Development of an HPLC–UV/Vis method for the determination of dyes in a
gasoline sample employing different pre-treatments
Magno Aparecido Gonçalves Trindade
, Maria Valnice Boldrin Zanoni
, Frank-Michael Matysik
Department of Analytical Chemistry, Institute of Chemistry-Araraquara, São Paulo State University, UNESP, Rua Francisco Degni, s/n, Bairro Quitandinha, 14800-900
Araraquara, SP, Brazil
University of Regensburg, Institute of Analytical Chemistry, Chemo- and Biosensors, 93040 Regensburg, Germany
Received 4 August 2009
Received in revised form 13 November 2009
Accepted 24 November 2009
Available online 9 December 2009
Solvent Blue 14
Solvent Orange 7
Solvent Red 24
A simple method was developed for the determination of the dyes Solvent Blue 14 (SB-14), Solvent
Orange 7 (SO-7) and Solvent Red 24 (SR-24), based on high-performance liquid chromatography (HPLC)
coupled with UV–Vis detection. The dyes were separated employing a reverse phase C-18 column, with
gradient elution using a mobile phase containing acetonitrile/water. In conjunction with suitable sample
pre-treatment protocols, the method was applied to the quantiﬁcation of the dyes in gasoline samples.
Ó 2009 Elsevier Ltd. All rights reserved.
Petroleum-derived fuels are used for a variety of different pur-
poses and are therefore taxed at different rates in sectors such as
ﬁshing, mining, generation of electrical energy, heating, agricul-
ture, transport and leisure. This creates an immense market for
dyes used to demarcate the various products. In order to guarantee
the identity of speciﬁc types of fuel, discourage adulteration, stan-
dardize quality, as well as to control distribution and use, markers
and/or dyes are commonly added to fuels including diesel oil, pet-
rol, alcohol, and aviation kerosene [1–6]. Frequently, dyes soluble
in organic (usually non-polar) solvents, known as solvent dyes,
are used to color hydrocarbon fuels and other hydrocarbon-based
non-polar substances. Solvent Blue 14 (SB-14), Solvent Orange 7
(SO-7) and Solvent Red 24 (SR-24) (Fig. 1) are found as legally re-
quired components of fuels, but being readily available are also
sometimes added illegally to defraud the consumer.
Despite the importance of detection and quantiﬁcation of dyes
in petroleum products, few analytical methods have been de-
scribed in the literature. The high-performance liquid chromatog-
raphy (HPLC) technique has been used, coupled to ultraviolet
absorption and diode array detectors [7–10], mass spectrometry
detectors , and derivative spectroscopy . In general, these
procedures have not been sufﬁciently sensitive to detect low con-
centrations and typically require long analysis times and tedious
sample pre-treatment steps. On the other hand, there are not chro-
matographic methods for the determination of the dyes SB-14 and
SO-7 in fuel samples.
Thus, the objective of the present work was to develop an ana-
lytical method, using HPLC with UV–Vis detection, for the quanti-
ﬁcation of SB-14, SO-7 and SR-24 in gasoline employing three
different sample pre-treatment procedures.
2. Experimental section
2.1. Chemicals, reagents and standard solutions
Acetonitrile (HPLC grade, Merck), hexane (for analysis, Acros
Organics), methanol (HPLC grade, Merck) and ultra-pure water
(Simplicity System, Millipore) were used throughout the experi-
ments. The SB-14 standard (98% purity) was obtained from Acros
Organics, while SO-7 and SR-24 standards (90% and 80% purity,
respectively) were obtained from Sigma–Aldrich.
Stock standard solutions containing 300–400 mg L
of the dyes
were prepared by individually weighing out appropriate amounts
of the solids, followed by dissolution in 25 mL of acetonitrile. The
solutions were stored in glass ﬂasks in a freezer. Working stan-
dards containing different concentrations of mixed or individual
dyes were prepared by a dilution of aliquots of the stock solutions
0016-2361/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: +55 (16) 3301 6619; fax: +55 (16) 3322 7932.
E-mail address: firstname.lastname@example.org (M.V.B. Zanoni).
Fuel 89 (2010) 2463–2467
Contents lists available at ScienceDirect
journal homepage: www.elsevier.com/locate/fuel