The main results of dissertation are summarized in the following thesis points.
1. SEPARATION OF HALOACETIC ACIDS AND INORGANIC ANIONS ON N-DECIL-2.2.2. CRYPTAND BASED MACROCYCLIC ANION EXCHANGE ANALYTICAL COLUMN
The analytical separation of haloacetic acids (monochlor-acetic acid (MCA), monobrom-acetic acid (MBA), dichlor-acetic acid (DCA), brom-chlor-acetic acid (BCA), dibrom-acetic acid (DBA), trichlor-acetic acid (TCA), monobrom-dichlor-acetic acid (MBDCA), monochlor-dibrom-acetic acid (MCDBA) and tribrom-acetic acid (TBA), they can’t be separated by isocratic elution was performed by gradient elution method with the presence of inorganic anions ( F−, Cl−, NO3−, Br−, SO42−, PO43−) on macrocyclic ion exchange phase. Due its structure the Cryptand A1 N-decil-2.2.2. column is perfectly suitable to realise the capacity gradient by changing of metal ion of eluent in the host/guest complexforming process. Since the ionic concentration of the eluent remains the same there is minor baseline distortion during the chromatographic run in this method.
2. OPTIMIZING GRADIENT ELUTION FOR THE EFFECTIVE SEPARATION OF HALOACETIC ACIDS
(a) Based on the retention results of separations using capacity gradient of macrocyclic solid phase it was established that the wide range of haloacetic acids can also be separated with base line resolution and short retention times both with short and long retention by combination of alkaline hydroxid (LiOH, KOH, NaOH) eluents.
(b) The systematical study of capacity of analytical separation column resulted that the LiOH eluent provides a very low (1,5-8 µequiv/column) capacity of the column (Li+-cryptate) by the use of KOH (K+-cryptate) it approximates to the maximum value (70-73 µequiv/column), and with NaOH eluent (Na+-cryptate) the capacity increases significantly (35-73 µequiv/column) with increase of concentration of NaOH eluent (10-3M < C < 10-1M). The system allows the selectivity control of the column capacity by the choice of eluent cation (Li, Na or K). The differences of retention times of haloacetic acids can be governed systematically by the eluent type and concentration.
(c) With the optimal values of gradient elution a gradient program was determined with the combination of eluents. In this method the time of gradient step, the type and concentration of eluent ensures optimal separation conditions. The optimal conditions were determined based on the number of recognized haloacetic compounds, time-consuming and expected resolution of the separation. The gradient method based on these experimental consideration has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the 3rd minute of the separation.
3. STUDY OF RETENTION OF METAL-CHELATE COMPLEXES ON ANION EXCHANGE COLUMN CONTAINING PELLICULARE STATIONARY PHASE (a) Based on a systematic retention data set of transition metal (Cu, Zn, Co, Al)
chelate complexes and polyamino-carboxylate ligands (EDTA, DCTA) an high performance anion chromatographic method has been developed using alkaline carbonate eluent and AS9-HC anion exchangers functionalized with alkyl-alkanol quaternary ammonium groups. An advantageous condition of the method is that the similar basic pH-range (9-11) is favourable to the stability of the metal complexes and also to their elution. The retention time of complex components was determined as a function of eluent composition and pH of mobile phase.
(b) By the change of eluent parameters it was established that increasing the total concentration of eluent system results decreasing of retention times. Increasing in pH leads to a decrease in retention, because the predominant form of eluent is
the divalent carbonate. The optimal separation conditions of eluent were determined (9,44 < pH <11,03, C = 9,0 mM for copper chelates (EDTA Cu-DCTA), C = 8,0 mM for zinc chelates (Zn-EDTA, Zn-DCTA)). To the separation of chelate ions with smaller resolution (ZnEDTA2-, ZnDCTA2-) with high rate of hydrogencarbonate in the eluent is necessary because the elution power of hydrogencarbonate is smaller than that of carbonate.
4. THE SIMULTANEOUS SEPARATION OF POLYAMINO-CARBOXYLATE
ANIONS, INORGANIC ANIONS AND TRANSITION METAL CATIONS CAN BE REALIZED
(a) Designated retention interval of the IC column effluent was collected and used to further ICP analysis. Collection protocols for the heart-cutting procedure were applied in the analysis of Cu and Zn containing peaks Aliquots of these fractions of CuEDTA/CuDCTA and ZnEDTA/ZnDCTA peaks were identified and confirmed the retention order by ICP spectroscopy.
(b) The peaks of free ligands, EDTA were also identified from the effluent at the appropriate retention interval, using FTIR-ATR spectroscopy method. The symmetric and asymmetric COO-valence vibrations (1800-1300 cm-1) characterizing the EDTA ligands can be followed on the IR spectra. Our experiments verify that the simultaneous separation of anionic ligands and metal chelate complexes can be achieved, and subsequently detected.
(c) The di-, tri-, and tetravalent negative charged forms of polyamino-carboxylate ligands can be separated by anion exchange chromatography. In the case of EDTA ligand these components are the coeluated EDTA4- / EDTA3-, the NaEDTA3-, the NaHEDTA2- and the Na2EDTA2-. This is possible because the rate of interconversion is slow relative to the time of development of the chromatogram. The FTIR-ATR measurements also confirm these results.
5. THE PARAMETERS OF SELECTIVE SEPARATION OF METAL-CHELATE COMPLEXES AND HALOACETIC ACIDS CAN BE PLANNED
Based on the retention data of transition metal-chelate complex anions can be established that the simultaneous separations of inorganic anions and complex metalions can be achieved using pH =9,0−11,0 and CNaCO 6,0 9,0mM
3
2 = −
carbonate eluent. The retentions can be provided in order of inorganic, organic anions < anionic chelate ligands (EDTA < DCTA) < metal chelate complex anions. In the case of haloacetic acids the employed step-gradient (NaOH / LiOH) allows that the retentions are realized in order of chloro < bromo, mono-
< di- < tri-halogenated acetic acid. The calibration linearities in the range of 0,01 – 0,4 mM sample concentration in the case of the same metal ion, but different ligand R2=0,9931 for CuEDTA ion, R2=0,9894 for CuDCTA ion, respectively.
In the same concentration range R2=0,9997, R2=0,9996 are for MCA and MBA.