Standard Addition Research Articles

Evaluation of four different standard addition approaches with respect to trueness and precision.

This work provides a statistical analysis of four different approaches suggested in the literature for the estimation of an unknown concentration based on data collected using the standard addition method. These approaches are the conventional extrapolation approach, the interpolation approach, inverse regression, and the normalization approach. These methods are compared under the assumption that the measurement errors are normally distributed and homoscedastic. Comparison is done with respect to the two most important characteristics of every estimator, namely trueness (bias) and precision (variability). In addition, the authors supply, if not already available, mathematical formulas to approximate both quantities. Also, a real-world data set is used to illustrate the performance of all four methods. It turns out, that, given that all assumptions underlying the use of the standard addition method apply, the common extrapolation method is still the most recommendable method with respect to bias and variability. Nonetheless, if additional concerns come into play, other methods like, for example, the normalization approach in the case of increased problems with outliers might also be of interest for the practitioner.

Two-Phase Extraction for Comprehensive Analysis of the Plant Metabolome by NMR.

Metabolomics is the area of research, which strives to obtain complete metabolic fingerprints, to detect differences between them and to provide hypothesis to explain those differences (Schripsema J, Dagnino D, Handbook of chemical and biological plant analytical methods. Wiley, New York, 2015). However, obtaining complete metabolic fingerprints is not an easy task. Metabolite extraction is a key step during this process, and much research has been devoted to finding the best solvent mixture to extract as much metabolites as possible.Here a procedure is described for analysis of both polar and apolar metabolites using a two-phase extraction system. D2O and CDCl3 are the solvents of choice, and their major advantage is that, for the identification of the compounds, standard databases can be used because D2O and CDCl3 are the solvents most commonly used for pure compound NMR spectra. The procedure enables the absolute quantification of components due to the addition of suitable internal standards. The extracts are also suitable for further analysis with other systems like LC-MS or GC-MS.

A stable method for ionic rare earth element extraction and quantitative analysis of total quantity and composition of batch samples.

The development of a stable, high-precision and batch ion-adsorption rare earth element detection method is highly anticipated in the delineation and evaluation of the mining value of rare earth element mines. In this study, a novel mixed extractant of ammonium sulfate + ammonium citrate + aceto-sodium acetate buffer was used to significantly improve the extraction efficiency of rare earth elements. Following a series of parameter optimizations, an off-line internal standard addition method and the collision mode of the inductively coupled plasma-mass spectrometer were used to improve the detection efficiency for batch samples, effectively eliminating oxide interference between the rare earth elements and improving the detection accuracy. The detection limit for ion-adsorption rare earth elements was 3.4 μg g-1 and the detection range was 12-8000 μg g-1. More importantly, the spiked and recovery experiments carried out in multiple laboratories with internal quality control samples show that the relative deviation was -5.61 to 3.79%, which indicates that the method has sufficient stability. Establishment of this method will help to improve the comprehensive utilization efficiency of rare earth resources and provide important support for rare earth element mining.

CCQM-K158 elements and inorganic arsenic in rice flour

Main text KRISS and NMIJ jointly coordinated the CCQM-K158 comparison on elements and inorganic As in polished rice flour. The study comprised two parts, Part A and Part B. Successful participation in formal international comparisons is essential for documenting calibration and measurement capability claims (CMCs) by national metrology institutes (NMIs) and designated institutes (DIs). CCQM-K158 specifically supports CMCs within the food category, corresponding to the sample matrix labeled "High organic content" in the new CC table for broad claims. Simultaneously, the CCQM-P200 comparison ran in parallel with the key comparison CCQM-K158. In Part A, sixteen NMIs/DIs participated. Participants were requested to measure the mass fractions of Cu, Hg, K, Na, Pb, and Sb in rice flour, expressed in mg·kg-1, on a dry mass basis. Most NMIs/DIs adopted microwave-assisted acid digestion in a closed vessel for sample pretreatment, except for NIS, which used open vessel acid digestion with heating. Majority of the participants used isotope dilution (ID) ICP-MS, except for K and Na. ICP-MS or ICP-OES with standard addition calibration and k0 INAA were also applied specially for elements of which ID is impossible or difficult to access. ICP-MS, ICP-OES, AAS methods were also used with external calibration. In Part B, fifteen NMIs/DIs participated. Participants were requested to evaluate the mass fractions, expressed in mg·kg-1, of total arsenic and inorganic arsenic (the sum of As (III) and As (V)) in polished rice flour. For total As, thirteen NMIs/DIs reported their analytical results, where all the NMIs/DIs, except for JSI, adopted ICP-MS with a microwave acid digestion. JSI adopted k0-INAA after pelletizing the sample. For inorganic As, seven NMIs/DIs reported their analytical results, where all the NMIs/DIs adopted liquid chromatography-ICP-MS with a thermostatically controlled extraction using diluted acids. The results of all the participating NMIs/DIs were evaluated against the key comparison reference value (KCRV). The KCRV and associated uncertainty were estimated from reported results, excluding outliers, using NIST decision tree (NDT) as an estimator of the KCRVs. Successful participation in CCQM-K158 Part A demonstrates measurement capabilities for determining mass fractions of alkali and alkaline earth (K, Na), transition (Cu, Hg, Pb), and metalloid/semi-metal (Sb) elements in mass fraction range above 0.05 mg kg-1, in high organic content matrices such as grains, beans, and related samples. Similarly, successful participation in CCQM-K158 Part B demonstrates measurement capabilities to determine mass fractions of total arsenic and water-soluble arsenic species such as inorganic arsenic (the sum of As (III) and As (V)), mono-, di-, tri-, and tetra-methyl arsenic compounds (MAA, DMAA, TMAO, TeMA), arsenocholine (AsC), and arsenobetaine (AsB), in mass fraction range above 0.05 mg·kg-1 in grains, beans, and related samples. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Alternative method using Multiple-Injection Capillary Zone Electrophoresis with direct UV detection and single-point standard addition for determination of sorbate and benzoate in ready-to-drink tea

Alternative method using Multiple-Injection Capillary Zone Electrophoresis with direct UV detection and single-point standard addition for determination of sorbate and benzoate in ready-to-drink tea

Study on Differential Pulse Anodic Stripping Voltammetry Method for Simultaneous Determination of Trace amount of Zn, Cd, Pb, Cu in some Cough Syrups in Vietnam

The optimal measurement parameters of differential pulse anodic stripping voltammetry method (DP-ASV) to simultaneously determine the trace amount of the four elements Zn, Cd, Pb, Cu have been studied, including the sweep rate, pulse amplitude, drop size of mercury, initial purge, equilibration time. The analytical procedure was applied to determine Zn, Cd, Pb, Cu in 12 cough syrup samples in Viet Nam, including 6 functional food samples and 6 medicinal samples. The quantitative echnique used was standard addition and the applicability of quantitative elements in self - made samples was studied. Cough syrup analysis samples were digested using the wet ashing method in microwave oven. Research results show that there are no regular differences in elements content between medicinal cough syrup samples and functional food samples, except for functional food samples TP08 which has Pb content and the syrup medicine sample TH03 which has Cu content many times higher than other types. However, the content of the studied elements is within the allowable limits according to curent regulations (QCVN 8-2:2011/BYT; 46/2007/QĐ-BYT, WHO). The method has low detection limits and limit of quantification with ppb level, the relative standard deviations (% RSD) of repeated measurements are less than 3%, and recovery reflects the accuracy of the analytical method for elements ranging from 61.0 % to 87.5 %, which meets AOAC requirements for trace.

Design and Characterization of Novel Naphthalimide Fluorescent Probe for H2S Detection in Human Serum.

In this work, a novel fluorescent probe (compound 2) based on the Intramolecular charge transfer (ICT) mechanism was designed and successfully applied to determine H2S in human serum. Fluorophore 1,8-naphthalimide was chosen, while the azide group was the recognition group for H2S determination. By introducing p-toluidine moiety on the imide part of the molecule, a donor-acceptor (D-A) conjugated system was formed. Prepared compound 2 was characterized using 1H, 13C NMR spectroscopy, and elemental analysis. Fluorescence spectra measurements were carried out, and several influences on fluorescence intensity were investigated, including pH, time dependence, selective response, and influence of H2S concentration. Conducted experiments, including the calculated detection limit of the prepared fluorescent probe, which was found to be 0.085 µmol·L- 1, showing that compound 2 could be applied for H2S detection in human serum and could detect low micromolar concentrations of H2S. Finally, compound 2 was successfully applied to detect H2S in a human serum sample, whereby the concentration of H2S was 17.2 µmol·L- 1. The accuracy of the H2S determination was confirmed with the standard addition method.

Ultrafast Microwave-Synthesized 2D/1D MnO2/Carbon Nanotube Hybrid for Bilirubin Detection in Simulated Blood Serum.

Hybridization of carbon nanotubes (CNTs) and manganese dioxide (MnO2) integrates the biocompatibility and outstanding electrocatalytic activity of MnO2 with the exceptional conductivity of CNTs, thus providing a superior synergistic sensing platform for the detection of biomolecules. However, the existing methods for synthesizing MnO2/CNT hybrids are complex and inefficient, resulting in low yields and limited surface functionalities. Hence, in this study, we present a low-cost and ultrafast solid-phase synthesis of the MnO2/CNT hybrid using a facile microwave technique to detect a crucial biomolecule bilirubin. The successful synthesis of the MnO2/CNT hybrid is confirmed through characteristic Raman and X-ray diffraction peaks, while morphology is analyzed by imaging techniques such as FESEM and HRTEM. The MnO2/CNT/nickel foam (NF) sensor is thereafter used for the electrochemical detection of bilirubin. The sensor demonstrates a wide linear detection range from 10 nM to 1 mM, with a sensitivity of 6.87 mA nM-1 cm-2 toward bilirubin, as determined through the differential pulse voltammetry technique. The lower limit of detection is noted at 3.3 nM (=3.3 S/m). Furthermore, the as-fabricated sensor showcases high selectivity against the interfering species. Real-time analysis conducted in simulated blood serum using the standard addition method reveals an outstanding recovery percentage of approximately 98%. The conductive MnO2/CNT hybrid interacts robustly with bilirubin, aided by the porous NF substrate for stability, catalytic activity, and rapid electron transfer, enabling sensitive bilirubin detection. The work provides an ultrafast, low-cost, and high-yield solid-phase microwave synthesis of MnO2/CNT hybrid material and broadens its application in the detection of biological specimens for clinical diagnosis and biomedical research.

Development and optimisation of the biosensor for aspartate aminotransferase blood level determination.

This work presents the development and optimisation of an amperometric biosensor for determining aspartate aminotransferase (AST) activity in blood serum, using glutamate oxidase and platinum disc electrodes. AST is a key biomarker for diagnosing cardiovascular and liver diseases. The biosensor's bioselective membrane composition and formation protocol and the working solution (aspartate 8mM, α-ketoglutarate 2mM, pyridoxal-5-phosphate 100µM) were optimised. The sensor demonstrated high selectivity, stability (70% retention over 2months at - 18°C), and sensitivity (2.37 nA min⁻1 per 10 U L⁻1), with a dynamic range of 0-500 U L⁻1 and a limit of detection of 1 U L⁻1. Comparative analysis showed the calibration curve method outperforms the standard addition method for AST measurement in serum samples. Additionally, a reference spectrophotometric technique was adapted for AST level determination, showing a strong correlation (r = 0.989) with the biosensor results. This research offers a fast, affordable, and accurate tool for early check-ups of liver and heart conditions. The biosensor's flexibility and ease of use make it suitable for further development into point-of-care testing and personalised healthcare techniques.

Selection of internal standards for the determination of rare earth elements by atomic emission spectrometry with microwave plasma

The method of atomic emission spectrometry with excitation spectra in microwave plasma was used to determine the composition of lanthanum sulfide crystals and europium-doped gadolinium oxide, as well as elements in the melt (tin, boron, and lithium). Calibration curves for rare earth elements are nonlinear and do not provide the required accuracy of analysis. To reduce errors and linearize the calibration curves, the internal standard method was used. Molecular ions N2, N2+ and OH did not correct for changes in plasma conditions and inter-element effects. Internal standard elements were selected based on the proximity of the first ionization potential to the analytes, considering Ba, Al, Ga, and In. The use of these elements as internal standards allowed the linearization of calibration curves, achieving an analytical accuracy of 95−105%. The found total mass of the elements was 97−103% of the sample mass, with accuracy confirmed by the method of standard additions.

Evaluation of Automatic Analysis Software for 1H NMR Spectra Quantification. Impact of Signal Broadening and EDTA Addition.

NMR is a well-established analytical technique that enables the identification and quantification of several compounds in complex mixtures. The implementation of automated analysis software enhances this process by comparing sample spectra with a library of standard reference spectra. One of the key parameters in libraries is the signal line width; however, this may result in a concentration bias for compounds with broad signals, particularly those that are complexing. This study aims to evaluate the quantification of seven compounds commonly present in wine with complexing activity. Four automatic programs and manual deconvolution were used to quantify mixtures of these compounds at known concentrations, both in the presence of cations and with the addition of ethylenediamine-tetraacetate (EDTA) as a chelating agent. Additionally, malate was quantified in a wine sample using the standard addition method, both with and without EDTA. The findings illustrate that three of the programs, which employ the signal width value, underestimate compound concentrations in the presence of cations due to signal broadening. This error was mitigated by the EDTA addition. In contrast, the remaining software, which did not utilize signal line width, obtained similar concentrations in both cases. Future investigations involving the automatic analysis of compounds with complexing activity should take care of sample preparation and/or algorithm selection. Furthermore, future software development should consider allowing flexible adjustments of signal line width in their workflow.

Atomic absorption and inductively coupled plasma atomic emission determination of iron and manganese in medicinal salt mixtures

Complete extraction of analytes from samples and the homogeneity of analyzed solutions were achieved using ultrasonic treatment (20 minutes). The sensitivity, precision, and accuracy of atomic absorption determination of analytes were improved by using Triton X-100 (4%) and calibration solutions based on iron and manganese acetylacetonates. It was demonstrated that sensitivity increased by 1.7 times for manganese and 1.5 times for iron. The iron and manganese content in medicinal salt mixtures was determined using both atomic absorption and inductively coupled plasma atomic emission methods. The results obtained by these two independent methods were compared, showing that the dispersions are homogeneous and the variation in results is minor, attributed to random error. The accuracy of the atomic absorption results was verified using the standard addition method and by varying the sample weight, confirming that systematic error is negligible. The detection limits established by the atomic absorption method were Cmin=0.009 g/mL for iron (Cmin, lit=0.015 g/mL) and Cmin=0.003 g/mL for manganese (Cmin, lit=0.004 g/mL).

Ultrasensitive electrochemical detection of miDNA-21 in human serum based on synergistic signal amplification by conducting polymers and bimetallic nanoparticles

MicroRNA-21 (miRNA-21) is a class of small non-coding RNAs that play a crucial role in the regulation of post-transcriptional gene expression. By leveraging the principle of base complementary pairing, the detection of miRNA-21 can be achieved through its analogue, MicroDNA-21 (miDNA-21), which possesses an identical sequence. Utilizing screen-printed carbon electrodes (SPCE), a conducting polymer (polypyrrole, Ppy), and metal nanocomposites (gold-platinum nanoparticles, Au@Pt NPs) were sequentially electrodeposited to create an electrochemical biosensor for the detection of miDNA-21. This biosensor employed ferrocyanide/ferricyanide (Fe(CN)63−/4−) as the electrochemical signaling probe, and its structure was elucidated via field emission scanning electron microscopy (FESEM) and Energy Dispersive Spectrometer (EDS). Quantitative detection was facilitated through differential pulse voltammetry (DPV), yielding a concentration range and linear fitting equation of 10.00–7.00 × 10.00−14 mol/L: ΔI = 0.5143 lgc + 9.191, R2 = 0.9986. The limit of detection (LOD) was determined to be 2.90 × 10−15 mol/L, with a sensitivity of 9.42 μA/μmol/L·cm2. Subsequent performance assessments confirmed the sensor’s excellent selectivity, reproducibility, and stability. Evaluation using the standard addition method, with normal human serum as the matrix, yielded recoveries ranging from 98.97 % to 102.70 %, and relative standard deviation (RSD) values below 1.00 %. These results demonstrate the method’s viability for practical application in detecting miRNA in human serum.

Potentialities of semi-continuous anaerobic digestion for mitigating antibiotics in sludge.

The behavior and removal of roxithromycin (ROX), oxytetracycline (OTC), chlortetracycline (CTC), and enrofloxacin (ENR) were investigated during the steady state of sludge anaerobic digestion (AD) in semi-continuous mode (37°C). Sludge was spiked at realistic concentrations (50μg/L of each antibiotic) and then used to feed the bioreactor for 80days. Antibiotics were extracted from the substrate and digested sludge samples by accelerated solvent extraction (ASE). Accurate determination of antibiotics was obtained by the standard addition method (SAM) associated with the liquid chromatography-tandem mass spectrometry (LC-MS/MS). The presence of antibiotics at a concentration of 2.5μg/g TS had no inhibitory effects on methane (CH4) production, total and volatile solids (TS and VS) removal as well as chemical oxygen demand (COD) removal. During the steady-state, antibiotics were removed significantly by 50, 100, and 59% respectively for the ROX, OTC, and CTC. Furthermore, ENR removal was not statistically significant and was estimated at 36%. This study highlighted that AD process could partially remove parent compounds, but ROX, CTC, and ENR persisted in the digested sludge. Hence, AD could be considered as a sludge treatment for mitigating, but not suppressing, the release of antibiotics through sludge application.

Exploring the association between serum magnesium level and autism spectrum disorder using validated spectrofluorimetric method.

Magnesium is an essential mineral in biological systems and has a significant impact on brain health. Its deficiency has been found to correlate with irregular metabolic processes and neurodevelopmental disorders. The objective of this research was to establish and validate an analytical approach based on the standard addition methodology for determining endogenous magnesium levels in the serum of autistic and healthy children. Analytically, the approach involved functionalizing fluorescent graphene quantum dots with a magnesium-phosphomolybdic acid ion pair complex, followed by measuring magnesium-induced fluorescence quenching on the functionalized graphene quantum dots, which is concentration-dependent. The approach was validated in accordance with the ICH M10 requirements for bioanalytical technique validation, and it reliably quantified magnesium concentrations in the serum of both autistic and healthy children. The study found that autistic children have considerably lower serum magnesium concentrations than healthy children (P < 0.01), indicating a correlation between magnesium deficiency and autism spectrum disorder. The average serum magnesium levels (mg/dl) recorded for the autistic and healthy groups were 2.03 ± 0.33 and 2.28 ± 0.26, respectively.

Pioneering NMR-based dereplication for identifying novel quinolone additives in personal care products: A new frontier in public health protection

Personal care products (PCPs) are often adulterated with antimicrobial agents, such as quinolones, which pose risks to consumer safety and challenge regulatory oversight. Current detection methods rely on standard reference substances and are limited in identifying novel quinolone isomers and structural derivatives. In this study, we present the first use of MixONat, an advanced dereplication tool, combined with 13C NMR spectroscopy to detect illegal quinolone additives in PCPs. Key advancements include the establishment of an in-house quinolone database, innovative sample pretreatment methods, and the integration of these elements to improve the detection of new illegal additives in PCPs. Standard addition experiments in both blank matrices and commercial cosmetics successfully identified new quinolones not included in the database, with effective differentiation of stereoisomers such as ofloxacin and levofloxacin. The proposed approach significantly improves detection efficiency and accuracy, bolstering PCP safety regulations and contributing to public health protection.

Platform for Aldehyde and Ketone Quantitation Using Surface-Enhanced Raman Spectroscopy.

Colorimetric methods for aldehyde and ketone analyses are plagued by interferences. Each aldehyde or ketone generates a blue color, but with a different reaction coefficient. It is, therefore, not possible to differentiate these compounds from a single test. By using surface-enhanced Raman spectroscopy, we demonstrate unique fingerprints for each reaction product, enabling aldehyde and ketone speciation. With the further addition of an isotopologue internal standard, we demonstrate aldehyde and ketone quantification at levels lower than those possible with colorimetric techniques. This method paves the way for a powerful and practical tool for analyzing these crucial chemical building blocks.

Direct Determination of Metallic Contamination on and in Wafers Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry

A new analytical technique has been developed for determination of metallic impurities on and in wafers using LA-GED-MSAG-ICP-MS. Up to 300 mm wafer can be analyzed directly without using a small enclosed chamber. Particles generated by a femto-second laser ablation were aspirated together with particle free clean air by an ejector and introduced to the ICP-MS (Inductively Coupled Plasma Mass Spectrometry) via GED (Gas Exchange Device). Particles in air could not be introduced to the plasma of ICP-MS directly because the Ar plasma could not be sustained when air was introduced. The GED exchanged air with Ar efficiently (> 99.98%), the particles came out from GED in Ar gas stream that could be introduced to the plasma of ICP-MS. For quantitation of LA-ICP-MS, MSAG (Metal Standard Aerosol Generation) was used. MSAG could introduce nearly a 100% of aqueous multi-element standard solution to the plasma of ICP-MS, which allowed precise quantitation using the method of standard addition while ablating wafer samples. The technique was used for the following applications:- Metallic contamination mapping of a wafer. Multiple spots (1 cm2/spot) of 300 mm wafer were laser ablated and analyzed by ICP-MS as shown in Fig.1. E6 - E7 atoms/cm2 of detection limit was obtained. The conventional VPD-ICP-MS technique uses a 1 mL scan solution to collect metallic impurities on an entire wafer surface of 300 mm wafer, and the collected solution is analyzed by ICP-MS giving E6 - E7 atoms/cm2 detection limit. It was impossible to get the contamination mapping information at such a low concentration. TRXRF has also been commonly used for the same purpose, but the detection limit is E10 - 12 atoms/cm2.- Particle measurement on a wafer. A spike recovery test of 20 and 50 nm Au nano-particle standard on Si wafer was performed, and individual nano-particle signals were detected by ICP-MS. The number of Au particle recovery was more than 85%. 200 nm SiO2 particles on Si wafer were also detected after the optimization of laser parameters.- Metallic contamination mapping on a wafer bevel. Several metallic contaminants were detected at certain spots of bevel, and E4 atoms of spot contamination could be detected.- Depth profile analysis of an ion implanted wafer. The laser ablation was performed on the same area repeatedly and the profile of As ion implanted wafer could be carried out in atmospheric pressure. This technique was also used for analysis of multi-layer film wafers.This paper explains how the new technique overcame the issues of the conventional LA-ICP-MS technique; why an entire wafer could not be analyzed and why an accurate quantitative analysis was impossible. Figure 1

Fabrication of 4-methoxyphenol chemical sensor with graphene oxide conjugated binary Co3O4/Y2O3 nanocomposite by linear sweep voltammetry

Combining binary metal nanoparticles (MNPs) with two-dimensional materials can create innovative nanocomposites with unique physical and chemical properties, which are particularly useful for developing efficient electro-chemical sensing systems. This study presents a unique approach for detecting and validating the hazardous substance 4-Methoxyphenol (4-MP) electrochemical approach with conjugated nanocomposite (NC). This approach utilizes an electrochemical sensor constructed on a glassy carbon electrode (GCE), modified with hybrid composite material including graphene oxide (GO) conjugated binary yttrium oxide (Y2O3) and cobalt oxide (Co3O4) as GO@Co3O4/Y2O3 NCs. After preparing the NCs using the solid-state chemical method, various techniques were used to characterize the materials by using various techniques including Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Ultraviolet–Visible Spectroscopy (UV/Vis), Brunauer–Emmett–Teller Surface Area Analysis (BET), and Transmission Electron Microscopy (TEM). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and impedance spectroscopy (EIS) were used to examine the electrochemical characterization and sensing application of the fabricated electrodes. Under standard laboratory circumstances, we used LSV to measure the 4-MP detection limit, which linear dynamic range (LDR) from 0.67 to 2.08 M. Based on the calibration curve’s slope, the sensor’s sensitivity was found to be 2.9 µAµM−1cm−2. It was calculated the limit of quantification (LOQ) of 0.19 M and a lower limit of detection (LOD) of 0.057 M. Compared to other modified electrodes for 4-MP detection, the composite electrode demonstrated superior electrocatalytic performance. The GO@Co3O4/Y2O3 NCs sensor demonstrates excellent selectivity, even among several interfering substances and metal ions. For optimization, different phosphate buffered saline (PBS) solutions with pH values ranging from 5.7 to 8.0 were used to evaluate the sensor activity. The sensor’s effectiveness in detecting unknown 4-MP concentrations was tested in various real-samples, including seawater, industrial wastewater, tap water, and well water, using a standard addition method. This study introduces a new approach for developing an electrochemical sensor aimed at monitoring environmental chemicals. The sensor incorporates cobalt nanoparticles on carbon materials to introduce the inorganic-carbon composite materials for the safety in environmental and healthcare applications on a large scale.

Application of continuous wavelet transforms for simultaneous estimation of domperidone and lansoprazole in capsule formulations

UV–Vis spectroscopy remains essential in pharmaceutical research and quality control due to its accessibility, simplicity, and effectiveness. However, overlapping spectra resulting from multicomponent drug formulations present challenges. Here, we describe a signal processing strategy using continuous wavelet transform (CWT) to resolve overlapping spectra of domperidone (DMP) and lansoprazole (LSP) for simultaneous quantification. Three different wavelet functions (Symlets 3, Coiflets 1, Daubechies 10), were found to be suitable for this purpose. Linear calibration curves were constructed using the CWT zero-crossing technique and the methods were validated by analyzing a set of synthetic mixtures, intra-and inter-day samples, and standard addition samples. The assay results of commercial capsule samples were compared with those obtained by derivative spectroscopy, and no significant statistical difference was observed. The proposed CWT methods demonstrated good compliance with the label claims and proved to be reliable, versatile, fast, and cost-efficient analytical methods without the need for preliminary separation procedures.