Papers by Nikos Thomaidis
Analytical Letters, 2019
The Eleventh Aegean Analytical Chemistry Days (AACD2018) was held in Chania, Crete, Greece during... more The Eleventh Aegean Analytical Chemistry Days (AACD2018) was held in Chania, Crete, Greece during the period from 25 to 29 September 2018. The scientific framework consisted of 13 oral sessions and 2 poster sessions. Papers in fields such as atomic and molecular spectrometry, mass spectrometry, bioanalytical and clinical analysis, chromatography and separation techniques, electroanalytical methods and biosensors, speciation analysis, sample preparation, chemometrics, quality control/quality assurance and chemical metrology, environmental analysis, food analysis and pharmaceutical analysis were presented during this five-day conference. The social program included a visit to the Botanical Park of Chania and dinner with Cretan dishes and a post-conference one-day excursion to Knossos and Herakleio. During the closing ceremony, it was announced that the next AACD will be organized in Turkey by
Food fraud, being the act of intentional adulteration of food for financial advantage, has vexed ... more Food fraud, being the act of intentional adulteration of food for financial advantage, has vexed the consumers and the food industry throughout history. According to the European Committee on the Environment, Public Health and Food Safety, fruit juices are included in the top 10 food products that are most at risk of food fraud. Therefore, reliable, efficient, sensitive and cost-effective analytical methodologies need to be developed continuously to guarantee fruit juice quality and safety. This review covers the latest advances in the past ten years concerning the targeted and non-targeted methodologies that have been developed to assure fruit juice authenticity and to preclude adulteration. Emphasis is placed on the use of hyphenated techniques and on the constantly-growing role of MS-based metabolomics in fruit juice quality control area.
Averaged 7-day composite effluent wastewater samples from twelve wastewater treatment plants (WWT... more Averaged 7-day composite effluent wastewater samples from twelve wastewater treatment plants (WWTPs) in nine countries () in the Danube River Basin were collected. WWTPs' selection was based on countries' dominant technology and a number of served population with the aim to get a representative holistic view of the pollution status. Samples were analyzed for 2248 chemicals of emerging concern (CECs) by wide-scope target screening employing LC-ESI-QTOF-MS. 280 compounds were detected at least in one sample and quantified. Spatial differences in the concentrations and distribution of the compounds classes were discussed. Additionally, samples were analyzed for the possible agonistic/antagonistic potencies using a panel of in vitro transactivation reporter gene CALUX® bioassays including ERα (estrogenics), anti-AR (anti-androgens), GR (glucocorticoids), anti-PR (anti-progestins), PPARα and PPARγ (peroxisome proliferators) and PAH assays. The potency of the wastewater samples to cause oxidative stress and induce xenobiotic metabolism was determined using the Nrf2 and PXR CALUX® bioassays, respectively. The signals from each of the bioassays were compared with the recently developed effect-based trigger values (EBTs) and thus allowed for allocating the wastewater effluents into four categories based on their measured toxicity, proposing a putative action plan for wastewater operators. Moreover, samples were analyzed for antibiotics and 13 antibiotic-resistant genes (ARGs) and one mobile genetic element (intl1) with the aim to assess the potential for antibiotic resistance. All data collected from these various types of analysis were stored in an on-line database and can be viewed via interactive map at https://norman-data.eu/EWW_DANUBE.
Pomegranate juice is one of the most popular fruit juices, is well-known as a "superfood", and pl... more Pomegranate juice is one of the most popular fruit juices, is well-known as a "superfood", and plays an important role in healthy diets. Due to its constantly growing demand and high value, pomegranate juice is often targeted for adulteration, especially with cheaper substitutes such as apple and red grape juice. In the present study, the potential of applying a metabolomics approach to trace pomegranate juice adulteration was investigated. A novel methodology based on highresolution mass spectrometric analysis was developed using targeted and untargeted screening strategies to discover potential biomarkers for the reliable detection of pomegranate juice adulteration from apple and red grape juice. Robust classification and prediction models were built with the use of unsupervised and supervised techniques (principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA)), which were able to distinguish pomegranate juice adulteration to a level down to 1%. Characteristic m/z markers were detected, indicating pomegranate juice adulteration, and several marker compounds were identified. The results obtained from this study clearly demonstrate that Mass Spectrometry (MS)-based metabolomics have the potential to be used as a reliable screening tool for the rapid determination of food adulteration.
Background: The main representatives of hemicellulose are xylans, usually decorated β-1,4-linked ... more Background: The main representatives of hemicellulose are xylans, usually decorated β-1,4-linked d-xylose polymers, which are hydrolyzed by xylanases. The efficient utilization and complete hydrolysis of xylans necessitate the understanding of the mode of action of xylan degrading enzymes. The glycoside hydrolase family 30 (GH30) xylanases comprise a less studied group of such enzymes, and differences regarding the substrate recognition have been reported between fungal and bacterial GH30 xylanases. Besides their role in the utilization of lignocellulosic biomass for bioenergy, such enzymes could be used for the tailored production of prebiotic xylooligosaccharides (XOS) due to their substrate specificity.
A platform for archiving liquid chromatography high-resolution mass spectrometry (LC-HRMS) data w... more A platform for archiving liquid chromatography high-resolution mass spectrometry (LC-HRMS) data was developed for the retrospective suspect screening of thousands of environmental pollutants with the ambition of becoming a European and possibly global standard. It was termed Digital Sample Freezing Platform (DSFP) and incorporates all the recent developments in the HRMS screening methods within the NORMAN Network. In the workflow, raw mass spectral data are converted into mzML, then mass spectral and chromatographic information on thousands of peaks of each sample is extracted into Data Collection Templates. The 'digitally frozen' samples can be retrospectively screened for the presence of virtually any compound amenable to LCeMS using a combination of information on its (i) exact mass, (ii) predicted retention time window in the chromatogram, (iii) isotopic fit and (iv) qualifier fragment ions. Its potential was demonstrated on monitoring of 670 antibiotics and 777 REACH chemicals from the Joint Black Sea Surveys (JBSS).
Laboratory Automation & Information Management, 1999
Flow injection methods developed for the analysis of edible oils are critically reviewed. Oil qua... more Flow injection methods developed for the analysis of edible oils are critically reviewed. Oil quality control can be automated using flow injection methods for the determination of acidity, peroxide value, iodine value, 2-thiobarbituric acid reacting substances, antioxidants, sterols, pesticide residues, aniline and heavy metals. Applications range from mere sample transportation to the detector to hyphenated flow injection-chromatographic techniques. q 1999 Elsevier Science B.V. All rights reserved.
The methylation of mercury has been investigated and documented mainly in sediments, fish and mic... more The methylation of mercury has been investigated and documented mainly in sediments, fish and microorganisms, while limited number of relevant studies is available for wastewater. The procedure of mercury methylation can occur via biological pathway (by microorganisms) and via chemical or photochemical reactions.
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Papers by Nikos Thomaidis