e-journal

Towards broadening thermospray flame furnace atomic absorption spectrometry: Influence of organic solvents on the analytical signal of magnesium

---

This study demonstrates the influence of the solvent when thermospray flame furnace atomic absorption
spectrometry (TS-FF-AAS) is employed for the determination of elements of low volatility, taking magnesium
(Mg) as leading case. Several organic solvents/water solutions of different characteristics (density,
surface tension, viscosity, etc.) and proportions were employed for the TS-FF-AAS analytical determination.
To this end, solutions containing methanol, ethanol and isopropanol in water were assayed.
Measurements were performed at different acetylene/air ratios of the combustion flame and then, the
corresponding response surfaces were obtained. Methanol/water 75% v/v as carrier and a fuel rich flame
were found as the most sensitive alternative.
In the light of these findings and in order to explain the changes on the analytical signal, the influence
of the solvent characteristics, the sample droplet size and the redox environment was studied. An estimation
of the temperature of different zones of the heated flame furnace based on a modified signal ratio
pyrometry method was analyzed for comparative purposes. A full discussion is provided throughout
the paper.
Once obtained the best conditions for analysis, Mg was determined in samples of effervescent vitamin
tablets comparing two different solvents. The tablets were dissolved in methanol/water 75% v/v and ethanol/
water 75% v/v and then, directly introduced in the TS device. The methanol/water 75% v/v dissolution
yielded a slightly higher sensitivity when compared to ethanol/water and thus, the latter was selected
due to its lower toxicity. The obtained figures of merit are: LOD (3rb): 0.021 mg L-1; LOQ (10rb):
0.068 mg L-1, sensitivity: 0.086 L mg-1; RSD%: 3.55, dynamic linear range 0.068–5 mg L-1. Comparison
of the results was performed by flame atomic absorption spectrometry (FAAS), showing a good
agreement (95% confidence level, n = 5). Whilst the FAAS approach needed sample mineralization as
no complete solubility was attained with both alcohol/water solvents, TS allowed direct introduction
of the sample with an excellent recovery of the analyte after spiking. The whole TS procedure was more
economic (lower amount of reagents and wastings, lower time of operation) and faster (60 h-1 sampling
throughput) than FAAS.
Nonetheless, the main objective of this work is to show that an analytical signal different from zero can
be obtained for Mg via TS by simply choosing the adequate operational variables that allow an optimization
of the mass transfer of the analyte into the atomizer and a favorable dynamics of desolvation/
atomization.
This approach could broad TS analytical capabilities to other elements of lower volatility as it is shown
here for the case of Mg.

Keywords: Thermospray, Organic solvents, Droplet size, Cell temperature, Optimization of the analytical signal, Magnesium determination

---

Ketersediaan

Tidak ada salinan data

Informasi Detail

Judul Seri

Analytical Chemistry Research

No. Panggil

-

Penerbit

New York : Elsevier Science Inc.., 2015

Deskripsi Fisik

Analytical Chemistry Research 4 (2015) 1–7

Bahasa

English

ISBN/ISSN

http://dx.doi.org/10

Klasifikasi

-

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

4 (2015)

Subjek

KIMIA ANALITIK

Info Detail Spesifik

-

Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

Komentar

---

Anda harus masuk sebelum memberikan komentar