Analytica

Halloumi cheese has recently gained a Protected Designation of Origin (PDO) indicator, which is related to the place (Cyprus) in which halloumi cheese is made. The PDO label is linked with several requirements, e.g., milk species, quantities, etc.; thus, it is important to study this product regarding authenticity. The utility of using two spectroscopic techniques, hyperspectral imaging (HSI) (400–1000 nm) and conventional near-infrared spectroscopy (NIR) (800–2500 nm) were assessed for the discrimination of 17 Cypriot halloumi cheese types, which could be categorized as of cow or goat–sheep origin. The aim of this study was to obtain spectral information for halloumi cheese using other promising infrared and imaging spectroscopic techniques as a comparison to a previously acquired mid-infrared (MIR) spectroscopy dataset. NIR and HSI are both fast and easy techniques in application, both of which provide significant information in food analysis. Chemometric analysis was crucial for interpreting the spectroscopic data by applying the unsupervised methods: principal component analysis (PCA) and hierarchical cluster analysis (HCA). The HSI model was found to be based intuitively on the appearance of cheese samples after freeze-drying (e.g., color; yellow/white, and texture; oily/dry), while the NIR grouping of samples was determined to be based on composition, mainly fat, protein and lactose content of the cheese samples. The HSI model returned distinct clusters of the two halloumi cheese types, cow and goat–sheep origin, with one outlier (16/17 accuracy; 94%), while the NIR model proved less accurate (13/17; 76%). Full article

A new TLC–densitometric method has been developed for the identification and quantification of paracetamol (PA), propyphenazone (PP) and caffeine (C) in Saridon tablets using the NP-TLC technique combined with densitometry. This method allows for the simultaneous determination of PA, PP, and C in the same sample. Among all the tested chromatographic conditions, the mixture consisting of chloroform + toluene + ethyl acetate + ethanol + acetic acid (18:18:7.5:5.0:0.3, v/v/v/v/v) and a silica gel 60F₂₅₄ plate proved to be the most effective for the separation of the three tested active pharmaceutical ingredients (APIs) and substances related to paracetamol. The full validation of the proposed NP-TLC method proved that it is specific, precise, accurate, robust and sensitive. The percentage content in relation to the content declared by the manufacturer was for propyphenazone 99.8%, paracetamol 101.6% and caffeine 100.8%, which was in accordance with pharmacopoeial requirements. The results presented indicate the possibility of using the developed method in the routine control of pharmaceutical preparations containing these APIs. The proposed method is economical and more sensitive compared to the previously proposed planar methods for the simultaneous determination of APIs. What is more, the presented method may be an excellent economical alternative when the HPLC method is unavailable for such a determination. Full article

Marine algae are a valuable source of polysaccharides. However, the information available on sulfated polysaccharides from microalgae is limited. Navicula sp. is a microalga present in the Sea of Cortez, of which little is known regarding their polysaccharides’ properties. This study investigated the physicochemical and microstructural characteristics of Navicula sp. sulfated polysaccharide (NSP). The Fourier transform infrared spectrum of NSP showed distinctive bands (1225 and 820 cm⁻¹, assigned to S–O and C–O–S stretching, respectively), confirming the molecular identity. NSP registered molecular weight, intrinsic viscosity, a radius of gyration, and a hydrodynamic radius of 1650 kDa, 197 mL/g, 61 nm, and 36 nm, respectively. The zeta potential, electrophoretic mobility, conductivity, and diffusion coefficient of the molecule were −5.8 mV, −0.45 µm cm/s V, 0.70 mS/cm, and 2.9 × 10⁻⁹ cm²/s, respectively. The characteristic ratio and persistence length calculated for NSP were 4.2 and 1.3 nm, suggesting a nonstiff polysaccharide chain conformation. The Mark–Houwink–Sakurada α and K constants were 0.5 and 1.67 × 10⁻¹, respectively, indicating a molecular random coil structure. NSP scanning electron microscopy revealed a rough and porous surface. Knowing these polysaccharides’ physicochemical and microstructural characteristics can be the starting point for elucidating their structure–function relationship as a valuable tool in advanced biomaterial design. Full article

This work developed a conductive ink composed of carbonaceous material for printing electrochemical sensors. The optimized ink comprises graphite, carbon black, and nail polish, respectively (35.3:11.7:53%), as well as acetone as a solvent. The proportion was optimized with consideration of the binder’s solubilization, the ink’s suitability for the screen-printing process, and lower electrical resistance. The materials used, and the resulting ink, were analyzed by way of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The charge transfer resistance (Rct) obtained was 0.348 kΩ. The conductive ink was used to print an electrode on a PET substrate, and a flexible and disposable electrode was obtained. The electroactive area obtained was 13.7 cm², which was calculated by the Randles-Sevcik equation. The applicability of the device was demonstrated with a redox probe, providing a sensitivity of 0.02 µ A L mmol⁻¹. The conductive ink has adequate homogeneity for producing electrodes using the screen-printing technique, with a low estimated production cost of $ 0.09 mL⁻¹. Full article

Argan kernels, fruits regurgitated by goats, are 30% cheaper than the regular kernels used to prepare food argan oil. The use of such argan kernels as a cosmetic ingredient, after refining, is thus economically attractive. The oxidative stability of argan oil prepared from sub-quality kernels is not known. In the present paper, the physicochemical quality, oxidative stability indices, and bioactive compounds of refined argan oil (RAO) obtained from sub-quality kernels and virgin argan oil (VAO) were compared and evaluated over a period of storage of 12 weeks at 60 °C. Quality parameters consisted of free fatty acids (FFAs), peroxide value (PV), p-anisidine value (p-AV), UV extinction coefficients (K232 and K270), total oxidation, iodine and saponification values, induction time, fatty acid composition, and tocopherol content. Our outcomes reveal that the combined effects of refining and storage generally resulted in high values of the routinely measured quality indices, including FFA, p-AV, K270, K232, and PV. Likewise, refining reduced the levels of individual tocopherols and unsaturated fatty acids (USFAs) but increased saturated fatty acids (SFAs). Similar trends were observed under storage with decreased levels of tocopherols and high SFA for both RAO and VAO. Storage also resulted in an increased level of USFAs in the case of RAO but not in VAO. The obtained results show that RAO was more sensitive to oxidation than VAO. At room temperature, RAO had a shorter induction time of six months, implying that RAO will have a shorter shelf life compared to VAR. Thus, such instability means that the refining process for argan oil must be carried out with great care, and this oil needs to be protected once refined. Full article

Optical detection devices have become an analytical tool of interest in diverse fields of science. The search for methods to identify and quantify different compounds has transposed this curiosity into a necessity, since some constituents threaten the safety of life in all its forms. In this context, 30 years ago, Prof. Prasanna de Silva presented the idea of sensors as Molecular Logic Gates (MLGs): a molecule that performs a logical operation based on one or more inputs (analytes) resulting in an output (optical modification such as fluorescence or absorption). In this review, we explore the implementation of MLGs based on the interference of a second input (second analyte) in suppressing or even blocking a first input (first analyte), often resulting in INHIBIT-type gates. This approach is interesting because it is not related to attached detecting groups in the MLG but to the relation between the first and the second input. In this sense, flexible and versatile MLGs can be straightforwardly designed based on input selection. To illustrate these cases, we selected examples seeking to diversify the inputs (first analytes and interfering analytes), outputs (turn on, turn off), optical response (fluorescent/colorimetric), and applicability of these MLGs. Full article

Chemical ultraviolet filters are widely used in a variety of cosmetic products to protect the skin from the harmful effects of UV radiation. In order to guarantee consumers’ health, the content in sunscreens is regulated in a number of countries. Many analytical methods are used to determine UV filters in cosmetics samples. In recent years, attention has been paid to the fact that the methods should have a small impact on the environment. This work examined the greenness of 10 reported chromatographic methods in the literature for the determination of UV filters in cosmetic samples using two new tools: analytical greenness metric (AGREE) and analytical greenness metric for sample preparation (AGREEprep). Microextraction methods of sample preparation in the AGREEprep assessment show a higher score of greenness. The results recommended the use of both tools to assess the greening of methods before planning laboratory analytical methods to measure their ecological impact on the environment. Full article

A novel Eu(tta)₃([4,4′-(t-bu)₂-2,2′-bpy)] complex (tta-thenoyltrifluoroacetone), a ratiometric luminescent-based optical sensor for the quantitative determination of aluminum ion, is synthesized and characterized using XRD and ¹H NMR. The XRD data reveal the slightly distorted octahedral structure. The complex displays a bright red emission at 613 nm in methanol which is characteristic of europium (III) complexes. Upon the addition of Al³⁺ ions, the red emission disappears, and a new blue emission at 398 nm emerges, manifesting the ratiometric nature of the complex. The turn-off of the red emission and turn-on of the blue emission are attributed to Eu-Al trans-metalation, as supported by Raman data that show the emergence of Al-O vibrations at 418, 495, and 608 cm⁻¹ concomitant with the disappearance of Eu-O and Eu-N bond vibrations. Most aluminum sensors are known to suffer from interferences from other metals including Cu²⁺, Co²⁺, and Cd²⁺. However, the sensor reported here is tested for 11 common cations and shows no interference on sensitivity. To the best of our knowledge, this is the first known Eu-based luminescence sensor that successfully exhibited the ability to detect aluminum ions in ppb levels in aqueous environments. The calculated Al³⁺ binding constant is 2.496 × 10³ ± 172. The complex shows a linear relationship in the range of 0–47.6 ppb (1.76 × 10⁻⁶ M) Al³⁺ and the limit of detection (LOD) is 4.79 ppb (1.77 × 10⁻⁷ M) in MeOH. ICP-OES is used for validation of the sensor complex in water and then it was used for quantitative detection of Al³⁺ ions in water as a real-life application. The complex can accurately detect Al³⁺ ions in the range of 4.97–24.9 ppb (1.84 × 10⁻⁷ M–9.2 × 10⁻⁷ M) with an LOD of 8.11 ppb (2.99 × 10⁻⁷ M). Considering that the aluminum ion serves no recognized function within the human body, its accumulation can lead to severe neurological disorders, including Parkinson’s and Alzheimer’s diseases. With the LOD value significantly lower than the WHO-recommended maximum permissible level of 200 ppb for aluminum in drinking water, even without high-power laser-aided signal enhancement, the sensor shows promise for detecting trace amounts of aluminum contamination in water. Therefore, it can significantly aid in the monitoring of even the smallest aluminum ion contamination in drinking water, industrial effluents, and natural water bodies. Full article

Gold nanoclusters are peculiar objects promising in view of qualitative and quantitative determination of various species, including heavy metal ions and biological molecules. We have recently discovered that introducing sodium azide in the reaction mixture during gold nanocluster synthesis in the presence of citrate and adenosine monophosphate can tune the product emission from blue to yellow. Taking advantage of the factorial design of the experiment, we have optimized the synthesis conditions to obtain pure blue and yellow emitters and investigate their sensitivity to a series of inorganic salts. The experiments have revealed selective quenching of the nanocluster’s fluorescence in the presence of mercury(II) ions. Full article

The incidence of colorectal cancer (CRC) is increasing worldwide. It has variable signs and symptoms starting from changes in bowel habit to nausea and vomiting. Chemotherapeutic agents are often prescribed in CRC such as Capecitabine (CCB) and 5-Fluorouracil (FU). CCB is the prodrug of FU in oral dosage form, which makes it preferable by physicians, since no hospitalization is needed for drug administration. CCB is activated to FU in a three-step reaction producing 5′-deoxy-5-fluorocytidine (DFCR) (by carboxylesterase (CES) enzyme), then 5′-deoxy-5-fluorouridine (DFUR) (by cytidine deaminase (CDD) enzyme) and finally FU (by thymidine phosphorylase (TP) enzyme), the active form, which is later deactivated to give 5,6-dihydro-5-fluorouracil (DHFU). Different patients exhibit variable drug responses and adverse in response to CCB therapy, despite being treated by the same dose, which could be attributed to the occurrence of different possible enzyme single nucleotide polymorphisms (SNPs) along the activation and deactivation pathways of CCB. The most commonly occurring toxicities in CCB therapy are hand-foot syndrome and diarrhea. This study aims at developing and validating a new method for the simultaneous determination of CCB and its metabolites by HPLC-UV, followed by a correlation study with the toxicities occurring during therapy, where predictions of toxicity could be based on metabolites’ levels instead of the tedious process of genotyping. A new superior analytical method was optimized by a quality-by-design approach using DryLab^® 2000 software achieving a baseline resolution of the six analytes within the least possible gradient time of 10 min. The method also showed linearity (in a range from 1 to 500 μg/mL), accuracy, precision and robustness upon validation: The LOD was found to be 3.0 ng/mL for DHFU and CCB, and 0.3 ng/mL for DFUR, DFCR and FU. The LOQ was found to be 10.0 ng/mL for DHFU and CCB, and 1.0 ng/mL for DFUR, DFCR and FU. The clinical results showed a positive correlation between the concentration of DFCR and mucositis and between the concentration of DFUR and hand-foot syndrome, confirming that this technique could be used for predicting such toxicities. Full article

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by fungi of the genus Paracoccidioides. Serological tests are auxiliary in the diagnosis of PCM. However, the lack of standardization is a central problem in serodiagnosis and antibody titration. The objective of this study was to propose a methodology based on Fourier transform infrared spectroscopy (FTIR) for predicting antibody titers in patients with PCM. A total of 118 serum samples from patients with PCM were included, for which antibody titration using double immunodiffusion (DID) was previously performed. Serum samples were analyzed by attenuated total reflection (ATR)-FTIR and a supervised analysis with partial least squares regression (PLS) was used to predict the antibody titers. The PLS model with two latent variables and with the use of one orthogonal signal correction (OSC) showed a determination coefficient (R²) higher than 0.9999 for both the calibration and prediction set. The model was able to predict the antibody titers from patients with PCM with a minimal error. Therefore, modeling with FTIR/ATR and multivariate calibration proved to be a fast and highly accurate method for antibody titration, replacing the need for antigen production and performance of traditional serological tests. Full article

Nowadays, adulteration of traditional food products is a very important field in the general food authenticity sector. Moreover, it is important to create databases with authentic traditional products. In Cyprus, research about the traditional dairy products is scarce. Anari is predominantly made from goat’s and sheep’s milk, but milk from cows can also be used. It is produced during the process of Halloumi cheese making. Classification of Halloumi and Anari cheese took place in two classes, thus per cheese type, and after that in milk species subclasses such as cow and goat-sheep origins for each cheese type. This research study aims to enlighten the field of food authenticity in terms of traditional Cypriot dairy products. The first step of the methodology is the freeze-drying process for lyophilization of samples. Forty-four samples have been analyzed thus far, including both Halloumi and Anari cheese. Measurements for each sample were obtained by using Fourier Transformed Infrared (FTIR) Spectroscopy. Interpretation of the extensive data was undertaken via Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA), and through the SIMCA chemometrics package. Characterization of Anari cheese by applying FTIR took place. In terms of cheese type, Halloumi and Anari cheese samples were classified correctly. In addition, Anari samples were classified correctly regarding the milk species’ origin. The proposed experimental procedure along with chemometrics allow the detection of the milk species’ origin of traditional Anari samples, highlighting the importance of FTIR spectroscopy in combination with chemometrics in food authenticity. Creation of a database with Anari samples from Cyprus has started, and this is a very important step towards authenticity of traditional dairy products of Cyprus. Full article

To meet consumer demand for fermented beverages with a wide range of flavors, as well as for quality assurance, it is important to characterize volatiles and their relationships with raw materials, microbial and fermentation processes, and the aging process. Sample preparation techniques coupled with comprehensive 2D gas chromatography (GC×GC) and mass spectrometry (MS) are proven techniques for the identification and quantification of various volatiles in fermented beverages. A few articles discuss the application of GC×GC for the measurement of fermented beverage volatiles and the problems faced in the experimental analysis. This review critically discusses each step of GC×GC-MS workflow in the specific context of fermented beverage volatiles’ research, including the most frequently applied volatile extraction techniques, GC×GC instrument setup, and data handling. The application of novel sampling techniques to shorten preparation times and increase analytical sensitivity is discussed. The pros and cons of thermal and flow modulators are evaluated, and emphasis is given to the use of polar-semipolar configurations to enhance detection limits. The most relevant Design of Experiment (DoE) strategies for GC×GC parameter optimization as well as data processing procedures are reported and discussed. Finally, some consideration of the current state of the art and future perspective, including the crucial role of AI and chemometrics. Full article

Continuous monitoring of body movements or physicochemical health indicators by various wearable devices with intriguing geometries has attracted increasing research attention. Among them, fiber-based wearable devices have been intensively investigated due to the ease of fabrication, excellent flexibility and adaptability, and abundant applicable working mechanisms. Although various spinning methods can prepare composite fibers, obtaining highly conductive fibers at high filler-loading fractions has always been difficult. In addition, most synthetic fibers are designed only for specific applications, exhibiting narrow applicability. This work proposed a dual-functional smart fiber-based sensor that could work based on either piezoresistive or electrochemical mechanisms. Through the wet spinning of dopes containing nanosized carbon black and thermoplastic polyurethane, nanocomposite fibers with decent electrical conductivities (2.10 × 10² S m⁻¹ or 4.77 × 10⁻³ Ω·m), high mechanical stretch abilities and toughness (ε_max~2400%, K_IC = 61.44 MJ m⁻³), as well as excellent self-heal abilities (η ≥ 64.8%), could be obtained. Such coupled electromechanical properties endowed the as-synthesized fibers with strain-sensing or biomarker monitoring capabilities based on piezoresistive or electrochemical mechanisms. The proposed novel dual-functional smart fibers demonstrated potential for multifunctional wearable health monitoring devices. Full article

Procedures for determination of the residual solvent and volatile impurity content in pharmaceutical products usually rely on dissolution in a solvent, followed by headspace-gas chromatography (HS-GC) analysis. Whereas chromatographic systems can utilize a wide variety of solvents, direct-injection mass spectrometry (DIMS) techniques have fewer solvent options, because elimination of the chromatographic column means that the instrument is more susceptible to saturation. Since water has the lowest impact, it has almost always been the default solvent for DIMS. In this study, selected ion flow tube mass spectrometry (SIFT-MS)—a DIMS technique—was applied to the systematic evaluation of the proportion of solvent that can be utilized (with aqueous diluent) without causing instrument saturation and while maintaining satisfactory analytical performance. The solvents evaluated were N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolidinone (DMI), dimethyl sulfoxide (DMSO), methanol, and triacetin. All solvents are compatible with headspace-SIFT-MS analysis at 5% (min) in water, while DMI, DMAC, and DMSO can be used at higher concentrations (50, 100, and 25%, respectively), though suffering substantial diminution of the limit of quantitation for non-polar analytes at higher proportions of non-aqueous solvent. Analytical performance was also evaluated using linearity, repeatability, and recovery measurements. This work demonstrates that organic solvents diluted in water can be utilized with headspace-SIFT-MS and provide an approach for evaluation of additional diluent solvents. Full article

In recent years, indiscriminate consumption and dumping of antibiotics have become destructive to human health and causes ecotoxicological pollution. Here, the irregular particle nanosized dendrite structure of lanthanum-doped cerium oxide (LCO) decorated with sheet-like reduced graphene oxide (RGO) composite was utilized to detect the sulfonamide-based drug sulfadiazine (SZ). LCO@RGO nanocomposite was prepared using the hydrothermal method, the synergistic effect between LCO and RGO facilitates electron transferability and conductivity which enhances the electrochemical properties toward the detection of SZ. The detection of SZ expressed a lower detection limit (0.005 µM) and linear range (0.01–265 µM) of the fabricated LCO@RGO/GCE electrode toward SZ, analyzed using the highly sensitive DPV technique. Also, DPV was utilized to determined shows good repeatability, reproducibility, and storage stability of fabricated LCO@RGO/GCE. Moreover, effective practicability was proven in human blood serum and river water samples with great recovery results. All the above probes the synthesized LCO@RGO’s thriving and outstanding electrocatalytic performance of this nanocomposite’s highly sensitive detection of SZ in real biological and environmental samples. Full article

Every day, more and more consumers choose to drink bottled water instead of tap water, since they believe that it is superior in quality. One of the criteria used by European consumers to choose bottled water is the geographical region of the spring. The flavor of the water is an additional factor that influences consumers’ choices. As a result, determining the flavor of water is gaining popularity and is thus turning into a prominent field of study. However, studies on the potential environmental factors that affect the sensory characteristics of water (i.e., “terroir” of water) are limited. To this end, we investigated the composition of natural mineral water spring from Mount Smolikas in Greece over a two-year period to find any potential alterations in water composition. The physicochemical parameters (pH, conductivity, turbidity, color, and total hardness) of the water samples were examined, along with their content in metal ions, inorganic salts (cations and anions), and total organic carbon. Additionally, the water samples were analyzed for their content of off-odor volatile compounds (i.e., 2-methylisoborneol and geosmin) that can be naturally found in water. The study also examined the correlation of climate conditions (accumulated rainfall and mean temperature) with the parameters above using a principal component analysis and a multivariate correlation analysis. The results showed that the physicochemical characteristics of water samples complied with European regulations. Metals, anions, and cations were all below the corresponding parametric values established by the European Commission. The off-odor organic compounds, 2-methylisoborneol, and geosmin, had average concentrations of 9.4 and 2.7 ng/L, respectively. Chromium and aluminum elevated concentrations might be attributed to specific ores present near the water source, while pH, conductivity, total hardness, nitrates, and off-odor compounds levels could be fluctuated due to local climate conditions. The study revealed a good positive correlation (>0.7) between the quantity of rainfall and the level of potassium cations. Moreover, a strong negative correlation (>0.9) was observed between magnesium cations and the mean temperature of the local area. The study can be used as a benchmark for future studies to determine the terroir of mineral water. Full article

The metallome has been involved in the pathological investigation into ocular tissue for decades; however, as technologies advance, more information can be ascertained from individual tissue sections that were not previously possible. Herein, a demonstration of complementary techniques has been utilized to describe the distribution and concentrations of essential metals in both wildtype (WT) and rhodopsin (Rho^−/−) ocular tissues. The multimodal approach described is an example of complementary datasets that can be produced when employing a multifaceted analytical approach. Heterogenous distributions of copper and zinc were observable within both WT and Rho^−/− tissue by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the distributions of further trace elements notoriously problematic for ICP-MS analysis (phosphorous, Sulfur, chlorine, potassium, calcium, iron, and aluminum) were analysed by particle-induced X-ray emission (PIXE). Full article

In this study, gold nanoparticles (AuNPs) were synthesized using the Turkevich method. This article explains the didactic step-by-step synthesis, showing pictures of the entire process, including a well-explained mechanism and characterization study. Synthesis involves the reduction of NaAuCl₄ using sodium citrate at high temperatures (approximately 90 °C). The two main mechanisms used to explain AuNPs synthesis via the Turkevich method are also discussed. The first mechanism considers that a nanowire intermediary and the other proposes that aggregate intermediates are not formed at any time during the synthesis. The materials (NaAuCl₄ and AuNPs) were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). The UV-Vis spectrum exhibits an absorption maximum at 521 nm because of the surface plasmon resonance (SPR) absorption band of the AuNPs. The SEM images of NaAuCl₄ show crystals with cubic shapes, while the AuNPs have an average particle size of approximately 16–25 nm and particles that appear mainly spherical. To confirm the particle shapes, AFM was conducted, and it was possible to clearly observe individual spherical nanoparticles and their aggregates, and the average diameter of these AuNPs was approximately 12–19 nm. The XRD pattern of AuNPs showed four main characteristic peaks corresponding to the (111), (200), (220), and (311) planes, confirming the presence of cubic (FCC) gold. The DLS presented an average particle size of 3.3 ± 0.9 nm and a polydispersity index (PDI) of 0.574. AuNPs were synthesized using a simple and rapid method. The resulting spherical and ultra-small particles can be used in several applications. Full article