Dual-capillary electroencapsulation of mesoporous silicon drug carrier particles for controlled oral drug delivery

The feasibility of electroencapsulation of mesoporous silicon (PSi) micro- and nanoparticles as a method to seal the PSi particles in mechanically processable solid units, and to facilitate time and site specific drug release from the pores of PSi particles, is of interest in the present work. Suitable microcapsules and micromatrix particles were produced in a single-step process using a setup with two electrospraying nozzles kept at high electric potentials of opposite polarities. The structures of the produced particles were analyzed by microscope and X-ray micro- and nanotomography imaging, and optimization of the electroencapsulation process production efficiency is discussed.     

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%.     

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.     

Conformational study of 1,4-thiazinan-3-one

The proton NMR spectra of several 1,4-thiazinan-3-ones were analyzed using LAOCOON. The geminal and vicinal coupling constants indicate that the ring conformation of this heterocycle is a half-chair similar to δ-valerolactam. Molecular mechanics calculations show that the energy of the boat is only slightly higher than that of the half-chair. The conformational equilibria of methyl-substituted compounds were calculated by the coupling constant method. These energies are compared to those obtained by molecular mechanics.     

Mass Spectroscopy of the Antileukemic Drug MGBG and Related Bis(Amidinohydrazones) [‘Bis(Guanylhydrazones)’]

The first study on the mass spectroscopy of various bis(amidinohydrazones) is reported. The compounds studied included the investigational antileukemic drugs methylglyoxal bis(amidino-hydrazone) [‘methylglyoxal bis(guanylhydrazone)’, MGBG] and glyoxal bis(amidinohydrazone), as well as seven mono- and dialkylglyoxal analogs thereof. The results indicate that the free bases of these high-melting compounds are volatilized well enough to allow a facile detection of the molecular ions and to make mass spectroscopy of the underivatized compounds a suitable method for the verification of the identity of the substances. This result is of importance considering the development of novel analogs and derivatives. A compilation of electron-impact mass spectra is reported and possible fragmentation routes are outlined. The fragmentation of the various congeners appears to occur essentially similarly, the main paths involving breakage of the carbon-carbon single bond in the glyoxal moiety or breakage of either one of the nitrogen-nitrogen single bonds.     

Controlled oxidation of iron nanoparticles in chemical vapour synthesis

Enteric-coated formulations can delay the release of drugs until they have passed through the stomach. However, high concentration of drugs caused by rapidly released in the small intestine leads to the intestinal damage, and frequent administration would increase the probability of missing medication and reduce the patient compliance. To solve the above-mentioned problems, aspirin-loaded enteric-coated sustained-release nanoparticles with core–shell structure were prepared via one-step method using coaxial electrospray in this study. Eudragit L100-55 as pH-sensitive polymer and Eudragit RS as sustained-release polymer were used for the outer coating and inner core of the nanoparticles, respectively. The maximum loading capacity of nanoparticles was 23.66 % by changing the flow rate ratio of outer/inner solutions, and the entrapment efficiency was nearly 100 %. Nanoparticles with core–shell structure were observed via fluorescence microscope and transmission electron microscope. And pH-sensitive and sustained drug release profiles were observed in the media with different pH values (1.2 and 6.8). In addition, mild cytotoxicity in vitro was detected, and the nanoparticles could be taken up by Caco-2 cells within 1.0 h in cellular uptake study. These results indicate that prepared enteric-coated sustained-release nanoparticles would be a more safety and effective carrier for oral drug delivery.     

Generalization of the B *‐algebra (C0(X),∥ ∥∞)

We give a generalization of the Stone–Weierstrass property for subalgebras of C (X), with X a completely regular Hausdorff space. In particular, we study in this paper some subalgebras of C₀(X), with X a locally compact Hausdorff space, provided with weighted norm topology. By using the Stone–Weierstrass property, we then describe the ideal structure of these algebras. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ionisation and appearance potentials in structure analysis. A review

The suitability of mass spectrometric IP and AP measurements for different structural determinations has been critically considered and the pertinent literature reviewed.