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13. Solid-Phase Extraction and HPLC
Analysis of Trace Aldehydes as their 2,4-Dinitrophenylhydrazones in
Local Thai Wines
Saksit Chanthai1*,
Theerayut Charoentud1, Chalerm Ruangviriyachai1,
Paiboon Danvirutai2
1Department
of Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen
40002,
Thailand
sakcha2@kku.ac.th
2Department
of Biotechnology and
Fermentation
Research
Center
for Value Added Agricultural Products, Faculty of Technology,
Khon
Kaen
University,
Khon Kaen 40002,
Thailand
(Received 02 December 2005; accepted 20 February 2006)
Abstract:
Appropriate sample preparation and analytical methods for some
aldehydes, namely formaldehyde, acetaldehyde, 2-furaldehyde,
isobutyraldehyde and benzaldehyde, in local fruit wines using 2,4-dinitrophenylhydrazine
(DNPH) as derivatizing agent and separation of their hydrazone
products by HPLC have been studied. The derivatization reaction was
carried out in acidic solution of the DNPH. Signal background of the
methods was decreased dramatically by experimental optimization of
DNPH derivatization and solid-phase extraction. The maximum recoveries
of the aldehyde-DNPH derivatives were obtained in pH of about 1.5
within 30 min. Sample clean up using Sep-pak C18 cartridge
was necessary prior to separation. The optimization of the mobile
phase for a reversed phase HPLC analysis of five aldehyde-DNPH
derivatives was achieved by gradient elution using a mixture of
methanol and water, resulting in complete separation within 15 min.
The concentration ranges found in various kinds of fruit wines were
0.023-0.575, not detectable (ND)-17.50, ND-0.425, ND-0.730 and ND-0.350
mgL-1 for formaldehyde, acetaldehyde, 2-furaldehyde,
isobutyraldehyde and benzaldehyde, respectively. The recoveries of the
method varied from 94.0-102.0 % for a 20-mL sample volume. The method
precision termed as relative standard deviation was less than 7.7% at
0.25 mgL-1 for all aldehydes analyzed. The limits of
detection and of quantitation varied from 0.75-2.2
mgL-1
and 2.6-7.6
mgL-1,
respectively. The standard curves showed good linearity with r2
in the range of 0.9992-0.9997 between 0.05 and 15 mgL-1,
indicating that the method was useful for monitoring trace aldehydes
in wines.
Keywords:Aldehydes,2,4-Dinitrophenyl
hydrazine, Wine, Derivatization, Solid phase extraction, HPLC
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