Determination of Lead in Submicroliter Samples of Whole Blood using Laser Diode Thermal Vaporization
|Fakulta / Pracoviště MU
|A new method for determination of trace elements in submicroliter sample volumes, laser diode thermal vaporization (LDTV) inductively-coupled plasma mass spectrometry (ICP-MS) is presented. Submicroliter samples for LDTV ICP-MS are deposited onto a suitable substrate sheet containing an absorber. After drying, samples are desorbed from the substrate in a commercial laser ablation chamber equipped with a near infrared continuous-wave diode laser and analyzed with an ICP quadrupole mass spectrometer. The laser induces pyrolysis and/or burning of the substrate and the generated aerosol is carried out into the plasma torch. Selection of experimental arrangement and laser wavelength as well as optimization of experimental conditions, e.g., raster type, scan speed, additives etc. was examined. An arrangement employing common paper as the substrate, commercial printer black ink as the absorber and 808 nm diode laser was chosen. The limits of detection of Co, Ni, Zn, Mo, Cd, Sn and Pb deposited on the pre-printed paper were found to be in a low pg range. The technique was applied to determination of lead in whole blood without any sample treatment. Other applications included analysis of Co in a drug preparation and tin in canned food. Potential coupling with planar and microcolumn separations will be discussed. In summary, LDTV ICP-MS is suitable for quantitative elemental analysis of low volume samples (typically 100 – 500 nL). The method does not require an expensive high-energy pulse laser, which makes it a promising alternative to nebulizers. Other advantages are also easy archiving, transportation, option of prearranged multi-elemental calibration sets and high throughput due to minimization of memory effects.