An all solid-state femtosecond laser (l 0 y775 nm, pulse duration y170 fs, maximum pulse energy y0.5 mJ) with a Gaussian beam profile was used for depth profiling of Cu-Ag and TiN-TiAlN multi-layers on silicon and iron substrates. Laser-induced breakdown spectroscopy (LIBS) in argon was used for characterisation of the Cu-Ag samples, while laser ablation in a vacuum with time-of-flight mass spectrometry (TOF-MS) was applied for the characterisation of the TiN-TiAlN samples. The thickness of the individual Cu and Ag layers was 600 nm. Each individual TiN and TiAlN layer was 280 nm thick. The LIBS experiment was performed in the pressure range 10-1000 mbar. Variation of the pulse fluence from 0.8 to 1.5 J cm 22 caused a change of the ablation rate from 15 to 30 nm per pulse. The first layers of Cu and Ag could be satisfactorily resolved by LIBS. In femtosecond laser ablation TOF-MS a lower fluence (about 0.3 J cm 22 ) than in LIBS could be applied. The TiN-TiAlN multi-structures were well resolved. The Gaussian-type beam of the femtosecond laser limited the contrast of the detected depth profiles in both schemes. The complementary sensing techniques enable study of technical and physical limitations in the use of femtosecond laser ablation.

Melittin is a membrane-active peptide from bee venom with promising antimicrobial and anticancer activity. Herein we report on a simple and selective method for labeling of the tryptophan residue in melittin by the organometallic fragment [(C5 H5 )Ru](+) in aqueous solution and in air. Ruthenium coordination does not disturb the secondary structure of the peptide (as verified by 2D NMR spectroscopy), but changes the pattern of its intermolecular interactions resulting in an 11-fold decrease of hemolytic activity. The high stability of the organometallic conjugate allowed the establishment of the biodistribution of the labeled melittin in mice by inductively coupled plasma MS analysis of ruthenium.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is a fuel additive that has been marketed for use in unleaded gasoline since December 1995. The widespread use of this additive has been suggested to cause health risks, but limitations in data regarding its degradation products and their toxicity prevent an accurate evaluation. To monitor the organomanganese compounds, it is clearly advantageous to employ low-cost, high-sensitivity, manganese-specific instrumentation to perform speciation. In this work, instrumentation fitting these criteria was obtained by the combination of high-performance liquid chromatography (HPLC) with diode laser atomic absorption spectrometry (DLAAS) and was used to determine MMT, its nonmethylated derivative, cyclopentadienyl manganese tricarbonyl (CMT), and inorganic manganese. DLAAS was shown to be a versatile analytical technique for total Mn determination, with a detection limit of 1 ng/mL and a linear dynamic range (LDR) of almost 5 orders of magnitude. Analytical figures of merit for HPLC-DLAAS included a detection limit of 2 ng(as Mn)/mL, a LDR of 3 orders of magnitude, and an analysis time of three minutes. The organometallic compounds are characterized by rapid photolysis in sunlight, and hence, experiments were performed to evaluate whether normal laboratory lighting is suitable for their determination. Our results showed that normal laboratory protocols may be employed except that the organomanganese compounds should be stored away from light except during sample introduction procedures. The ability of the instrumentation to selectively preconcentrate organomanganese compounds while removing inorganic manganese was demonstrated. Sufficient resolution was obtained to determine a 20-fold excess of CMT compared with MMT. The ability of the system to do practical analysis was demonstrated by the accurate determination of MMT in spiked samples of gasoline, human urine, and tap water. These results demonstrate the suitability of HPLC-DLAAS for the speciation of MMT and its derivatives in industrial, toxicological, and environmental samples.

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