Oxidációs eljárás kidolgozása talajvizek szerves mikroszennyezőinek eltávolítására

A vízszennyezés évtizedek óta nagy problémát jelent a környezetnek, és egyre nagyobb fejtörést az emberiségnek, főleg az érintett szakembereknek. Nemcsak lokális, rövid idejű gondot okoz, hiszen a víz körforgása globális mértékű és a különböző környezeti elemekben való szennyezőanyag-felhalmozódás miatt a hatások hosszú ideig jelentkezhetnek. A szennyezés elleni védekezések első lépése a megelőzés. Ennek érdekében számos törvény, országok közötti megállapodás és európai szintű rendelkezés született a vízszennyezés elkerülésére. Ha a probléma már megvan, akkor merül fel a szennyezés megszüntetésének kérdése. Ennek keretében életbe lépnek a kármentesítést és a terület remediálását célzó intézkedések. A különböző típusú szennyezőanyagok eltávolítására kidolgozott módszerek közös jellemzője, hogy hatékonyan, káros melléktermékek keletkezése nélkül igyekeznek a víz egészséges állapotát helyreállítani. Tudományos diákköri munkám kísérleti részét az Imsys Mérnöki Szolgáltató Kft. és az ELTE KKKK talajvíz remediációjával foglalkozó közös kooperációs projektjének keretein belül végeztem. Munkám során VOC vegyületek környezeti talajvízből történő eltávolítására dolgoztam ki oxidációs eljárást. A kísérleti körülmények optimálásához triklór-etilén (TCE) modellvegyületet használtam. Elsődleges célom volt egy olyan oxidációs eljárás – ferrát technológia – kidolgozása, mely hatékonyan képes a TCE eltávolítására különböző mátrixú víztípusokból. Tanulmányoztam a minták kiindulási TCE koncentrációjának, a pH-nak és az alkalmazott ferrát mennyiségének hatását a TCE eltávolítására, továbbá a keletkező melléktermékek megjelenésére. Munkám során a gőzfázis vizsgálatát headspace technikát alkalmazó gázkromatográf-tömegspektrométer (HS/GC-MS) rendszerrel, míg a folyadékfázis analízisét szilárdfázisú mikroextrakciós (SPME) minta-előkészítést követő GC-MS analitikai módszerrel végeztem

High Performance Anion Chromatography of Gadolinium Chelates

High performance anion chromatography (HPIC) method to separate ionic Gd chelates,[GdDTPA]2− , [GdEDTA]− , [GdDCTA]− and free matrix anions was developed. At alkaline pHs, polydentate complexing agents such as ethylene-diamine-tetraacetate, diethylene-triamine penta-acetate and trans-1,2-diamine-cyclohexane-tetraacetate tend to form stable Gd chelate anions and can be separated by anion exchange. Separations were studied in the simple isocratic chromatographic run over the wide range of pH and concentration of carbonate eluent using suppressed conductivity detection. The ion exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity of Gd chelates. Parameters of optimized resolution between concurrent ions were presented on a 3D resolution surface. The applicability of the developed method is represented by the simultaneous analysis of Gd chelates and organic/inorganic anions. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was used for confirmation of HPIC results for Gd. Collection protocols for the heart-cutting procedure of chromatograms were applied. SPE procedures were also developed not only to extract traces of free gadolinium ions from samples, but also to remove the high level of interfering anions of the complex matrices. The limit of detection, the recoverability and the linearity of the method were also presented

Unbiased Determination of Adsorption Isotherms by Inverse Method in Liquid Chromatography

The Inverse Method is a widely used technique for the determination of adsorption isotherms in liquid chromatography. In this method, isotherm is determined from the overloaded peak profile of the component by the iterative solution of the mass balance equation of liquid chromatography. Successful use of this method requires a prior assumption of equation of isotherm (Langmuir, BET etc.). In this work, we have developed an inverse method that gives results of similar accuracy to the frontal analysis without assuming the equation of the isotherm. The oversaturated peaks were calculated using a spline fitted to data points instead of the derivative of the isotherm. The distribution of the isotherm points were optimized for minimizing the difference between the measured and calculated overloaded peaks. The accuracy of the developed method was verified with synthetic benchmark peaks and by the determination of isotherm of buthyl-benzoate under real conditions. The results confirmed that the accuracy of the developed method is similar to that of Frontal Analysis

Study of Efficiency of Capacity Gradient Ion-Exchange Stationary Phases

Highly efficient columns are necessary for the modern analytical applications of liquid chromatography. In this work, the separation efficiency of ion-exchange capacity gradient stationary phases combined with eluent concentration gradient was studied by a theoretical approach. In the course of our work three different scenarios of capacity gradients were used with different shapes (linear, convex and concave). The resolutions of different gradient columns were calculated for each scenario. As a reference, a uniform column was considered, which had the same analysis time as the non-uniform column. In the case of separation of ions with same charges, the gradient column offered only a marginal advantage compared to the uniform column due to the bandwidth compression caused by the capacity gradient. In the case of ions with different charges, however, the advantage of the gradient column was more significant. This was mainly due to the increased retention time difference of solutes. Ion-exchange capacity gradient columns may be a new way to separate ions more efficiently

Analysis of Non-Ionic Surfactant Triton X-100 Using Hydrophilic Interaction Liquid Chromatography and Mass Spectrometry

It is well known that surfactants increase the solubility of hydrophobic organic compounds and cause adverse environmental effects. The removal of these compounds from the contaminated soil or ground-water is particularly difficult due to their water soluble feature. In this work, an ultra-high performance hydrophilic interaction liquid chromatographic method was developed for the separation of oligomers of Triton X-100 octylphenol-polyethoxylate non-ionic surfactant. Liquid chromatography-mass spectrometry (LC-MS) was used to identify the Triton X-100 compounds. There was a 44 mass unit difference between two adjacent peaks that is the molar mass of one ethylene oxide group (–CH 2 CH 2 O–). A quadratic retention model was applied for the estimation of retention of the examined non-ionic surfactant and the optimization of gradient elution conditions. The optimized method was suitable for the baseline separation of 28 Triton X-100 oligomers in five minutes

Impact of the column on effluent pH in cation exchange pH gradient chromatography, a practical study

In ionexchange chromatography, the pH gradient mode becomes more and more popular today for the analysis of therapeutic proteins as this mode can provide higher or alternative selectivity to the com- monly used salt gradient mode. Ideally, a linear pH response is expected when performing linear gra- dients. However up to now, only a very few buffer systems have been developed and are commercially available which can perform nearly linear pH responses when flowing through a given column. It is also known that a selected buffer system (mobile phase) can work well on one column but can fail on other column. The goal of this study was to practically evaluate the effects that ionexchange columns (weak and strong exchangers) might have on effluent pH, when performing linear pH gradient separations of therapeutic monoclonal antibodies. To attain this objective, the pH was monitored on-line at the column outlet using a specific setup. To make comprehensive observations of the phenomenon, four different mobile phase conditions and five cation exchange columns (weak and strong exchangers) were employed. The obtained pH responses were systematically compared to responses measured in the absence of the columns. From this work, it has become clear that both the column and mobile phase can have significant effects on pH gradient chromatography and that their combination must be considered when developing a new method. Phase systems (column + mobile phase) providing linear pH responses are indeed the most suitable for separating mAbs with different isoelectric points and, with them, it is possible to elute mAbs across wide retention time ranges and with high selectivity

Tuning selectivity in cation-exchange chromatography applied for monoclonal antibody separations, part 1: Alternative mobile phases and fine tuning of the separation

tCation exchange chromatography (CEX) of therapeutic monoclonal antibodies is generally performedwith either salt gradient (MES buffer + NaCl) or using commercial pH gradient buffer. The goal ofthis study was to find out some alternative buffer systems for CEX separation of mAbs, which mayoffer alternative selectivity, while maintaining similar peak shapes. Among the new buffers that weretested, (N-morpholino)ethanesulfonic acid (MES) / 1,3-diamino-2-propanol (DAP), and citric acid / 2-(cyclohexylamino)ethanesulfonic acid (CHES) systems were particularly promising, especially whencombining them with a moderate salt gradient of NaCl. This two buffer system provides an equivalent orslightly better separation than the standard, mobile phases for therapeutic mAbs.It was also demonstrated that working with salt-mediated pH gradients, allows to extend the pos-sibilities in method development, since the concentration of salt in the mobile phase has a significantimpact on selectivity. Using HPLC modeling software (Drylab), it was possible to successfully developCEX methods for authentic mAb samples within only 6 h, by optimizing the gradient steepness and saltconcentration in the B eluent

Optimization of MS-Compatible Mobile Phases for IEX Separation of Monoclonal Antibodies

Characterization of monoclonal antibodies (mAbs) and related products requires the identification of chromatographic peaks with mass spectrometry (MS). However, the conventional salt- and pH-gradient elution techniques used in ion-exchange chromatography (IEX) are inherently incompatible with MS. Ammonium acetate- and ammonium carbonate-based mobile phase systems have been recently applied in IEX-MS, but the influence of the eluent composition on peak shape and retention has not been discussed nor studied systematically until now. The aim of the present study was to understand the impact of ionic strength, buffer capacity, and pH-response on the retention behaviour and peak shape of mAb species