Contained events in the Mont-Blanc nucleon stability experiment

Summary The Mont-Blanc nucleon stability experiment is reviewed and some of the more recently observed contained events are described.

---

Riassunto Si esamina l'esperimento di stabilità del nucleone del Monte Bianco e si descrivono gli eventi contenuti osservati piú recentemente.

---

Резюме Заново анализируется эксперимент по стабильности нуклона под Мод-Бланом. Обсуждаются недавно наблюдавшиеся сопутствующие события.

     

GC-FID/MS method for the impurity profiling of synthetic d-allethrin

A GC/FID/MS method was developed for the identification and quantification of d-allethrin (DA) and its major impurities in commercial samples. Optimisation of the experimental conditions was carried out considering such important requirements as resolution, reproducibility, detection limits of 0.1% (m/m) for the impurities, and short analysis time. Under the optimised final conditions the method was validated for specificity, precision (CV% = 0.133 at 2.10 mg/mL and CV% = 0.035 at 3.00 mg/mL), linearity (0-3.00 microg injected), limits of detection (0.09 ng injected) and quantitation (0.28 ng injected), and robustness. The DA related impurities were identified by using a GC/MS method with ion trap mass detection and also by comparison with synthesised standards. The most abundant impurities were crysolactone, allethrolone, chrysanthemic acid, and chloro-derivatives of DA.     

Stereoselective determination of allethrin by two-dimensional achiral/chiral liquid chromatography with ultraviolet/circular dichroism detection

A two-dimensional achiral/chiral HPLC method with circular dichroism (CD) detection was optimized for the stereochemical resolution and determination of the elution order of the eight stereoisomers of synthetic allethrin. A monolithic silica HPLC column (Chromolith, Merck, 100 mm x 4.6 mm i.d.) was put orthogonally to an enantioselective OJ Daicel column (250 mm x 4.6 mm i.d.) by means of a switching valve. The resolution of cis and trans diastereoisomers on the silica column was obtained by using a mobile phase consisting of n-hexane:tert-butyl methyl ether (96:4) (v/v) at a flow rate of 1 ml min(-1). The cis and trans peaks were then switched to the enantioselective OJ column separately in two subsequent injections. The resolution of the four trans stereoisomers was accomplished by using n-hexane:tert-butyl methyl ether (90:10) (v/v), while the mobile phase composition for the four cis stereoisomers consisted of n-hexane:isopropanol (99.3:0.7) (v/v). The CD based detection system allowed the determination of the elution order on the basis of the CD signals of the single stereoisomers, together with the injection of pure stereoisomers. Under the final conditions, the validated method was applied to the determination of stereoisomeric composition and absolute configuration of the prevailing stereoisomers of real samples, i.e. commercial batches of different sources of d-allethrin.     

In‐situ measurements of mass transport rate in vapour growth of hexamethylenetetramine crystal layers

This paper refers to the implementation of a remote optical imaging system suitable for in‐situ mass transport rate measurements in the growth of crystalline layers when grown in closed cylindrical ampoules by a physical vapour transport (PVT) technique. By means of this system, the measurements are carried out by taking photographs, at regular time intervals, of the source material volume as it reduces itself because of mass transfer. After storing the photographs, in real time, in a PC, a suitable software allows to estimate the mass transport rate during the growth process. The authors report here on the detailed setting up of such system when aimed at measuring the growth rate, as it varies with time, of hexamethylenetetramine (HMT, urotropine) crystal layers. A presentation and discussion of the results of these measurements have previously been reported. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)