Vibrational characterization of the pesticide molecule Tebuconazole

Pesticide use worldwide exhibits a positive effect on agricultural production while it may negatively affect organisms living in soil, water or the air. Importantly, numerous negative health effects also occur in humans exposed to (accumulated) pesticides or their metabolites over a long period of time. To prevent both environmental catastrophes and adverse human health impacts, initial studies of the selected pesticides need to be performed together with the constant post-approval control; risk assessment analysis and on site monitoring have to be continuously carried out. Given this, Raman spectroscopy, especially surface-enhanced Raman spectroscopy (SERS), during the last decade has become a powerful analytical technique since it can offer quick, selective, and in situ detection of selected pollutants found in analyzed samples at very low concentrations. Moreover, the structural changes caused by the pollutant-biomacromolecule interaction can also be recognized in the molecule-specific Raman spectral signatures of biomolecules. In this study, we report a vibrational characterization of the fungicide molecule Tebuconazole (TB) which is listed to be a possible carcinogen. Even though its international and common use there is no evidence about the use of Raman/SERS spectroscopy to detect it sensitively and selectively as well as to analyse its impacts on biological systems. Therefore, we have recorded and calculated Raman and infrared spectra of TB. Furthermore, SERS spectra of TB were also registered and comprehensively analysed in view of the employed SERS substrates, dependence on the excitation wavelengths and pH of the analysed molecular systems. The molecule of TB interacts preferentially through the triazole moiety with the colloidal metal nanoparticles (NPs) whereas the silver NPs prepared by reduction of silver nitrate with hydroxylamine hydrochloride resulted to be the most effective ones. Consequently, the limit of detection was determined to be 1.4 μM≈430 ppb. The present paper thus could serve significantly for further investigations focused on both conducting vibrational analyses of structurally related molecules as well as providing a more precise explanation of the mechanism of action of TB and its influence on biological macromolecules.

Study of the Degree of Cure through Thermal Analysis and Raman Spectroscopy in Composite-Forming Processes

The curing of composite materials is one of the parameters that most affects their mechanical behavior. The inspection methods used do not always allow a correct characterization of the curing state of the thermosetting resins. In this work, Raman spectroscopy technology is used for measuring the degree of cure. The results are compared with conventional thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). Carbon fiber specimens manufactured with technologies out of autoclave (OoA) have been used, with an epoxy system Prepreg System, SE 84LV. The results obtained with Raman technology show that it is possible to verify the degree of polymerization, and the information is complementary from classical thermal characterization techniques such as TGA and DSC; thus, it is possible to have greater control in curing and improving the quality of the manufactured parts.

A mass spectrometric stochastic dynamic diffusion approach to selective quantitative and 3D structural analyses of native cyclodextrins by electrospray ionization and atmospheric pressure chemical ionization methods

The paper addressed shortcoming with highly precise and selective 3D structural analysis of native cyclodextrins in mixture using ions observable at low m/z-region by ESI- and APCI-mass spectrometry. Because of, the quantitative and structural analyses of CDs, in general, are vexed by a set of complications. The study outlines our own stochastic dynamic approaches to the latter issues based on new model relations, quantifing the measurable MS outcome intensity. They introduce the so-called stochastic dynamic mass spectrometric diffusion "D_SD" parameter, exhibiting high accuracy, precision, sensitivity and selectivity, respectively. It is linearly connected with the so-called quantum chemical diffusion parameter "D_QC" according to Arrhenius's theory. The most important upshot is that statistical parameters r = 0.99₆₃₉-0.99₉₈₁ has been obtained correlating between D_SD and D_QC parameters. Therefore, we determine high accurately 3D molecular and electronic structures of analytes by mass spectrometry. Fragment peaks at m/z 313, 279, 272, 252, 231, 214, 198, 171, 158 and 141 are examined. Mixtures of CDs and monomeric and acyclic oligomer carbohydrates glucose (1), sucrose (2), raffinose (3), melezitose (4) and cellotriose (5) are also studied. Our method is able to account precisely for the effect of the temperature under ESI- and APCI-MS conditions, as well. Correlative analysess between D_SD parameters of ESI- and APCI-MS measurements under different temperatures is also shown. Chemometric tests are used. Another important results and conclusions, among others, to draw from this research are: (i) excellent linear correlation between D_SD and D_QC parameters of r = 0.99₆₃₆ is found looking at common ions at m/z 141, 158 and 171, belonging to 2-formyl-3,4-dihydroxy-pyranylium, 4,5,6-trihydroxy-6H-pyran-2-carbaldehyde and 3,4,5-trihydroxy-6-oxo-6H-pyran-2-ylmethylidyne-oxonium ions. Thus, we distinguish precisely between the last structure and 3-formyl-4,5-dihydroxy-2,7-dioxa-8-oxonia-bicyclo[4.2.0]octa-1(8),3,5-triene cation. In the case of ion at m/z 141 subtle electronic effects are distinguished between the mentioned structure and the charged 3,4-dihydroxy-6H-pyran-2-carbaldehyde one. The method determines precisely very similar structurally poly-OH-substituted derivatives. Because of, (ii) absolute reproducibility (r = 1) of D_SD parameters of ESI-MS spectra is obtained studying the shown in point (i) MS peaks of β-CD between j^th and j^th numbers of experiments. The statistical equation is Dⁱ_SD = (0.51 ± 3.1.10^-5) × D^j_SD; (iii) the APCI- and ESI-MS provide identical results studying common MS ions of CDs and the correlation between D^APCI_SD and D^ESI_SD parameters excludes from error, due to, experiment; and (iv) The correlation between theory and experiment accounting for the factor temperature within our model equations shows r = 0.98₂₈ looking at the MS peaks at m/z 313 280, 279, 274 and 252, respectively. The effect of the temperature under both ESI- and APCI-MS conditions on the 3D molecular and electronic structures of CDs is precisely studied, respectively.

A luminescence nanosensor for Ornidazole detection using graphene quantum dots entrapped in silica molecular imprinted polymer

A luminescence nanosensor has been developed for analysis of Ornidazole in biological samples using graphene-quantum-dot-embedded silica molecular imprinted polymer (GQD-SMIP) as a selective probe for this analyte. The GQD-SMIP was found to possess a strong fluorescent emission at 450 nm upon excitation at 365 nm. This emission was found to linearly quench in the presence of Ornidazole in a concentration range of 0.75 to 30 μM. A detection limit of 0.24 μM was reached using the probe and the sensor was successfully used in the determination of the analyte in plasma samples.

In situ chemically specific mapping of agrochemical seed coatings using stimulated Raman scattering microscopy

Providing sufficient, healthy food for the increasing global population is putting a great deal of pressure on the agrochemical industry to maximize crop yields without sustaining environmental damage. The growth and yield of every plant with sexual reproduction, depends on germination and emergence of sown seeds, which is affected greatly by seed disease. This can be most effectively controlled by treating seeds with pesticides before they are sown. An effective seed coating treatment requires a high surface coverage and adhesion of active ingredients onto the seed surface and the addition of adhesive agents in coating formulations plays a key role in achieving this. Although adhesive agents are known to enhance seed germination, little is understood about how they affect surface distribution of actives and how formulations can be manipulated to rationally engineer seed coating preparations with optimized coverage and efficacy. We show, for the first time, that stimulated Raman scattering microscopy can be used to map the seed surface with microscopic spatial resolution and with chemical specificity to identify formulation components distributed on the seed surface. This represents a major advance in our capability to rationally engineer seed coating formulations with enhanced efficacy.

Solid-state UV-MALDI mass spectrometric quantitation of fluroxypyr and triclopyr in soil

The work presented here refers firstly to solid-state UV-MALDI-Orbitrap-mass spectrometric analysis of fluroxypyr (A) and triclopyr (B) in soils under laboratory conditions. The experimental design has involved the following: (a) determination of analytes A and B in polycrystalline composites of organic materials 1-7, based on 2-piperidine (pyrrolidine or piperazine)-1-yl-ethyl ammonium salts in order to determine the effect of sample preparation techniques on method performance using commercial herbicide formulations and (b) analysis of non-(X j,k,l (i) ) and sterilized (Y j,k,l (i) ) soil samples (i-fold rate 1, 10, 100, or 1,000; j-pesticide type A or B; k-time (0, 5, 10, 20, and 50 days) and l = 1-3 replicated samples) having clay content ∈ 5.0-12.0 %, silt ∈ 23.0-51.1 %, sand ∈ 7.2-72.0 %, and pH ∈ 4.0-8.1. In order to obtain a high representativeness of the data toward real-field experiments, the pollution scheme has involved 1-, 10-, 100-, and 1,000-fold rates. The firstfold rate has concentration of pollutant A of 2.639 × 10(-4) g in 625 cm(2) soil horizon of 0-25 cm(2) (5 cm depth) according to registration report (PSM-Zulassungbericht) of German Federal Office of Consumer Protection and Food Safety (Bundesamt für Verbraucherschutz und Lebensmittelsicherheit) 6337/26.10.2009. The experimental design has involved quincunx systematic statistical approach for collection of soil samples. The performance has been compared with the corresponding statistical variable obtained, using an independent HPLC-ESI-(APCI-)-MS/MS analysis.

Uranyl-water-containing complexes: solid-state UV-MALDI mass spectrometric and IR spectroscopic approach for selective quantitation

Since primary environmental concept for long storage of nuclear waste involved assessment of water in uranium complexes depending on migration processes, the paper emphasized solid-state matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) and IR spectroscopic determination of UO2(NO3)2·6H2O; UO2(NO3)2·3H2O, α-, β-, and γ-UO3 modifications; UO3·xH2O (x = 1 or 2); UO3·H2O, described chemically as UO2(OH)2, β- and γ-UO2(OH)2 modifications; and UO4·2H2O, respectively. Advantages and limitation of vibrational spectroscopic approach are discussed, comparing optical spectroscopic data and crystallographic ones. Structural similarities occurred in α-γ modifications of UO3, and UO2(OH)2 compositions are analyzed. Selective speciation achieved by solid-state mass spectrometry is discussed both in terms of its analytical contribution for environmental quality assurance and assessment of radionuclides, and fundamental methodological interest related the mechanistic complex water exchange of UO3·H2O forms in the gas phase. In addition to high selectivity and precision, UV-MALDI-MS, employing an Orbitrap analyzer, was a method that provided fast steps that limited sample pretreatment techniques for direct analysis including imaging. Therefore, random and systematic errors altering metrology and originating from the sample pretreatment stages in the widely implemented analytical protocols for environmental sampling determination of actinides are significantly reduced involving the UV-MALDI-Orbitrap-MS method. The method of quantum chemistry is utilized as well to predict reliably the thermodynamics and nature of U-O bonds in uranium species in gas and condensed phases.

A novel UV-MALDI-MS analytical approach for determination of halogenated phenyl-containing pesticides

The paper highlighted the capability of the UV-MALDI mass spectrometry, employing the Orbitrap analyzer for solid-state assay of halogenated phenyl-pesticides in mixtures. It is successfully applied for the analysis of eighteen (1)-(18) molecular objects of Fenarimol (1) type and their condensation products (P5)-(P12). The full method and technique validation is performed using the dried droplet sample preparation technique on embedded analytes in novel organic matrix crystals of N-(1H-benzoimidazol-2-yl)-guanidine (M4) and (E)-phenyl-2-pyridyl ketone oxime (M5), resulting to successful ionization of the analytes. Since the sampling technique in the UV-MALDI method is a key step in the overall process impacting significantly the metrology through the reproducibility of the data, the crystallization of M4, M5 and matrix-analyte in situ morphology of the samples is controlled by single crystal X-ray diffraction. The achieved promising metrology of LODs, of 0.46ngkg(-1) (1.53ngkg(-1) LOQs), is several orders of magnitude lower than the reported ecotoxicological effect values of studied pesticides. It is confirmed by the partial validated protocol based on ESI-MS. Inasmuch that LC-MS/MS is a method of choice for foodstuffs monitoring of organic contaminations, due to its routine quantitative analytical procedures, it is often characterized with the difficulties of the chromatographic separation of the closely structured analytes at a large scale of experimental conditions, complex multi-step sampling pretreatments, which inevitably alert the variables through the systematic and random errors. In this respect, notwithstanding the complex quantitative UV-MALDI-Orbitrap-MS procedure, conceptually different from the LC-MS/MS one, its high resolving power, capability for achieving meaningful analytical qualitative, quantitative and structural information of low-molecular weight analytes, its instrumental and sampling operation flexibility, applicable for a large scale of foodstuff matrices, and operating at the analyte concentrations of up to fgg(-1) make UV-MALDI-Orbitrap-MS a perspective method of choice for an extensive implementation in the foodstuffs monitoring practice for control of the most essential task related to the assessment of the human health risks from environmental and foodstuff contaminations.

Quantitative Analysis of Substituted -Dimethyl-tryptamines in the Presence of Natural Type XII Alkaloids

This paper reports the qualitative and quantitative analysis (QA) of mixtures of hallucinogens, N,N-dimethyltryptamine (DMT) (1), 5-methoxy- (1a) and 5-hydroxy- N,N-dimethyltryptamine (1b) in the presence of β-carbolines (indole alkaloids of type XII) {(2), (3) and (5)}. The validated electronic absorption spectroscopic (EAs) protocol achieved a concentration limit of detection (LOD) of 7.2.10-7 mol/L {concentration limit of quantification (LOQ) of 24.10-7mol/L} using bands (λmax) within 260±0.23-262±0.33 nm. Metrology, including accuracy, measurement repeatability, measurement precision, trueness of measurement,and reproducibility of the measurements are presented using N,N- dimethyltryptamine (DMA) as standard. The analytical quantities of mixtures of alkaloids 4, 6 and 7 are: λmax 317±0.45, 338±0.69 and 430±0.09 for 4 (LOD, 8.6.10-7 mol/L; LOQ, 28.666, mol/L), as well as 528±0.75 nm for 6 and 7 (LOD, 8.2. 10-7 mol/L; LOQ, 27.333, mol/L), respectively. The partially validated protocols by high performance liquid chromatography (HPLC), electrospray ionization (ESI), mass spectrometry (MS), both in single and tandem operation (MS/MS) mode, as well as matrix/assisted laser desorption/ionization (MALDI) MS are elaborated. The Raman spectroscopic (RS) protocol for analysis of psychoactive substances, characterized by strong fluorescence RS profile was developed, with the detection limits being discussed. The known synergistic effect leading to increase the psychoactive and hallucinogenic properties and the reported acute poisoning cases from 1-7, make the present study emergent, since as well the current lack of analytical data and the herein metrology obtained contributed to the elaboration of highly selective and precise analytical protocols, which would be of interest in the field of criminal forensic analysis.