Inter-day Analysis Research Articles

Green synthesis of thiazole bis-imines as fluorometric sensor for determination of lead in environmental, biological, and food samples

In this work, we describe for the first time the synthesis of a thiazole bis-imine fluorometric sensor for the selective determination of Pb2+ in environmental, biological, and food samples. The novel molecules were obtained through a multicomponent reaction using a green and environmentally sustainable methodology. Synthesized chemical sensors were characterized using spectroscopic techniques to structural elucidation, including UV–Vis, FTIR-ATR, 1H and 13C NMR. One of these sensors exhibited remarkable selectivity for the Pb2+ ion at pH 3, forming a stable 1:1 (metal:ligand) complex. Additionally, the reaction conditions for complex formation were optimized, resulting in a method with a linear range of 0.667–10 μg L−1 and a detection limit of 0.18 μg L−1. Furthermore, method validation reinforced its reliability, showing low relative standard deviation in both intra-day and inter-day analyses. Recovery experiments ranged from 83.53 % to 119.10 %. This study represents a significant and innovative advancement in the development of rapid, sensitive, and alternative methods for the detection of potentially toxic metals in a wide range of samples employing a green multicomponent reaction of thiazole bis-imines.

Analytical Method Validation and Simultaneous Determination of Ketotifen Fumarate and Cyproheptadine Hydrochloride in Divided Powder by RP-HPLC Method

Ketotifen fumarate and cyproheptadine HCl are the most popular prescription for children at “X” hospital in Yogyakarta. The interest for studying this divided powder was related to the stability test towards human health. Hence, it was important to developed a validated analytical method to quantify content of active drug from sample. In this study, a reversed phase HPLC (RP-HPLC) method was validated and applied for determining content of ketotifen fumarate and cyproheptadine hydrochloride in divided powder. The developed RP-HPLC method was met the requirement of selectivity and sensitivity. Calibration curve formulas of ketotifen fumarate and cyproheptadine hydrochloride were y = 27714x-79111 (r=0.9945) and y = 26324x+72581 (r=0.9935) in the range of 10.9-54.5 and 10.6-53.0 µg/mL, respectively. Accuracy and intermediate precision were assessed on both standard solution and samples spiked with standard solution of ketotifen fumarate and cyproheptadine hydrochloride. It was found that both standard solution and the spiked samples solution were met the requirement of recovery of 80-110% and RSD of less than 7.3% for intraday and interday analysis. Content of ketotifen fumarate and cyproheptadine hydrochloride in sample (n=7) were 16.574±0.098 and 30.640±0.035 µg/mL, respectively. It can be concluded that the RP-HPLC method was successfully validated and applied in the determination of ketotifen fumarate and cyproheptadine hydrochloride in divided powder.

On-line enrichment and separation of glycoprotein by capillary electrophoresis based on pH response coating column

A capillary column coated with 3-aminophenylboronic acid (APBA)-functionalized gold nanoparticles (AuNPs@APBA) was prepared via electrostatic self-assembly. The coated column exhibited anti-nonspecific adsorption of glycoproteins, enabling selective online enrichment during capillary electrophoresis (CE). First, gold nanoparticles (AuNPs) were synthesized using the sodium citrate reduction method. Then, APBA was self-assembled electrostatically on the surface of the AuNPs to obtain AuNPs@APBA. This nanomaterial was bonded to the inner wall of a capillary through ion adsorption to produce a AuNPs@APBA-coated capillary column. Glycoproteins were adsorbed via bond formation with boric acid groups under alkaline conditions (pH 8) to generate borate esters. Under acidic conditions (pH 3), the borate esters dissociated to release the glycoproteins, thereby achieving the selective online enrichment and separation of glycoproteins. The AuNPs and AuNPs@APBA were characterized using Fourier transform infrared spectroscopy, and their sizes and Zeta potentials were determined. In addition, the electroosmotic flow (EOF) of the AuNPs@APBA-coated capillary column was measured. The results showed that the surface of the AuNPs was successfully modified with APBA and that AuNPs@APBA was adsorbed on the inner wall of the capillary. The peak area of ovalbumin (OVA) on the AuNPs@APBA-coated column was 26.46 times higher than that on a bare column via conventional electrophoresis. In contrast, the peak area of bovine serum albumin (BSA) only increased by 8.47 times, indicating that the AuNPs@APBA coated column selectively enriched glycoproteins. Evaluation of the reproducibility and stability of this method revealed that the AuNPs@APBA coated capillary column could be used continually for 33-67 h. The relative standard deviations (RSDs) of the peak areas for intra-day (n=5) and inter-day (n=6) analyses were 2.2% and 3.0%, respectively. The developed method was successfully applied to enrich glycoproteins in a 1×106-fold diluted egg white sample. Glycoproteins were not detected using conventional electrophoresis on the bare column, whereas the AuNPs@APBA-coated capillary column effectively enriched and separated glycoproteins, resulting in a peak area of 10469 mAU·ms. Furthermore, the entire enrichment and separation process was completed within 3 min. This new online enrichment and separation method for glycoproteins has the advantages of low sample consumption, simple operation, and high separation efficiency.

A highly structured Au-grafted nanoporous gold for surface-enhanced Raman scattering detection of ferbam

The expansive potential of surface-enhanced Raman scattering (SERS) has been well-established; however, the primary bottleneck hindering its routine analytical and commercial implementation is the poor signal reproducibility and challenges in substrate fabrication. Thus, the current work attempts to synthesize a scalable and reproducible nanoporous gold (npAu) decorated with gold (Au) nanoparticles to generate a highly structured Au@npAu nanocomposite. The substrate fabrication completes via three distinct routes: i) selective dealloying to form npAu on the Au film, ii) the fast deposition (i-t = −0.8 V, t = 10.0 s) of Au atoms across the npAu surface, and finally iii) the precise growth control of the generated Au@npAu by a series of by oxidation-reduction cycles (−0.03 to −0.4 V for 80.0 segments at ν = 50.0 mVs−1). The simulations of the dealloyed npAu and the final Au@npAu nanocomposite showed that the reduced interparticle spacing and ligament size in the Au@npAu nanocomposite is crucial for forming abundant "hot spot" regions with highly concentrated electromagnetic fields. The Au@npAu substrate reproducibility was assessed on 400.0 sites for SERS spectral acquisition with a relative standard deviation of 9.22 %. Furthermore, the Au@npAu was checked under different preparation batches for intra- and inter-day analysis and storage for 20.0 days with good stability. Finally, the substrate was checked for direct SERS detection of ferbam residues with a 4.34 × 10−9 mol L−1 sensitivity and examined in real samples with satisfactory recoveries (97.63 ± 1.95%–99.16 ± 0.24 %). This work offers a promising avenue towards highly reproducible, scalable and universal Au@npAu SERS substrate fabrication in diverse SERS-related applications.

Investigation of monosodium glutamate content in flavors, seasonings, and sauces from local markets in Turkey.

Monosodium glutamate (MSG) is a flavor-enhancing compound used to elevate the flavor profiles of various foods. This flavor enhancer is the sodium salt of L-glutamic acid and is widely used in foods, such as flavorings, seasonings, sauces, and instant soups. The potential health effects of MSG consumption, particularly the health issues that excessive consumption could lead to, have been the focus of social concerns. It is stated that excessive consumption of MSG can cause cardiovascular diseases, obesity and diabetes, kidney damage, hypertension, anxiety, and memory impairment. The maximum permissible amount of MSG in foods is set at 10 g/kg according to the Turkish Food Codex. The aim of this study is to develop an appropriate method for analyzing the MSG content within the various food samples like flavorings, seasonings, and spices sold in Turkish local markets. The validation parameters of the developed method were examined and it was found that the developed method corresponds to the recommended values. The limit of detection and the limit of quantitation values were calculated as 4.78 ng/mL and 15.93 ng/mL, respectively. Recovery % was determined to be 100.96% in intra-day and 132.22% in inter-day analyses for the precision of the method. The results compared to the values specified in the Turkish Food Codex Food Additives Regulation and samples that purportedly did not contain MSG on their labels were found to contain MSG.

Dispersive micro Solid-Phase extraction with Bimetallic Ni, Zn-MOF sorbent and gas chromatography method for Organophosphorus pesticide determination in environmental water samples

A dispersive micro solid-phase extraction coupled with the GC-FID method was developed to determine three Organophosphorus pesticides: Fenitrothion, Chlorpyrifos, and Diazinon. Various sorbents, including Fe3O4 NPs, Zn-MOF, Ni-MOF, Bimetallic Ni, Zn-MOF, and Fe3O4 NPs@SiO2@ Bimetallic Ni, Zn-MOF, were synthesized and evaluated for their extraction efficiency of OPPs. Fe3O4 NPs@SiO2@ Bimetallic Ni, Zn-MOF was identified as the optimal sorbent based on its performance. The affective factors in the procedure were optimized using one factor of the time and experimental design methods. The significant factors in this method included sorbent amount, extraction time, and desorption solvent volume with an optimum value of 37 mg, 8.3 min, and 231 µL, respectively. Under optimized conditions, the method exhibited distinct linear ranges for Fenitrothion, Chlorpyrifos, and Diazinon, ranging from 0.24 to 259, 0.17–234, and 0.25–247 ng mL−1, respectively, with high corresponding R2 values (0.9947, 0.9929, and 0.9943). The limits of detection (LOD) were determined based on three times the standard deviation of the blank sample divided by the slope of the calibration curve for each OPP to be 0.07, 0.05, and 0.07 ng mL−1 for Fenitrothion, Chlorpyrifos, and Diazinon, respectively, while the limits of quantification (LOQ) were 0.24, 0.17, and 0.25 ng mL−1. Precision was assessed by calculating intra-day and inter-day relative standard deviation (RSD%) values in one day and three consecutive days with three replicates of each analysis for three concentrations of 10, 25, and 50 ng mL−1, which were found to be below 4.27 %, 4.35 %, and 4.32 % for Fenitrothion, Chlorpyrifos, and Diazinon, respectively, for intra-day analysis, and below 5.43 %, 5.11 %, and 5.29 % for inter-day analysis, respectively. Additionally, the enrichment factor (EF) values for Fenitrothion, Chlorpyrifos, and Diazinon with a concentration of 20 ng mL−1 were determined to be 78.6, 82.4, and 75.7, respectively. Analysis of spiked real samples in two concentrations of 5.0 or 25.0 ng mL−1, such as tap water, river water, dam water, and well water, revealed recovery percentages in the range of 91.2 % to 97.7 %, with relative standard deviations ranging from 3.79 % to 4.98 %, further validating the method’s reliability for practical applications. Overall, the method provides wide linearity, low LODs and LOQs, responsible RSDs, high EFs, and proper recovery percentages for determining OPPs.

Elimination patterns of dimetridazole in egg of laying hens and tissues of broiler after oral administration.

Dimetridazole (DMZ) is a broad-spectrum anti-anaerobic and antiprotozoal drug extensively used for the control of blackhead disease in poultry (especially turkeys). The presence of DMZ and its metabolites in animal food poses potential risks to human health. In this study, we developed a high-performance liquid chromatography tandem mass spectrometry (HPLC/MS-MS) method for the precise detection of DMZ and its metabolite 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI). Our results demonstrate a strong linear relationship (r2 > 0.99) between the concentrations of DMZ and HMMNI in tissues and egg within the range of 1~100 ng/g. The limits of detection (LOD) were determined to be 0.5 ng/g, with corresponding limits of quantification (LOQ) at 1.0 ng/g. Furthermore, average recoveries in tissues and egg fell within the range of 84.90% to 103.01%, with coefficients of variation below 15% for both intra-day and inter-day analyses. To investigate the residue elimination pattern of DMZ and HMMNI, diets containing 500 mg/kg DMZ were fed to healthy SanHuang chicken and Hy-line Gray laying hens for 10 consecutive days. The results indicated that the concentration of HMMNI consistently exceeded that of DMZ during the same period, in both broiler tissues and egg. Sebum showed the slowest elimination of DMZ and HMMNI, becoming undetectable after 168 h of withdrawal. In egg, residues of both substances peaked on the first day after drug withdrawal, followed by slow elimination with half-lives of 0.45 days for DMZ and 0.66 days for HMMNI. Based on these findings, WT1.4 software was used to calculate a withdrawal time of 11 days for broilers and an egg abandonment period of 14 days after withdrawal for laying hens, providing a scientific basis for the safe and rational use of DMZ in poultry farming.

Determination of 16 ultraviolet–absorbing compounds in marine invertebrates by using LC-USI-MS/MS coupled with QuEChERS

In this study, we examined multiple endocrine-disrupting ultraviolet-absorbing compounds (UVACs) in marine invertebrates used in personal care products and packaging. Modified QuEChERS and liquid chromatography UniSpray ionization tandem mass spectrometry were used to identify 16 UVACs in marine invertebrates. Matrix-matched calibration curves revealed high linearity (r ≥ 0.9929), with limits of detection and quantification of 0.006–1.000 and 0.020–3.000 ng/g w.w., respectively. In oysters, intraday and interday analyses revealed acceptable accuracy (93%–120%) and precision (≤18%), except for benzophenone (BP) and ethylhexyl 4-(dimethylamino) benzoate. Analysis of 100 marine invertebrate samples revealed detection frequencies of 100%, 98%, 89%, 64%, and 100% for BP, 4-hydroxybenzophenone, 4-methylbenzophenone, 4-methylbenzylidene camphor, and benzophenone-3 (BP-3), respectively. BP and BP-3 were detected at concentrations of 4.40–27.39 and < 0.020–0.560 ng/g w.w., respectively, indicating their widespread presence. Overall, our proposed method successfully detected UVACs in marine invertebrates, raising concerns regarding their potential environmental and health effects.

Incorporation of Cu-TATAB metal-organic framework within polyurethane nanocomposite for enhanced thin film microextraction of some chlorinated pesticides

In this research, electrospun nanofibers based on copper-based metal organic framework (MOF)/polyurethane (PU) were prepared in order to achieve an applicable and superior extractive phase. The incorporation of MOF, in the synthesized nanocomposite contributed to the enhanced sorption efficiency. The prepared sorbent was implemented for the thin film microextraction (TFME) of target compounds with subsequent quantification using gas chromatography-mass spectrometry (GC–MS). To obtain the maximum efficiency of the synthesized sorbent, the influential parameters on extraction and desorption steps, including the MOF percentage in nanocomposite, desorption solvent type and its volume, desorption time, solution ionic strength and extraction time were optimized. After method development, the linear dynamic range (0.02–700 μg L−1), limits of detection (LODs) (0.005–0.1 μg L−1) and limits of quantification (LOQs))0.02–0.33 μg L−1(were calculated. The relative standard deviations values for intra-day and inter-day analysis were found to be in the range of 4.3–5.3 % and 6.2–8.1 %, respectively. The developed method was validated for the TFME of model organochlorine (OC) pesticide residues in fish, soil and water samples. the recovery values for the spiked samples at two concentration levels of 5 and 100 µg l-1 were found in the range of 72–110 %.

A simple method for the determination of acyclovir concentrations in human plasma using high-performance liquid chromatography

BackgroundAcyclovir is an anti-viral medication given to treat herpes simplex and herpes zoster infection. In some severe conditions such as herpes encephalitis, acyclovir is administered intravenously. However, high acyclovir doses may cause acute kidney injury and low acyclovir dose may predispose the patient to inadequate exposure to acyclovir which could be fatal in some conditions. In such cases, the acyclovir plasma concentrations will potentially guide the diagnosis and management of the kidney injury. In this study, we provide a simple and time-efficient method for analyzing acyclovir in human plasma using high-performance liquid chromatography (HPLC).ResultsThe process starts with a single protein precipitation step by adding acetonitrile to deproteinize 300 µL of plasma. The chromatographic separation conditions consist of a mobile phase of water: methanol (97:3, v/v), a flow rate of 1 mL/min, a run time of 17 min, and a detection wavelength of 254 nm. The calibration curve was linear over the range of (0.70–60 mg/L) (r2 ˃ 0.99). The retention times of acyclovir and the internal standard were around 15 and 12 min, respectively. The intra-day and inter-day analysis of acyclovir in plasma using this method exhibited accuracy and precision of less than 7%, which lies within the acceptable range. Different greenness assessment tools confirmed that the proposed method is eco-friendly.ConclusionThe proposed method of analysis of acyclovir in the plasma using HPLC is simple, green and accurate method. This method could be applied in clinical settings where monitoring acyclovir concentrations is essential as it has wide range of the concentrations that could be detected.

Quantification of phenolic compounds in dietary supplements and antioxidant activities

Dietary supplements (DS) are products that are recommended for the treatment of various health issues, especially during the global pandemic, and the accuracy of the labeling information of these supplements plays a significant role in human health. In this study, a novel high performance liquid chromatography-diode array detector (HPLC-DAD) method was developed and validated to determine the accuracy of the labeling information of commercial dietary supplements containing phenolic compounds (rutin, quercetin, and resveratrol). The mobile phase, flow rate, and column temperature were optimized. Validation studies were carried out to prove the validity of the developed method. The limit of detection (LOD) and limit of quantification (LOQ) values ​​of rutin, quercetin, and resveratrol were found in the range of 4.83-6.62 ng/mL and 16.09-22.07 ng/mL, respectively. Recoveries% were calculated in the range of 99.52-100.19% and 99.78-100.34% in the intra-day and inter-day analysis, respectively. The IC50 values of the dietary supplement extracts obtained by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method ranged from 0.08 to 0.76 mg/mL. Total Antioxidant Capacity (TAC) values of DS1, DS2, DS3, DS4, DS5, measured employing the Cupric Reducing Antioxidant Capacity (CUPRAC) method, were found to be 0.09, 0.03, 0.10, 0.10 and 0.40 mmol trolox per gram of extract, respectively. KEY WORDS: Dietary supplement, HPLC-DAD, Phenolic compound, Antioxidant activity Bull. Chem. Soc. Ethiop. 2024, 38(4), 853-862. DOI: https://dx.doi.org/10.4314/bcse.v38i4.3

Natural kapok fiber as a green and efficient adsorbent for in-syringe solid-phase extraction in the determination of antidepressants in biofluids

Effective antidepressant monitoring is crucial for safe treatment, with liquid chromatography being the primary detection method. Due to the complexity of biofluids, meticulous sample preparation is vital to remove interferences and concentrate analytes. In this study, a novel solid-phase extraction method utilizing unprocessed kapok fiber (KF) as an eco-friendly and efficient sorbent, ingeniously incorporated within an in-syringe device for the extraction of antidepressants from biofluids was introduced. The extraction process displayed several advantages, including simplicity and rapidity (less than 3 min with minimal manual intervention), as well as the potential for automation, which represents significant advancements in sample preparation techniques. The method demonstrated excellent analytical performance when coupled with high-performance liquid chromatography-ultraviolet detection, achieving good linearity (R2 ≥ 0.991), excellent relative recovery (92.6–107.5 %), high precision in intraday and interday analyses (RSDs within 0.8–6.0 % and 1.2–7.9 %, respectively), and good sensitivity with limits of quantification between 5–10 ng/mL. Notably, given the use of a renewable and biodegradable material with KF, and a low-toxicity desorption solvent with ethanol, the developed method stands out for its environmental sustainability, aligning with green analytical chemistry principles. Its application to real biological samples validates its efficacy as a rapid and reliable tool for clinical and forensic monitoring of antidepressants. Moreover, the low cost of this method facilitated by the economical nature of KF and the reusability of syringes further enhances its practicability. This study presents a unique approach by employing natural and renewable KF as adsorbents, thereby eliminating the need for complex material synthesis and making a pioneering contribution to the field of analytical chemistry for drug analysis in complex matrices.

Abstract 1044: Low-cost, high-sensitivity InSituPlex® mIF assays on the Parhelia Omni-Stainer™

Abstract Background: Multiplex immunofluorescence (mIF) is an important tool for extracting complex phenotypic information from normal or diseased tissues, and provides accurate and predictive insights on the tissue microenvironment faster. For patient samples in translational and clinical research, high sensitivity, specificity, and reproducibility are critical; however, throughput and cost considerations are also important in designing clinical studies. Enabling an easy-to-use high-performance assay such as InSituPlex® on robust and affordable auto-stainers like the Parhelia Omni-Stainer™ can allow researchers to gain a deeper understanding of the tissue micro-environment through high-quality multiplexed biomarker detection in a fraction of the time and cost. Methods: We performed Ultivue InSituPlex® assays with OmniVUE™ panels using the Parhelia Omni-Stainer™, a low-cost, high-throughput tissue auto-stainer with reduced requirements for reagents with a minimal dead volume. We compared the whole-slide staining performance across replicates using human tonsil and tumor tissue arrays across multiple independent runs over multiple days. The stained slides were scanned using the Zeiss AxioScan.Z1 high-throughput imaging system, and image batches were processed using Ultivue’s UltiStacker.AI and UltiAnalyzer.AI software. Results: Tighter temperature control of the slide in the Omni-Stainer supports optimal InSituPlex® signal amplification. Intra-run and inter-day analysis on serial sections of human tonsil and tumor tissue arrays demonstrated a high degree of consistency in InSituPlex® assay performance, specifically with marker-specific signal intensities and cell densities. The Omni-Stainer facilitates the use of low reagent volumes at each step of the assay due to its efficient reagent use, thus lowering the cost of reagents per slide. Conclusions: This study demonstrated a fast, simple and robust workflow to perform high-performance InSituPlex® mIF assays on the low-cost, high-throughput Parhelia Omni-Stainer™. Ultivue’s configurable OmniVUE™ mIF panels can be run on the Omni-Stainer with reduced associated reagent costs per slide. This workflow can support larger clinical and translational studies in a more cost-effective fashion, leading to in-depth analysis of tissue microenvironment through highly precise multiplexed biomarker detection. Citation Format: Kevin Hwang, Lauren Duro, Alex Veith, Nelson Wedin, Nikolay Samusik, Je H. Lee. Low-cost, high-sensitivity InSituPlex® mIF assays on the Parhelia Omni-Stainer™ [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1044.

Development and Validation of Micro-Azocasein Assay for Quantifying Bromelain.

The proteolytic activity of enzymes may be evaluated by a colorimetric method with azocasein. Hence, we developed a micro-assay to quantify bromelain using azocasein. A total of 250 µL of 1.0% azocasein in dH2O was added to 250 µL of test solution, vortexed and incubated at ambient room temperature/30 min. The reaction was terminated with 1500 µL of 5% trichloroacetic acid, vortexed and centrifuged. A total of 150 µL of 0.5M NaOH was added to 150 µL of supernatant in triplicates, and absorbance was recorded at 410 nm. The linearity of the calibration curve was tested with 200-800 µg/mL serial dilutions. The detection limit, precision, accuracy, and robustness were tested along with the substrate enzyme reaction time and solvent matrix effect. Good linearity was seen with serially diluted 200 µg/mL bromelain. The limit of quantification and limit of detection were 5.412 and 16.4 µg/mL, respectively. Intra-day and inter-day analyses showed a relative standard deviation below 2.0%. The assay was robust when tested over 400-450 nm wavelengths. The assays performed using dH2O or PBS diluents indicated a higher sensitivity in dH2O. The proteolytic activity of bromelain was enhanced with L-cysteine or N-acetylcysteine. Hence, this micro-azocasein assay is reliable for quantifying bromelain.

Sustainable beeswax modified cellulose paper for the determination of tricyclic antidepressants in biofluids

This article describes the synthesis of sorptive phases for bioanalysis based on the modification of cellulose paper with natural beeswax as sorbent, resulting in a substrate completely renewable and sustainable. The preparation of the sorptive phases consisted of the dissolution of beeswax in hexane, followed by its drop-casting on cellulose paper and subsequent evaporation of the solvent. The beeswax modification of paper renders it hydrophobic, enabling the extraction of the target analytes, i.e., imipramine, desipramine, amitriptyline and trimipramine, via hydrophobic interactions. The main variables affecting the extraction performance were investigated (e.g., pH, ionic strength, extraction time, eluent composition, agitation speed). The analytical workflow combines a straightforward sampling, simultaneous extraction of 30 samples in 1 h, and the rapid (<2 min) determination of the analytes via direct infusion mass spectrometry. The method provided limits of detection in the range 2.0 and 3.2 μg L−1, and the precision, expressed as relative standard deviation, was better than 5.4 % and 8.5 % for intra and inter-day analyses, respectively. The accuracy, in terms of relative recovery, ranged from 90 % to 121 % using saliva as model biofluid.

Ascorbate functionalized Au@AgNPs SERS sensor combined random frog-partial least squares for the prediction of chloramphenicol in milk

The residue of chloramphenicol (CAP) in milk is a great threat to human health. Therefore, the study designed a simple ultrasensitive label-free surface-enhanced Raman scattering (SERS) sensing system for milk employing ascorbate functionalized core-shell gold-silver nanoparticles (Au@AgNPs) synthesized with 2.1 of 10 mM AgNO3 coupled chemometric method. Au@AgNPs with an enhancement factor of 6.99 × 106 was applied to acquire the SERS spectrum of CAP and showed linearity in the range of 0.0001–1000 µg/mL with 1st derivative random frog-partial least squares (RF-PLS) model. Three chemometric models were comparatively applied, among them, the RF-PLS model showed the best results and achieved a correlation coefficient in calibration = 0.985 and prediction = 0.9783 with prediction error (RMSEP) = 0.475 µg/mL with a limit of detection of 2.73 × 10−5 µg/mL. Moreover, recovery of intra- and inter-day analysis was 88–94.38% with a relative standard deviation (RPD) of < 10%. Furthermore, high-performance liquid chromatography (HPLC) analysis was conducted to compare the results with the developed method, and an insignificant (p > 0.05) difference was observed, indicating that the constructed method has good accuracy for the prediction of CAP in milk.

Microextraction experimental and forcefield theoretical modelling study on exploring a silica-enriched oil palm frond biomass for the determination of polycyclic aromatic hydrocarbons in Psidium guajava

In this study, a dispersive micro-solid phase extraction (D-µ-SPE) based on oil palm frond-based silica (OPF-SiO2) sorbent was investigated for the determination of four polycyclic aromatic hydrocarbons (PAHs) in Psidium guajava integrated with high-performance liquid chromatography (HPLC-DAD). The physicochemical characterization of the acid-treated and thermally extracted OPF-SiO2 by FTIR showed peaks at 806 cm−1 and 446 cm−1 allotted to siloxane stretching vibrations and siloxane terminating vibrations, while the FESEM spectrum of EDX analysis corroborated the presence of silicon in OPF-SiO2. Likewise, the XRD diffractograms displayed prominent peaks at 2θ = 24°, indicating a predominantly amorphous silica structure. The XRF analysis further corroborated this result, which revealed that silica constituted 78 % of the major elemental composition. The established optimized condition of D-µ-SPE extraction of PAHs required 60 mg of sorbent, an extraction time of 15 min using acetonitrile as the elution solvent, and a 5 min desorption time. The prepared sorbents exhibited a high affinity for PAHs through van der Waals and hydrogen bonding. The D-µ-SPE was linear between 50 and 5000 µg kg−1 for naphthalene, fluorene, anthracene, and pyrene (R2 = 0.9921–––0.9997). The RSDs were acceptable for intraday (0.65–1.52 %, n = 3) and interday (0.60–1.92 %) analyses, coupled with low detection limits (2.33–4.90 µg kg−1) and satisfactory relative recovery (95.05–108.88 %). The experimental results supported the subsequent forcefield theory calculations for the PAHs and the OPF-SiO2 composite’s interactions. Analytical GREEnness (AGREE) with a metric score 0.60 indicates that the developed approach is green.

Investigating drug residues in Mongolian milk using a newly developed method with high performance liquid chromatography and a photo diode array.

Despite the beneficial impacts of using drugs in animal husbandry, the risks of drug residues in animal products are a concern worldwide. Therefore, most countries have developed systems and methods to detect and monitor drug residues in animal products using high performance liquid chromatography (HPLC) with mass spectrometry (MS). However, MS detectors are not available in all universities; thus, we developed a new method suitable for ultraviolet detection. We first validated a new method targeting tetracycline and albendazole in milk and evaluated these drug residues in 50 samples collected from farms and supermarkets in Mongolia. The practical limit of quantification (PQL) calculated in our newly developed method was suitable to detect the maximum residual limits defined in Codex Alimentarius, and the accuracy and precision of a new method were comparable to previous studies. In particular, inter-day analysis showed great precision, with albendazole showing a 99% recovery rate with ± 3.3 of relative standard deviation (RSD). In addition, we evaluated our drugs contamination, but targeted drugs residues were not detected in the current sample set. However, this may reflect the decreased use of tetracycline in the veterinary field and seasonal use of albendazole in Mongolia. Therefore, these drugs must be continuously monitored. To the best of our knowledge, this is the first report about drug residues in milk published in an international journal by a Mongolian domestic institution. Further investigations of drug residue in Mongolia are urgently needed.

Ranolazine Quantification in Human Plasma: A QbD-Guided LC-MS Method Development and Validation

The present research outlines a comprehensive and systematic approach for the development and validation of a bioanalytical Liquid chromatography–mass spectrometry (LC-MS) method to quantify ranolazine in human plasma. The study employs principles of quality by design (QbD) to enhance method robustness, precision, and accuracy. The primary goals of this research were to create a reliable LC-MS method for the accurate quantification of ranolazine in human plasma and to validate this approach in accordance with established standards set by regulatory bodies. A secondary objective was to explore the application of QbD principles to optimize method performance. The study resulted in the successful development of an LC-MS method that exhibits exceptional specificity, sensitivity, accuracy, and precision in the quantification of ranolazine in human plasma. Specificity tests revealed no interference from endogenous plasma components. The method demonstrated good sensitivity with limit of quantitation (LoQ) of 5 ng/mL and limit of detection (LoD) of 2 ng/mL. Accuracy, as assessed through recovery studies, showed mean recoveries of 98, 99, and 101% for three different spiked concentrations. Precision, expressed as RSD, was below 5% for both intra-day and inter-day analyses. Linearity studies resulted in a calibration curve with an R² value of 0.9998. By employing QbD principles, the method demonstrated improved robustness, thus minimizing the impact of variability during sample analysis. Robustness experiments revealed minimal effects on precision and accuracy when varying critical parameters. This research not only presents a reliable LC-MS method for ranolazine quantification but also underscores the importance of incorporating QbD principles in bioanalytical method development. The validated method holds significant implications for clinical research, pharmacokinetic studies, and therapeutic drug monitoring. By enhancing the accuracy and robustness of ranolazine quantification, this method contributes to the advancement of pharmaceutical and clinical research, ultimately benefiting patient care and treatment outcomes.

Theory and protocol of dual mode unity solid-phase microextraction

The solid-phase microextraction (SPME) bias problem limits comprehensive analysis of volatile compounds in real samples. The study introduces dual mode unity solid-phase microextraction (DMU-SPME) as a novel SPME mode to achieve balanced extraction of both volatile and low-volatile compounds. The DMU-SPME method exhibits excellent linearity (R2 ≥ 0.994), low quantitation limits (0.12–240 μg/L), and notable stability (relative standard deviations below 20 % for both intra-day and inter-day analyses). In practical application to soy sauce, the DMU-SPME method identified a total of 107 compounds, encompassing all those detected by both headspace solid-phase microextraction (HS-SPME) and direct immersion solid-phase microextraction (DI-SPME). Theoretical insights indicate that DMU-SPME is less influenced by Kfs0 and Kfs in comparison to HS/DI-SPME, rendering it suitable for complex matrices containing both volatile and low-volatile compounds. In conclusion, DMU-SPME emerges as a highly effective extraction mode for analyzing volatile and low-volatile compounds in food, medical, and environmental samples.