Improvement of the analytical performance of the FAAS method by hydraulic high pressure sample introduction

J. Posta, B. Dereckei

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Abstract

The hydraulic high pressure nebulization (HHPN) system is a totally new and effective sample introduction method in atomic spectrometry. The liquid sample is forced through a special nozzle with high pressure (5-40 MPa) generated by an HPLC pump. The nozzle involves a Pt-Ir plate with an orifice of 10-30 μm through which the constant flow (1-3 ml/min) of high pressure liquid produces a fine mist. The aerosol yield is more than 50%. The analyte solution is introduced with a probe feed valve through a sample loop into the high pressure solvent stream and passes along with the transport medium (water, organic solvent) to the nebulizing nozzle. This new sample introduction system was coupled with a flame atomic absorption spectrometry (FAAS) instrument to investigate the improvement of analytical performance compared to conventional pneumatic nebulization. As a consequence of the improved aerosol yield of HHPN, the sensitivity of FAAS is increased by factors of 2-3 and 6-8 on the basis of peak height and peak area of the transient analyte signal, respectively. The long-term (1-3 h) stability of the system is excellent. The RSD in the normal analytical working range is 1-2%, depending on the element. The droplet size distribution of aerosols produced by pneumatic and nebulization HHPN has been measured. In the case of HHPN the smaller droplet size explains the moderated matrix effect of 10-30% NaCl on the determination of Co, Cu, Mn, and Ni. In FAAS one of the advantages of HHPN sample introduction is the analysis of highly concentrated and viscous solutions. Many elements (e.g., Cr, Cu, Mn, Mo, V) have been quantified as traces in saturated pro analysi suprapure chemicals (2% LiBO2, 10% KH2PO4, 20% SbCl3 in 24% HCl, 30% NaCl, 50% MgSO4 · 7H2O, 60% Co(NO3)2, 85% H3PO4) and highly salted waste waters. Solutions were introduced without any difficulties because their higher viscosity was automatically compensated by the flow rate-regulated high-pressure pump. On the other hand, pneumatic nebulization of these samples was difficult or in some cases totally impossible.

Original languageEnglish
Pages (from-to)271-279
Number of pages9
JournalMicrochemical Journal
Volume46
Issue number3
DOIs
Publication statusPublished - Dec 1992

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ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy

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