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An analytical methodology based in the combination of Thin Film Microextraction with Laser-induced Breakdown Spectroscopy (TFME-LIBS) was investigated, for the first time, for detection of Cu, Cr, Ni and Pb in aqueous solutions. In this methodology, the analytes were extracted in a thin film of adsorbent material deposited on a solid support, which was introduced in the sample to analyse. After extraction, the analytes retained in the adsorbent were analysed by LIBS. In order to obtain adsorbent films useful for the microextraction step, two different experimental procedures for film generation, denoted as Drop Casting Deposition and Mould Deposition, were evaluated. In both cases, graphene oxide was used as adsorbent material. The mould deposition procedure was found to produce more homogeneous graphene oxide layers, leading to more uniform distribution of the adsorbed analytes on the graphene oxide surface. Experimental parameters affecting the TFME procedure, such as the adsorbent amount and extraction time, were studied. Under optimum microextraction conditions, the analytical figures of merit of the proposed TFME-LIBS method were evaluated, leading to limits of detection ranging from 41 μg kg−1 and 52 μg kg−1. Method trueness, evaluated from the analysis of a real sample of bottle water, led to recovery values about 70%, indicating the existence of strong matrix effects probably due to the presence of major cations in the bottle water. After 50% dilution of the sample with deionized water, recoveries values improved to 100%–108%. This work was supported by the Spanish Ministry of Economy and Competitiveness [CTQ2016-79991-R], the Regional Government of Valencia (Spain) [PROMETEO/2013/038 and PROMETEO/2018/087]; and the University of Alicante [UAUSTI17-04 and UAUSTI18-04]. L. Ripoll is grateful to the Ministry of Economy and Competitiveness for her PhD fellowship (FPI-MICINN (BES-2012-058759)).

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This doctoral thesis proposes sample preparation combined with the use of laser-induced breakdown spectroscopy (LIBS) for analysis of difficult-to-mineralize samples focusing on the analytical development of LIBS as well as for the development of sample preparation for the technique. The LIBS technique consists of focusing a laser pulse with high fluence (> GW s-1) under the surface of a sample. Following the incidence of this laser pulse, atoms are vaporized, atomized, ionized and brought into an excited energy state. When atoms and ions return to their lowest energy levels, they release photons of specific wavelengths that are translated into the electromagnetic spectrum. The technique has inherent challenges in the analysis of solid samples, which are mostly its applications, such as microheterogeneity and high limits of detection (LOD). Although the technique has great ability in solid sample analysis, it can also be used for liquid sample analysis, however, some specific problems arise, such as sample splashing with laser pulse impact and low reproducibility, and sample preparation can help minimize them. As goal, the present thesis focuses on the development of sample preparation of nickel ores, solder masks and sunscreens for analysis of elements of interest in each of the presented samples. The strategy for the analysis of nickel ore and sunscreen samples consisted of converting the matrix of liquid to solid in order to minimize the problems inherent to liquid analysis by LIBS. For this, polyvinyl alcohol (PVA), a water-soluble polymer, was used. For solder masks, the samples were completely dried on glass support for further analysis. Chemometric tools were used during the work to aid in data processing (normalization), exploratory analysis (PCA (principal component analysis)) and univariate and multivariate calibration (PCR (principal component regression), PLS (partial least squares), MLR (multiple linear regression)). Esta tese de doutorado propõe preparos de amostra aliados a utilização da técnica espectroanalítica de emissão atômica induzida por laser (laser-induced breakdown spectroscopy, LIBS) para análise de amostras de difícil mineralização com foco no desenvolvimento analítico da LIBS bem como para o desenvolvimento de preparo de amostras para a técnica. A técnica LIBS consiste na focalização de um pulso de laser com alta fluência (> GW s-1) sob a superfície de uma amostra. Após a incidência desse laser, os átomos são vaporizados, atomizados, ionizados e levados a um estado de energia excitado. Quando átomos e íons retornam aos seus níveis energéticos mais baixos liberam fótons com comprimentos de onda específicos que são traduzidos em espectro eletromagnético. A técnica possui desafios inerentes à análise de amostras sólidas, que são majoritariamente suas aplicações, como microheterogeneidade e altos limites de detecção (LOD). Apesar da técnica possuir grande habilidade na análise de amostras sólidas, pode também ser usada para análise de amostras líquidas, no entanto, alguns problemas específicos surgem, como espalhamento da amostra com o impacto do pulso de laser e baixa reprodutibilidade, e o preparo das amostras pode ajudar a minimizá-los. Como objetivo, a presente tese se concentra no desenvolvimento de preparo de amostras de minério de níquel, máscara de solda e protetores solares para análise de elementos de interesse em cada uma das amostras apresentadas. A estratégia para análise de amostras de minério de níquel e protetor solar consistiu na conversão da matriz de líquido para sólido no intuito de minimizar os problemas inerentes à análise de líquidos por LIBS, para isso, álcool poli vinílico (PVA), polímero hidrossolúvel, foi utilizado. Para máscaras de solda, as amostras foram totalmente secas em suporte de vidro para posterior análise. Ferramentas quimiométricas foram utilizadas durante o trabalho para auxílio do tratamento de dados (normalizações), análise exploratória (PCA (principal component analysis)) e calibração uni e multivariada (PCR (principal component regression), PLS (partial least squares), MLR (multiple linear regression)). CNPq: 160152/2015-1 CAPES: Código de Financiamento 001

The combination of electrospray deposition with laser-induced breakdown spectroscopy (ESD-LIBS) was investigated as a potential approach to the detection and quantification of Zn, Cd, Cr and Ni, at trace levels, in aqueous samples. In this analytical procedure, the aqueous samples were first converted into solids in an electrospray system. To this end, micro-volumes of liquids were electro-sprayed onto a heated substrate, leading to the generation of solid residues. Afterwards, the as-obtained residues were analysed by LIBS. Three calibration methodologies were tested with the proposed ESD-LIBS methodology, namely external calibration, conventional standard addition calibration and on-line standard addition calibration. In all cases, the analytical features of the ESD-LIBS method were assessed. The obtained limits of detection ranged from 9 μg kg−1 to 57 μg kg−1, depending on the element and on the calibration modality used. Method trueness, evaluated from the analysis of a real sample of tap water, was highly dependent on the calibration method. The use of external calibration led to recovery values in the range of 18–123%, indicating the existence of strong matrix effects. This drawback was overcome with the application of conventional standard addition and on-line standard addition calibration modalities, for which recovery values were improved to the ranges 91–110% and 90–105%, respectively. Among them, the use of on-line standard addition provides a sensitive and accurate methodology with possibilities of automation. L. Ripoll is grateful to the Ministry of Economy and Competitiveness for her PhD fellowship (FPI-MICINN (BES-2012-058759)).

TEZ12009 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2019. Kaynakça (s. 51-53) var. XXI, 55 s. : res. (bzs. rnk.), tablo ; 29 cm. Bu tezin amacı, iki tür metamalzeme tabanlı sensör tasarımı ve üretimidir. Sensörlerden biri, rezonatörün sekizgen formunu ve numune tutucuyu kullanarak sudaki Metanol veya Etanolün saflığını belirler. Diğeri, örneğin Amonyak, Aseton, Saf su, İzo Propil Alkol (IPA) ve Propilen Etilen Glikol (PEG) gibi sıvıları birbirinden ayırmaya yarayan ve farklı malzemeleri belirleyebilen iletim hattı bütünleşik altıgen şekilli rezonatör formu kullanan sensör tasarlanmıştır. Önerilen ilk yapı 8-12 GHZ frekans bandında kullanılmıştır ve ikinci yapı 1-8 GHZ frekans bandında kullanılabilir. Her iki çalışmada da önemli olan şey, dalga şeklinin rezonans frekansındaki değişimleridir. Malzemelerin çıkış dalga formu (S11 veya S12) dielektrik geçirgenliği göz önünde bulundurularak liner şekilinde değişmelidir. Metal tabaka ve rezonatör için bakır ayrıca alt tabaka için FR-4, Isola IS680 (3.2DK) (kayıplı) kullanıldı. Hem sayısal hem de deneysel testler için sonuçların uyum içinde olduğu gözlendi. Önerilen yapılar, bazı malzemelerin saflığını belirlemede ve bazı malzemelerin tespitinin gerekli olduğu birçok uygulamada kullanılabilir. The aim of this thesis is to design and fabricate two kind of metamaterial based sensor. One of them, determine purity of Methanol’s and Ethanol’s mixture in the water by using the octagonal form of resonator and the sample holder. Other one is designed by utilizing transmission line integrated hexagonal shaped metamaterial based sensor which can detect and determine some materials with each other for example determining of Ammoniac, Pure water, Iso Propyl Alcohol (IPA) and Propylene Ethylene Glycol (PEG). First proposed structure has been employed in the 8-12 GHZ frequency band and the second structure can be used in the 1-8 GHZ frequency band. The important thing in the both of two work are the changes of the waveform at the resonance frequency. The output waveform of materials (reflection coefficient S11 or transmission coefficient S12) must be change in liner figure by considering the dielectric coefficient. We use copper for metal layer and resonator and also use FR-4, Isola IS680 (3.2DK) (lossy) for substrate layer. We simulate one unit cell of these two kind of metamaterial sensor by CST microwave software and then achieve the results and evaluate them. Both the numerically and experimentally tests, give same outcomes and results and they will be in good agreement with each other. These proposed structure can be used in many application where the purity and determining of some materials might be necessary.

In this work, the combination of dispersive micro solid-phase extraction (DµSPE) with laser-induced breakdown spectroscopy (LIBS) was evaluated for simultaneous preconcentration and detection of Zn, Cd, Mn, Ni, Cr and Pb in aqueous samples. Two adsorbent materials were tested in the microextraction step, namely graphene oxide and activated carbon. In both cases, the microextraction process consisted in the dispersion of a small quantity of adsorbent in the sample solution containing the analytes. However, while the use of activated carbon required a previous chelation of the metals, this step was avoided with the use of graphene oxide. After extraction, the analytes retained in the adsorbents were analysed by LIBS. Several experimental factors affecting the extraction of the metals (adsorbent amount, pH and extraction time) were optimized by means of the traditional univariate approach. Under optimum microextraction conditions, the analytical features of the proposed DµSPE-LIBS methods were assessed, leading to limits of detection below 100 µg kg−1 and 50 µg kg−1 with the use of activated carbon and graphene oxide, respectively, as adsorbents in the DµSPE process. Trueness evaluation of the most sensitive procedure was carried out by spike and recovery experiments in a real sample of tap water, leading to recovery values in the range 98–110%. This work was supported by the Spanish Ministry of Economy and Competitiveness, (Spain) (Project no. CTQ2016-79991-R and fellowship number BES-2012-058759 (FPI-MICINN)); the Regional Government of Valencia (Spain) (Project no. PROMETEO/2013/038); and the University of Alicante, (Spain) (Grant no. UAUSTI16-04).

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a widely accepted method for direct sampling of solid materials for trace elemental analysis. The number of reported applications is high and the application range is broad; besides geochemistry, LA-ICP-MS is mostly used in environmental chemistry and the life sciences. This review focuses on the application of LA-ICP-MS for quantification of trace elements in environmental, biological, and medical samples. The fundamental problems of LA-ICP-MS, such as sample-dependent ablation behavior and elemental fractionation, can be even more pronounced in environmental and life science applications as a result of the large variety of sample types and conditions. Besides variations in composition, the range of available sample states is highly diverse, including powders (e.g., soil samples, fly ash), hard tissues (e.g., bones, teeth), soft tissues (e.g., plants, tissue thin-cuts), or liquid samples (e.g., whole blood). Within this article, quantification approaches that have been proposed in the past are critically discussed and compared regarding the results obtained in the applications described. Although a large variety of sample types is discussed within this article, the quantification approaches used are similar for many analytical questions and have only been adapted to the specific questions. Nevertheless, none of them has proven to be a universally applicable method.

A rapid and efficient Dispersive Liquid–Liquid Microextraction (DLLME) followed by Laser-Induced Breakdown Spectroscopy detection (LIBS) was evaluated for simultaneous determination of Cr, Cu, Mn, Ni and Zn in water samples. Metals in the samples were extracted with tetrachloromethane as pyrrolidinedithiocarbamate (APDC) complexes, using vortex agitation to achieve dispersion of the extractant solvent. Several DLLME experimental factors affecting extraction efficiency were optimized with a multivariate approach. Under optimum DLLME conditions, DLLME-LIBS method was found to be of about 4.0–5.5 times more sensitive than LIBS, achieving limits of detection of about 3.7–5.6 times lower. To assess accuracy of the proposed DLLME-LIBS procedure, a certified reference material of estuarine water was analyzed. The authors are grateful to the Spanish Government (project no. CTQ2011-23968) and Regional Government of Valencia (Spain) (project no. ACOMP/2013/072) for the financial support.

In this work, an analytical methodology based on single drop microextraction (SDME) followed by Laser-Induced Breakdown Spectrometry (LIBS) has been tested for trace metal determination in liquid samples. By this method, analytes in the samples were extracted into a small volume of toluene as ammonium pyrrolidinedithiocarbamate (APDC) chelates. After that, the analyte-enriched toluene was dried on a solid substrate and, finally, the resulting solid residue was analyzed by LIBS. Analyte extraction by the SDME procedure was optimized for the first time by using a multivariate optimization approach. Under optimum SDME conditions, analytical figures of merit of the proposed SDME-LIBS methodology were compared to those of the direct LIBS analysis method (i.e., without the SDME procedure). An estuarine water certified reference material was analyzed for method trueness evaluation. The results obtained in this study indicate that SDME-LIBS methodology leads to a sensitivity increase of about 2.0–2.6 times the ones obtained by LIBS. Detection limits of SDME-LIBS decrease according to the obtained sensitivity improvement, reaching values in the range 21–301 μg kg−1 for the analytes tested. The measurement repeatability was similar in both SDME-LIBS (13–20% RSD) and LIBS (16–20% RSD) methodologies, mainly limited by the LIBS experimental setup used in this work for LIBS analysis of liquid samples. The SDME-LIBS analysis of the certified reference material led to recovery values in the range of 96% to 112%. The authors are grateful to the Spanish Government (projects CTQ2011-23968) and the Regional Government of Valencia (Spain) (ACOMP/2013/072) for the financial support. M.A.A. is grateful to the University of Alicante for his PhD fellowship. This work is part of the PhD degree of M.A.A.

We present an improved approach to the impedance spectroscopy of conductive liquid samples using four-electrode measurements. Our method enables impedance measurements of conductive liquids down to the sub-Hertz frequencies, avoiding the electrode polarization effects that usually cripple standard impedance analysers. We have successfully tested our apparatus with aqueous solutions of potassium chloride and gelatin. The first substance has shown flat spectra from $\sim$100 kHz down to sub-Hz range, while the results on gelatin clearly show the existence of two distinct low frequency conductive relaxations., 5 pages, 6 figures

500 σ., Το Εργαστήριο Πυρηνικής Τεχνολογίας του ΕΜΠ δραστηριοποιείται στις μετρήσεις ουρανίου με εφαρμογή διαφόρων μετρητικών τεχνικών. Προς επέκταση της αναλυτικής δυνατότητας του Εργαστηρίου προσετέθη στο μετρητικό του δυναμικό μια μονάδα Ανάλυσης Κινητικής Φωσφορισμού ΚΡΑ-11, για τον φωσφοριμετρικό προσδιορισμό συγκέντρωσης ουρανίου σε υγρά δείγματα. Η παρούσα ΔΔ αφιερώθηκε στην μελέτη, ανάπτυξη, εφαρμογή και βελτιστοποίηση πρακτικών που θα καθιστούσαν την φωσφοριμετρική διάταξη του Εργαστηρίου μια αξιόπιστη μετρητική τεχνική ανάλυσης υγρών δειγμάτων ουρανίου. Αφού μελετήθηκε το θεωρητικό υπόβαθρο της φωσφοριμετρίας και επήλθε εξοικείωση με τις λειτουργίες της μονάδας ΚΡΑ-11, αναπτύχθηκε μεθοδολογία για την παρασκευή προτύπων βαθμονόμησης ουρανίου, ενώ βελτιστοποιήθηκε το πρωτόκολλο βαθμονόμησης, με συνέπεια την μείωση της συνεισφερόμενης αβεβαιότητας στην τελική μέτρηση σε αποδεκτά επίπεδα. Διενεργήθηκαν μετρήσεις πολυάριθμων διαλυμάτων ουρανίου και περιβαλλοντικών νερών στο πλαίσιο αξιολόγησης της μετρητικής διαδικασίας, ενώ βελτιστοποιήθηκαν τα προτεινόμενα πρωτόκολλα. Αναπτύχθηκαν και εφαρμόστηκαν μέθοδοι χημικής επεξεργασίας για υγρά δείγματα με πιο σύνθετες ή ρυπασμένες μήτρες. Η μεθοδολογία πιστοποιήθηκε μέσω επιτυχούς συμμετοχής στην ραδιοπεριβαλλοντική άσκηση διασύγκρισης ALMERA 2009, ενώ τέθηκε σε εφαρμογή σε βρόχινα νερά από επιβαρυμμένη ραδιολογικά περιοχή στο πλαίσιο ραδιοπεριβαλλοντικής έρευνας του ΕΠΤ. Τα αποτελέσματα συμφωνούσαν με α-φασματοσκοπικές αναλύσεις επιβεβαιώνοντας την αξιοπιστία της μεθόδου, βελτιώνοντας παράλληλα έως και 10 φορές τον χρόνο εκτίμησης του τελικού αποτελέσματος. Αναπτύχθηκε επίσης η μεθοδολογία για τον προσδιορισμό συγκέντρωσης ουρανίου σε δείγματα ούρων με την φωσφοριμετρική διάταξη. Προσαρμόσθηκε μέθοδος χημικής επεξεργασίας και εφαρμόσθηκε σε δείγματα ούρων μελών του προσωπικού του Εργαστηρίου, τα οποία βρέθηκαν να εμπίπτουν στα φυσιολογικά όρια της ICRP. Η μεθοδολογία επεξεργασίας ούρων πιστοποιήθηκε μέσω επιτυχούς ανάλυσης δείγματος της ραδιοτοξικολογικής άσκησης διασύγκρισης PROCORAD 2010. Τέλος, στο πλαίσιο περιορισμού του λειτουργικού κόστους της μονάδας ΚΡΑ-11 διερευνήθηκε η δυνατότητα χρήσης εναλλακτικών υλικών ανάλυσης. Παρασκευάσθηκε διάλυμα συμπλοκοποίησης για την προστασία του φωσφορισμού από απλό φωσφορικό οξύ το οποίο, καίτοι φτωχότερο σε συμπλοκοποιητική ικανότητα από το αντίστοιχο εμπορικό διάλυμα, δεν υστερούσε σε ακρίβεια, ενώ επιμήκυνε σημαντικά την ωφέλιμη διάρκεια μιας βαθμονόμησης., The Nuclear Engineering Laboratory of the NTUA is involved in uranium analysis by using various measurement techniques. In order to extend the Laboratory’s analytical capabilities, a Kinetic Phosphorescence Analyser KPA-11 was added to the methods employed, to conduct phosphorimetric determination of uranium concentration in liquid samples. The present Thesis describes the study, development, application and optimisation of practices that constituted the phosphorimetric apparatus of the Laboratory a reliable technique for determining uranium concentration in liquid samples. After reviewing the theoretical principles governing phosphorimetry and becoming familiar with the main functions of the KPA-11 unit, the methodology for the production of uranium calibration standards was developed, and the calibration protocol was optimised, leading to reduced contribution of uncertainty in the final measurement result. Numerous measurements of uranium solutions and environmental waters were conducted in order to assess the measurement process, while optimising the recommended measurement protocols. Chemical treatment methods were developed and applied for liquid samples of more complex or polluted matrices. The methodology’s validity was verified by successfully participating in the ALMERA 2009 intercomparison, while its efficacy was tested in an environmental radiation study conducted by the Laboratory in rain water samples collected from a radiologically burdened location. Results were in agreement with a-spectroscopic analyses, verifying the method’s reliability, while reducing by tenfold the time required for obtaining a result. The methodology for determining uranium concentration in urine samples with the phosphorimetric apparatus was also developed. A chemical treatment method was adjusted and applied to urine samples of staff members of the Laboratory, the uranium concentration of which was found within the ICRP limits. The method’s validity was verified by successfully determining the uranium concentration of a urine sample from the PROCORAD 2010 intercomparison. Finally, in order to reduce running costs of the KPA-11 unit, the possibility of using alternative analysis objects was examined. A complexant solution for phosphorescence protection was prepared from phosphoric acid that, despite its poorer complexing capabilities compared to its commercial counterpart, did not lack in accuracy, while it prolonged a calibration’s lifetime significantly., Άγγελος Β. Ευσταθόπουλος

In the laboratory for material structure investigation the X-ray emission spectrometry methods have been successfully applied for routine analysis of solid, powder and liquid materials. Non-aqueous solutions (organo-metallic phosphates), pickling products (nickel ore in sulphuric acid) and samples for pollution control (waste waters and soil) were analised qualitatively and semiquantitatively by x-ray spectrometric solution technique. The samples were directly measured in polypropylene liquidspecimen cell 3515 made by Spex and PW 1527/90 made by Philips, or as supported specimens on glass-fibre paper and cellulose. Measurements were made in a Philips x-ray spectrometer PW 1410/10 with chromium and rhodium target radiation. Vacuum, air and helium were used as radiation path media. Our experience in the application of the x-ray spectrometric solution technique shows that it is acceptable because it: - is non-destructive ; - enables direct measurement i.e. no sample preparation is necessary ; - requires small volumes of solution ; - is economical and fast. By adapting the existing x-ray spectrometer for analysis in helium path medium it is possible to measure light elements directly. This also anables a wide application of this technique for sample analysis in everyday practice.