Atomic spectrometry ICP MS sample introduction methods

Sample introduction and sample preparation is one of the most important parts of the entire ICP MS system. We developed two new sample introduction techniques for analysis of liquid samples.

Substrate assisted laser desorption (SALD)

SALD ICP MS allows quantitative analysis of metals in liquid samples with defined volumes (typically 200 nL). Samples are deposited onto a laser light absorbing substrate, dried, desorbed with a pulse laser and analyzed with an ICP MS.

SALD ICP MS was used for the determination of trace elements in biological samples: for determination of copper in disulfiram-treated myeloid leukemia U937 cells or in crystals of blue exploding protein of Neocapritermes taracua termit.
The low limits of detection (tens to hunderts of fg) allow using SALD for off-line coupling with microcolumn separations. More about coupling of microcolumns to MS can be found here.

Metalic nanoparticles deposited on plastic substrate can be also analyzed using the SALD ICP MS. The use of mass spectrometer working with sufficiently short integration times, in so called single-particle mode, allows counting of individual nanoparticles as well as determination of their size.

Diode laser thermal vaporization (DLTV)

The DLTV is an original method of aerosol generation for ICP MS. DLTV combines advantages of commonly used sample introduction technique for ICP MS – nebulizers (analysis of liquid samples and low-cost system) and laser ablation commonly used for solid samples (archiving, minimal or no sample preparation) with preservation of high sensitivity.

DLTV_grafikaDLTV

Submicroliter sample volumes are deposited on a carrier with substrate and absorber, such as preprinted filter paper. The diode laser radiation induces pyrolysis of the substrate with samples and the generated aerosol is then carried out into the ICP MS. The limits of detection of metals were found to be in a low pg range. The technique was applied to determine lead in whole blood, cobalt in a drug and tin in canned food.

A laboratory-build prototype of low-cost chamber for DLTV was constructed. Prototype is made of equipment commonly used in analytical laboratory: glass tube and near infrared continuous-wave diode laser attached to a common syringe pump.

cellDLTV cell prototype

DLTV ICP MS can be easily coupled with thin layer chromatography (TLC). In this case, cellulose or silica gel stationary phase on TLC sheets serves as the DLTV substrate. Developed separation channels are overprinted with black ink lines and scanned with the diode laser. TLC – DLTV ICP MS was demonstrated on speciation of cobalamins (vitamin B12) and currently we are working on speciation of selenium containing compound in algae.

Both SALD and low-cost DLTV ICP MS are suitable for quantitative elemental analysis of low volume samples (typically 100 – 500 nL). Other advantages of the techniques are easy archiving and transportation and option of prearranged calibration sets on substrate.

References

Benešová, I.; Dlabková, K.; Zelenák, F.; Vaculovič, T.; Kanický, V.; Preisler, J. "Direct Analysis of Gold Nanoparticles from Dried Droplets Using Substrate-Assisted Laser Desorption Single Particle-ICP MS" Anal. Chem. 2016, 88, 2576–2582. http://dx.doi.org/10.1021/acs.analchem.5b02421

Bednařík, A.; Tomalová, I.; Kanický, V.; Preisler, J.: "Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry", J. Chomatogr. A 2014, 1364, 271–275. http://dx.doi.org/10.1016/j.chroma.2014.08.069

Foltynová, P.; Bednařík, A.; Kanický, V.; Preisler, J.: “Diode laser thermal vaporization ICP MS with a simple tubular cell for determination of lead and cadmium in whole blood“ J. Anal. Atom. Spectrom. 2014, online: http://dx.doi.org/10.1039/c4ja00113c
Available as a "hot" article:"http://blogs.rsc.org/ja/category/hot-article/

Foltynová, P.; Kanický, V.; Preisler, J. “Diode Laser Thermal Vaporization Inductively Coupled Plasma Mass Spectrometry.“ Anal. Chem. 2012, 84, 2268-2274. http://dx.doi.org/10.1021/ac202884m

J. Šobotník, T. Bourguignon, R. Hanus, Z. Demianová, J. Pytelková, M. Mareš, P. Foltynová, J. Preisler, J. Cvačka, J. Krasulová, Y. Roisin “Explosive Backpacks in Old Termite Workers” Science 2012, 337, 436.

Jungová, P.; Navrátilová, J.; Peš, O.; Vaculovič, T.; Kanický, V.; Šmarda, J.; Preisler, J. “Substrate-assisted laser desorption inductively-coupledplasma mass spectrometry for determination of copper in myeloid leukemia cells” J. Anal. Atom. Spectrom. 2010, 25, 662-668.

Navrátilová, J.; Jungová, P.; Vaňhara, P.; Preisler, J.; Kanický, V.; Šmarda, J. “Copper ions regulate cytotoxicity of disulfiram to myeloid leukemia cells”. Int. J. Mol. Med. 2009, 94, 1923-1930.

Peš, O.; Jungová, P.; Vyhnánek, R.; Vaculovič, T.; Kanický, V.; Preisler, J. “Off-Line Coupling of Capillary Electrophoresis to Substrate-Assisted Laser Desorption Inductively Coupled Plasma Mass Spectrometry.“ Anal. Chem., 2008, 80, 8725-8732.