Establishment and enforcement of food standards in the U.K. and the EEC

Food legislation is enacted throughout the world, both to protect the health of the consumer and to prevent fraud. The food analyst plays a major part in the enforcement of such legislation, particularly as modern analytical techniques now enable trace constituents at ng/g levels to be detected.     

Research on the aromas. On the aroma of coffee. II. Pyrazines and pyridines

Pyrazines and pyridines occurring in a coffee concentrate are analyzed by two procedures. 24 compounds have been identified and the presence of some 10 more is revealed. The syntheses, mass and infrared spectral data of reference compounds are given.     

N.M.R. and X-ray diffraction of the 7,7'-disodiumcromoglycate-water lyomesophases

Aqueous solutions of 7,7'-disodiumcromoglycate (7,7'-DSCG) form a variety of mesophases, whose natures depend on concentration and temperature. We have used optical microscopy, N.M.R. (of ²H, ¹⁷O and ²³Na) and X-ray techniques to construct a phase diagram for this system and to characterize the various mesophases. In the concentration range 3 to 25 wt % 7,7'-DSCG four different mesophases are found. On cooling the isotropic solution an opaque gel phase is first obtained, followed on further cooling by a birefringent glassy liquid. At concentrations below 14wt% it is nematic, while at higher concentrations it appears to be a different, more ordered, phase. At lower temperatures a hexagonal phase is formed which finally solidifies on cooling to - 15°C. The N.M.R. and X-ray characteristics of these mesophases are discussed.     

Crystallinity and the effect of ionizing radiation in polyethylene. I. Crosslinking and the crystal core

An extensive study has been carried out on the effect of ionizing radiation on polyethylene in the form of solution-grown single crystals to follow up preceding investigations which had indicated that the radiation-induced effects along the fold surfaces could be significantly different from those within the crystal interior. In this first part of the series, radiation-induced crosslinking was investigated in the case of “crystal core” material. This material, obtained by removal of the fold surface by oxidative degradation with ozone, consists of isolated foldfree crystal layers of dicarboxylic acids of uniform length, the length itself depending on the fold length of the starting crystal. This “core material” was irradiated by γ rays and the effect of crosslinking was followed by GPC analysis by recording the development of dimer, trimer, etc., peaks in the chromatograms. For a given dose, the fractional amount of crosslinked material is independent of the chain length. This, together with other effects described, provides unambiguous evidence that crosslinking occurs at the chain ends or, in other words, that there is no crosslinking within the interior of the paraffinoid lattice. Further, no permanent scission was observed to occur within the lattice, at least in amounts detectable by the present molecular weight measurements. The obvious significance of these effects for radiation studies on paraffinoid substances in general, beyond those of the present long-chain dicarboxylic acids, is discussed prior to utilizing them in the study of chain-folded polyethylene crystals in the following parts of the series.     

Carbon-13 n.m.r. investigation on the nitrogen methylation of the mono- and diazanaphthalenes

The ¹³C n.m.r. spectra of the N-methylated mono- and diazanaphthalenes have been recorded and analysed. It has been shown that N-methylation as well as N-protonation in cinnoline occur predominantly at the β-nitrogen atom. N-methylation and N-protonation show a similar effect on the ¹³C chemical shifts.     

Methylene malonamide. I. Synthesis and reactivity of the monomer

The first confirmed synthesis of methylene malonamide (MeMal) is reported. This monomer was prepared by the thermal elimination or fluoride-ion-initiated elimination of trimethylsilyl chloride from α-chloro-α(trimethylsilyl-2-methyl) malonamide. Spectral data for the monomer are given. MeMal has been shown to be unstable in a variety of protic organic solvents, including water and alcohols, thus giving the appropriate (α-methyl) substituted malonamides. MeMal is stable in most aprotic solvents.