Ion chromatography: A comprehensive review of sample preparation methods for analysis of halogens and allied nonmetals in critically challenging inorganic matrices.

The inorganic matrices such as metal concentrates, steel, cement, glass, clay, coal, graphite, rocks and sediments, ores etc. play a pivotal role in infrastructure development, transportation, and energy. The presence of non-metallic elements particularly halogens influence their quality, processing cost, and environment dynamics. The analysis of non-metals in such matrices is critically challenging due to their hardness, rigidity, and non-digestibility. This comprehensive review provides a critical comparison of various sample preparation methods in conjunction with pros and cons of advanced techniques for the detection of non-metals in complex matrices, particularly focusing on ion chromatography. Moreover, the review also addresses the challenges related to the enrichment and automation of non-metals analysis. In addition, the previous literature on non-metals determination in diverse range of inorganic matrices has been tabulated for the first time. These insights are intended to guide researchers, quality control analysts, environmental scientists, and policymakers in enhancing pollution monitoring and control strategies.

An Innovative Aggregation-Induced Emission-Based NIR Fluorescent Probe for Visualizing Carboxylesterases in Living Cells, Zebrafish, and Tumor-Bearing Mice.

In the human body, carboxylesterases (CEs) play crucial roles in xenobiotic metabolism and lipid homeostasis. But abnormal expression of CEs is highly associated with some diseases, such as hyperlipidemia, diabetes, and liver cancer. Therefore, it is of great importance to develop an efficient tool for the accurate detection of CEs in living organisms. Herein, an innovative near-infrared (NIR) fluorescent probe, TTAP-AB, was designed for CE detection based on the aggregation-induced emission (AIE) mechanism. This probe exhibits rapid response (2 min), excellent sensitivity (limit of detection = 8.14 × 10-6 U/mL), and high selectivity to CEs. Additionally, owing to its good biocompatibility, the TTAP-AB probe enables the monitoring of dynamic changes in CE levels under drug-induced modulation in living cells and zebrafish. More importantly, the TTAP-AB probe was successfully employed to image liver tumors and assist in tumor resection through the real-time monitoring of CEs, indicating that TTAP-AB is promising to guide liver cancer surgery. Therefore, the TTAP-AB probe can not only enrich the strategies for CE detection in biological systems but also has great potential for some clinical imaging applications, including medical diagnosis, preclinical research, and imaging-guided surgery.

A Mitochondria-Targeting Fluorescent Probe for the Dual Sensing of Hypochlorite and Viscosity without Signal Crosstalk in Living Cells and Zebrafish.

Hypochlorite (ClO-) and viscosity both affect the physiological state of mitochondria, and their abnormal levels are closely related to many common diseases. Therefore, it is vitally important to develop mitochondria-targeting fluorescent probes for the dual sensing of ClO- and viscosity. Herein, we have explored a new fluorescent probe, XTAP-Bn, which responds sensitively to ClO- and viscosity with off-on fluorescence changes at 558 and 765 nm, respectively. Because the emission wavelength gap is more than 200 nm, XTAP-Bn can effectively eliminate the signal crosstalk during the simultaneous detection of ClO- and viscosity. In addition, XTAP-Bn has several advantages, including high selectivity, rapid response, good water solubility, low cytotoxicity, and excellent mitochondrial-targeting ability. More importantly, probe XTAP-Bn is successfully employed to monitor the dynamic change in ClO- and viscosity levels in the mitochondria of living cells and zebrafish. This study not only provides a reliable tool for identifying mitochondrial dysfunction but also offers a potential approach for the early diagnosis of mitochondrial-related diseases.

Ionic Liquids in Pharmaceutical and Biomedical Applications: A Review.

The unique properties of ionic liquids (ILs), such as structural tunability, good solubility, chemical/thermal stability, favorable biocompatibility, and simplicity of preparation, have led to a wide range of applications in the pharmaceutical and biomedical fields. ILs can not only speed up the chemical reaction process, improve the yield, and reduce environmental pollution but also improve many problems in the field of medicine, such as the poor drug solubility, product crystal instability, poor biological activity, and low drug delivery efficiency. This paper presents a systematic and concise analysis of the recent advancements and further applications of ILs in the pharmaceutical field from the aspects of drug synthesis, drug analysis, drug solubilization, and drug crystal engineering. Additionally, it explores the biomedical field, covering aspects such as drug carriers, stabilization of proteins, antimicrobials, and bioactive ionic liquids.

Photocatalytic degradation of air pollutant by modified nano titanium oxide (TiO2)in a fluidized bed photoreactor: Optimizing and kinetic modeling.

Volatile organic compound (VOC) removal by photocatalytic oxidation (PCO) is the practical and economical process to reduce air pollutants. Many conditions, such as temperature, initial concentration of VOC, relative humidity, gas flow rate, and light intensity, affected this process. Therefore, finding the optimal operating conditions for the PCO process can increase the efficiency of the process and also operate the process more economically. Also, it is possible to scale up the process with more confidence by the kinetics modeling of the process and finding the rate constants. In this study, the effect of gas flow rate, light intensity, and VOC inlet concentration were investigated. The results show that the flow rate of 15 lit/min is more efficient, and the effect of the pollutant input concentration and light intensity directly affects the conversion percentage. The kinetic study of acetaldehyde removal was investigated in the fluidized bed reactor, and the best kinetic model was proposed based on reactor model regression on the outlet concentration data. The best model describes a langmuir-hynshelwood type model with adsorbed acetaldehyde's inhibition effect on the catalyst's surface. The R2 coefficient for the best kinetic type is 0.98.

Synergy of cystamine and pyraclostrobin against Fusarium graminearum involves membrane permeability mitigation and autophagy enhancement.

The application of fungicide mixture is one of the most important measures to extend the service life of highly selective fungicides. Pyraclostrobin (PYR), which has been extensively used to control plant diseases by inhibiting mitochondrial respiration of pathogenic fungi, is at a high risk of resistance development. In this study, the potential of PYR alone or in combination with cystamine, an inhibitor of microbial transglutaminase, to suppress Fusarium graminearum was tested in vitro and in vivo. A synergistic effect of PYR/CYS mixture was observed both in vitro and when applied to etiolated wheat coleoptile. The control effect of PYR/CYS mixture on F. graminearum was better than that of PYR alone, which was reflected by the increased protection effect. The discrepancies of membrane permeability and the redox-physiological state were observed between PYR and PYR/CYS treatments, suggesting that an increased PYR availability in F. graminearum mycelia could be related with the observed synergistic action. Moreover, a synergistic profile was observed between PYR and CYS in regard of massive autophagosomes in mycelia, indicating that enhanced autophagy could be involved in the mode of action of PYR/CYS mixture. The differential content of mitochondrial metabolites between PYR and PYR/CYS treatments also provided evidence for CYS contribution to the fungicidal action of PYR/CYS mixture. The results provide insight into the synergistic mechanism of action of PYR/CYS mixture and an effective way to enhance the efficiency of PYR to combat F. graminearum.

Electrochemically functionalized graphene for highly sensitive detection of nitrofurazone.

Graphene nanosheets (GS) were prepared by ultrasonic exfoliation of bulk graphite in N-methyl-2-pyrrolidone with the assistance of sodium pyrophosphate. The obtained GS suspension was modified on a glassy carbon electrode (GS/GCE), and then functionalized at different voltages (e.g. 1.0, 1.4 and 1.6 V) for 2 min in pH 7.0 phosphate buffer. The electrochemically functionalized GS/GCE (i.e. EGS/GCE) possesses more oxygen-containing groups and a higher defect level. More importantly, the active response area, electron transfer ability and interface adsorption capacity of the EGS/GCE enhanced remarkably. The possible mechanism of the performance enhancement is discussed, and the sensing application of the EGS/GCE in the detection of nitrofurazone (NFZ) is investigated. Compared with the GS/GCE, the EGS/GCE is much more active for NFZ oxidation and greatly increases the detection sensitivity. As a result, a highly sensitive electrochemical detection method has been developed for NFZ, with a detection limit of 2.1 nM. The practical application of the EGS/GCE was tested in fish meat samples, showing good accuracy and feasibility.

Preparation and application of nano petal-shaped covalent organic frameworks modified polystyrene-divinylbenzene- glycidylmethacrylate microspheres for the extraction of illicit drugs from wastewater.

A novel nano petal-shaped covalent organic frameworks modified magnetic polystyrene-divinylbenzene-glycidylmethacrylate (NP-COF@Mag-PS/DVB/GMA) microsphere has been synthesized. It is a perfect combination of high productivity of PS/DVB/GMA microspheres and excellent enrichment efficiency of COF particles, and the excellent properties of NP-COF@Mag-PS/DVB/GMA microspheres are characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The sorbent can extract illicit drugs via the reverse-phase interactions provided by benzene ring on the polymer backbone and the hydrogen bonding interactions provided by functional group (-NH-) on the COF particles. Based on using NP-COF@Mag-PS/DVB/GMA as sorbents, an easiness-to-handle of magnetic dispersive solid phase extraction (Mag-dSPE) procedure is proposed for the simultaneous preconcentration of 12 illicit drugs from wastewater. The obtained results show high extraction efficiency of NP-COF@Mag-PS/DVB/GMA to illicit drugs with recoveries between 81.6 and 116%. Furthermore, a liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) method for the determination of 12 illicit drugs from wastewater at sub-ppt levels has been proposed and validated with the pretreatment of samples by Mag-dSPE. The limits of quantification (LOQs) for the 12 illicit drugs are between 0.40 and 4.90 ng/L. Validation results on linearity, specificity, trueness and precision, as well as on application to the analysis of 12 illicit drugs in ten real samples demonstrate the applicability to environment monitoring analysis.

The dynamic causality in sporadic bursts between CO2 emission allowance prices and clean energy index.

This study examines the dynamic causality between the carbon emission market and the clean energy market, using an information flow-based, quantitative Liang causality analysis which is firmly grounded on physics and derived from first principles. The dynamic causal relationships between European Union Allowance (EUA) prices and clean energy index allow us to explore whether the causality in return or in variance from CO2 emission allowances to the clean energy index is time-varying. The results show that the causal relationships in return and in variance between EUA and Clean Energy Index (CEI) are drastically time-varying. For the causality in return, a significant unidirectional long-term and stable causality from CEI to EUA is identified after March 2020. For that in variance, a bidirectional causality is found after March 2020, but values after 2020 are opposite to those in return. It seems when fluctuations in the clean energy market are low, the clean energy market has a weak causal effect on the carbon emission market but when volatility in the clean energy market is increasing, causalities between the two markets are significantly strengthened. These results obtained through this rigorous causality analysis can serve as a reference for academics, market participants, and policymakers to understand the underlying links between EUA prices and clean energy index.

The Relationship between Crude Oil Futures Market and Chinese/US Stock Index Futures Market Based on Breakpoint Test.

Combined with the B-P (breakpoint) test and VAR-DCC-GARCH model, the relationship between WTI crude oil futures and S&P 500 index futures or CSI 300 index futures was investigated and compared. The results show that breakpoints exist in the relationship in the mean between WTI crude oil futures market and Chinese stock index futures market or US stock index futures market. The relationship in mean between WTI crude oil futures prices and S&P 500 stock index futures, or CSI 300 stock index futures is weakening. Meanwhile, there is a decreasing dynamic conditional correlation between the WTI crude oil futures market and Chinese stock index futures market or US stock index futures market after the breakpoint in the price series. The Chinese stock index futures are less affected by short-term fluctuations in crude oil futures returns than US stock index futures.

Determination of Organophosphorus Esters in Fall Protection Equipment by Accelerated Solvent Extraction and Solid-Phase Extraction Coupled with LC-MS/MS Detection.

An analysis method was established to determine 14 organophosphorus ester (OPE) flame retardants in fall protection equipment by combining accelerated solvent extraction (ASE) and solid-phase extraction (SPE) with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The ASE parameters were optimized as follows: static extraction with acetonitrile at 80°C for 5 min for two cycles. The combined extract was purified with the ENVI-18 cartridge before further analysis. A HILIC column was used to separate the OPEs using an acetonitrile/water mixture as the mobile phase with the detection by the electrospray ionization mass spectrometry, which was operated under the positive mode. Under optimized conditions, the limit of detection for the target OPEs ranged in 0.015-1.33 ng/g, with a spike recovery of 71.6%-114% and a relative standard deviation of 0.8%-11.2%. The developed method was used to analyze OPEs in fall protection equipment (safety helmets and ropes), where OPEs were all detectable. Safety ropes displayed a higher concentration of OPEs than ones in safety helmets, with the pollutants being mainly triphenyl phosphate, 2-ethylhexyl diphenyl phosphate (EHDPP), tri(2-ethylhexyl) phosphate, and tri-n-butyl phosphate in the range of 11.07 ng/g‒815.53 ng/g. The EHDPP was the dominant compound in safety helmets with the concentration from 26.84 to 95.29 ng/g, while the other OPEs in safety helmets were lower than 5.136 ng/g. The potential health and environmental risks of these fall protection equipment during their use and disposal call for further attention.

Preparation of sheet-like covalent organic frameworks and their application for efficient preconcentration of 4-(tert-octyl)-phenol and 4-nonylphenol in textiles.

In the design of highly ordered (covalent organic frameworks) COFs with "ordered domains size and orientation" construction in a well-defined arrangement, the molecular monomers are the key factors. Here, the effect of molecular monomers on the construction of COFs has been studied, and two kinds of molecular monomers, i.e., ethanediamine (flexible amine ligand) and 4,4'-diaminobiphenyl (rigid amine ligand) have been used for developing sheet-like COFs-I and sheet-like COFs-II, respectively. Furthermore, they have been evaluated in the dispersive solid phase extraction (dSPE) procedure for textiles prior to the analysis of alkylphenol by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). The results showed that, the optimal usage amount of sheet-like COFs-II used in the dSPE procedure was less than that of sheet-like COFs-I, which may be explained by much higher adsorption capacity of sheet-like COFs via hydrogen-bonding and π-π stacking interactions. Rectilinear calibration graphs were obtained for 4-(tert-octyl)-phenol (4-tOP) and 4-nonylphenol (4-NP) in the range 0.2-20 µg/kg with determination coefficient (r2) higher than 0.9990, and the limits of detection (LODs) of 4-tOP and 4-NP were 0.039 µg/kg and 0.048 µg/kg, respectively. The developed method has been successfully applied to analysis of 50 textile samples, in which 4-tOP and 4-NP were found in six samples with concentrations in the range of 1.6 µg/kg-20.9 µg/kg.

Gastrointestinal symptoms and fecal nucleic acid testing of children with 2019 coronavirus disease: a systematic review and meta-analysis.

In order to understand the clinical manifestations and incidence of gastrointestinal symptoms of coronavirus disease (COVID-19) in children and discuss the importance of fecal nucleic acid testing.We retrospectively analyzed studies on gastrointestinal symptoms and fecal nucleic acid detection in pediatric COVID-19 patients from January 1, 2020 to August 10, 2020, including prospective clinical studies and case reports. The results of fecal nucleic acid detection were analyzed systematically. Stata12.0 software was used for meta-analysis.The results showed that the most common gastrointestinal symptoms in children with COVID-19 were vomiting and diarrhea, with a total incidence of 17.7% (95% Cl 13.9-21.5%). However, the prevalence of gastrointestinal symptoms in other countries (21.1%, 95% CI 16.5-25.7%) was higher compared to China (12.9%, 95% CI 8-17.7%). In Wuhan, the pooled prevalence was much higher (41.3%, 95% CI 3.2-79.4%) compared to areas outside Wuhan in China (7.1%, 95% CI 4.0-10.3%). The positive rate of fecal nucleic acid testing in COVID-19 children was relatively high at 85.8% (91/106). Additionally, 71.2% (52/73) were still positive for fecal nucleic acid after respiratory tract specimens turned negative. One and two weeks after the respiratory tract specimens turned nucleic acid-negative, 45.2% (33/73) and 34.2% (25/73) patients, respectively, remained fecal nucleic acid-positive. The longest interval between the respiratory tract specimens turning negative and fecal specimens turning negative exceeded 70 days. Conclusions and relevance: gastrointestinal symptoms in pediatric COVID-19 are relatively common. Attention should be paid to the detection of fecal nucleic acids in children. Fecal nucleic acid-negative status should be considered as one of the desegregation standards.

Assessment of the risk of musculoskeletal adverse events associated with fluoroquinolone use in children: A meta-analysis.

BACKGROUND: The use of fluoroquinolone antibiotics has been restricted in children because of their potential to cause adverse musculoskeletal events. This study was performed to systematically evaluate whether there is a difference between fluoroquinolone and non-fluoroquinolone antibiotics in terms of their associated risk of adverse musculoskeletal events in children. METHODS: Cochrane Library, Embase, and PubMed databases were used to retrieve studies related to fluoroquinolone and non-fluoroquinolone-induced musculoskeletal adverse events in children. A meta-analysis was performed using Stata 11. RESULTS: A total of 10 studies were included in the analysis. The combined results showed that there was no statistical difference between fluoroquinolone and non-fluoroquinolone groups in terms of musculoskeletal adverse events in children (risk ratio = 1.145, 95% confidence interval = 0.974 - 1.345, P = .101). Subgroup analysis was performed using a random-effects model. Here, the effects on the trovafloxacin and levofloxacin groups were significantly different from that of the control group. However, musculoskeletal adverse events due to either drug was not reported after long-term follow-up. CONCLUSIONS: The results showed that fluoroquinolone and non-fluoroquinolone antibiotics were not different in terms of their ability to cause musculoskeletal adverse events in children. For this reason, fluoroquinolone antibiotics can be used in children as appropriate. PROSPERO REGISTRATION NUMBER: CRD42019133900.

Colorimetric determination of tetrabromobisphenol A based on enzyme-mimicking activity and molecular recognition of metal-organic framework-based molecularly imprinted polymers.

A sol-gel method is presented to synthesize molecularly imprinted polymers (MIPs) composed with a copper-based metal-organic framework (referred to as MIP/HKUST-1) on a paper support to selectively recognize tetrabromobisphenol A (TBBPA). The imprinting factor is 7.6 and the maximum adsorption capacity is 187.3 mg g-1. This is much better than data for other MIPs. The degradation of TBBPA is introduced in the procedure. Due to the selective recognition by the MIP, the enzyme-mimicking properties of HKUST-1 under the MIP layer became weak due to the decrease of residue imprinted cavities. And adsorbed TBBPA can be degraded under consumption of hydrogen peroxide (H2O2). The combined effect of H2O2 and HKUST-1 cause the coloration caused by catalytic oxidation of 3,3',5,5'-tetramethylbenzidine to become less distinct. This amplification strategy is used for the ultrasensitive and highly selective colorimetric determination of TBBPA. The gray intensity is proportional to the logarithm concentration of TBBPA in the range of 0.01-10 ng g-1. The limit of detection is as low as 3 pg g-1, and the blank intensities caused by TBBPA analogues are <1% of that caused by TBBPA at the same concentration, this implying excellent selectivity. The spiked recoveries ranged from 94.4 to 106.6% with relative standard deviation values that were no more than 8.6%. Other features include low costs, rapid response, easy operation and on-site testing. Graphical abstractSchematic representation of colorimetric determination of tetrabromobisphenol A (TBBPA) by paper-based metal-organic framework-based molecularly imprinted polymers (MIP/HKUST-1 composites) using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate.

Coiled molecularly imprinted polymer layer open-tubular capillary tube for detection of parabens in personal care and cosmetic products.

Personal care and cosmetic products (PCPs) are the primary exposure pathway of humans to parabens and their safety has become a public concern. However, sample pretreatment of PCPs is a great challenge due to their complexities and diversity. In this study, epoxide modified molecularly imprinted polymers (MIPs) were synthesized using ethylparaben as a template, methacrylic acid and isobutyl vinyl ether as co-monomers and glycidilmethacrylate as a post-modified monomer. MIP layer open-tubular tubes were prepared by modifying branched polyethylenimine and then grafting MIPs onto the inner surface of Teflon capillary tubes. The tube was coiled to effectively increase mass transfer and coupled to an HPLC-UV system for parabens detection in PCPs. Matrix interference was significantly decreased while efficient enrichment and recoveries were obtained. Under optimized conditions, the linear range for parabens detection was 0.5-600 ng mL-1 with detection limits of 0.2 to 0.3 ng mL-1. The system was used to study the contents of parabens in popular PCPs. The concentrations of parabens in 108 PCPs ranged from <0.5 ng g-1 to 2856 µg g-1 with geometric mean of 250.3 µg g-1. Almost all of the products contained at least one kind of parabens; methyl paraben (geometric mean: 182.9 µg g-1) and n-propyl paraben (geometric mean: 42.5 µg g-1) were the predominant compounds had been found in the samples. This method could be useful for human exposure assessment towards parabens.

Improvement on metabolic syndrome in high fat diet-induced obese mice through modulation of gut microbiota by sangguayin decoction.

ETHNOPHARMACOLOGICAL RELEVANCE: Our previous research found that Sangguayin (SGY) deccoction made by four dietary and medicinal plant components (Leaf of Morus alba L., Root of Pueraria lobata (Willd.) Ohwi., Root of Dioscorea opposita Thunb. and Fruit of Momordica charantia L.) showed significant anti-diabetic effects on db/db mice and high fat diet induced obese mice. Nevertheless, it remained unclear what the role of gut microbiota in the hypoglycaemia effects of SGY. AIMS OF THE STUDY: This study aimed to examine the beneficial effects of Sangguayin Deccoction against metabolic syndrome and and its regulating role in gut microbiota and hepatic metabolome. MATERIALS AND METHODS: C57BL/6J mice were divided to a normal chow diet (NCD), high-fat diet (HFD), and high-fat diet with Sangguayin Decoction (HFD-SGY, oral dose of 250 mg/kg/d) for 16 weeks. Next generation sequencing was applied for analyzing the gut microbial community of colonic contents. Further, untargeted metabolomic analysis based on LC-MS was used for determining the changes of hepatic metabolites. Hepatic genes expression were measured by quantitative PCR. RESULTS: SGY supplement decreased blood glucose level and glucose intolerance. Illumina MiSeq sequencing revealed that SGY increased Verrucomicrobia phylum, resulting in a bloom of Akkermansia, and eventually upregulated the contents of Lachoclostridium and Roseburia. Additionally, dietary SGY decreased bacteria including Faecalibaculum, and Blautia. Moreover, the hepatic lipid metabolism was notably altered by SGY treatment. The oxidation of glutamione metabolism idecreasees, production of poly-unsaturated fatty acid (PUFA) got significant increase in liver tissue. The reversion of PUFA metabolism by SGY may act through PPARα mediated Fads1 and Fads2 gene expression. The altered metabolites in liver showed intimate correlatship with modified genera. CONCLUSION: Data indicated that SGY reshaped gut microbial structure and improved PUFA metabolism. These functions of SGY may alter hepatic lipid metabolism, conferring preventative effects against high-fat diet induced metabolic syndrome.

Online clean-up setup for the determination of non-fluorescent acidic pharmaceutical drugs in complex biological samples.

Analysis of acidic pharmaceuticals in complex biological samples is a challenging and formidable task due to the existence of interfering constituents within the sample matrices. Therefore, in order to avoid analytical column clogging and suppression/enhancement of signals of the analyte of interest, herein a simple, cost-effective and quick online ion chromatography based clean-up setup was introduced. This system was further coupled with a cost-effective homemade photochemically induced fluorimetric (PIF) setup for direct online conversion of non-fluorescent acidic pharmaceutical drugs into their respective fluorescent species. This advantageous system was favorably applied for the determination of four non-fluorescent acidic compounds in two complex biological samples (human serum and oral fluid) with minimum labor and organic solvent consumption. At optimized conditions, the developed method has shown good sensitivity, selectivity, satisfactory recoveries (88.68-102.14%) and low limits of detection (0.35-8.10 µg/L) with minimum or zero matrix effect.

Determination of nitenpyram and 6-chloronicotinic acid in environmental samples by ion chromatography coupled with online photochemically induced fluorescence detector.

A simple, cost-effective, sensitive, and quick method for the determination of nitenpyram and its metabolite 6-chloronicotinic acid in environmental samples was developed by coupling an ion chromatograph with a fluorescence detector and a post-column photochemical reactor. This developed analytical method involved a rapid sample extraction by modified and miniaturized quick, easy, cheap, effective, rugged, and safe method followed by isocratic ion chromatographic separation of nitenpyram and 6-chloronicotinic acid into an IonPac™ AS11-HC column protected by IonPac™ AG11A guard column by running 30 mM NaOH + 10% acetonitrile mobile phase. A homemade post-column photochemical reactor was also integrated with the ion chromatographic system for online transformation of both analytes into their respective highly fluorescent photoproduct in basic media without using an extra pump. The developed method was validated by following SANTE/11945/2015 guidelines on analytical quality control and validation procedures. The method showed a good linear response (r > 0.999), improved limit of detection (0.101-0.132 µg/L), minimum or no matrix effect, excellent recoveries (90.2-100.10%) and relative standard deviations were found to be ≤6.50%.

Porous SnO2 nanoparticles based ion chromatographic determination of non-fluorescent antibiotic (chloramphenicol) in complex samples.

Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product. We report a green, simple, selective and cost effective ion chromatographic method for CAP sensitive determination in three complex matrices including milk, human urine and serum. The synthesized sorbent not only selectively adsorbed and degraded the matrix/interferences but also selectively reduced the non-fluorescent antibiotic CAP into a fluorescent species. This developed ion chromatographic method exhibited good selectivity, linearity (r2 ≥ 0.996) and limit of detection (LOD) was in the range 0.0201-0.0280 µg/kg. The inter- and intraday precisions were also satisfactory having a relative standard deviation (RSDs) less than 14.96% and excellent recoveries of CAP in the range of 78.3-100.2% were retrieved in various complex samples.