Scientific interests of Maryna Zui’s Group

New methods of  solid-phase and liquid-liquid microextraction and their application  in chromatographic analysis

 

Scientific group of Assoc. Prof. of the chair of Analytical Chemistry, Ph.D. Maryna Zui solves the following tasks:

  • 1. Development of new methods of solid-phase microextraction and liquid-liquid microextraction of organic compounds: biomarkers, toxicants, plasticizers, preservatives, UV filters, etc.
  • 2.   Combination of microextraction methods for the isolation and preconcentration of organic compounds with derivatization methods and HPLC or GC determination.
  • 3. Synthesis of new hybrid organosilica coatings and their application in solid-phase microextraction methods.

The methods developed by us for the determination of phthalates, aldehydes, parabens, and benzophenones have been successfully applied to the analysis of natural and drinking water, cosmetic products, food products, and medicines. They are characterized by simplicity, accessibility, rapidity, high sensitivity, and sufficient reproducibility.

MICROEXTRACTION is the extraction of an analyte into a small volume: from 1 μl to 1-2 ml of solvent or a small mass of sorbent - up to 5 mg from a liquid, solid, or gaseous sample with a volume of up to 5-10 ml (or a mass of up to 5 g). Microextraction is divided into liquid-liquid microextraction (LLME) and solid-phase microextraction (SPME).

SPME is based on sorption of analytes from a liquid/solid sample onto SPME device (Fig. 1), which is classical SPME, or from gas phase above a solution/solid sample onto SPME device, which is headspace SPME (Fig. 2). The main advantages of SPME are high preconcentration coefficients and the possibility to analyze complex samples (for example, blood plasma).

Steps of headspace SPME

  • • Preparation of the analyte solution (pH, ionic strength, derivatization).
  • • Thermostate a hermetically sealed vial with analyte solution or a solid sample at optimal temperature.
  • • Sorption of analyte from gas or liquid phase onto the coating of SPME device/fiber.
  • • Desorption: thermal desorption for GC or elution with organic solvents for HPLC analysis.

 

The main types of SPME that are known today and the chromatogram of aldehyde derivatives with O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine are shown in Fig. 3a and 3b.

Fig.1. SPME Device (Supelco production).

Fig. 2. Scheme of headspace solid-phase microextraction.

Fig. 3: a) - Main types of SPME: in a capillary tube/column; in a vial; on a fiber coating; on sorbent particles packed in various SPME devices; on a stirrer; on a disk/membrane (G. Ouyang, J. Pawliszyn. Trends in Analytical Chemistry, 2006. 25(7): 692-703); b) - chromatogram of aldehyde derivatives with O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine.

 

LLME is the extraction of analyte from aqueous solution into extraction phase by adding one or mixture of organic solvents, forming two or three phases that are immiscible or separated by semi-permeable polymer membranes (Fig. 4).

For preconcentration purposes 10-1000-fold differences in phase volumes, vortex mixing, ultrasonic treatment, temperature control, salting out, "green chemistry" solvents, etc. are used. The advantage of this method is the high extraction speed (several minutes) and high preconcentration coefficients.

Fig. 4. Scheme of dispersive liquid-liquid microextraction.

We synthesize and investigate PDMS coatings consisting of polydimethylsiloxane chains and modified with aminopropyl, cyanopropyl, phenyl, N-2-aminoethyl-3-aminopropyl, and other groups. Photographs of some of our coatings are shown in Fig. 5. New PDMS coatings are characterized by high thermal stability, allowing the separation of non-polar and semi-polar analytes from polar compounds, which can give a significant matrix background in real samples. Using the synthesized coatings, a method was developed for the determination of prohibited Sudan I dye in spices. The microextraction scheme is illustrated in Fig. 6.

Fig. 5. Photos of synthesized coatings.

Fig. 6.  Scheme of SPME for Sudan I Dye extraction from spices.

 

Where is microextraction used?

  • EPA US standard (EPA METHOD 8315A) for the determination of carbonyl compounds in air and drinking or natural waters;
  • Determination of residual solvents in pharmaceuticals;
  • Determination of biomarkers - short-chain aliphatic acids in biological samples of gastroenterological patients;
  • Determination of super ecotoxicants: phenols, phthalates, polychlorinated biphenyls, polycyclic aromatic hydrocarbons in natural waters and soil extracts;
  • Determination of biomarkers: short-chain aldehydes, ketones, dialdehydes, carboxylic acids, ethers in biological samples of patients with diabetes, cardiovascular, and pulmonary diseases.

Selected publications

  1. A. Mosendz, V. Levchyk, M. Zui. Derivatization, solid-phase microextraction and gas chromatography for determination of dialdehydes ‒ biomarkers of oxidative stress. Toxicological & Environmental Chemistry, 2024. 1-14.
  2. I.B. Zakharkiv, M.F. Zui, V.N. Zaitsev. Determination of aliphatic aldehydes C1–C5 with headspace solid phase microextraction in tap water: derivatization in-solution versus on-fiber. Chemical Papers, 2024. 78(1): 435-445.
  3. A. Mosendz, V. Levchyk, M. Zui. The preconcentration of aromatic aldehydes on polydimethylsiloxane-divinylbenzene fiber. Molecular Crystals and Liquid Crystals, 2021. 719(1): 71-83.
  4. Igor Zakharkiv, Maryna Zui, Vladimir Zaitsev. Determination of phthalate esters in water and liquid pharmaceutical samples by dispersive liquid-liquid microextraction (DLLME) and gas chromatography with flame ionization detection (GC/FID). Analytical Letters, 2020. 53(7): 1-18.
  5. B.A. Shnayder, V.M. Levchyk, M.F. Zui, N.G. Kobylinska. Hybrid Organosilica Coatings for Solid Phase Microextraction: Highly Efficient Adsorbents for Determination of Trace Parabens. Protection of Metals and Physical Chemistry of Surfaces. 2019. 55 (4): 657-666.
  6. V. M. Levchyk, M. F. Zui. Gas Chromatographic determination of parabens after derivatization and dispersive microextraction. French-Ukrainian Journal of Chemistry, 2015. 3(2): 72-79.
  7. Zakharkiv, I.B., Zui, M.F. & Zaitsev, V.N. Dispersive liquid-phase microextraction for determination of phthalates in water. Journal of Water Chemistry and Technology, 2015. 37: 78-84.
  8. V.N. Zaitsev, M.F. Zui. Review. Preconcentration by solid-phase microextraction. Journal of analytical chemistry, 2014. 69(8): 715-727.