Convenient microwave-assisted synthesis of 1-chloroethyl phosphates

An efficient microwave-assisted synthesis of 1-chloroethyl phosphates was developed. Protected vinyl chlorophosphates undergo a fast conversion to the chloroethylidene phosphates in the presence of HCl with excellent yields up to 900 times faster than at the standard NTP conditions.     

Strategies for organic impurity quantification by H NMR spectroscopy: Constrained total-line-shape fitting

A constrained total-line-shape (CTLS) fitting strategy for organic impurity analysis from ¹H NMR spectra was developed and assessed by studying two examples. In general, total-line-shape fitting allows integration of overlapping lines without suffering from baseline artifacts as much as traditional integration methods. It is shown here that the constrained total-line-shape fitting, where the spectral structures of the multiplets to be fitted are taken into account in form of constraints, allows quantification of seriously overlapping lines and when the signals are close to the root of major signals. Also, a method for removal of ¹³C satellite signals is described. The results indicate that our approach significantly improves the usefulness of qNMR in impurity analysis and that impurity levels of 0.1 mol%, which in some cases means down to 0.01 wt%, can be easily determined with relative standard error smaller than 10%.     

Platinum(II)-bis(9-methyladenine) complexes; N1-->N6 migration of Pt(II)vs deamination of coordinated methyladenine

Stepwise migration of coordinated Pt(II) from the endocyclic N1 site to the exocyclic amino group occurs in the bis(9-methyladenine-N1) complex of cis-Pt(II)(NH(3))(2) in basic solution, whereafter deamination of the 9-methyladenine still coordinated at N-1 competes with a second migration step.     

Characterization of ARC/CL wheat flour and potato powder reference materials for content of total dietary fiber

Summary ARC/CL wheat flour and potato powder reference materials (RMs) prepared by the Central Laboratory of the Agricultural Research Centre of Finland, earlier specified for contents of essential and toxic trace elements, were characterized for contents of total dietary fiber (TDF). Recommended concentration values established were obtained on the basis of an interlaboratory comparison study conducted involving 10 reference laboratories recognized for their reliability in TDF determinations. The recommended TDF contents established were based on an enzymatic-gravimetric method employed by the participating laboratories to determine TDF or water insoluble (WIS) and water soluble (WS) DF which were then added up to obtain TDF. After exclusion of outliers the recommended concentration values were expressed as the medians ±95% confidence limits of the average values by the participating laboratories. The coefficient of variation obtained for the recommended concentration range of TDF was within 7% for both RMs.     

Effect of sample matrix on the determination of total petroleum hydrocarbons (TPH) in soil by gas chromatography–flame ionization detection

Research papers in different fields of analytics indicate that the effect of matrix-induced chromatographic response enhancement (matrix effect) is a commonly encountered problem in gas chromatography applications. In this paper, an example of the effect of sample matrix on the quantitative determination of total petroleum hydrocarbons (TPH) by GC–FID in soil is presented. Two types of soil were selected for the evaluation. Extraction and analysis of the soil samples was in accordance with CEN prEN 14039. The relative systematic error resulting from the matrix effect was obtained for three different TPH concentrations by statistical comparison of the slopes of the matrix-matched calibration lines and a pure solvent calibration line. Too high TPH concentrations were obtained when conventional solvent calibration was used for quantitation. This demonstrates that matrix-matched calibration should be exploited in the determination of petroleum hydrocarbons in soil samples. However, there was also significant enhancement of the response due to an interfering matrix with decreasing analyte concentration. Enhancement seems to be especially evident in the quantification of TPH over the concentration range encountered in polluted environments. As a result, even when matrix-matched calibration is used for quantitation, it is still necessary to establish the range over which a linear response can be expected. Otherwise too high results for sample TPH concentrations will be obtained.     

Characterization of a total diet reference material (ARC/CL HDP) for contents of essential and toxic elements

Summary A total diet reference material (RM) was prepared by employing material leftover from a nationwide Finnish hospital diet study. The material was carefully homogenized using Ti-blades, freeze-dried, rehomogenized with Ti-blades, passed through a 2 mm nylon sieve and carefully mixed in large glass cylinders. Homogeneity of the material divided into 20 g samples in polyethylene bottles was tested by taking ten 0.5 g samples from the beginning and end of the bottling line and analyzing them for Zn and Mg. The homogeneity was within 1.0% for both Zn and Mg. An interlaboratory comparison study involving reliable reference laboratories that employed a total of seven methods based on independent analytical principles was conducted on the contents of 14 mineral elements. After the exclusion of outliers the recommended concentrations (on a dry weight basis) expressed as the medians±95% confidence limits were established as follows: Ca=2.86±0.124 mg/g, Mg=785±25 g/g, K=9.42±0.30 mg/g, Na=7.87±0.57 mg/g, Fe=30.4±0.9 g/g, Mn=12.9±0.58 g/g, Zn=28.9±1.3 g/g, Cu=3.18±0.19 g/g, Mo=262±35 ng/g, Ni=271±38 ng/g, Se=181±17 ng/g, Pb=43±8 ng/g, Cd=21±3 ng/g and Hg=6.6±3.6 ng/g. All of the above recommended concentration ranges, except that for Ni, fell into category A, i.e. values recommended with a high degree of confidence according to the certification criteria established by Pszonicki.     

LC/MS/MS identification of glycosides produced by biotransformation of cinnamyl alcohol in Rhodiola rosea compact callus aggregates

Cinnamyl alcohol was added to the media of compact callus aggregates (CCA) of Rhodiola rosea for stimulating the production of cinnamyl glycosides. The biotransformation reaction produced high amounts of rosin, while only a very low amount of rosavin was produced. As the consumption rate of cinnamyl alcohol was much higher than production of rosin, the aqueous methanol extracts of compact callus aggregates were studied by liquid chromatography-mass spectrometric methods and four new unexpected biotransformation products of cinnamyl alcohol were identified.     

Zur Stereoisomerie der 2,6-Dichlor-4-methoxyheptane

2,6-Dichloro-4-methoxy-heptanes may exist as 2 optical active isomers and 2 meso compounds. By double addition of ,-dichloro-dimethylether to propene a mixture of these stereoisomers was obtained. They were separated by HPLC. Using¹H- and¹³C-NMR-spectroscopy their configuration could be established.

     

Persistent luminescence — Quo vadis?

The present status of the persistent luminescence mechanisms is reviewed and the remaining unsolved details are discussed. These details include the identification and role of defects in the Eu²⁺-doped and R³⁺ co-doped alkaline earth aluminates (MAl₂O₄) and disilicates (M₂MgSi₂O₇; M:Ca, Sr, Ba) which can be partly resolved by the thermoluminescence (TL) measurements. The use of the synchrotron radiation - presently only sparsely used in the studies of persistent luminescence - is introduced: the oxidation state of the presumed R²⁺/R³⁺/R^IV species occurring in the persistent luminescence materials during the luminescence processes were examined with synchrotron radiation XANES (and EXAFS) methods. The band gap energies (E_g), the defect-related luminescence as well as the 4f⁷→4f⁶5d¹ transition energies were derived from the synchrotron radiation excitation spectra of the materials. Subsequently, the early steps of the density functional theory (DFT) calculations involving the solution of the persistent luminescence mechanisms (band gap energies, position of the Eu²⁺ levels) are discussed. Some remaining challenges are eventually highlighted.