Borbála Antal

Estimation of Activation Energy from the Survival Yields: Fragmentation Study of Leucine Enkephalin and Polyethers by Tandem Mass Spectrometry

AbstractA simple collision model for multiple collisions occurring in quadrupole type mass spectrometers was derived and tested with leucine enkaphalin a common mass spectrometric standard with well-characterized properties. Implementation of the collision model and Rice-Ramsperger-Kassel-Marcus (RRKM) algorithm into a spreadsheet software allowed a good fitting of the calculated data to the experimental survival yield (SY) versus collision energy curve. In addition, fitting also ensured to estimate the efficiencies of the kinetic to internal energy conversion for Leucine enkephalin in quadrupole-time-of-flight and triple quadrupole instruments. It was observed that the experimental SY versus collision energy curves for the leucine enkephalin can be described by the Rice-Ramsperger-Kassel (RRK) formalism by reducing the total degrees of freedom (DOF) to about one-fifth. Furthermore, this collision model with the RRK formalism was used to estimate the critical energy (Eo) of lithiated polyethers, including polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetrahydrofurane (PTHF) with degrees of freedom similar to that of leucine enkephalin. Applying polyethers with similar DOF provided the elimination of the effect of DOF on the unimolecular reaction rate constant. The estimated value of Eo for PEG showed a relatively good agreement with the value calculated by high-level quantum chemical calculations reported in the literature. Interestingly, it was also found that the Eo values for the studied polyethers were similar. Figureᅟ

Rapid detection of hazardous chemicals in textiles by direct analysis in real-time mass spectrometry (DART-MS).

Residues of chemicals on clothing products were examined by direct analysis in real-time (DART) mass spectrometry. Our experiments have revealed the presence of more than 40 chemicals in 15 different clothing items. The identification was confirmed by DART tandem mass spectrometry (MS/MS) experiments for 14 compounds. The most commonly detected hazardous substances were nonylphenol ethoxylates (NPEs), phthalic acid esters (phthalates), amines released by azo dyes, and quinoline derivates. DART-MS was able to detect NPEs on the skin of the person wearing the clothing item contaminated by NPE residuals. Automated data acquisition and processing method was developed and tested for the recognition of NPE residues thereby reducing the analysis time.

Direct analysis in real time mass spectrometry (DART-MS) of highly non-polar low molecular weight polyisobutylenes

Low molecular weight polyisobutylenes (PIB) with chlorine, olefin and succinic acid end-groups were studied using direct analysis in real time mass spectrometry (DART-MS). To facilitate the adduct ion formation under DART conditions, NH4 Cl as an auxiliary reagent was deposited onto the PIB surface. It was found that chlorinated adduct ions of olefin and chlorine telechelic PIBs, i.e. [M + Cl]- up to m/z 1100, and the deprotonated polyisobutylene succinic acid [MH]- were formed as observed in the negative ion mode. In the positive ion mode formation of [M + NH4 ]+ , adduct ions were detected. In the tandem mass (MS/MS) spectra of [M + Cl]- , product ions were absent, suggesting a simple dissociation of the precursor [M + Cl]- into a Cl- ion and a neutral M without fragmentation of the PIB backbones. However, structurally important product ions were produced from the corresponding [M + NH4 ]+ ions, allowing us to obtain valuable information on the arm-length distributions of the PIBs containing aromatic initiator moiety. In addition, a model was developed to interpret the oligomer distributions and the number average molecular weights observed in DART-MS for PIBs and other polymers of low molecular weight. Copyright

Uncatalyzed reactions of 4,4′-diphenylmethane-diisocyanate with polymer polyols as revealed by matrix-assisted laser desorption/ionization mass spectrometry

The uncatalyzed reactions of polyols including polypropylene glycol (PPG, Mn = 2000 g mol−1), polytetrahydrofuran (PTHF, Mn = 1000 g mol−1), poly(e-caprolactone)-diol (PCLD, Mn = 2000 g mol−1) and polypropylene glycol glycerol triether (PPG_GL, Mn = 1000 g mol−1) with 4,4′-diphenylmethane-diisocyanate (MDI) were studied using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The reactions between these polyols and MDI were monitored in time and first-order consecutive reaction kinetics for the formations of polyols end-capped with MDI units were established. The fractional MALDI-TOF MS intensities obtained for the different polymer series at various reaction times were converted into molar fractions versus time data by means of the estimated relative MALDI-TOF MS response factors from which the corresponding rate constants and the relative reactivities of the hydroxyl groups of polyols were determined. It was found that the pseudo first-order rate constants for the polyol-MDI reaction decreased in the order of PCLD > PTHF > PPG ≈ PPG_GL. It was also ascertained that the reactivity of the unreacted hydroxyl groups of the diols does not change significantly after the first one has reacted. On the contrary, in the case of PPG_GL it was found that the reactions of the hydroxyl groups with MDI proceed faster after any of the three hydroxyl groups has reacted, suggesting a positive substitution effect for this system.

Micropropagation of Leuce-poplars and evaluation of their development under sandy site conditions in Hungary

Abstract Leuce-poplars are a native stand-forming tree species throughout Hungary. Several species or selections of them are used as ornamental plants in parks or to line streets and highways. They cover approximately 4.0 per cent of the total forested area in Hungary (70000 ha). The white (grey) poplar belongs to the Leuce poplars and plays a significant role in sand fixation, regional forestation, and nature conservation. The National Agricultural Research and Innovation Centre, Forest Research Institute or NARIC-FRI (formerly known as the Forest Research Institute) is involved in long-term breeding work for the selection of fast-growing white poplar trees under dry conditions. In vitro multiplication of trees is applied mainly to fruit growing trees in Hungary; in forestry research it is used primarily for selective breeding. This paper presents a short overview of the most important issues concerning the biotechnology of different Populus species, the related research on micropropagation trials, and the results of field investigations of micropropagated Leuce-poplar clone experiments. Kivonat Leuce-nyárak mikroszaporítása és homokterületen történő termesztésük kiértékelése Magyarországon. A Leuce-nyárak őshonos állományalkotó fafajok Magyarországon. Néhány fajukat, illetve szelekciójukat parkokban, utcák, utak mentén díszfaként használják. Magyarországon az összes erdősült területnek kevesebb mint 4%-át teszik ki (70000 ha). A Leuce-nyárakhoz tartozó fehér (szürke) nyár jelentős szerepet játszik a homoktalajok megkötésében, azok erdősítésében, és természetvédelmi szempontból is fontos. Száraz termőhelyi viszonyokra szelektált, gyorsan növő Leuce-nyárak hosszútávú nemesítési munkája folyik a ˗ korábban Erdészeti Tudományos Intézet, ma már ˗ a Nemzeti Agrárkutatási és Innovációs Központ Erdészeti Tudományos Intézetében (NAIKERTI). Magyarországon fás növények esetében in vitro szaporítási eljárásokat főleg a gyümölcstermesztésben alkalmaznak, az erdészeti kutatásban elsősorban a szelekciós nemesítés során használják. Jelen tanulmány rövid áttekintést nyújt a különböző nyár fajok legfontosabb biotechnológiai vonatkozásairól, a kapcsolódó mikroszaporítási kísérletekről, valamint mikroszaporítással előállított Leuce-nyár klónok termesztési kísérleteinek eredményeiről.

Juvenile Growth and Morphological Traits of Micropropagated Black Locust (Robinia Pseudoacacia L.) Clones under Arid Site Conditions

Abstract - In Hungary black locust (Robinia pseudoacacia L.) is considered as an important exotic stand-forming tree species growing mostly under unfavourable ecological conditions for forest management. Due to climate change effects its importance is increasing in many other countries, too. As a result of a selection programme new black locust clones were tested in clone trials. Juvenile growth and the morphological as well as phenological traits of four micropropagated black locust clones were evaluated in central Hungary under dry site conditions. Significant differences (P<5%) were found for DBH and field survival rate values. At age of 7 the clone R.p. ‘Bácska’ (’KH 56A 2/5’) appears to be especially promising for mass propagation. Tissue culture can be considered as a suitable tool for propagating superior individuals and offers new prospects for the rapid cloning of selected genotypes used for plantation forestry. Kivonat Mikroszaporított fehér akác (Robinia pseudoacacia L.) klónok fiatalkori növekedése és morfológiai jellemzői száraz termőhelyeken. Magyarországon a fehér akác (Robinia pseudoacacia L.) fontos állományalkotó egzóta fafaj, főként az erdőgazdálkodás számára kedvezőtlen termőhelyeken. A klímaváltozás hatásai miatt a fafaj jelentősége folyamatosan növekszik több más országban is. Egy szelekciós program eredményeként új akác klónokat állítottunk elő klónkísérletek létesítése céljából. Jelen tanulmányban négy mikroszaporítással előállított akác klónt értékeltünk fiatalkori növekedésük, továbbá morfológiai és fenológiai jellemzőik alapján Közép-Magyarországon száraz termőhelyi viszonyok között. Szignifikáns különbséget (P<5%) találtunk a mellmagassági átmérő és a megmaradási értékek tekintetében. 7 éves korban az R.p. ‘Bácska’ (’KH 56A 2/5’) klón különösen ígéretesnek tűnik a tömegszaporításra. A szövettenyésztéses szaporítási eljárás megfelelő eszköznek tekinthető az ültetvényes fatermesztés területén kiváló minőségű egyedek klónos elszaporítására, új távlatokat nyújtva ezzel a kiválasztott genotípusok gyors klónozására.