Analytical Parameters Research Articles

A-338 Assessing the Technical and Analytical Performance of Point of Care Testing Devices for Blood Lipids Measurements

Abstract Background Cardiovascular diseases (CVDs) are the leading cause of death worldwide, causing over 17 million deaths each year. According to the World Health Organization (WHO), 85% of CVD deaths are due to heart disease and strokes, and over 75% occur in low- and middle-income countries (LMICs). Early detection and treatment are key to preventing consequences of CVD. Point-of-care testing (POCT) devices require minimal laboratory infrastructure and can be used to screen hard-to-reach populations for CVD risk. These devices are increasingly used in traditional care settings including hospitals and primary healthcare, and in non-traditional settings such as pharmacies. Although POCT devices offer fast and convenient testing, the analytical performance of these devices must produce accurate and reliable results, and have technical suitability for use. Several POCT devices for total cholesterol (TC) and other blood lipids are commercially available, however, the operational and analytical performance of these devices is not fully known. Methods Eight POCT devices for blood lipids were used in this study. For the technical assessment, a checklist was developed and applied, outlining the operational functionality and environmental conditions of the devices. Some relevant technical parameters in this checklist included requirements for temperature/humidity and power/voltage, storage conditions, and assay/test time. The analytical performance was assessed for parameters, such as accuracy and imprecision, using paired whole blood and serum donor samples for TC. In addition, these analytical parameters were assessed for serum High Density Lipoprotein-cholesterol (HDL-c) and Low Density Lipoprotein-cholesterol (LDL-c) samples on seven POCT devices. All samples were representative of a clinically relevant concentration range for TC, HDL-c, and LDL-c. Accuracy was compared to reference values obtained by the CDC reference measurement procedures. Results The mean bias for TC ranged among devices from -8.17% to 11.99% for whole blood and -7.89% to 7.02% for serum, respectively. The mean imprecision for TC in whole blood ranged from 1.94% to 11.63%, and in serum from 1.72% to 12.70%. The mean bias for serum HDL-c samples ranged from -7.33% to 17.36%, and for serum LDL-c samples from -20.92% to 5.04%. The mean imprecision for serum HDL-c samples ranged from 2.39% to 24.27% and for serum LDL-c samples ranged from 3.14% to 18.33%. For three of the eight devices, about 25% of the whole blood measurements and 50% of the serum measurements were reported outside of the measurement range and not included in the assessment. Comparing these non-reports with the reference values of these samples indicate that all of the reference values for whole blood and about 80% of the reference values for serum were actually within the measurement range of the device. Conclusions The technical assessment was helpful in building screening capacity in areas with limited laboratory infrastructure. The analytical assessment indicates notable differences in accuracy and precision for lipids measured in whole blood and serum, with serum measurements being more likely within performance requirements used by CDC's standardization programs. Additional studies to assess other devices and/or analytes, and future work to assist manufacturers improve the analytical performance of POCT devices are needed.

B-051 Clinical Validation of Vectra® DA: A Multi-Biomarker Based Test for the Objective Measurement of Disease Activity in Patients with Rheumatoid Arthritis

Abstract Background The Vectra® DA test measures serum levels of 12 protein biomarkers associated with rheumatoid arthritis (RA) and uses these levels in an algorithmic calculation to generate a numeric score that represents RA disease activity where established categories are low for scores 1 to 29, moderate for 30 to 44, and high for 45 to 100. LabCorp Specialty Lab in Calabasas, CA completed the quantitative analytical validations of 12 Vectra biomarkers (SAA, CRP, VCAM-1, IL-6, TNF-RI, EGF, VEGF-A, Leptin, Resistin, MMP-1, MMP-3, and YKL-40) and the clinical verification of the Vectra score algorithm. Methods The Vectra test consists of the quantitative measurements of EGF, Leptin, MMP-1, TNF-R1, VEGF, MMP-3, Resistin, VCAM, YKL-40, CRP, SAA and IL-6 using multiplex immunoassay platforms. The data acquired from each biomarker assay is processed through an algorithm where a composite Vectra score adjusted based on age, gender, and adiposity of the patient is computed. Analytical parameters validated for each biomarkers include sensitivity, precision, accuracy, specificity and stability. Precision was validated using pooled human serum controls at low, moderate, and high Vectra score levels. Method comparison was performed using 584 clinically defined serum samples. Quantitatively measured analyte values and computed Vectra scores by the Labcorp Vectra assay were compared with Vectra data produced by Myriad laboratory. Results Intra- and inter-assay sample precision of the final Vectra score was <13% and <18%, respectively. Sample stability using freshly collected serum subject to ambient and refrigerated temperature up to 14 days and frozen up to 364 days and up to 6 freeze-thaw cycles were acceptable. Of 584 clinical Vectra data compared, Labcorp vs Myriad, 96% of data were comparable within the acceptable criteria. Correlation of Vectra score from Labcorp and Myriad was excellent. A linear least square model resulted in a correlation coefficient (R) of 0.981 and a Deming slope of 1.009. Qualitative method comparison of Vectra scores resulted in excellent agreement of risk of radiographic progression and rheumatoid arthritis disease activity. A 91% agreement of risk category match between Labcorp and Myriad and 100% agreement of Vectra scores within 1 risk category was achieved. Conclusions We validated the Vectra® DA multiplex assay for measuring serum levels of 12 protein biomarkers associated with RA. Vectra combines biomarker levels into a personalized disease score that represents a patient’s RA inflammation and predict their risk of radiographic progression. High Vectra® DA scores (> 44) have been associated with a 20% 1-year risk of radiographic progression while low scores (< 30) carry only a 1% risk. Thus, the Vectra score provides an objective measurement of RA disease activity that can be used in combination with existing assessment tools to aid physicians to manage patients with RA.

Water quality assessment using national Water Quality Index (WQI): a case study of the Song Be River, Bing Duong Province, Vietnam

Abstract The Song Be River is a vital water source in Binh Duong Province, Vietnam, playing a crucial role in supplying water for domestic use and agriculture, as well as supporting local ecosystems. However, due to the recent rapid economic and industrial growth, the river’s water quality has encountered significant challenges, particularly from the improper discharge of untreated wastewater from various sources and activities. This study conducts a comprehensive analysis of the Song Be River’s water quality by employing the Water Quality Index (WQI) in conjunction with Geographic Information System (GIS) technology. Subsequently, several strategies are also proposed to effectively manage and enhance the water quality of the Song Be River. Over the period from March 2023 to March 2024, 52 samples were collected from four monitoring points (SB1, SB2, SB3, and SB4) along the Song Be River, with a frequency of once per month. All analytical parameters (such as NH4 +_N: 0.01–0.61 mg l−1, NO2 −_N: 0.014–0.03 mg l−1, Fe: 0.01–0.81 mg l−1, Chemical Oxygen Demand (COD): 4–26 mg l−1, Dessolved Oxygen (DO): 3.8–6.6 mg l−1, Suspendid Solids (SS): 5–69 mg l−1, Coliform: 1200–4300 MPN/100 ml, Total phosphorous: 0.01–0.08 mg l−1 and Total nitrogen: 1.16–4.5 mg l−1) fell within the permissible limits according to the Vietnamese National Standards. Furthermore, the WQI ranged from 73 to 100, indicating that the water quality of The Song Be River is good and suitable for domestic use.

Update on Tissue Factor Detection in Blood in 2024: A Narrative Review.

Tissue factor (TF) is a transmembrane protein essential for hemostasis. Different forms of active TF circulate in the blood, either as a component of blood cells and extracellular vesicles (EVs) or as a soluble plasma protein. Accumulating experimental and clinical evidence suggests that TF plays an important role in thrombosis. Many in-house and commercially available assays have been developed to measure TF-dependent procoagulant activity or antigen in blood and have shown promising results for the prediction of disease outcomes or the occurrence of thrombosis events in diseases such as cancer or infectious coagulopathies. This review addresses the different assays that have been published for measuring circulating TF antigen and/or activity in whole blood, cell-free plasma, and EVs and discusses the main preanalytical and analytical parameters that impact results and their interpretation, highlighting their strengths and limitations. In the recent decade, EVTF assays have been significantly developed. Among them, functional assays that use a blocking anti-TF antibody or immunocapture to measure EVTF activity have higher specificity and sensitivity than antigen assays. However, there is still a high variability between assays. Standardization and automatization are prerequisites for the measurement of EVTF in clinical laboratories.

Catalytic effect of the in-situ rhodium(III) complexes in surfactant medium on the auto-oxidation of 1,2-hydroxyphenylthiourea: A theoretical and experimental study for rhodium(III) sensing

1,2-hydroxyphenylthiourea(HPTU) undergoes auto-oxidation to form an yellow colored dimer. The process of auto-oxidation is enhanced by the presence of trace quantities of transition metal ions and transition metal complexes that act as catalysts. In the current study, catalytic potential of rhodium(III) complexes on the auto-oxidation of 1,2-hydroxyphenylthiourea(HPTU) was studied theoretically using quantum mechanical calculations and experiments were carried out using photometry and fluorometry. DFT studies inferred that [Rh(Py)6]Cl3 showed a better catalytic activity in the dimerization of HPTU. Theoretical studies were subsequently validated through experiments using photometric methods and the range of detection was determined to be 6 ng/mL–100 ng/mL. The detection limit was observed to be 2 ng/mL. Analytical parameters such as pH, reagent concentration, metal ion concentration, appropriate activators and surfactants were established.

Evaluation of prognostic factors of body composition, nutritional and analytical parameters in hospitalized patients at nutritional risk

Evaluation of prognostic factors of body composition, nutritional and analytical parameters in hospitalized patients at nutritional risk

Straightforward electroanalytical sensing of nitrate in cyanobacteria growth media at electrified liquid-liquid interface

Nitrate is one among the necessary substance in the biosphere as its presence is pivotal to ensuring healthy vegetation and human health while its excess causes serious adversities. In this work, we utilized the electrified liquid-liquid interface (eLLI) and voltammetry to develop an alternative approach that enables onsite periodic monitoring of nitrate ions in cyanobacteria growth medium. The signal attributed to nitrate detection was directly related to its interfacial ion transfer behavior and not the redox properties. The ion transfer voltammograms of nitrate at eLLI delivered useful analytical parameters of linear detection range from 20 to 500 μM paired with detection and quantification limits of 1.5 and 14.6 μM, respectively. Further, the influence of chloride ions, and other anionic species present in the algae grow media were studied towards the determination of nitrates. We also optimized an in-situ chemical precipitation strategy to eliminate the influence of chloride ions that significantly improved the accuracy of the eLLI-based nitrate sensor. eLLI-based nitrate sensor delivered a remarkable analytical performance to determine nitrate levels in Z8 medium composed of nitrate and other nutrients (medium serving as the optimal environment for algae growth). eLLI based nitrate sensor was successful towards periodic monitoring of nitrate levels in Microcystis aeruginosa cyanobacteria samples cultured in Z8 medium.

Supramolecular Solvent Liquid Phase Microextraction of Voriconazole İn Pharmaceutical and Environmental Samples With High Performance Liquid Chromatography Detection

In this study, a new analytical method based on the supramolecular solvent liquid phase microextraction (Ss-LPME) and HPLC was developed for the analysis of voriconazole as an active drug in the class of antifungals with a wide spectrum of action at trace levels. Nano/micro sized supramolecular phase formed in 1-decanol, tetrahydrofuran and aqueous environment was used as extraction agent for separation and preconcentration of trace level of voriconazole. For the optimization of the Ss-LPME method, important analytical parameters such as the effect of sample solution pH, volume of 1-decanol, amount of THF, ultrasounic irridation time, centrifugation time and sample solution volume on the extraction efficiency were evaluated. Optimal conditions of the Ss-LPME; pH: 8, 1-decanol volume: 200 µL, THF volume: 300 µL, ultrasounic irridation time:10 min and centrifugation time: 8 min. For the developed Ss-LPME/HPLC procedure, the limit of detection (LOD), limit of quantification (LOQ) and enhancement factor (EF) were found 2.7 µg·L-1, 8.8 µg·L-1 and 36, respectively. The Ss-LPME/HPLC procedure was applied to waste water, lake water and drug samples. The fact that recovery values ranging from 100% to 108.5% were obtained for these real samples proved that this method can be used successfully in the matrix environments studied

Industrial IoT-Based Energy Monitoring System: Using Data Processing at Edge

Edge-assisted IoT technologies combined with conventional industrial processes help evolve diverse applications under the Industrial IoT (IIoT) and Industry 4.0 era by bringing cloud computing technologies near the hardware. The resulting innovations offer intelligent management of the industrial ecosystems, focusing on increasing productivity and reducing running costs by processing massive data locally. In this research, we design, develop, and implement an IIoT and edge-based system to monitor the energy consumption of a factory floor’s stationary and mobile assets using wireless and wired energy meters. Once the edge receives the meter’s data, it stores the information in the database server, followed by the data processing method to find nine additional analytical parameters. The edge also provides a master user interface (UI) for comparative analysis and individual UI for in-depth energy usage insights, followed by activity and inactivity alarms and daily reporting features via email. Moreover, the edge uses a data-filtering technique to send a single wireless meter’s data to the cloud for remote energy and alarm monitoring per project scope. Based on the evaluation, the edge server efficiently processes the data with an average CPU utilization of up to 5.58% while avoiding measurement errors due to random power failures throughout the day.

Prussian-Blue-Nanozyme-Enhanced Simultaneous Immunochromatographic Control of Two Relevant Bacterial Pathogens in Milk

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens.

High–precision determination of carbon stable isotope in silicate glasses by secondary ion mass spectrometry: Evaluation of international reference materials

Secondary ion mass spectrometry (SIMS) has been used for isotope analysis of volatile components dissolved in silicate melts for decades. However, carbon in situ stable isotope analysis in natural silicate glasses has remained particularly challenging, with the few published attempts yielding high uncertainties. In this context, we characterized 31 reference silicate glasses of basaltic and basanitic compositions, which we then used as reference materials to calibrate δ13C − value analyses in silicate glasses by SIMS. This set of reference materials covers a wide range of CO2 concentrations (380 ppm – 12,000 ppm) and δ13C values (−28.1 ± 0.2 to −1.1 ± 0.2 ‰, ±1σ). The sets of reference materials were analyzed using large−geometry SIMS at two ion microprobe facilities to test reproducibility across different instrumental setups. The instrumental mass fractionation (IMF) varied widely with two different large−geometry SIMS instruments as well as with different analytical parameters such as field aperture size and primary beam intensity. We found that a precision better than ±1.1 ‰ (both average internal and external precision, ±1σ) for CO2 content higher than 1800 ppm could be achieved using a primary beam intensity of less than 5 nA, resulting in a final spot size of 10–20 μm, allowing precise analysis of δ13C in mineral−hosted melt inclusions. This level of precision was achieved at CO2 concentrations as low as 1800 ppm. This advance opens a wide range of new possibilities for the study of δ13C − value in mafic melts and their mantle sources. The reference materials are now available at the CNRS–CRPG ion microprobe facility in Nancy, France and will be deposited at the Smithsonian National Museum of Natural History, Washington, USA where they will be freely available on loan to any researcher.

Synthesis of magnetic multi-walled carbon nanotubes with layered double hydroxide (M-MWCNTs@MnAl-LDH) nanocomposite as an adsorbent for lead extraction

MnAl layered double hydroxide hybrid with magnetic-multiwalled carbon nanotubes was synthesized by a hydrothermal method and used for the extraction of Pb(II) (lead) from spices and water samples in the dispersive solid phase microextraction (dSPμE) technique using FAAS. The as-prepared adsorbent MMWCNTs@MnAl-LDH was characterized by XRD, FTIR, EDX, and SEM techniques. Various analytical parameters were optimized, including pH 8, adsorbent dosage of 5 mg, HNO3 eluent concentration of 1 mol L−1, eluent volume of 3 mL, eluent time of 60 s, and sample volume of 20 mL, for quantitative lead recoveries, with an LOD of 0.314 μg L−1, an LOQ of 1.048 μg L−1, and PF of 11.53. Under the optimized conditions, the linearity ranges from 0.5 to 500 μg L−1 (R2 = 0.9997). For the validation test of the established dSPμE procedure, Certified reference materials (CRMs) were used, yielding satisfactory recovery results ranging from 97.8 to 102.7 %. The method was applied to determine lead in turmeric, tap water, and industrial water samples.

LDL-c/HDL-c Ratio and NADPH-Oxidase-2-Derived Oxidative Stress as Main Determinants of Microvascular Endothelial Function in Morbidly Obese Subjects.

The identification of obese subjects at higher risk for cardiovascular disease (CVD) is required. We aimed to characterize determinants of endothelial dysfunction, the initial step to CVD, in small omental arteries of visceral fat from obese subjects. The influences of analytical parameters and vascular oxidative stress mediated by NADPH-oxidase-2 (NOX2) on endothelial function were determined. Specimens were obtained from 51 obese subjects undergoing bariatric surgery and 14 non-obese subjects undergoing abdominal surgery. Obese subjects displayed reduced endothelial vasodilation to bradykinin (BK). Endothelial vasodilation (pEC50 for BK) among obese subjects was significantly and negatively associated with low-density lipoprotein cholesterol (LDL-c)/high-density lipoprotein cholesterol (HDL-c) ratio (r = -0.510, p = 0.0001) in both women and men, while other metabolic parameters and comorbidities failed to predict endothelial function. The vascular expression of NOX2 was upregulated in obese subjects and was related to decreased endothelial vasodilation (r = -0.529, p = 0.0006, n = 38) and increased oxidative stress (r = 0.783, p = 0.0044, n = 11) in arterial segments. High LDL-c/HDL-c (>2) and high NOX2 (above median) were independently associated with reduced endothelial function, but the presence of both conditions was related to a further impairment. Concomitant elevated LDL-c/HDL-c ratio and high vascular expression of NOX2 would exacerbate endothelial impairment in obesity and could reveal a deleterious profile for cardiovascular outcomes among obese subjects.

Numerical Analysis of the Effect of the Non-Phase-Change Gas on the Atmospheric CO<sub>2</sub> Decompression Capture Characteristics by Cryogenic Heat (Temporal Change of Various Quantities in the Process and the Effect of Analytical Parameters on the Formation Characteristics of Dry Ice)

Numerical Analysis of the Effect of the Non-Phase-Change Gas on the Atmospheric CO<sub>2</sub> Decompression Capture Characteristics by Cryogenic Heat (Temporal Change of Various Quantities in the Process and the Effect of Analytical Parameters on the Formation Characteristics of Dry Ice)

Novel usage of perinone polymer as solid contact in ion-selective electrodes

The paper presents the use of a new perinone polymer (PPer) as an intermediate layer and the development of a new type of potassium ion-selective electrodes with solid contact. The PPer layer was applied to the surface of a glassy carbon electrode using potentiodynamic polymerization from an electrolyte solution containing perinone precursors (Per). Subsequently, the surface of the electrode after application of the polymer was examined using a microscope and an optical profilometer. To check the quality of the prepared ion-selective electrodes, a series of tests were carried out and the analytical and electrical parameters of the electrodes were determined. Electrode modifications using PPer improved the electrode parameters, especially the stability and reversibility of the potential, compared to the control electrode covered only with an ion-sensitive membrane. The best electrode was the electrode modified with PPer applied in 10 cycles, which, as a result of the modification, allowed better parameters to be obtained – slope 58.86 mV/decade, LOD 1.2 × 10−6 M, linearity range 5 × 10−6 – 1 × 10−1 M. A very low short-term potential drift value of 2.7 × 10−4 mV/s was obtained as well as an extremely satisfactory SD value of 1.1 mV from E0 measurements. The modification also improved electrical properties and gave a negative result of the water layer test.

Natural deep eutectic based dispersive liquid-liquid microextraction and solidified floating organic drop for cadmium determination by electrothermal atomic absorption spectrometry with multivariate optimization (DLLME-SFOD-NADES-ETAAS)

A novel method was developed for cadmium determination based on dispersive liquid-liquid microextraction and solidified floating organic drop by multivariate optimization with electrothermal atomic absorption spectrometric detection using a natural deep eutectic solvent (NADES) of (L)-menthol and formic acid. Important factors, including pH, final concentration of PAN, mole ratio of formic acid, volume of NADES, type of dispersive solvent, and vortex time, were assessed using two-level fractional factorial design (FFD), and circumscribed central composite design (CCC). The analytical performance parameters, encompassing linearity range, limit of detection (LOD), limit of quantification (LOQ), and precision, were evaluated. The linearity range ranged from 0.72 to 2.50 ng/L, with corresponding LOD and LOQ values of 0.22 and 0.72 ng/L, respectively. Precision was evaluated by conducting three replicates of the three concentration levels, resulting in %RSD values of 11.8 %, 5.1 %, and 3.9 %, respectively. An enrichment factor (EF) of 112 was achieved. The optimized method was applied for cadmium determination in various matrices, including drinking water, environmental water, seafoods, yielding %recovery in the ranges of 78.05–102.41 %. Finally, comparison of t-values between the developed method and CRMs demonstrated satisfactory results at a 95 % confidence level.

Estimation of isoniazid by digital image colorimetry: an integration of green chemistry and smartphone technology

BackgroundThis study proposes a simple digital image colorimetric method using a smartphone for the quantitative analysis of isoniazid in pharmaceutical medications. The analytical methodology employed in this study involved the utilization of the reaction between isoniazid and FC reagent under alkaline conditions. The chemical reaction led to the creation of a complex with a blue-gray color, exhibiting a peak absorption at a wavelength of 760 nm. An Android application was employed to perform a smartphone-based determination based on separating the captured color into different color channels such as red, blue, green, etc. The experimental procedure involved the utilization of three smartphones for the determination, which was subsequently followed by a comparative analysis of the results obtained from these devices using spectrophotometric measurements.ResultsThe B channel had the highest level of optimization in terms of analytical parameters. The limits of detection (LOD) were 0.586, 2.478, and 1.396 µg/ml for S1, S2, and S3, respectively, and for the spectrophotometer, it was found to be 0.416 µg/ml. Similarly, LOQs were determined as 1.673, 7.511, 4.232, and 1.302 µg/ml. A %RSD of 1.3 for precision and an LOD of 0.013 g dm−3 were obtained for the spectroscopic method. The % recovery in the accuracy study was found to be 99.69, 101.804, 109.28, and 100.13 for S1, S2, S3, and spectrophotometer, respectively.ConclusionThe colorimetric results from smartphone application are similar to those from spectrophotometric analyses.

Biocompatible sensors for ammonia gas detection

In this work, three different dyes have been tested for the determination of gaseous ammonia. This gas is one of the products of microbial degradation and therefore its presence is an indicator of deterioration and could be used as a food freshness indicator.Three different sensors have been prepared and tested, two of them using the natural pigments curcumin and anthocyanin and the other one using bromothymol blue. All of them are biocompatible and therefore allowed to use in contact with food.Different compositions, materials for deposition, stability and reversibility for ammonia gas detection have been studied under high humidity conditions simulating real packaged food conditions. Colorimetry is the technique used to obtain the analytical parameter, the H coordinate of the HSV colour space, simply using a camera, avoiding the use of complex instrumentation.Sensibility, toxicity grade and stability found show that the sensor could be implemented in packaged food and form the basis of a freshness indicator for the food industry.

3D printed oxygen gas sensor with a Pt-nanoparticles decorated N-doped carbon catalyst and an amine-polymer composited ionic liquid gel electrolyte

A 3D-printed electrochemical oxygen gas sensor was developed using a Pt nanoparticle-decorated N-doped carbon (PtNC) catalyst and an ionic liquid gel electrolyte incorporated with polyethyleneimine. At first, N-doped carbon particles were synthesized hydrothermally, followed by the decoration of a tiny amount of Pt nanoparticles using a microwave reactor. The working electrode was printed with a composite of high-impact polystyrene (HIPs), graphite powder (Gr), and a PtNC catalyst (HIPs/Gr/PtNC), then counter and reference electrodes were separately printed without the PtNC catalyst. The sensing materials were characterized using various analytical methods, including SEM, XPS, Raman, ICP-AES, CV, and EIS. Prior to detecting oxygen gas, the 3D sensor surface was pretreated with potential cycling in an acidic solution. Additionally, a composite gel electrolyte was prepared by incorporating polyethyleneimine into an ionic liquid, which was then coated onto the sensor surface to enhance sensitivity and ensure long-term stability. The analytical parameters using the final sensor were optimized in terms of Pt contents, 3D-printing polymer type, and ionic liquid gel concentration. The amperometric measurements demonstrated a wide dynamic range from 0.1 % to 100 % with the detection limit of 0.13 ± 0.05 % at a 90 % response time of 3.6 ± 0.4 s. To validate the reliability of the proposed sensor, the measurement of O2 content was performed for room air and standard oxygen gas, revealing reliable and stable results for six months.

A Newly Validated HPLC-DAD Method for the Determination of Ricinoleic Acid (RA) in PLGA Nanocapsules.

The assessment of ricinoleic acid (RA) incorporated into polymeric nanoparticles is a challenge that has not yet been explored. This bioactive compound, the main component of castor oil, has attracted attention in the pharmaceutical field for its valuable anti-inflammatory, antifungal, and antimicrobial properties. This work aims to develop a new and simple analytical method using high-performance liquid chromatography with diode-array detection (HPLC-DAD) for the identification and quantification of ricinoleic acid, with potential applicability in several other complex systems. The method was validated through analytical parameters, such as linearity, limit of detection and quantification, accuracy, precision, selectivity, and robustness. The physicochemical properties of the nanocapsules were characterized by dynamic light scattering (DLS) to determine their hydrodynamic mean diameter, polydispersity index (PDI), and zeta potential (ZP), via transmission electron microscopy (TEM) and quantifying the encapsulation efficiency. The proposed analytical method utilized a mobile phase consisting of a 65:35 ratio of acetonitrile to water, acidified with 1.5% phosphoric acid. It successfully depicted a symmetric peak of ricinoleic acid (retention time of 7.5 min) for both the standard and the RA present in the polymeric nanoparticles, enabling the quantification of the drug loaded into the nanocapsules. The nanocapsules containing ricinoleic acid (RA) exhibited an approximate size ranging from 309 nm to 441 nm, a PDI lower than 0.2, ζ values of approximately -30 mV, and high encapsulation efficiency (~99%). Overall, the developed HPLC-DAD procedure provides adequate confidence for the identification and quantification of ricinoleic acid in PLGA nanocapsules and other complex matrices.