceramic material after a two-step heat treatment: gelation at 60 °C and reactive sintering at 1,180 °C. The decomposition of the gel is monitored with infrared spectroscopy and TGA. The high-temperature heat treatment results in ZrW₂O₈ with its characteristic negative thermal expansion behaviour α_{[75–130 °C]}: −9.8 ± 1.6 μm/m °C and α_{[175–300 °C]}: −1.2 ± 0.2 μm/m °C.     

Preparation of a sewage sludge laboratory quality control material for butyltin compounds and their determination by isotope-dilution mass spectrometry

The characterisation of a laboratory quality control material (QCM) for dibutyltin (DBT) and tributyltin (TBT) in sewage sludge is described. The reference values were determined by the use of two different types of isotope-dilution mass spectrometry: gas chromatography–mass spectrometry and gas chromatography–inductively coupled plasma mass spectrometry. To avoid possible analytical errors such as non-quantitative extraction and species degradation during sample preparation, different extraction methods were tested (microwave- and ultrasound-assisted extraction and mechanical stirring). The reference values were based on the unweighted means of results from the homogenisation and characterisation studies. The reference values obtained were 1,553 ± 87 and 534 ± 38 ng Sn g^-1 for DBT and TBT, respectively. In the uncertainty budget estimation, the sample inhomogeneity and between-method imprecision were taken into account. The concentrations of DBT and TBT in QCM are similar to those in the harbour sediment certified reference material PACS-2. Likewise, the levels of DBT and TBT are in the range of these compounds normally present in sewage sludge worldwide. In the future, the QCM will be used for an intercomparison study on DBT and TBT in sewage sludge, and as a day-to-day QCM during studies concerning the application of sewage sludge as an additive to artificial soil or as a raw material in civil engineering construction.     

A quantitative structure-activity relationship study of antifungal analogues of 3,4-substituted 5-((1H-1, 2, 4-triazol-1-yl)methyl)-4H-1,2,4-triazole

A series of 5-((1H-1, 2, 4-triazol-1-yl)methyl)-4H-1,2,4-triazole derivatives were prepared and evaluated for their antifungal activities. Quantitative structure–activity relationship studies were performed on these compounds using physicochemical parameters as independent parameters and antifungal activity as a dependent parameter, where antifungal activity correlated best (correlation coefficient r > 0.8) with physicochemical parameters (Hammett’s constants σ _p , F) and van der Waals volume V ₁. Results are interpreted on the basis of multiple regression and cross-validation methodology. Furthermore, the domain of applicability which indicates the area of reliable predictions is defined. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Chemical structures of A1–26 and A39; synthetic procedures; synthesis schemes; mps, yields, ¹H NMR; elemental analyses of compounds and single crystal X-ray diffraction of compounds.     

Effect of 5-hydroxy- and 5,8-dihydroxy-1,4-naphthoquinones on the hydrolytic activity of <Emphasis Type="Italic">α</Emphasis>-galactosidase

The effect of natural and synthetic polyhydroxy-1,4-naphthoquinones on the hydrolytic activity of α-galactosidase from marine bacteria was studied. It was shown that the inhibiting properties relative to the enzyme depended on the nature of the substituents, their number, and their position in the structure of these compounds. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 59–63, January–February, 2009.     

Environmental analysis of fluorinated alkyl substances by liquid chromatography–(tandem) mass spectrometry: a review

Fluorinated alkyl substances (FASs) are widely distributed contaminants that have been found in many environmental, human and biological samples throughout the world. Perfluorochemicals are used in many industry and consumer products, such as polymers and surfactants, because they have unique and useful properties (they are stable, chemically inert and generally unreactive). However, these compounds have also been found to be toxic, persistent and bioaccumulative. In recent years various analytical methods have been developed for the analysis of FASs in environmental samples. Most of these methods are based on liquid chromatography coupled to mass spectrometry (LC–MS) or tandem mass spectrometry (LC–MS/MS), since this is considered to be the technique of choice. This article reviews the various LC–(tandem)MS methods described so far for the analysis of FASs in water, sediment, sludge and biota samples. It discusses the main experimental conditions used for sample pretreatment and for analysis as well as the most relevant problems encountered and the limits of detection achieved.     

A new lignan from the leaves of <Emphasis Type="Italic">Loropetalum chinensis</Emphasis>

Investigation on the EtOH extract of the leaves of Loropetalum chinensis led to the isolation of seven compounds (1–7). Their structures were identified using spectroscopic methods. Among these compounds, compound 1 is a new lignan, and 2–7 were isolated from this plant for the first time.     

Determination of Hormones and Non-ionic Surfactant Degradation Products in Small-Volume Aqueous Samples from Soil Columns Using LC-ESI-MS-MS and GC-MS

The leaching of two estrogens, 17β-estradiol and estrone, and two degradation products of non-ionic surfactants, octylphenol and nonylphenol, through a soil column were studied to estimate their transport behavior. Different concentration methods (lyophilization, solid phase extraction, and liquid–liquid extraction) were evaluated for analyzing these compounds in small effluent fractions (30–50 mL) collected. Liquid chromatography-mass spectrometry (LC-MS-MS) and gas chromatography-mass spectrometry (GC-MS) were employed for quantitative analysis of these compounds. After comparison, the lyophilization-LC-MS-MS method was found to be best suited for the analysis of the two estrogen hormones and the liquid–liquid extraction-GC-MS method best for the analysis of the two phenols in small samples in the soil column study. Because of their high sorption capacity, these compounds were mostly sorbed in the upper part of the soil column and were difficult to detect in column effluent.     

Quantification of human and veterinary antibiotics in water and sediment using SPE/LC/MS/MS

An analytical method was developed and tested for four different groups of veterinary antibiotics in both river water and sediment matrices. Solid phase extraction (SPE) was used to enrich and to clean up the aqueous sample. Also, Mcllvaine and ammonium hydroxide buffer solutions were used to extract the compounds from the sediment matrix. High performance liquid chromatography (HPLC) equipped with tandem mass spectrometry (MS/MS) was used to separate and quantify the samples. The range of recoveries (in percent) for tetracyclines (TCs), sulfonamides (SAs), macrolides (MLs), and ionophore polyethers (IPs) in the water matrix were 102.2–124.8, 76.6–124.3, 89.5–114.7, 82.7–117.5 with 1–13 (%) of relative standard deviation respectively with three different concentrations. For sediment, the percent recovery ranges were 32.8–114.8, 62.4–108.9, 53.4–128.4 and 51.3–105.4 for TCs, SAs, MLs and IPs, respectively. The relative standard deviation ranged from 16 – 27 (%) over three different concentrations. The limit of quantification (LOQ) was determined by two different methods and calculated to be in the range of 0.01–0.04 μg/l and 0.3–2.5 μg/kg for TCs, SAs, and MLs in water and sediment, respectively. For IPs, the LOQ was 0.001–0.003 μg/l in river water and 0.4–3.6 μg/kg for sediment. The sediment concentration measured in an agriculture-influenced river was much higher than in the overlying water matrix, indicating a high degree of sediment partitioning for these compounds.     

Synthesis of spiro-cyclopropane derivatives containing multiple chiral centers

Tandem asymmetric double Michael addition/internal nucleophilic substitution of the novel chiral source, 5-(l-menthyloxy)-3-bromo-2(5H)-furanone with nucleophilic alcohol compounds has been investigated. The tandem asymmetric reaction can afford four new stereogenic centers with one reaction and give optically pure spiro-cyclopropane derivatives 5a--5d which are difficult to obtain by routine methods. The synthetic method for 5a--5d was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [α]~(20),IR,~1H NMR,~(13)C NMR, MS and elementary analysis. The absolute configuration of the sprio [5-l-menthyloxy-3-bromo butyrolactocyclopropane-3″, 3′(4′-methyloxy-5′-menthyloxybutyrolactone)] (5a) was established by X-ray crystallography. The work can provide important synthetic strategy in synthesis of some new optically active spiro-cyclopropane analogues and some biologically active molecules with complex structure.