科学补碘:消除碘缺乏病的成败关键

碘对甲状腺功能具有双向作用,在消除碘缺乏病的同时,切不可忽略全民食盐加碘后高碘甲状腺病的防治。分别从水碘和尿碘两个方面论述了碘与甲状腺病之间的双向关系,并根据流行病学调查数据和全国碘缺乏病监测数据确定了盐碘与尿碘之间的数学关系,计算了食盐碘含量的最适宜范围,提出了下调食盐碘含量、设计区域化碘盐和补碘个性化的科学补碘新策略。     

Proficiency testing programmes as a tool in food quality assurance: Overview of Italian experiences

Proficiency testing involves the performance of test procedures on routine samples by a number of laboratories. Interlaboratory proficiency testings provide multiple benefits to participants since they play a key-role in the total quality control of laboratory activities. They serve as a means of self-improving, as a mechanism of continuing education and as a source of information for accreditation agencies. This review highlights basic principles, benefits, criteria and capabilities of a proficiency testing programme for food analysis laboratories as well as their role in the implementation of rapidly developing food control legislation.     

Molecular iodine: a powerful catalyst for the easy and efficient synthesis of quinoxalines

Various biologically important quinoxaline derivatives were efficiently synthesized in excellent yields using inexpensive, nontoxic, and readily available bench top chemical, iodine in catalytic amount (10 mol %). Besides this, a systematic study was carried out to evaluate parameters such as solvent and catalyst loading. Several aromatic as well as aliphatic 1,2-diketones and aromatic 1,2-diamines, such as substituted phenylene diamines, tetra amines were further subjected to condensation using catalytic amounts of iodine to afford the products in excellent yield.     

First example of the activation of polymethylhydrosiloxane with molecular iodine: a facile synthesis of 3,6-dihydropyran derivatives

Glycals react rapidly with polymethylhydrosiloxane (PMHS) in the presence of a catalytic amount of molecular iodine under mild conditions to afford the corresponding 3,6-dihydropyran derivatives in excellent yields. Et₃SiH/I₂ was also found to be effective for this conversion.     

Gallium iodide/iodine as a versatile reagent for the aza-Prins cyclization: an expeditious synthesis of 4-iodopiperidines

4-Iodopiperidines are prepared in good yields and with high selectivity by means of aza-Prins-cyclization using a catalytic amount of gallium(III) iodide and a stoichiometric amount of iodine under mild reaction conditions. This is the first report on the preparation of 4-iodopiperidines via aza-Prins-cyclization.     

Oxidative synthesis of azacyclic derivatives through the nitrenium ion: application of a hypervalent iodine species electrochemically generated from iodobenzene

Oxidation of the methoxyamide derivatives 1, 4, and 7 has been examined to elaborate efficient synthetic methodology of the azacyclic derivatives 2, 3, 5, 6, and 8, which would be applicable as synthetic intermediates of complicated bioactive substances. In addition to direct anodic and PIFA [phenyliodine(III) bis(trifluoroacetate)] oxidations, an active species derived from iodobenzene generated under electrolytic conditions was examined as an oxidant, and its synthetic efficacy was demonstrated in comparison of the reaction outcomes with other oxidation methods. In the oxidation, the methoxy substitution of substrates modulated the cyclization mode to provide the azaspiro- (2, 8) or quinolinone-type (3, 5, 6) products.     

Facile and efficient synthesis of lactols by a domino reaction of 2,3-epoxy alcohols with a hypervalent iodine(III) reagent and its application to the synthesis of lactones and the asymmetric synthesis of (+)-tanikolide

The domino reaction of 2,3-epoxy-1-alcohol derivatives, namely tetrasubstituted 2,3-epoxy-1-alcohols and 2- or 3-alkyl trisubstituted 2,3-epoxy-1-alcohols, with PhI(OCOCF(3))(2) in the presence of H(2)O is described in detail. In this reaction, several types of lactol derivatives can be directly obtained from the 2,3-epoxy-1-alcohol derivatives in a single operation. The obtained lactols were successively converted into the corresponding lactones. This reaction is applicable to the construction of optically active lactone compounds. The asymmetric total synthesis of (+)-tanikolide, an antifungal marine natural product, has been effectively achieved by using this reaction.     

Molecular iodine in isopropenyl acetate (IPA): a highly efficient catalyst for the acetylation of alcohols, amines and phenols under solvent free conditions

Iodine in isopropenyl acetate (IPA) is a highly efficient catalyst for the acetylation of a variety of alcohols, phenols and amines under solvent free conditions. Primary, secondary, tertiary alcohols, amines and mono to polyhydroxy phenols and anilines with electron donating or withdrawing substituents can be easily acetylated in good to excellent yield at 85-90 °C.     

Optimization and validation of an ion‐pair RP‐HPLC‐UV method for the determination of total free iodine in rabbit plasma: application to a pharmacokinetic study

An ion‐pair reverse‐phase high performance liquid chromatographic method with UV–vis detection has been developed for the determination of total free iodine in rabbit plasma after vaginal administration of povidone–iodine (PVP‐I). Sample preparation was done by protein precipitation with acetonitrile in 96‐well format and aspirin was used as the internal standard. The 100 µL sodium thiosulfate solution (5 g L^?1) was added to 100 µL plasma sample before protein precipitation, to convert the total free iodine in plasma to iodide (I^?). Separation was performed on a C₁₈ column (200 × 4.6 mm i.d., 5 µm). The mobile phase consisting of a mixture of water phase (containing 10 mmol L^?1 18‐crown‐6 ether, 5 mmol L^?1 octylamine and 5 mmol L^?1 sodium dihydrogen phosphate, pH adjusted to 6.0 with phosphoric acid) and acetonitrile in the ratio 70:30 (v/v) was delivered isocraticly at a flow rate of 1.0 mL min^?1. The method was sensitive with a lower limit of quantification of 0.005 µg mL^?1, with good linearity (r² > 0.9990) over the linear range of 0.005–2 µg mL^?1. All the validation data, such as linearity, accuracy and precision, were within the required limits. The method was successfully applied to study the pharmacokinetic of PVP–I in rabbits after vaginal administration. Copyright © 2009 John Wiley & Sons, Ltd.     

A state-of-the-science review of analytical methods for urinary dialkylphosphate metabolites in the assessment of exposure to organophosphate pesticides: From 2000 to 2022

The general population and workers are exposed to organophosphate insecticides, one of the leading chemical classes of pesticides used in rural and urban areas. This paper aims to conduct an integrative review of the most used analytical methods for identifying and quantifying dialkylphosphate—which are metabolites of organophosphate insecticides—in the urine of exposed workers, discussing their advantages, limitations and applicability. Searches utilized the PubMed, the Scientific Electronic Library Online and the Brazilian Digital Library of Theses and Dissertations databases between 2000 and 2021. Twenty-five studies were selected. The extraction methods most used were liquid–liquid extraction (LLE) (36%) and solid-phase extraction (SPE) (36%), with the SPE being more economical in terms of time and amount of solvents needed, and presenting the best percentage of recovery of analytes, when compared with LLE. Nineteen studies (76%) used the gas chromatography method of separation, and among these, 12 records (63%) indicated mass spectrometry used as a detection technology (analyzer). Studies demonstrate that dialkylphosphates are sensitive and representative exposure biomarkers for environmental and occupational organophosphate exposure.     

Stereospecific Sulfur-Mediated Cleavage of a Spirocyclobutanone: Synthesis of a Fully Functional Precursor to the CP Compounds

A reaction sequence made up of a Sakurai reaction, ketene cyclization, sulfur-directed Baeyer–Villiger reaction, and tandem lactone cleavage/isomerization provided the fully functionalized core of the CP compounds. Key steps were the methanolysis of 1 , which leads via 2 to the CP precursor 3 .     

Proficiency testing as a tool for implementing internal quality control: the case of ochratoxin A in cocoa powder

This paper describes the interlaboratory study aimed at assessing the performance of 18 laboratories (14 national and 4 European) for Ochratoxin A (OTA) determination in cocoa powder samples. The study was tested at three levels of OTA covering the range in which presumably European regulatory limits could fall in the near future. For the extraction step, almost all laboratories used an aqueous solution of sodium hydrogen carbonate with the exception of one laboratory using dichloromethane consistently with the ELISA procedure adopted in the study. The clean-up step was performed by utilizing the immunoaffinity columns by the two main manufacturers (R-Biopharm Rhone and VICAM) and for the quantitative analysis, HPLC was used by all the participants except one using ELISA. From the output of the study, it can be concluded that at low level (0.19 μg/kg) 10 out of 18 (56%), at medium level (0.45 μg/kg) 11 out of 18 (61%), and at high level (1.45 μg/kg) 12 out of 18 (67%) results fell within the satisfactory ranges. This interlaboratory study provides an estimate of the performance of national and European laboratories involved in OTA determination in cocoa powder samples, which sounds extremely valuable in view of potential future legislation by the European Commission.     

Oxidative C-H functionalization: a novel strategy for the acetoxylation/alkoxylation of arenes tethered to 3,4-dihydroisoquinolines

1-Aryl-3,4-dihydroisoquinolines undergo smooth acetoxylation/alkoxylation in the presence of 5 mol % Pd(OAc)₂ and a stoichiometric amount of PhI(OAc)₂ by means of C-H activation to produce the corresponding acetoxy- and alkoxy-1-aryl-3,4-dihydroisoquinoline derivatives respectively in good yields with high regioselectivity. It is a first example on oxidative functionalization of arenes tethered to dihydroisoquinoline moiety via the C-H activation.     

PRIRODA-04: a quantum-chemical program suite. New possibilities in the study of molecular systems with the application of parallel computing

Main characteristics are described of the PRIRODA quantum-chemical program suite designed for the study of complex molecular systems by the density functional theory, at the MP2, MP3, and MP4 levels of multiparticle perturbation theory, and by the coupled-cluster single and double excitations method (CCSD) with the application of parallel computing. A number of examples of calculations are presented.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 804–810, March, 2005.     

Metabolic profiling of infant urine using comprehensive two-dimensional gas chromatography: Application to the diagnosis of organic acidurias and biomarker discovery

Comprehensive two-dimensional gas chromatography (GC × GC) time-of-flight mass spectrometry (ToFMS) was applied to the analysis of urinary organic acids from patients with inborn errors of metabolism. Abnormal profiles were obtained from all five patients studied. Methylmalonic academia and deficiencies of 3-methylcrotonyl-CoA carboxylase and medium chain acyl-CoA dehydrogenase gave diagnostic profiles while deficiencies of very long chain acyl-CoA dehydrogenase and mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase gave profiles with significant increases in dicarboxylic acids suggestive of these disorders. The superior resolving power of GC × GC with ToFMS detection was useful in separating isomeric organic acids that were not resolved using one-dimensional GC. A novel urinary metabolite, crotonyl glycine, was also discovered in the mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase sample which may be a useful specific diagnostic marker for this disorder. The quantitative aspects of GC × GC were investigated using stable isotope dilution analyses of glutaric, glyceric, orotic, 4-hydroxybutyric acids and 3-methylcrotonylglycine. Correlation coefficients for linear calibrations of the analytes ranged from 0.9805 to 0.9993 (R²) and analytical recoveries from 77% to 99%. This study illustrates the potential of GC × GC–ToFMS for the diagnosis of organic acidurias and detailed analysis of the complex profiles that are often associated with these disorders.     

Solid-Phase Synthesis of Macrocyclic Systems by a Cyclorelease Strategy: Application of the Stille Coupling to a Synthesis of (S)-Zearalenone

No heteroatom required! In many solid-phase syntheses, after the release from the polymer support a heteroatom (e.g. O, S, N) remains in the substrate as a residue of a linking protecting group. With polymer-bound tin reagents cleavage and cyclization of the substrate with C–C bond formation (see picture) can now be achieved by intramolecular Stille coupling. S =substrate.