Application of dried blood spots combined with high-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometry for simultaneous quantification of vincristine and actinomycin-D

A sensitive, specific and efficient high-performance liquid chromatography-tandem mass spectrometry assay for the simultaneous determination of vincristine and actinomycin-D in human dried blood spots is presented. Dried blood spots were punched out of a collection paper with a 0.25-in.-diameter punch. The analytes were extracted from the punched-out disc using sonication during 15 min in a mixture of acetonitrile–methanol–water (1:1:1, v/v/v) containing the internal standard vinorelbine. Twenty-microlitre volumes were injected onto the HPLC system. Separation was achieved on a 50 × 2.1 mm ID Xbridge C₁₈ column using elution with 1 mM ammonium acetate–acetonitrile (70:30, v/v) adjusted to pH 10.5 with ammonia and run in a gradient with methanol at a flow rate of 0.4 mL/min. HPLC run time was 6 min. The assay quantifies vincristine from 1 to 100 ng/mL and actinomycine-D from 2 to 250 ng/mL using a blood sample obtained by a simple finger prick. Validation results demonstrate that vincristine and actinomycin-D can be accurately and precisely quantified in human dried blood spots with the presented method. The assay can now be used to support clinical pharmacologic studies with vincristine and actinomycin-D.     

Novel Xylan Gels Prepared from Oat Spelts

Gels and pastes are used in many areas including application in the cosmetic, pharmaceutical and medical industries. A xylan derivative with pasty consistency was prepared in addition to the synthesis of xylan ethers and esters. The water content of the gel can be widely varied. The gel is formed although the xylan contains no cross-linking group. The hydrophobic and hydrophilic nature of the xylan gel can be adjusted by modifying the xylan. All of the gels can be dried using different methods (air drying, solvent exchange as well as freeze drying) and the dried gels can again disperse in water. The gels were characterised by porosity measurements (mercury intrusion), dynamic vapour sorption (DVS), scanning electron microscopy (SEM) and dispersion stability investigation respectively.     

Synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-man,a terminal trisaccharide of Leishmania type-2 glycoinositolphospholipids

The synthesis of alpha-D-Galp-(1-->3)-beta-D-Galf-(1-->3)-D-Man, present in the type-2 glycoinositolphospholipids and in the core of the lipophosphoglycan of Leishmania, is described. The glycosyl aldonolactone approach, followed by reduction of the lactone with diisoamylborane, was utilized for the introduction of the internal galactofuranosyl unit and the trichloroacetimidate method for the O-glycosidation reaction. A high-yield synthesis of the beta-D-Galf-(1-3)-D-Man unit, also present in the lipopeptidophosphoglycan of Trypanosoma cruzi, is reported.     

Experimental Charge Density Studies of Cyclotetrasilazane and Metal Complexes Containing the Di‐ and Tetraanion

The homologous series of parent octamethylcyclotetrasilazane (c‐NH‐SiMe₂‐)₄, ( 1 ), the lithium complex [(THF)₂Li₂(c‐N‐SiMe₂‐NH‐SiMe₂‐)₂]₂, ( 2 ), containing the cyclic dianion, and [(THF)₂LiAl(c‐N‐SiMe₂‐)₄]₂, ( 3 ), accommodating the unprecedented tetraanion [Me₂SiN]^4‐ was synthesized to investigate the nature of the covalent Si‐N single bond in the presence of various metals. These model compounds show a wide diversity of Si‐N(H), Si‐N(M), Si‐N(H, M) and M‐N bonds and serve as bench‐mark systems to study polar bonds by high‐resolution low‐temperature X‐ray structure analysis. Experimental charge density studies reveal highly polar Si‐N bonds with remarkable ionic contribution, even in the non‐metallated starting material 1 . The Li‐N and Li‐O bonds have to be classified as almost purely ionic bonds with topological properties not far from those determined for NaCl.     

Syntheses of beta-d-Galf-(1-->6)-beta-d-Galf-(1-->5)-d-Galf and beta-d-Galf-(1-->5)-beta-d-Galf-(1-->6)-d-Galf,trisaccharide units in the galactan of Mycobacterium tuberculosis

The galactofuran is a crucial constituent of the cell wall of mycobacteria. An efficient synthesis of the two trisaccharide units of the galactan is described. The strategy relies on the use of substituted d-galactono-1,4-lactones as precursors for the internal and the reducing galactofuranoses. Dec-9-enyl beta-d-Galf-(1-->6)-beta-d-Galf-(1-->5)-beta-d-Galf (2) and dec-9-enyl beta-d-Galf-(1-->5)-beta-d-Galf-(1-->6)-beta-d-Galf (9) so far reported as convenient substrates for the galactofuranosyl transferase, and possibly useful for immunological studies, were obtained by the trichloroacetimidate method of glycosylation.     

The far-infrared spectra of pyridine complexes of transition metal(II) isothiocyanates

The infrared spectra (500–140 cm^?1) of the complexes [M(pyridine)_n(NCS)₂] (n = 2, M = Mn, Co, Ni, Cu, or Zn; n = 4, M = Mn, Fe, Co, or Ni) are discussed. The v/M-pyridine and v/M-NCS bands are assigned by observing the band shifts induced by isotopic labelling of the coordinated pyridine and isothiocyanate, by comparing the spectra with those of the [M(pyridine)₂Cl₂] complexes and from symmetry considerations based on their known structures. The two types of metal-ligand stretching bands occur within a rather narrow frequency range and there is evidence of some vibrational coupling between these two modes. Some earlier assignments of vM-pyridine bands require revision. The spectra of the yellow [Fe(py)₄(NCS)₂] complex and its violet oxidation product suggest that the oxidation reaction involves the transformation of trans-[Fe(py)₄(NCS)₂] into cis-[Fe(py)₃(NCS)₃]     

A new strategy of solution calibration in laser ablation inductively coupled plasma mass spectrometry for multielement trace analysis of geological samples

Because multielement trace analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is often limited by the lack of suitable reference materials with a similar matrix composition, a novel quantification strategy using solution calibration was developed. For mass spectrometric multielement determination in geological samples a quadrupole-based LA-ICP-MS is coupled with an ultrasonic nebulizer (USN). In order to arrange matrix matching the standard solutions are nebulized with a USN during solution calibration and simultaneously a blank target (e.g. lithium borate) is ablated with a focused laser beam. The homogeneous geological samples were measured using the same experimental arrangement where a 2% nitric acid is simultaneously nebulized with the USN. Homogeneous targets were prepared from inhomogeneous geological samples by powdering, homogenizing and fusing with a lithium borate mixture in a muffle furnace at 1050?°C. Furthermore, a homogeneous geological glass was also investigated. The quantification of analytical results was performed by external calibration using calibration curves measured on standard solutions. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS, measured concentrations in homogeneous geological targets were also corrected with relative sensitivity coefficients (RSCs) determined using one standard solution only. The analytical results of LA-ICP-MS on various geological samples are in good agreement with the reference values and the results of other trace analytical methods. The relative standard deviation (RSD) for trace element determination (N = 6) is between 2 and 10%.     

Trace analysis of high-purity graphite by LA–ICP–MS

Laser-ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) has been established as a very efficient and sensitive technique for the direct analysis of solids. In this work the capability of LA–ICP–MS was investigated for determination of trace elements in high-purity graphite. Synthetic laboratory standards with a graphite matrix were prepared for the purpose of quantifying the analytical results. Doped trace elements, concentration 0.5 μg g^–1, in a laboratory standard were determined with an accuracy of 1% to ± 7% and a relative standard deviation (RSD) of 2–13%. Solution-based calibration was also used for quantitative analysis of high-purity graphite. It was found that such calibration led to analytical results for trace-element determination in graphite with accuracy similar to that obtained by use of synthetic laboratory standards for quantification of analytical results. Results from quantitative determination of trace impurities in a real reactor-graphite sample, using both quantification approaches, were in good agreement. Detection limits for all elements of interest were determined in the low ng g^–1 concentration range. Improvement of detection limits by a factor of 10 was achieved for analyses of high-purity graphite with LA–ICP–MS under wet plasma conditions, because the lower background signal and increased element sensitivity. Received: 4 January 2001 / Revised: 27 March 2001 / Accepted: 28 March 2001