Page 51 - Zbornik_Konf_2019

https://doi.org/10.15414/2019.9788055220703

4 International Scientific Conference Abstracts Book
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USING AN AZO COUPLING REACTION TO DETERMINE 2,6‐DIMETHOXYANILINE
BY METHOD HPLC
Ivan Maga

National Medical University, Kyiv, Ukraine; E-mail: ivan_maga@outlook.com
The 2,6-dimethoxyaniline (DMA) is the product of biodegradation of many pesticide
active ingredients: matrine (Bayer), callisto (Syngenta), etc, which have or have had wide
application in agriculture for the cultivation of various crops. MA is a yellow powder with
melting point 71–74 °C, boiling point 254 °C, density 1.096 g/mL, refractive index 1.4770 (at
80 °C). In addition to pesticides, DMA is an intermediate commonly used in the synthesis of
dyes, pigments, pharmaceuticals, and other important products. DMA has toxic and
carcinogenic properties. To convert DMA into the hydrophobic form and improve its
metrological characterization, the derivatization reaction with 4-nitrophenyldiazonium cation
was used which results in the formation of DMA azo compound. The formation of azoderivate
largely depends on the pH of the medium. To study this effect, the derivatization reaction was
performed in a wide range of hydrogen ion concentration: of 3.7 to 13.4 pH. Important for the
formation of DMA azo compound is the reagent concentration. To study this impact, a series of
experiments were performed, with the concentration of diazonium cation varied from 1 to 30-
fold amount relative to the DMA amount. The IR spectra were recorded by Abatop (Nicolatt,
USA) spectrometer with KBr pellets. Liquid chromatography was carried out using Perkin-
Elmer (USA) chromatograph with a spectrophotometer detector. A stainless steel column
(250×4.6 mm) was filled with Silasorb The chromatography was performed in isocratic
elution mode: mobile phase content acetonitrile water = 2 : 1; flow rate 1.2 cm /min; λ = 389
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nm; sample input 20 μL. The chromatography results were processed using the “Multichrom”
and “Millenium” software. For extraction and retrieval of azoderivate, several organic solvents
(hexane, toluene, o-xylene, dichloromethane, chloroform, dichloroethane, ethyl acetate, butyl
acetate, isoamyl acetate) were studied. The best extragents were dichloromethane and
chloroform. For practical purposes, chloroform was used. The extract was examined
chromatographically. The retention time was 8.1 minutes; a single symmetrical peak was
observed indicating that no imposition of impurities occurs, which otherwise would prevent
the determination. The triazene was prepatively isolated. The solid residue − triazines DMA −
was analyzed for the content of carbon, bromine, hydrogen, and nitrogen. The elemental
analysis confirmed the triazene composition. The structure of synthesized triazene was also
confirmed by IR-spectroscopy; in particular by absorption at 1575, 1596 cm − 1 due to
stretching vibrations of a hydrogen atom bonded to a nitrogen atom in the triazene >N-H
group. The dissociation constant of the imino-group proton is calculated from pH-dependent
changes in the absorption of triazene solutions at maximum absorption of anionic form. The
linear dependence of the chromatographic peak area on DMA concentration was observed in
the range 30–4200 mg/dm . Based on these data, the methods to determine DMA in soils and
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wastewater using high-performance liquid chromatography were developed and tested on
model samples and real objects. The metrological processing of the results was made. This
simple, sensitive and accurate method provides an alternative way to rapidly analyze and
monitor DMA in soils and wastewater samples. The method, if suitably modified, can be used
to determine the DMA and other objects at some refinement analysis techniques.

Keywords: 2,6-dimethoxyaniline, azo coupling, HPLC, determination.

4 International Scientific Conference Agrobiodiversity Nutrition, Health and Quality of Human and Bees Life |51
th
September 11–13, 2019