Search Results (62)

Two approaches are described for construction of a screen-printed planar electrode (SPE) for potentiometric determination of iodide ion. The first, involves preparation and application of iron(II) bathophenanthroline tetraiodoplumbate complex ([Fe(bphen)₃][PbI₄]), as a sensitive and selective electroactive sensing material in a potentiometric electrode for iodide determination. The second is the use of a nano-sized poly(aniline-co-thiophene) (PANI-co-PT) as a solid-contact material in a planar miniaturized configuration. The SPE displays a Nernstian response for iodide ion with a calibration slope of −58.81 ± 0.69 mV/decade (R² = 0.9998) over a wide concentration range (9.17 × 10⁻⁷–6.94 × 10⁻³ mol/L), low detection limit (6.09 × 10⁻⁷ mol/L), rapid response time (5.0 ± 1.0 s) and long-life span (75 ± 3.0 d). The use of PANI-co-PT solid-contact layer significantly improves the ion-to-electron transduction, eliminates the formation of undesired thin water layer between the sensing membrane and the conducting substrate, prevents membrane delamination, enhances potential stability with a significantly reduced potential drift (8.32 ± 0.12 µV/min) and displays high redox capacitance (2.560 ± 0.040 mF). Water contact angle measurements confirm the increased hydrophobicity of the modified membrane electrode (from 44 ± 0.8° to 93 ± 1.4°) and demonstrate the membrane ability to repel moisture and further stabilize the sensor response. The proposed sensor is successfully integrated into a flow injection analysis (FIA) system to enable real-time and continuous iodide monitoring with high precision, high sample throughput and applicability for quality control of pharmaceuticals and environmental monitoring. Full article

A novel voltammetric sensor was constructed by modifying a glassy carbon electrode with a composite material consisting of platinum–nickel-doped tin oxide and carbon black (PtNiSnO₂-CB/GCE), enabling highly sensitive differential pulse voltammetry (DPV) determination of trazodone HCl (TRZ). The DPV experimental parameters, including the composition of the supporting electrolyte and instrumental settings, were carefully optimized to achieve maximum analytical efficiency. Within the linear range of 1–10 µM, quantification of TRZ molecules could be performed without the preconcentration step. When applying a 60 s accumulation time (in the range 0.02–0.2 µM of TRZ), the detection limit reached 4.1 nM (1.67 mg L⁻¹), indicating superior sensitivity compared to previously reported voltammetric techniques. The method demonstrated good reproducibility, with a relative standard deviation of 4.3% for 10 repeated measurements at 0.06 µM TRZ. The developed sensor exhibits excellent stability, simplicity of fabrication, and operational convenience. Its practical applicability was confirmed by the successful analysis of molecules of TRZ in diverse sample types, including pharmaceutical products, urine, plasma, river water, and artificial gastric and intestinal fluids, with recovery rates between 97.7% and 104.2%. Flow injection analysis (FIA) with amperometric detection was also performed for TRZ molecule determination. Full article

The aim of this study was to improve screening efficiency by establishing reasonable interpretation criteria for the use of flow injection analysis tandem mass spectrometry (FIA-MS/MS) in newborn screening (NBS) for X-linked adrenoleukodystrophy (X-ALD). FIA-MS/MS was employed to analyze very-long-chain acylcarnitines (ACs) and lysophosphatidylcholines (LPCs) and their ratios in dried blood spot (DBS) obtained from five X-ALD patients in the neonatal period (0–7 days old) and 7123 healthy neonate controls. By comparing these results and analyzing receiver operating characteristic (ROC) curves, we identified sensitive indicators for X-ALD screening in newborns. To evaluate the performance of different FIA-MS/MS screening indicators, we simultaneously analyzed 7712 neonatal DBS samples obtained for X-ALD screening using FIA-MS/MS and the established liquid chromatography tandem mass spectrometry (LC-MS/MS) method for quantitative detection of C26:0-lysophosphatidylcholine (C26:0-LPC). Furthermore, 84,268 newborn X-ALD screening results were retrospectively analyzed to further evaluate the screening performance of FIA-MS/MS. After the three-step optimization evaluation, the optimized first-tier sensitive screening indicators of FIA-MS/MS were C24:0-AC, C26:0LPC, and C24:0/C22:0-AC. Among the 7712 newborns screened, one case was confirmed to be double-positive. Within separate statistical analyses, based on LC-MS/MS screening alone (positive cutoff > 0.17 µmol/L), only seven cases (0.09%) were initially positive, with a positive predictive value (PPV) of 42.8%, and two additional ABCD1 VUS hemizygous males were detected. Through the retrospective analysis of 84,268 newborns, eight ABCD1 variants (six hemizygous males and two heterozygous females) were ultimately identified. Our study showed that the optimization of first-tier screening performance is particularly important if second-tier screening is not performed. Using LC-MS/MS for second-tier screening for X-ALD can significantly reduce the number of false positives, but the method still misses some false negatives. If it is used as a first-tier assessment, more VUS variant neonates can be detected. Full article

Background/Objectives: Low levels of lysophosphatidylcholine (LPC) in the blood can be used as a diagnostic marker for sepsis. SARS-CoV-2 infection, a more recent cause of sepsis, shares similarities with non-SARS-CoV-2 sepsis but also exhibits distinct features. We have recently shown that plasma cholesteryl ester levels are higher in patients with SARS-CoV-2 infection than in patients without, and this study analysed whether this may extend to differences in LPC, a bioactive constituent of lipoproteins. Methods: The plasma levels of 13 LPC species were measured by flow injection analysis tandem mass spectrometry (FIA-MS/MS) in 157 patients with systemic inflammatory response syndrome (SIRS), sepsis or septic shock. Of these patients, 24 had SARS-CoV-2 infection. Results: Patients with SIRS exhibited higher plasma levels of the minor LPC species LPC 15:0 and 22:4 compared to those with sepsis or septic shock. Five LPC species were also reduced in the plasma of 31 patients with liver cirrhosis; therefore, patients with cirrhosis or SIRS were excluded from subsequent analyses. Compared to 76 non-COVID-19 patients with sepsis or septic shock, SARS-CoV-2 infection in 21 patients was associated with significantly higher plasma levels of ten individual LPC species and total LPC concentration. In patients with sepsis/septic shock, LPC species showed negative correlations with procalcitonin and interleukin-6, and positive correlations with gamma-glutamyltransferase and cholesteryl ester levels. In contrast, no significant associations were observed between LPC levels and C-reactive protein, aminotransferases, or free cholesterol. Conclusions: Differential LPC levels, despite comparable disease severity, may serve as metabolic biomarkers to distinguish SARS-CoV-2 sepsis from other causes of sepsis and inform targeted therapeutic approaches. Full article

Coffee adulteration is a growing concern in the food industry due to economic and quality implications. This study evaluates a rapid, non-targeted fingerprinting method based on flow injection analysis–mass spectrometry (FIA-MS) for detecting common coffee adulterants. A total of 119 samples were analyzed, including 43 coffee samples and 76 samples of common coffee adulterants (16 chicory, 10 barley, and 50 flour samples). FIA-MS combined with chemometric analysis allowed for the classification of pure and adulterated coffee samples with over 95% accuracy. Compared to LC-MS, the FIA-MS method showed a similar performance while offering significantly faster analysis and lower solvent consumption, making it a practical and sustainable option for high-throughput screening. For PLS regression studies, calibration and prediction errors were consistently below 0.91% and 11.7%, respectively. Furthermore, the methodology was compared with a non-targeted LC-MS approach, showing an excellent performance. Full article

Chiral analysis is becoming increasingly important across various scientific fields, including chemistry, pharmaceuticals, biosciences, and more recently, metabolomics. In this context, a high-resolution and high-throughput method was developed for the simultaneous determination of the enantiomeric ratio (er) of seven pairs of amino acid (AA) enantiomers (Arg, Gln, His, Met, Pro, Tyr, and Trp) using flow injection analysis coupled with ion mobility-mass spectrometry (FIA-IM-MS) technology. Specifically, the Single Ion Mobility Monitoring (SIM²) mode on a TIMS-Tof^TM instrument enabled the rapid relative quantification of chiral compound mixtures. A linear model accurately described the relationship between enantiomeric ratio and IM-MS response for Arg, Gln, and Pro enantiomers, as evidenced by high R² values and unbiased residuals. In contrast, non-linear trends were observed for His, Tyr, and Trp, where a quadratic model significantly improved the fit. However, the linear model was retained for Met, despite an R² of about 0.98, due to its comparable performance and simplicity. Measurement accuracy was confirmed with very good recovery rates for er values of 0.95 and 0.99 across all AAs. Finally, the potential of the FIA-SIM²-MS approach in chiral analysis was demonstrated, particularly its ability to provide a reliable and efficient high-throughput tool for accurate er determination. Full article

Flow injection analysis (FIA) is widely used in drug screening, neurotransmitter detection, and water analysis. In this study, we investigated the electrochemical sensing performance of glassy graphene electrodes derived from pyrolyzed positive photoresist films (PPFs) via rapid thermal annealing (RTA) on SiO₂/Si and polycrystalline diamond (PCD). Glassy graphene films fabricated at 800, 900, and 950 °C were characterized using Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) to assess their structural and morphological properties. Electrochemical characterization in phosphate-buffered saline (PBS, pH 7.4) revealed that annealing temperature and substrate type influence the potential window and double-layer capacitance. The voltammetric response of glassy graphene electrodes was further evaluated using the surface-insensitive [Ru(NH₃)₆]^3+/2+ redox marker, the surface-sensitive [Fe(CN)₆]^3−/4− redox couple, and adrenaline, demonstrating that electron transfer efficiency is governed by annealing temperature and substrate-induced microstructural changes. FIA with amperometric detection showed a linear electrochemical response to adrenaline in the 3–300 µM range, achieving a low detection limit of 1.05 µM and a high sensitivity of 1.02 µA cm⁻²/µM. These findings highlight the potential of glassy graphene as a cost-effective alternative for advanced electrochemical sensors, particularly in biomolecule detection and analytical applications. Full article

Background/Objectives: Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates serum cholesterol levels and inflammation, both of which are dysregulated in inflammatory bowel disease (IBD). Free cholesterol (FC) and the various types of cholesteryl ester (CE) have different functions in the body. However, it is not yet known whether these lipids undergo parallel changes in male and female patients with active IBD, nor whether PCSK9 correlates with these lipids and disease severity in either sex. The present study measured the serum levels of PCSK9, FC, and 15 CE species in IBD patients, focusing on the associations of these molecules with sex, each other, and with disease severity. Methods: The serum PCSK9 levels of 80 IBD patients (42 males and 38 females) and 24 controls (12 males and 12 females) were measured by enzyme-linked immunosorbent assay. In addition, FC and 15 CE species levels of 53 randomly selected IBD patients and 16 controls were determined by direct flow injection analysis (FIA) using a high-resolution hybrid quadrupole-orbitrap mass spectrometer (FIA-FTMS). Results: Serum PCSK9 levels in controls and IBD patients were comparable and did not correlate with disease severity in IBD patients. There was no discernible difference in serum PCSK9, FC, and CE levels between patients with Crohn’s disease (CD) and those with ulcerative colitis (UC). FC and almost all CE species decreased in male patients with active IBD but were not related to disease severity in the female patients. The decrease in different CE species in male IBD patients with diarrhea compared to those with normal stool consistency appears to be related to IBD severity. Bile acids regulate serum cholesterol levels, and FC and CE levels were positively correlated with fecal levels of secondary bile acids in the patients with UC but not CD. This association also existed in male UC patients and could not be evaluated in women due to the small sample size. Conclusions: In active IBD, a reduction in FC and almost all CE species was observed only in males, while serum PCSK9 levels remained within normal ranges in both sexes. It can be hypothesized that blocking PCSK9 may further reduce serum cholesterol levels, which may have adverse effects in male patients with active IBD. Full article

Parenteral nutrition (PN) is a nutrient solution administered intravenously (IV) to premature babies. PN causes elevations of some amino acids in blood samples that are also biomarkers used in newborn screening (NBS). Therefore, PN status must be annotated by clinicians on dried blood spot (DBS) cards to reduce NBS laboratory burdens associated with potential false results; however, NBS laboratories continue to receive DBSs with misannotated PN status. N-acetyltyrosine (NAT), a water-soluble tyrosine analog used to increase tyrosine bioavailability in PN solutions, can be used as a blood-based biomarker of PN administration in NBS assays. Residual DBS specimens and manufactured DBSs were used in analyses. The assay was developed and validated using flow injection analysis tandem mass spectrometry (FIA-MS/MS) for the detection of NAT. NAT was only present in neonate DBSs with annotated PN administration and was multiplexed into first-tier newborn screening assays. NAT was highly correlated with amino acids present in PN solutions, such as arginine, leucine, methionine, phenylalanine, and valine. In our sample cohort, we determined an NAT cutoff could aid the identification of misannotated neonates administered PN. We also report the Amadori rearrangement product valine–hexose (Val-Hex) was quantifiable in neonates administered PN, which we suspect forms in the PN solution and/or IV lines. Here, we present the first known use of NAT as a biomarker of PN administration, which is currently being piloted by two U.S. NBS laboratories. NAT and Val-Hex can aid the identification of misannotated DBSs from neonates administered PN, thus decreasing false positive rates. Full article

Industrialization has led to environmental pollution with various hazardous chemicals including pollution with metals. In this regard, the development of highly efficient analytical methods for their determination has received considerable attention to ensure public safety. Currently, scientists are paying more and more attention to the automation of analytical methods, since it permits fast, accurate, and sensitive analysis with minimal exposure of analysts to hazardous substances. This review discusses the automated methods with fluorescent detection developed for metal determination since 2000. It is evident that flow-injection analysis (FIA) with no preconcentration or with solid-phase preconcentration are predominant compared to liquid-phase preconcentration systems. FIA systems are also more widespread than sequential injection analysis (SIA) systems. Moreover, a significant number of works have been devoted to chromatography-based methods. Atomic fluorescence detectors significantly prevail over molecular fluorescence detectors. It must be highlighted that most of the methods result in good figures of merit and performance characteristics, demonstrating their superiority in comparison with manual systems. Full article

Analytical instrumentation is essential for chemical analysis in many fields, including biology and chemistry, but it can be costly and inaccessible to many educational institutions because it often requires expensive and sophisticated equipment. To address this issue, there has been growing interest in developing new and accessible alternatives. In this study, we developed a low-cost and user-friendly spectrophotometric detector based on an Arduino UNO platform. This detector was coupled with a flow injection analysis system (FIA) and used to quantify the concentration of tartrazine in commercial beverages and candy samples. The proposed miniaturized detector offers an affordable and portable alternative to conventional spectrophotometers. We evaluated the performance of our detector by comparing its results with those obtained using high-performance liquid chromatography (HPLC-DAD), and the accuracy and precision were comparable. The results demonstrate the potential of the Arduino-based spectrophotometric detector as a cost-effective and accessible tool, with potential applications in food science, environmental monitoring, and other fields. Full article

The increasing consumption of food supplements demands the development of improved analytical methodologies to ensure their quality and authenticity. In this paper, two new approaches, liquid chromatography coupled to mass spectrometry (LC-MS) and flow injection analysis-(electrospray ionization) mass spectrometry (FIA-(ESI)MS), were optimized and validated for their application in the quantitative analysis of bioactive S-allyl-L-cysteine (SAC) in commercial aged garlic supplements (AGS). Although both methodologies were found to be useful for the sensitive and precise quantitation of SAC, the LC-MS approach allowed the differential determination of SAC and its bioactive diastereoisomer, S-1-propenyl-L-cysteine (S1PC), together with the identification of a number of organosulfur compounds typical of garlic. Mass fingerprints by FIA-(ESI)MS were proposed as an advantageous alternative to LC-MS analysis when the fast (4 min/sample) screening of AGS for their SAC content is intended, as in applications aimed at high-throughput quality control or standardization. Finally, the results gathered by the application of these two methodologies evidenced the highly variable composition of commercial AGS, as well as the identification of a number of potential composition frauds affecting their genuineness and benefits on health. Full article

(1) Background: Dyslipidemia represents a major risk factor for atherosclerosis-driven cardiovascular disease. Emerging evidence suggests a close relationship between cholesterol metabolism and gut microbiota. Recently, we demonstrated that the short-chain fatty acid (SCFA) propionate (PA) reduces serum cholesterol levels through an immunomodulatory mechanism. Here, we investigated the effects of oral PA supplementation on the human serum metabolome and analyzed changes in the serum metabolome in relation to the cholesterol-lowering properties of PA. (2) Methods: The serum metabolome of patients supplemented with either placebo or propionate orally for 8 weeks was assessed using a combination of flow injection analysis-tandem (FIA-MS/MS) as well as liquid chromatography (LC-MS/MS) and mass spectrometry using a targeted metabolomics kit (MxP^®Quant 500 kit: BIOCRATES Life Sciences AG, Innsbruck, Austria). A total of 431 metabolites were employed for further investigation in this study. (3) Results: We observed a significant increase in distinct bile acids (GCDCA: fold change = 1.41, DCA: fold change = 1.39, GUDCA: fold change = 1.51) following PA supplementation over the study period, with the secondary bile acid DCA displaying a significant negative correlation with the serum cholesterol levels. (4) Conclusions: Oral supplementation with PA modulates the serum metabolome with a particular impact on the circulatory bile acid profile. Since cholesterol and bile acid metabolism are interconnected, the elevation of the secondary bile acid DCA may contribute to the cholesterol-lowering effect of PA. Full article

A specific feature of mushrooms (including those of the genus Pleurotus) is their natural ability to absorb and accumulate many chemical substances present in their immediate environment, which makes them an excellent natural sorption material. Hence, fruiting bodies of mushrooms have been recognized for years as excellent indicators of the environment, reflecting its current state. Nevertheless, mushrooms can accumulate both health-promoting substances, such as bioelements, and toxic substances, such as heavy metals and organic compounds, including bisphenol A^® (BPA). This organic chemical compound in the phenol group, although it has been withdrawn in the EU since 2010, is widely present in the environment around us. In the present experiment, we aimed to determine the effect of adding BPA to liquid media for in vitro cultures of Pleurotus spp. The biomass increases were determined. Moreover, the degrees of adsorption and desorption of BPA from the obtained freeze-dried biomass in two different environments (neutral and acidic) were determined as a function of time. This is the first study to determine the bioavailability of adsorbed BPA in obtained biomass by extracting the mycelium into artificial digestive juices in a model digestive system. BPA was added to the liquid Oddoux medium in the following amounts: 0.01, 0.5, and 0.5 g/250 mL of medium. The amounts of adsorbed and desorbed BPA were determined by flow injection analysis (FIA) with amperometric detection. The addition of BPA to the substrate reduced the biomass growth in each of the discussed cases. BPA adsorption by the mycelium occurred at over 90% and depended on the morphology of the mushroom (structure, surface development, and pore size). BPA desorption depended on the pH of the environment and the desorption time. Mushrooms are an excellent natural remedial material, but BPA is extracted into artificial digestive juices; therefore, consuming mushrooms from industrialized areas may have health consequences for our bodies. Full article

Metabolomics, with its wealth of data, offers a valuable avenue for enhancing predictions and decision-making in diabetes. This observational study aimed to leverage machine learning (ML) algorithms to predict the 4-year risk of developing type 2 diabetes mellitus (T2DM) using targeted quantitative metabolomics data. A cohort of 279 cardiovascular risk patients who underwent coronary angiography and who were initially free of T2DM according to American Diabetes Association (ADA) criteria was analyzed at baseline, including anthropometric data and targeted metabolomics, using liquid chromatography (LC)–mass spectroscopy (MS) and flow injection analysis (FIA)–MS, respectively. All patients were followed for four years. During this time, 11.5% of the patients developed T2DM. After data preprocessing, 362 variables were used for ML, employing the Caret package in R. The dataset was divided into training and test sets (75:25 ratio) and we used an oversampling approach to address the classifier imbalance of T2DM incidence. After an additional recursive feature elimination step, identifying a set of 77 variables that were the most valuable for model generation, a Support Vector Machine (SVM) model with a linear kernel demonstrated the most promising predictive capabilities, exhibiting an F1 score of 50%, a specificity of 93%, and balanced and unbalanced accuracies of 72% and 88%, respectively. The top-ranked features were bile acids, ceramides, amino acids, and hexoses, whereas anthropometric features such as age, sex, waist circumference, or body mass index had no contribution. In conclusion, ML analysis of metabolomics data is a promising tool for identifying individuals at risk of developing T2DM and opens avenues for personalized and early intervention strategies. Full article