Spike Recovery Research Articles

Synthesis, characterization, and electrochemical application of novel poly(Cu2P4BCl4) based glassy carbon electrodes for determination of sulfamethoxazole in pharmaceutical serum and urine samples and Cow’s milk

The synthesis of the novel complex, [Cu2P4B]Cl4·H2O (in short Cu2P4BCL4), was confirmed by UV–Vis and FT-IR data after a straightforward ion exchange reaction. The electrochemical fabrication of the Nobel Cu2P4BCl4-based GCE was done potentiodynamically by scanning the potential of the glassy carbon electrode on the buffer solution containing 1.0 mM Cu2P4BCl4. EIS and CV were employed to characterize the surface of the developed sensor. The electroactive area and charge transfer capacity of the modified electrode were improved by about 2.5-fold area and 100-fold double-layer capacitor, respectively. The electrochemical activity of the Sulfamethoxazole (SMX) on the developed electrode was improved at around 3.1-fold peak intensities. The poly(Cu2P4BCl4)/GCE showed a wide linear range of the concentration of SMX from 0.1 to 200 µM at pH 6.5. The LOD and LOQ of the developed sensor were 0.112 nM and 0.375 nM, respectively, with the associated %RSD of 0.26 % (for n = 7). The validation of the real application of the fabricated electrode for the determination of SMX was investigated by detecting the cow’s milk sample, serum, and urine samples with spike recovery in the range of 97.5–103 %. The selectivity of the developed sensor towards SMX in the presence of potential interferants revealed an excellent recovery percentage in the range of 98.66–102.7 % in the presence of 50 to 200 % of potential interferents indicating an excellent accuracy and selectivity of the sensor. The stability and reproducibility of the Nobel sensor were investigated and revealed the best means for electrochemical determination of SMX from real cow’s milk, serum, and urine samples.

Conjugated molecularly imprinted polymers based on covalent organic frameworks: Fluorescent sensing platform for specific capture of urea and elimination of ethyl carbamate

This study described the preparation of an azide covalent organic framework-embedded molecularly imprinted polymers (COFs(azide)@MIPs) platform for urea adsorption and indirect ethyl carbamate (EC) removal from Chinese yellow rice wine (Huangjiu). By modifying the pore surface of COFs using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, COFs(azide) with a high fluorescence quantum yield and particular recognition ability were inventively produced. In order to selectively trap urea, the COFs(azide) were encased in an imprinted shell layer via imprinting technology. With a detection limit (LOD) of 0.016 μg L-1 (R2 = 0.9874), the COFs(azides)@MIPs demonstrated a good linear relationship with urea in the linear range of 0–5 μg L-1. Using real Huangjiu samples, the spiking recovery trials showed the viability of this sensing platform with recoveries ranging from 88.44 % to 109.26 % and an RSD of less than 3.40 %. The Huangjiu processing model system achieved 38.93 % EC reduction by COFs(azides)@MIPs. This research will open up new avenues for the treatment of health problems associated with fermented alcoholic beverages, particularly Huangjiu, while also capturing and removing hazards coming from food.

Candidate reference measurement procedure for serum 17‐hydroxyprogesterone quantification via isotope dilution liquid chromatography–tandem mass spectrometry

AbstractBackgroundAccurate quantification of 17‐hydroxyprogesterone (17‐OHP) in serum is vital for clinical and research applications. However, inter‐laboratory variability in test results exists owing to the lack of a standardized reference measurement procedure (RMP). Therefore, in this study, we developed a highly accurate, cost‐effective, and user‐friendly candidate RMP (cRMP) for analyzing 17‐OHP in serum.MethodsWe quantified 17‐OHP in serum using a one‐step liquid–liquid extraction method with the addition of 17‐OHP‐13C3, followed by liquid chromatography–tandem mass spectrometry. The ability of these methods to suppress interference was evaluated by chromatographic analysis. We assessed accuracy, specificity, the lower limit of quantitation, linearity, and matrix effects by following the standards specified by the Clinical and Laboratory Standards Institute. The consistency between the developed cRMP and the chemiluminescence method was evaluated through experiments with 120 clinical samples.ResultsThe developed cRMP required only 8 min for accurate quantification of serum 17‐OHP without bias from matrix effects or interference from 19 metabolites added as potential interferents. The method exhibited favorable measurement performance, with a quantitation limit of 0.086 ng/mL, linear range of 0.1–400 ng/mL, a total imprecision of ≤2.90%, spike recovery of 100.1%–100.6%, and relative deviations from assigned target values (RfB Institution) of −2.91% to 1.10%. The cRMP demonstrated good consistency with the conventional assay (chemiluminescence method), with a correlation coefficient R of 0.96977.ConclusionA cRMP with high accuracy, cost‐effectiveness, and convenient operation was developed for quantifying 17‐OHP in serum. Its simplicity and robust performance make it an invaluable addition to the arsenal of analytical tools available for laboratories. This method can enhance the accuracy and reliability of 17‐OHP measurements across various laboratories.

Aucklandia lappa Decne carbon dots guided chemiluminescence: A sensitive detection strategy for salicylic acid

In this study, a novel chemiluminescent system was developed utilizing carbon dots (CDs) for the sensitive detection of salicylic acid. P,Cl co-doped carbon dots (P, Cl-CDs) was synthesized using discarded Aucklandia lappa Decne leaves as precursor materials through a one-step hydrothermal method. The morphology, structure, elemental composition, and properties of P, Cl-CDs were characterized by various methods including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized P, Cl-CDs exhibited uniform particle size and excellent water solubility. It was observed that P, Cl-CDs could significantly enhance the chemiluminescence intensity of the acidic KMnO4 system by approximately 10 times. While salicylic acid could inhibit the acidic KMnO4 system sensitized by P, Cl-CDs. Based on this phenomenon, a new system for detecting salicylic acid was established. Under optimal experimental conditions, the concentration of salicylic acid displayed a linear relationship in the range of 1 to 100 μM, achieving a limit of detection (LOD) of 4.2 nM and a relative standard deviation (RSD) of 0.9 % (n = 11). The method was successfully applied to determine salicylic acid in aspirin tablets, yielding spike recoveries within the range of 96.9 %–104.3 %.

Simplified uv spectrophotometric analysis of abiraterone acetate in bulk and formulations

Abiraterone acetate is an orally administered selective androgen biosynthesis inhibitor It is an irreversible inhibitor of cytochrome CYP17AThis enzyme is expressed in testicular, adrenal, and prostatic tumour tissues and is required for androgen biosynthesis.Abiraterone is used in combination with prednisone to treat a certain type of prostate cancer that has spread to other parts of the body.A Novel, simple, accurate, precise and reproducible UV spectrophotometric method has been developed and validated for estimation of Abiraterone acetate bulk and its formulations. After determining the solubility we had selected methanol as a solvent and Abiraterone acetate has absorbance at the wavelength of maximum ?max254nm. The drug was characterized by the melting point test. Proposed method was precise with RSD less than 2%. linearity test was approved within the range of 10-60µg/ml for with the correlation coefficient (R2) of 0.9991. Accuracy was 100.03%. LOD and LOQ were 0.006µg/ml and 0.018µg/ml respectively. The spike recovery of Abiraterone acetate in tablet was 99.88%.

Perspective on sample preparation fundamentals

The primary objective of this contribution is to offer insights into fundamentals associated with typical sample preparation, facilitating rational design of new analytical technologies and effective optimization of existing techniques. Sample preparation stands a pivotal stage in the analytical process. Unfortunately, the optimization of associated parameters often relies on trial and error rather than systematic scientific methodologies. If an extraction method provides good recovery of spikes of standards, it is assumed that it works well and no further consideration is given to the underlying principles driving its performance. In the realm of sample preparation, the fundamentals of method optimization are not accorded the same significance as in other technologies, such as chromatography or mass spectrometry. Consequently, the fundamentals of sample preparation are typically overlooked in analytical chemistry curricula.A notable impediment to progress in the sample preparation area is underdeveloped understanding of the fundamentals of extraction, particularly when dealing with natural, often complex samples, where native analyte-matrix interaction is different compared to spikes. This stands in contrast to the physiochemically simpler systems employed in separation and quantification steps, such as chromatography and mass spectrometry.A careful consideration of the underlying principles of sampling and sample preparation can lead to the creation of more efficient and environmentally friendly technologies. Embracing these principles aligns with global shift towards more sustainable future, challenging the perception that sample preparation is solely an artistic endeavour and highlighting its potential as a scientifically grounded discipline.

Electrochemical detection of heavy metal ions in water using MWCNT/ZnO nanocomposite

A nanocomposite of multi-walled carbon nanotubes (MWCNTs) decorated with zinc oxide nanoparticles (ZnO NPs) was fabricated via an in-situ hydrothermal approach and implemented as a modified electrode for stripping voltammetric detection of dissolved heavy metal ions. The MWCNT/ZnO exhibited a high specific surface area of 53 m2/g and charge transfer conductivity amplified to 26 S/cm. By square wave voltammetry, the nanocomposite sensor achieved wide linear detection of Cu(II) from 1 to 800 ppb, Pb(II) from 5 to 1000 ppb, and Hg(II) from 1 to 900 ppb, along with low limits of detection reaching 0.8, 1.2, and 0.7 ppb, respectively. The 3–5X enhanced sensitivity versus an unmodified screen-printed carbon electrode confirms performance gains supplied by the tailored hybrid interface. Selectivity testing produced distinct, well-resolved oxidation peaks for each metal ion target that remained unaffected by high off-target concentrations of Mn(II), Co(II), and Fe(III) interferents. Accurate spike recoveries between 95% and 102% were obtained from quantifying ternary mixtures across various Cu(II):Pb(II):Hg(II) compositions, substantiating the capability for simultaneous multianalyte analysis. The simple preparation, high sensitivity and selectivity, and accuracy for direct water testing validates the nanocomposite as a practical portable sensor for on-site toxic heavy metal detection.

A luminescent organic cocrystal for detecting 2,4-dinitroaniline

2,4-dinitroaniline (2,4DNBA), a significant hazardous chemical, is extensively used in industry and agriculture. The chemical accumulates in the environment for a long time, causing irreversible damage to the ecosystem. Currently, it is quite challenging to identify it by common analysis and detection techniques. Herein, a luminescent organic cocrystal (TCNB-8HQ) was prepared using 1,2,4,5-tetracyanobenzene (TCNB) as the electron acceptor and 8-hydroxyquinoline (8HQ) as the electron donor. The prepared TCNB-8HQ was used as a fluorescent probe with a fast and specific response to 2,4DNBA. This detection method possessed a linear range of 0.5–200 μmol/L with a detection limit as low as 0.085 μmol/L to detect 2,4DNBA in real samples with satisfactory spiking recovery. As revealed by fluorescence spectrum and UV–vis absorption spectrum, the detection mechanism involved competitive absorption between cocrystal material and 2,4DNBA. Moreover, the feasibility of the system was explored by preparing portable indicator strips for 2,4DNBA from organic cocrystal (TCNB-8HQ). This study not only provided an environmentally friendly gram–level preparation strategy to synthesize the fluorescent material but also investigated their application in chemical detection.

Itemized determination of As, Sb, Bi, Se, and Ge in graphite sample by HG-AFS with high-temperature microwave digestion.

In this paper, we optimized a method for fast and accurate determination of five impurity elements (As, Sb, Bi, Se, and Ge) in graphite samples to overcome the shortcomings of existing methods, such as complicated equipment, cumbersome process, multiple-time preparation, separate determination, and large error in results. Graphite samples were digested with HNO3-H2SO4-HClO4-HF in a high-temperature and high-pressure microwave digestion apparatus, and the elements were extracted and determined separately by AFS (atomic fluorescence spectrometry). There is no element loss during the processing and analysis of this method. The spike recoveries (As: 90.30%-102.3%, Sb: 90.73%-110.0%, Bi: 90.00%-99.67%, Se: 93.33%-110.0%, Ge: 92.26%-104.2%) and precision (RSD%; As: 1.34%-8.96%, Sb: 2.67%-7.10%, Bi: 1.83%-4.58%, Se: 0.36%-3.25%, Ge: 4.41%-8.65%) meet the requirements of the corresponding quality specifications. The method has some advantages (such as no elemental loss, fast testing, strong element targeting, and accurate results), and thus can achieve batch determination of graphite samples. The optimized method for graphite sample and final solution preparations can be used for diverse spectrometric technologies, and that for spectrometer conditions have reference value for HG-AFS instruments.

Identification method of 2-methylisoborneol and geosmin in water by purge and trap-gas chromatography-mass spectrometry

To establishe an analysis and identification method for 2-methylisoborneol(2-MIB) and geosmin(GSM) in water using purge and trap-gas chromatography-mass spectrometry. The samples were enriched and analyzed using a purge and trap system, followed by the separation on a DB-624(30 m×0.25 mm, 1.4 μm) chromatographic column. Quantification was performed using gas chromatography-mass spectrometry with the selected ion monitoring and internal standard calibration. The calibration curves for 2-MIB and GSM showed an excellent linearity in the range of 1 to 100 ng/L with R~2 values greater than 0.999. The detection limit and quantification limit for both 2-MIB and GSM were 0.33 ng/L and 1.0 ng/L, respectively. Spike recovery experiments were further carried on the source water and drinking water at three concentration levels. It showed that the average recoveries were from 82.0% to 111.0% for 2-MIB while 84.0% to 110% for GSM. Additionally, the test precision of 2-MIB and GSM ranged from 1.9% to 7.3% and 1.9% to 5.0%(n=6), respectively. The analysis of multiple samples including the local source water, treated water and distribution network water confirmed the existence of 2-MIB and GSM. Compared to the national standard(GB/T 5750.8-2023), the proposed method enables fully automated sample introduction and analysis without the extra pre-treatment. It provides the advantages of simplicity, good repeatability and high accuracy.

Enantiomeric analysis of chiral phenyl aromatic compounds by coated capillary electrochromatography based on aMOF-on-MOF stationary phase.

Chiral phenyl aromatic compounds (CPACs) are widely used in drug development, food/cosmetic production, and other organic synthesis processes, and their different enantiomers have distinct physiological activities and application differences. A double-layer metal-organic framework composite (MOF-on-MOF) was obtained by in situ synthesis of chiral metal-organic framework (CMOM-3S) on the surface of an iron-based metal-organic framework (NH2-MIL-101(Fe)). According to ourinvestigation, MOF-on-MOF composite was for the first time applied tothe stationary phase of capillary electrochromatography (CEC), and enantioseparations of eight CPACs were accomplished. Compared with single CMOM-3S, the enantioseparation performance of the coated capillary columns based on NH2-MIL-101(Fe)@CMOM-3S was improved by 34.07 ~ 720.0%. The R-/S-mandelic acid in actual sample (apricot leaves) was detected by the newly CEC system to be 0.0118mgmL-1 and 0.0523mgmL-1, respectively. The spike recoveries were 96.60 ~ 104.7%, indicating its good stability and accuracy. In addition, the selective adsorption capacity of MOF-on-MOF composites was verified by adsorption experiments.

Analytical Methods for Extraction of Microplastics from Compost in Sri Lanka

Microplastics (MP) are the plastics with 1 μm-5 mm dimensions. Meanwhile, compost has been identified as a major source of MP in the soil, although compost is a great plant nutrient source, and it provides tremendous benefits for crops. This is primarily ascribed to most of the compost being produced through Municipal Solid Waste Management projects. However, due to the detrimental impacts on soil’s biological, physical, and chemical health, together with the high accumulation probability of MP caused by repeated application of compost, regulations should be implemented on the limitation of MP in compost. Even though there are a few different methods available in the literature for MP extraction and quantification in organic matter (OM)-rich matrices, like compost, sludge, and sediments, a properly validated, routine analytical procedure is missing in Sri Lanka Standards (SLS). Therefore, in this project, the effectiveness of four different MP extraction methods in the literature were compared and validated for compost, to implement an MP analysis method suitable for compost specifications in the SLS. The methodologies included MP extraction by density separation using NaCl or ZnCl2 solutions followed by digestion of OM using 30% KOH: NaOCl solution or Fenton’s reagent. The common MP analysis method for the four protocols was staining with the hydrophobic, fluorescent stain Nile Red, and visual observation. Digestion efficiency of OM and spike recovery of Polystyrene (PS), Polyvinyl Chloride (PVC), Polyethylene terephthalate (PET), High-Density Polyethylene (HDPE), and Polypropylene (PP) microplastics in 1-2 mm dimension by the four MP extraction methods were compared for the validation. T-tests (confidence level=95%) were carried out to determine the significant difference between the OM digestion efficiency in each of the four methods. Each of the combinations compared was significantly different from the other except for ZnCl2/Fenton and NaCl/30% KOH:NaOCl comparison. Meanwhile, the OM removal by ZnCl2/Fenton and NaCl/30% KOH:NaOCl excluding the density separation step also was not significantly different. The spike recovery analysis showed ZnCl2/Fenton combination as the best out of the tested combinations with above 95% recovery percentages for PS, PVC, PP and 100 for HDPE and PET by particle count. However, precipitate formations in the ZnCl2/Fenton combination might cause false negative or positive results for spike recovery when applied to the real samples with smaller MP. The extraction reagents, NaCl was not an ideal solution and ZnCl2 was a good solution for the MP types used. Moreover, in this project, double digestion of OM with NaCl/30% KOH:NaOCl before and after the density separation with ZnCl2 is suggested as a novel and more effective OM digestion protocol before Nile Red staining, and further validations are suggested prior to its final implementation.
 
 Keywords: Microplastics, Compost, Extraction, Organic matter

Deep eutectic solvent-based ferrofluid for highly efficient preconcentration and determination of metronidazole by vortex-assisted liquid-phase microextraction under experimental design optimization

To determine metronidazole in water samples, we developed an environmentally friendly, efficient, and straightforward ferrofluid-based liquid-liquid microextraction sample pretreatment technique. It is coupled with a high-performance liquid chromatography-ultraviolet analytical technique known for its sensitivity, speed, and precision. The magnetic separation of metronidazole-containing ferrofluid from the matrix was effortlessly achieved through the application of an external magnetic field, eliminating the need for centrifugation. Response surface optimization was employed to systematically determine the key experimental parameters influencing extraction efficiency, including pH, NaCl concentration, ferrofluid volume, and vortex duration. With a low detection limit (0.116 ng mL−1), a broad linear range between 0.5 and 700 ng mL−1 was achieved at optimal conditions. Additionally, acceptable spiking recoveries (94.3–97.3 %) and RSD values (≤3.7 %) for intra- and inter-day precision were attained in water samples. In conclusion, the effectiveness of the vortex and ferrofluid combination, along with the convenience of collection and elimination of the need for centrifugation, bestows a highly valuable technique for determining metronidazole in water samples.

First report for fluorometric determination of kasugamycin based on amino acid-functionalized bimetallic nanoclusters

A rapid and straightforward turn-off fluorescence sensor has been developed for the detection of kasugamycin (KASN) using tryptophan-capped silver/gold bimetallic nanoclusters (Trp@Ag-Au NCs). The sensor's parameters, including reaction time and solvent type, were optimized to enhance its performance. The fluorescence emission of Trp@Ag-Au NCs is quenched upon the addition of KASN due to the aggregation of the Trp@Ag-Au NCs induced by the electrostatic and non-covalent interactions between the negatively charged Trp@Ag-Au NCs and the positively charged KASN. The sensor exhibited excellent sensitivity for KASN detection, demonstrating a linear concentration range from 0.5 to 500 µM and a low limit of detection (LOD) of 0.14 µM, determined at a signal-to-noise ratio of 3. These values indicate the sensor's ability to accurately detect KASN even at low concentrations. To evaluate its practical utility, spike recovery analysis was performed in synthetic samples, confirming its effectiveness in real-world sample matrices. The optimized sensor parameters, wide linear range, low LOD, and successful application in various samples highlight the sensor's potential for practical use in various applications, including food safety and biomedical research. Its simplicity, rapidity, and sensitivity make it a promising tool for the detection of KASN.

Validation of a newly developed immunoassay for TDP-43 in human plasma

The level of TAR DNA-binding protein 43 (TDP-43) in human blood was reported to have potential for use as a specific fluid biomarker, which represents disease-specific pathologies, for TDP-43 proteinopathies, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), which involves the aggregation and deposition of TDP-43 in the nervous system. However, at present, no reliable immunoassay can precisely quantify TDP-43 in human plasma and detect the difference in plasma TDP-43 levels between patients with ALS and controls. We recently developed a novel ultrasensitive immunoassay to quantify TDP-43 in human plasma, and in this study, we analytically validated this assay for application as a diagnostic biomarker for TDP-43 proteinopathies. The novel TDP-43 assay was assessed for the limit of detection, lower limit of quantification, intra- and interassay variation, linearity, parallelism, and analytical spike recoveries. Additionally, 17 pilot plasma samples obtained from patients with ALS and age-matched controls were analyzed using the assay. Our novel TDP-43 assay showed sufficient analytical performance to quantify TDP-43 in human plasma, with high sensitivity (LOD and LLOQ of 0.109 and 0.759 pg/mL, respectively) and high intra- and interassay precision (%CV) below 15 %. The experimental results for spike recovery, parallelism, and dilution linearity were also acceptable. In addition, despite a small sample size, significant differences in the plasma levels of TDP-43 were found between patients with ALS and controls (ALS, 66.63 ± 20.52 pg/mL; control, 42.70 ± 23.06 pg/mL, p = 0.0330). These results support that our novel TDP-43 assay is a reliable and innovative method for the quantification of TDP-43 in human plasma and can be a potential blood-based biomarker for the diagnosis of TDP-43 proteinopathies. Further large-scale studies are warranted to validate its usefulness.

Carboxyl-functionalized two-dimensional MXene-Au nanocomposites were prepared as SERS substrates for the detection of melamine in dairy products.

In the present study, we address the limitations of conventional surface-enhanced Raman scattering (SERS) techniques for sensitive and stable detection of melamine in food products, especially dairy. To overcome these challenges, we developed a novel SERS-active substrate by incorporating gold nanoparticles (AuNPs) onto carboxyl-functionalized two-dimensional (2D) MXene material doped with nitrides, specifically Au-Ti2N-COOH. Our strategy leverages the unique physicochemical properties of MXene, a class of atomically thin, 2D transition metal carbides/nitrides, with tunable surface functionalities. By modifying the MXene surface with AuNPs and introducing carboxyl groups (-COOH), we successfully enhanced the interaction between the substrate and melamine molecules. The carboxyl groups form hydrogen bonds with the amino groups on the melamine's triazine ring, facilitating the adsorption of melamine molecules within the 'hotspot' regions responsible for SERS signal amplification. A series of characterization methods were used to confirm the successful synthesis of Au-Ti2N-COOH composites.Using Au-Ti2N-COOH as the SERS substrate, we detected melamine in spiked dairy product samples with significantly enhanced sensitivity and stability compared to nitride-doped MXene alone. The detection limit in liquid milk stands at 3.7008 μg kg-1, with spike recovery rates ranging from 99.84% to 107.55% and an approximate RSD of 5%. This work demonstrates the effectiveness of our approach in designing a label-free, rapid, and robust SERS platform for the accurate quantitation of melamine contamination in food, thereby mitigating health risks associated with melamine adulteration.

A novel ratiometric design of microfluidic paper-based analytical device for the simultaneous detection of Cu2+ and Fe3+ in drinking water using a fluorescent MOF@tetracycline nanocomposite.

The regular and on-site monitoring of ions in drinking water is essential for safeguarding public health, ensuring high water quality, and preserving the ecological balance of aquatic ecosystems. Thus, developing a portable analytical device for the rapid, cost-effective, and visual on-site detection of multiple environmental pollutants is notably significant. In the present work, a novel ratiometric microfluidic paper-based analytical device (μPAD) was designed and developed for the simultaneous detection of Fe3+ and Cu2+ ions in water samples taking advantages from built-in masking zone. The μPAD was functionalized with a greenish-yellow fluorescent Zn-based metal-organic framework@tetracycline (FMOF-5@TC) nanocomposite, and the ratiometric design was based on the change in emission color from greenish yellow (FMOF-5@TC) to blue (FMOF-5). The μPAD consisted of one sample zone linked to two detection zones via two channels: the first channel was for the detection of both ions, while the second was intended for detecting only Cu2+ ions and comprised a built-in masking zone to remove Fe3+ ions prior to reaching the detection zone. The corresponding color changes were recorded with the aid of a smartphone and RGB calculations. The linear ranges were 0.1-80 μM for Cu2+ and 0.2-160 μM for Fe3+, with limits of detection of 0.027 and 0.019 μM, respectively. The simple μPAD design enabled the simultaneous detection of Cu2+ and Fe3+ ions in drinking water samples with excellent accuracy and precision, with spike recoveries of 81.28-96.36% and 83.01-102.33% for Cu2+ and Fe3+, respectively.

Trace analysis of steroid hormones in tear films via liquid chromatography-high resolution mass spectrometry.

In this study, we developed an ultra-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (UPLC-Q-Orbitrap-MS) method for the analysis of seven steroid hormones in human tears. Tear samples were collected using Schirmer strips and extracted with methanol. The analytes were then subjected to a "one-step" clean-up process using solid phase extraction, and subsequently separated on a C18 column by UPLC. Detection was performed using an Orbitrap MS detector, operated at a resolution of 17 500 FWHM in parallel reaction monitoring mode with an HESI ion source under positive ionization. Our data showed the sensitivity with limits of detection for steroid hormones in tears ranging from 0.12 to 0.86 pg μL-1, and high correlation coefficients in the corresponding concentration range exceeding 0.99. The results also had high accuracy with spiking recoveries for spiked tear samples ranging from 78.2% to 96.7% and relative deviations of less than 15%. Furthermore, we successfully applied our method to detect the pg μL-1 level of steroid hormones in real human tear samples. Our findings showed the potential of this UPLC-Q-Orbitrap-MS method for the accurate and sensitive determination of steroid hormones in human tears, providing a valuable tool for ophthalmic and endocrine research.

Eco-friendly spectrophotometric methods for concurrent analysis of phenol, 2-aminophenol, and 4-aminophenol in ternary mixtures and water samples: assessment of environmental sustainability.

Recently, there has been a high demand for green procedures in analytical chemistry, particularly those utilizing eco-friendly solvents. In this context, three feasible derivative UV spectrophotometric methods namely, derivative ratio-zero crossing spectra (DRZCS), double divisor ratio spectra (DDRS), and successive derivative subtraction coupled with constant multiplication (SDS-CM) were developed to quantify a ternary mixture of phenol (P), 2-aminophenol (2-AP), and 4-aminophenol (4-AP) in real water samples simultaneously, using ethanol as a solvent. The established methods demonstrated a good linear range, covering 2-60 μg mL-1 for P and 2-50 μg mL-1 for 2-AP and 4-AP, in all approaches with a high correlation coefficient (R2 ≥ 0.9995). In compliance with ICH guidelines, the methods exhibited acceptable precision and accuracy, as indicated by good spike recovery with low relative standard deviations. The eco-friendliness of the UV spectrophotometric approach was assessed using analytical eco-scale (AES), analytical greenness (AGREE), and analytical greenness metrics for sample preparation (AGREEprep). These evaluations confirmed the eco-friendliness of the proposed methods in terms of solvents, energy consumption, and waste generation. The proposed procedure proved to be efficient in quantifying each component in laboratory-synthesized mixtures and real water samples, thanks to its simplicity, accuracy, sensitivity, and cost-effectiveness.

Capillary-flow driven microfluidic sensor based on tyrosinase for fast user-friendly assessment of pesticide exposures.

Pesticides are primarily used in agriculture to protect crops and extend their longevity. However, pesticide exposure has been linked to various acute and chronic health effects, raising significant environmental concerns. Current detection methods are often expensive and time-consuming, relying on complex instruments. Although enzyme-inhibition-based microfluidic paper-based analytical device (mPAD) platforms offer an easier alternative, they suffer from slow analyte transport and analyte adsorption issues in microchannels. Consequently, there is a need for a fast, simple, and cost-effective point-of-need platform for pesticide sensing. In this study, we present a rapid microfluidic platform for on-site pesticide residue detection. Unlike traditional mPAD platforms, our system transports pesticide samples through hollow capillary channels within seconds without adsorption of pesticides in the microchannels. While much research has focused on acetylcholinesterase inhibition on paper, this study is the first to introduce a tyrosinase inhibition-based assay on a paper platform for pesticide detection. Ziram, a representative dithiocarbamate pesticide, was detected using a colorimetric enzymatic inhibition assay. A limit of detection (LoD) of 1.5 ppm was obtained. In this study, we optimized the fast-flow device, assessed its stability and susceptibility to various interferences, and conducted real-sample tests using glove extraction to evaluate its capability in real-world settings. Spike recovery analysis revealed an extraction efficiency of 82.5% to 87.5% for leather gloves and 68.9% to 71.9% for nitrile gloves. This platform demonstrates strong selectivity against interferences, with the enzyme retaining 90% activity even after a week under the established storage protocols with room for further investigation. While primarily a proof of concept, this device shows promise as an additional tool for pesticide detection, with potential future integration into multiplexed devices.