Multi-Elemental Analysis of Hair and Fingernails Using Energy-Dispersive X-ray Fluorescence (ED XRF) Method Supported by Inductively Coupled Plasma Mass Spectrometry (ICP MS).

This work compared the multi-element analysis of human hair and nails using inductively coupled plasma mass spectrometry (ICP MS) with an easy, fast, cheap, non-destructive method using energy-dispersive x-ray fluorescence (ED XRF). The ICP MS-based method was more sensitive (over 30 elements could be quantified) and costly (requiring more time, samples, and chemicals). The EDX-based method required laboratory and certified reference materials made of hair for instrument calibration. It was less sensitive (16 elements could be quantified: S, Si, Ca, Br, Fe, Cu, Cr, Mg, Si, K, Mn, Ni, Zn, Se, Sr, Pb), but it allowed us to replace troublesome grinding with the dissolution of keratin-based material with an alkalic agent (tetramethylammonium hydroxide, TMAH) and the formation of stable-for-days pellets. This method is simple, enables automation, and, due to the modification of wells in the autosampler of the EDX system via the immersion of home-designed inserts, it requires smaller amounts of biological material and binder (down to 70 mg instead of 500 mg required by commercially available instrument) to perform analysis. It was concluded that the EDX-based method offers complementary selectivity and sensitivity to ICP MS with the possibility of sample reuse for further analysis.

Effect of synthetic surfactants and soapwort (Saponaria officinalis L.) extract on skin-mimetic model lipid monolayers.

The effect of a saponin-rich extract from rhizomes of Soapwort (Saponaria officinalis L) and four synthetic surfactants: sodium lauryl sulphate (SLS), sodium laureth sulphate (SLES), ammonium lauryl sulphate (ALS) and cocamidopropyl betaine (CAPB) on two model lipid monolayers is analyzed using surface pressure, surface dilatational rheology and fluorescence microscopy. The following monolayers were employed: dipalmitoylphosphatidylcholine/cholesterol mixture in a molar ratio of 7:3 (DPPC/CHOL) and Ceramide [AP]/stearic acid/cholesterol in a molar ratio of 14:14:10 (CER/SA/CHOL). They mimicked a general bilayer structure and an intercellular lipid mixture, respectively. Both lipid mixtures on Milli-Q water were first compressed to the initial surface pressure, Π0 = 30 mN/m and then the subphase was exchanged with the respective (bio)surfactant solution at 1% (w/w). All four synthetic surfactants behaved in a similar way: they increased surface pressure to about 40 mN/m and reduced the storage modulus of surface dilational surface rheology, E', to the values close to zero. The corresponding fluorescence microscopy pictures confirmed that the lipids mimicking the stratum corneum components were almost completely removed by the synthetic surfactants under the present experimental conditions. The components of the Soapwort extract (SAP) increased surface pressure to significantly higher values than the synthetic surfactants, but even more spectacular increase was observed for the storage modulus of the SAP-penetrated lipid monolayers (up to E'= 715 mN/m).