The paper presents chemical and structural analysis of geopolymer materials which are obtained by alkali-activated calcined clay (metakaolin) originated from Serbia under strictly defined conditions. ...Characterization of the metakaolin and geopolymers molecular structure has been done using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The paper presents the possibility of obtaining geopolymer structure and differences in chemical and structural characterization of these materials taking into account the concentration of NaOH as a variable parameter. The results of MALDI analysis of metakaolin and synthesized geopolymer structures using various matrix system: 2,4,6 trihydroxyacetophenone (THAP), α-cyano-4-hydroxycinnamic, 2,6 dihydroxyacetophenone and laser desorption/ionization, have shown that THAP matrix is the most appropriate for analysing these aluminosilicate materials.
In this work it has been shown that both the laser desorption/ionization mass
spectrometry (LDI MS) and the matrix assisted laser desorption/ionization
time-of-flight mass spectrometry (MALDI TOF MS) ...are the simple and quick
methods for determination of relative natural isotopic distribution of lead.
The analysis of metal salts with these approaches does not require any
time-consuming preparation of samples: a single run can take only a minute,
and numerous information can be obtained. Results obtained in this work show
that chosen matrix has no negative effect on quantitative determination of
lead isotopes and support once more the applicability of MALDI TOF MS for
lead isotope distribution determination in the sample, and accuracy of data
obtained. Additionally, the generation of PbnOn and PbnOn-1 (n: 2 - 6)
clusters have been successfully achieved in the positive mode, using the both
LDI and MALDI methods. All stoichiometries were confirmed using isotopic
pattern modelling.
This paper presents optimization of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer (MS) instrumental parameters for the analysis of ...chloro(2,2'',2"-terpyridine)palladium(II) chloride dihydrate complex applying design of experiments methodology (DoE). This complex is of interest for potential use in the cancer therapy. DoE methodology was proved to succeed in optimization of many complex analytical problems. However, it has been poorly used for MALDI-TOF-MS optimization up to now. The theoretical mathematical relationships which explain the influence of important experimental factors (laser energy, grid voltage and number of laser shots) on the selected responses (signal to noise ? S/N ratio and the resolution ? R of the leading peak) is established. The optimal instrumental settings providing maximal S/N and R are identified and experimentally verified.
This paper presents optimization of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer (MS) instrumental parameters for the analysis of ...chloro(2,2',2"-terpyridine)palladium(II) chloride dihydrate complex applying design of experiments methodology (DoE). This complex is of interest for potential use in the cancer therapy. DoE methodology was proved to succeed in optimization of many complex analytical problems. However, it has been poorly used for MALDI-TOF-MS optimization up to now. The theoretical mathematical relationships which explain the influence of important experimental factors (laser energy, grid voltage and number of laser shots) on the selected responses (signal to noise-S/N ratio and the resolution-R of the leading peak) is established. The optimal instrumental settings providing maximal S/N and R are identified and experimentally verified. Keywords: MALDI-TOF-MS, design of experiments (DoE), optimization, metallo-drugs. IZVOD (Naucni rad) U okviru ovog rada ispitane su mogucnosti koriscenja matematicke metodologije dizajniranja eksperimenta (Design of Experiments (DoE) methodology) za optimizaciju instrumentalnih parametara kod spektroskopije masa sa laserskom desorpcijom i jonizacijom uz pomoc "matrice" (MALDI-MS), za analizu Pd(terpy)ClCl x 2H.sub.2O kompleksa. Navedeni metalni kompleks predstavlja potencijalni lek u antikancer terapiji, tako da povecanje efikasnosti razvoja metoda njegove analize/karakterizacije, kao i uspostavljanje uslova za analizu proizvoda njegove interakcije sa biomolekulima, predstavljaju vazan zadatak. DoE metodologija obezbeduje sistematsko ispitivanje uticaja izdvojenih instrumentalnih parametara (predstavljaju ulazne promenljive ili faktore) na kljucne karakteristike kvalitetnog spektra (tzv. "odgovor") u cilju dobijanja pouzdane identifikacije. Eksperimentalno, spektar je poznat samo na tacno odabranim vrednostima instrumentalnih parametra (u odredenom rangu), ali se ne dobijaju informacije o spektru za vrednosti izmedu pomenutih parametra. Ispitivanje uticaja vrednosti instrumentalnih parametara, izmedu onih vec ispitanih, na kvalitet spektra, eksperimentalno predstavlja izuzetno komplikovan postupak, zbog velikog broja kombinacija. DoE metodologija uspostavlja matematicke relacije izmedu odabranih faktora i "odgovora", na osnovu malog broja pazljivo isplaniranih eksperimenata (Box-Behnken design-pristup). U analitickoj hemiji, ova metodologija uspesno je primenjena za optimizaciju hemijskih faktora kod hromatografskih, elektroana-litickih, termogravimetrijskih i drugih metoda. DoE pristup, do sada, primenjen je za optimizaciju instrumentalnih parametara u slucaju, atomske apsorpcione spektrometrije sa grafitnom kivetom, indukovano kuplovane plazme opticke emisione spektrometrije, indukovano kuplovane plazme spektrometrije masa, kod MALDI spektrometrije masa, ali ne za detekciju kompleksnih jedinjenja. Analiza kompleksa prelaznih metala uz pomoc MALDI-TOF-MS je poseban izazov zbog velikog broja signala koji poticu od izotopa prelaznih metala, tako da je rezolucija koju treba postici od velikog znacaja. Ulazni faktori (promenljive) u ovom radu bili su: intenzitet lasera, broj udaraca lasera i napon na "gridu", a vazne karakteristike spektara, kao sto su odnos signal/sum i rezolucija, predstavljaju trazeni "odgovor". Raspon vrednosti ulaznih faktora odreden je na osnovu preliminarnih eksperimentalnih podataka. Rezultati su pokazali da vrednosti odnosa signal/sum pokazuju jaku kvadratnu zavisnost od intenziteta lasera i umereno zavise od napona na "gridu" i broja udaraca lasera. Rezolucija linearno zavisi od intenziteta lasera i napona na "gridu". Medu nekoliko potencijalnih resenja izabrani inetenzitet lasera od 1220, napon na "gridu" od 79% i 360 udaraca lasera predstavljaju optimalne uslove za dobijanje kvalitetnog spektra Pd(terpy)ClCl x 2H.sub.2O kompleksa, sto je kasnije i eksperimentalno potvrdeno. Kljucne reci: MALDI-TOF-MS * DoE metodologija * Optimizacija * Lekovi na bazi metala
Well-balanced nutrition is important for the successful cultivation of healthy plants. In this paper, we demonstrate a nondestructive optical method that can sense a deficiency of certain nutrients. ...The setup was tested on hydroponically grown Ocimum basilicum. The plants were subjected to nutrient deficiency by the exclusion of one of the essential elements (Fe, Mg, P, N) from the hydroponic solution. A control group of plants, fed by the balanced hydroponic solution, was also grown under the same conditions. The proposed method tracks and records the optical transmittance of the plants' leaves. All groups exhibit clearly defined day-night Circadian rhythms. When compared to the control group, the treated plants exhibited modified circadian rhythms of the optical transmission, suggesting an early indicator of the plants' stress. The condition of the plants under test was also assessed by the more common (destructive) methods such as: measurements of the determination of the photosynthetic pigment content, dray weight determination and the efficiency of PSII. Several biological parameters were observed, calculated and compared to the graphs of optical transmission dependence in real time. Presented results have demonstrated a significant potential of the proposed optical method for the early detection of plants' stress in hydroponic cultivation.
PDF
