Critical evaluation of a high‐throughput analytical method for polychlorinated biphenyls in human serum: which detector for the establishment of the reference values?

A rapid screening method, previously developed and validated for the determination of 60 PCB congeners in human serum by using high-resolution gas chromatography coupled with low-resolution mass spectrometry, was applied to the establishment of the reference values in the general population. The reliability of this method was further confirmed by analyzing ten serum samples, obtained from the same population group involved in the original study, by electron impact ionization with either low- or high-resolution mass spectrometry. Analyses in electron capture negative ionization mode were also performed for the determination of 'dioxin-like' isomers. The data were found to be in good accordance with one another, especially for the congeners of highest environmental significance. Then, 162 real serum samples were analyzed for the presence of PCBs. Comparison with the results from other studies reported in the literature showed that a similar profile was observed; the most abundant congeners were #153, #180, #138 and #170. A statistical analysis was performed to determine whether there were significant correlations between PCB concentrations and specific variables such as age, gender, and dietary habits.     

Organometallic alkylation of 2-chloro-4,6-dimethoxy-1,3,5-triazine: a study

The reactivity of 2-chloro-4,6-dimethoxy-1,3,5-triazine (1) has been investigated in Pd- or Ni-catalyzed cross-coupling processes with organostannanes, Grignard reagents, organoalanes and organozinc halides. All organometallic reagents considered form new C-C bonds on the heteroaromatic ring and afford the corresponding 2-alkyl-4,6-dimethoxy-1,3,5-triazines in moderate to very good yields. The collected data allows the choice of the alkylating agent as well as the experimental conditions depending on the residue to transfer.     

Development of an HPLC method for the identification and dosage of non-allowed substances in cosmetic products. Part I: local anaesthetics and antihistaminics

An HPLC method with ultraviolet detection coupled with a solid-phase extraction sample clean up was developed for the analysis of five local anaesthetics and four antihistaminics in cosmetic products. The presence of these compounds in commercial cosmetic samples is fordbidden. Extracts from real samples were applied to a solid-phase extraction C₁₈ cartridge, and the analytes were eluted with 8:2 (v/v) acetonitrile/water containing 1 trifluoroacetic acid. HPLC separation was then performed for the identification and determination of the analytes using a Purospher RP-18 column, two gradient eluting systems and a photodiode-array detector. The accuracy of the method was verified by spiking experiments on home-made cosmetic samples. The analytical recoveries were satisfactory.     

Appending a tris-imidazole ligand with a Tyr 244 mimic on the distal face of bromoacetamidoporphyrin

[structure: see text] Bromoacetamidoporphyrin is a convenient synthon for the attachment of distal superstructures at room temperature in good yields. New models are presented that contain a tris-imidazole distal ligand set bound to the porphyrin in either a binary or trinary fashion. More importantly, one distal imidazole is cross-linked to a phenol mimicking Tyr(244), making this model the closest structural analogue yet reported of the metal free cytochrome c oxidase (CcO) active site.     

Multilinear regression and comparative molecular field analysis (CoMFA) of azo dye-fiber affinities. 2. Inclusion of solution-phase molecular orbital descriptors

For a data set with 30 direct azo dyes taken from literature, quantitative structure-activity relationship (QSAR) analyses have been performed to model the affinity of the dye molecules for the cellulose fiber. The electronic structure of the compounds was characterized using quantum chemical gas-phase (AM1) and continuum-solvation molecular orbital parameters. As regards the solution phase, COSMO appears to be better suited than SM2 in quantifying relative trends of the aqueous solvation energy. For the dye-fiber affinity, the leave-one-out prediction capability of multilinear regression equations is superior to CoMFA, with predictive squared correlation coefficients ranging from 0.63 (pure CoMFA) to 0.89. At the same time, solution-phase CoMFA is superior to previously derived AM1-based CoMFA models. As a general trend, the dye-fiber affinity increases with increasing electron donor capacity that corresponds to an increasing hydrogen bond acceptor strength of the azo dyes. The discussion includes the consideration of structural features that are likely to be involved in dye-fiber and dye-dye hydrogen bonding interactions, and possible links between CoMFA electrostatic results and the atomic charge distribution of the compounds.     

Use of multivariate analysis of MIR spectra to study bread staling

Different kinds of bread, stored at constant temperature and at controlled humidity conditions for a week since their manufacturing date, were analysed by Attenuated Total Reflectance-Fourier Transform InfraRed (ATR-FTIR) spectroscopy. The collected spectra were processed by Principal Component Analysis (PCA), in order to evaluate the changes occurring during bread ageing. For the sake of comparison, the 1060-950 cm spectral window has been also investigated by curve-fitting methods. It was observed that the first PC increases monotonically with ageing of samples. Furthermore, the more influential variables on PC1 correspond to spectral regions where are located stretching and bending bands, which are mainly attributed to typical starch bonds vibrations.     

Methyl and Phenylmethyl 2-Acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate in the Synthesis of heterocyclic systems: Preparation of 3-amino-4H-pyrido-[1,2-a]pyrimidin-4-ones

Methyl 2-acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 4 ) and phenyl-methyl 2-acetyl-3-{[2-(dimethylamino)-1(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 5 ) were prepared in three steps from the corresponding acetoacetic esters, and used as reagents for the preparation of N³-protected 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 10 – 12 , 5H-thiazolo[3,2-a]pyrimidin-5-one 13 , 4H-pyrido[1,2-a]-pyridin-4-one 19 and 2H-1-benzopyran-2-ones 20 – 23 . Free 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 24 – 26 were prepared from 10 – 12 by removal of the 2-(methoxycarbonyl)-3-oxobut-1-enyl or 3-oxo-2-[(phenyl-methoxy)carbonyl]but-1-envl as N-protecting group by various methods.     

A Simple Stereoselective Synthesis of Aplysinopsin Analogs

Simple and stereoselective syntheses of aplysinopsins and their analogs from either methyl 2‐[(2,2‐disubstituted ethenyl)amino]‐3‐(dimethylamino)prop‐2‐enoates 11 or 5‐[(dimethylamino)methylidene]imidazolidine‐2,4‐diones 20 are described. The structures of products are established by ¹H‐ and ¹³C‐NMR, and NOESY spectroscopy, and X‐ray crystal‐structure analysis.     

Enzyme-Linked DNA Displacement (ELIDIS) Assay for Ultrasensitive Electrochemical Detection of Antibodies**

Here we report the development of a method for the electrochemical ultrasensitive detection of antibodies that couples the programmability and versatility of DNA-based systems with the sensitivity provided by enzymatic amplification. The platform, termed Enzyme-Linked DNA Displacement (ELIDIS), is based on the use of antigen-DNA conjugates that, upon the bivalent binding of a specific target antibody, induce the release of an enzyme-DNA hybrid strand from a preformed duplex. Such enzyme-DNA hybrid strand can then be electrochemically detected with a disposable electrode with high sensitivity. We applied ELIDIS to demonstrate the sensitive (limit of detection in the picomolar range), specific and multiplexed detection of five different antibodies including three clinically relevant ones. ELIDIS is also rapid (it only requires two reaction steps), works well in complex media (serum) and is cost-effective. A direct comparison with a commercial ELISA kit for the detection of Cetuximab demonstrates the promising features of ELIDIS as a point-of-care platform for antibodies detection.