Establishment of the HPLC fluorescence detection method for plasma trace ivermectin and its pharmacokinetics in Bactrian camel.

BACKGROUND AND OBJECTIVE: Ivermectin (IVM), a widely used veterinary anthelmintic, lacks recommended doses for Bactrian camels. This study aims to establish its pharmacokinetics in Bactrian camels, comparing with other livestock. METHODS: A method for high-performance liquid chromatography fluorescence detection of IVM in plasma was developed. RESULTS: IVM exhibited linear scaling (y = 0.6946x + 0.0088, R2 = 0.9988) within 0.025-5 ng/mL, with a lower limit of quantification of 25.00 pg/mL, high recovery (>70%) and low RSD (<7%). In Bactrian camels, IVM injection showed a low Cmax, extended Tmax and apparent secondary absorption compared to cattle and sheep. CONCLUSIONS: Slow absorption and widespread distribution were observed, with peak concentration and area under the curve correlating positively with the dose. This study provides insights into IVM pharmacokinetics in Bactrian camels, informing dose determination and highlighting potential metabolic differences compared to other livestock.

Analysis of Gizzerosine in Foodstuffs by HPLC Involving Pre-column Derivatization with o-Phthaldialdehyde.

Gizzerosine [2-amino-9-(4-imidazolyl)-7-azanonanoic acid] is a toxic amino acid formed from histamine and lysine at high temperatures, and may be present in foodstuffs (e.g., fishmeal and meat-bone meal) for animals including cats and dogs. Here we developed a simple, rapid, sensitive, specific, and automated method for the analysis of gizzerosine in foodstuffs by high-performance liquid chromatography (HPLC) involving pre-column derivatization with o-phthaldialdehyde (OPA) in the presence of N-acetylcysteine (instead of the usual 2-mercaptoethanol or ethanethiol reagent). OPA reacted immediately (within 1 min) with gizzerosine in an autosampler at room temperatures (e.g., 20-25 °C), and their derivative was directly injected into the HPLC column. The highly fluorescent gizzerosine-OPA derivative was well separated from the OPA derivatives of all natural amino acids known to be present in physiological fluids (e.g., plasma), proteins and foodstuffs, and was detected at an excitation wavelength of 340 nm and an emission wavelength of 450 nm. The total time for chromatographic separation (including column regeneration) was 20 min per sample rather than 40 min and longer in previous HPLC methods. The detection limit for gizzerosine was at least 6 pmol/ml in an assay solution (HPLC vial) or at least 0.09 pmol per injection into the HPLC column. The analysis of gizzerosine was linear between 1 and 100 pmol per injection. When gizzerosine was extracted from foodstuffs, its detection limit was at least 875 pmol/g foodstuff or at least 0.21 mg/kg foodstuff. Our routine HPLC technique does not require any cleanup of samples or the OPA derivatization products (including the OPA-gizzerosine adduct), and is applicable for the analysis of gizzerosine in both foodstuffs and animal tissues.

[Simultaneous determination of six benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry].

OBJECTIVE: To establish a method for the simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products by high performance liquid chromatography-triple quadrupole mass spectrometry. METHODS: The samples were extracted with acetonitrile and purified by C_(18 )solid phase extraction column. The sample solution was separated by Waters ACQUITY UPLC BEH C_(18 )column(2.1 mm×50 mm, 1.7 µm) using 0.1% formic acid and methanol as mobile phase for gradient elution, determined in multiple reaction monitoring mode and quantified by internal standard method. RESULTS: Six benzodiazepine sedatives had a good linear relationship in the range of 1.0-50.0 µg/L with r>0.9990, the limits of detection and limits of quantification were 0.3 and 1.0 µg/kg. Average recoveries for the analytes at 3 spiked levels ranged from 74.2%-108.0% with relative standard deviations of 1.1%-6.7%(n=6). CONCLUSION: The method is simple, rapid, sensitive and accurate, which is suitable for simultaneous determination of 6 benzodiazepine sedatives residue in aquatic products.

[Determination of twelve halobenzoquinones in drinking water by solid phase extraction-ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for twelve halobenzoquinones(HBQs) in drinking water by solid phase extraction-ultra-performance liquid chromatography coupled with electrospray-tandem mass spectrometry(SPE-UPLC-MS/MS). METHODS: The drinking water was acidified with formic acid and concentrated by Bond Elut Plexa solid phase extraction column. The sample solution was separated using Waters ACQUITY HSS T3 column(100 mm×2.1 mm, 1.8 µm) with gradient elution using methanol-water containing 0.1% formic acid as mobile phase. The target compouds were detected in negtive electrospray ionization(ESI~-) and multiple reaction monitoring. RESULTS: The concentration of twelve HBQs showed good linearity in the range 5.0-150.0 ng/mL, respectively, with the correlation coefficients greater than 0.999. The limits of detection(LOD) of twelve HBQs were lower than 2.0 ng/mL, and the limits of quantification(LOQ) for twelve HBQs were lower than 5.0 ng/mL, respectively. The recoveries of three levels in the matrix were 70.0%-84.0%. The matrix effffect was 0.08-0.64. CONCLUSION: The SPE-UPLC-MS/MS method has high sensitivity, good accuracy and fast analysis speed for the detection of halobenzoquinones in drinking water.

Purification of triterpenoid saponins and 25R/25S-inokosterone from Achyranthes bidentata Bl. by high-speed countercurrent chromatography coupled silver nitrate coordination.

An effective method by high-speed countercurrent chromatography coordinated with silver nitrate for the preparative separation of sterones and triterpenoid saponins from Achyranthes bidentata Blume was developed. Methyl tert-butyl ether/n-butanol/acetonitrile/water (4:2:3:8, v/v/v/v) was selected for 20-hydroxyecdysone (compound 1), chikusetsusaponin IVa methyl ester (compound 4), 2'-glycan-11-keto-pigmented saponin V (compound 5), as well as a pair of isomers of 25S-inokosterone (compound 2) and 25R-inokosterone (compound 3), which were further purified by silver nitrate coordinated high-speed countercurrent chromatography. What is more, dichloromethane/methanol/isopropanol/water (6:6:1:4, v/v/v/v) was applied for calenduloside E (compound 6), 3ß-[(O-ß-d-glucuronopyranosyl)-oxy]-oleana-11,13-dien-28-oic acid (compound 7), zingibroside R1 (compound 8) and chikusetsusaponin IVa (compound 9). Adding Ag+ to the solvent system resulted in unique selectivity for 25R/25S isomers of inokosterone, which increased the complexing capability and stability of Ag+ coordinated 25S-inokosterone, as well as the α value between them. These results were further confirmed by the computational calculation of geometry optimization and frontier molecular orbitals assay. Comprehensive mass spectrometry and nuclear magnetic resonance analysis demonstrated the structures of the obtained compounds.

Simultaneous quantitation of 15 bioactive components in Yupingfeng granules by LC-MS/MS.

Yupingfeng granules (YPFG) is commonly used in the treatment of immunological diseases, inflammations, and pulmonary diseases. Several studies have found that chromones, flavones, and saponins were the major bioactive compounds of YPFG. However, few studies have reported accurate quantification methods of these compounds. This study aimed to establish a simple and rapid method by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine 15 bioactive compounds in YPFG. The experimental parameters including extraction methods, extraction solvents, extraction time, solid-liquid ratio, and LC-MS/MS condition were optimized. The linearity, precision, repeatability, stability, and recovery of the established method were evaluated. The contents of 15 bioactive compounds in seven batches of YPFG samples were analyzed by the established method and the results were compared with the values determined by HPLC. The optimal extraction condition was to extract 0.1 g of YPFG by ultrasound with 50 mL 50% ethanol for 30 min. A Waters ACQUITY UPLCBEH C18 column using the 0.1% formic acid water solution and acetonitrile as mobile phase with a gradient elution was applied to the chromatographic separation. The linearity, precision, repeatability, stability, and recovery of the method were within acceptable ranges. Compared with HPLC analysis methods in Chinese Pharmacopoeia and literature, the established method was faster, simpler, more accurate, and more reliable. The method of simultaneous determination of 15 components in YPFG by LC-MS might provide a basis for the study of the bioactive compounds and the improvement of the quality standard of YPFG.

UHPLC-MS/MS analysis and protective effects on neurodegenerative diseases of phenolic compounds in different parts of Diospyros kaki L. cv. Mopan.

Persimmon (Diospyros kaki L. cv. Mopan.), an important commercial crop belonging to the genus of Diospyros in the Ebenaceae family, is rich in bioactive phenolic compounds. In this study, the phenolic compounds from fruits, leaves, and calyces of persimmon were qualitatively and quantitatively determined by UPLC-Q-Exactive-Orbitrap/MS and UPLC-QqQ-MS/MS, respectively. Furthermore, the role of phenolic extract from different parts of persimmon on neuroprotective activity in vitro, through against oxidative stress and anti-neuroinflammation effect was firstly evaluated. The results showed that 75 phenolic compounds, and 3 other kinds of compounds were identified, among which 44 of phenolic compounds were quantified from different parts of persimmon. It is the first time that epicatechin-epigallocatechin, catechin-epigallocatechin, catechin-epigallocatechin (A-type), and glycoside derivatives of laricitrin were identified in persimmon extract. The dominated phenolic compounds in three parts of persimmon were significantly different. All phenolic extracts from each part of persimmon showed strong neuroprotective activities against H2O2-induced oxidative stress in PC-12 cells and LPS-induced BV2 cells. The fruit extract presented the strongest activity, followed by calyx and leaf extract. The systematic knowledge on the phytochemical composition along with activity evaluation of different parts of persimmon could contribute to their targeted selection and development.

Dicationic imidazole ionic liquid stationary phase for preservative detection and its application under mixed mode of HILIC/RPLC/IEC.

BACKGROUND: Food safety has always been a great concern, and the detection of additives is vital to ensuring food safety. Therefore, there is a necessity to develop a method that can quickly and efficiently separate and detect additives in food. High performance liquid chromatography is widely used in the analysis and testing of food additives. Ionic liquids have attracted wide attention in the preparation of high performance liquid chromatography stationary phases owing to their high stability, low vapor pressure and adjustable structure. RESULTS: We developed a novel dicationic imidazole ionic liquid stationary phase for the simultaneous determination of organic preservatives (sodium benzoate, potassium sorbate) and inorganic preservatives (nitrate and nitrite) in foodstuffs under mixed-mode chromatography. The method had the advantages of easy operation, high reproducibility, good linearity and precision. In the detection of these four preservatives, the limit of detection ≤0.4740 mg⋅L-1 and the limit of quantification ≤1.5800 mg⋅L-1. The intra-day and inter-day precision were less than 4.02%, and the recovery rate was 95.90∼100.19 %. At the same time, we also characterized the stationary phase, explored the mechanism and evaluated the chromatographic performance. The stationary phase was able to operate under the mixed mode of reversed phase/hydrophilic interaction/ion exchange chromatography, and it was capable of separating hydrophilic substances, hydrophobic substances, acids, and inorganic anionic substances with good separation efficiency and had high column efficiency. SIGNIFICANCE: In summary, the stationary phase has a promising application in the routine analysis of organic and inorganic preservatives in food. In addition, the stationary phase has good separation ability for hydrophilic, hydrophobic, ionic substances and complex samples, making it a prospective material for chromatographic separation.

[Metabolomics of quality formation of different cultivars of Peucedanum praeruptorum].

This study aims to reveal the quality formation of different cultivars of Peucedanum praeruptorum based on the metabolic differences and provide a theoretical basis for the development and utilization of this medicinal herb. The non-target metabonomics analysis based on ultra-high performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS) was conducted for six cultivars(YS, H, LZ, LY, LX, and Z) of P. praeruptorum of the same origin and at the same development stage. The principal component analysis, orthogonal partial least squares discriminant analysis, and univariate statistical analysis were carried out to screen the differential metabolites of different cultivars. The potential biomarkers associated with quality formation were predicted based on the mass-to-charge ratio, Kyoto Encyclopedia of Genes and Genomes pathway enrichment, information of relevant literature, and correlation analysis. The results showed that metabolites differed significantly among the six cultivars, and 571 and 465 differential metabolites were obtained in the positive and negative ion modes, respectively. From the differential metabolites, 22 potential biomarkers related to quality formation were predicted, which involved 9 metabolic pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, biosynthesis of phenylpropanoids, and biosynthesis of plant hormones. Compared with the YS cultivar, other cultivars showed decreased concentrations of psoralen, imperatorin, and luvangetin and increased concentrations of 7-hydroxycoumarine, esculetin, columbianetin, and jasmonic acid, which were involved in the biosynthesis of phenylpropanoids. The concentrations of 2-succinylbenzoate, heraclenol, and L-tyrosine involved in other metabolic pathways decreased, especially in the Z and H cultivars. Therefore, regulating the biosynthesis of phenylpropanoids is one of the key mechanisms for improving the cultivar quality of P. praeruptorum. The Z and H cultivars have better quality and metabolic processes than other cultivars and thus can be used for the screening and breeding of high-quality germplasm.

[Comparative study on excretion of Shuganning Injection and Scutellariae Radix extract in bile, urine, and feces of rats].

Scutellariae Radix extract is one of the important components in Shuganning Injection. In this study, an ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) method was established for simultaneously determining five components in Shuganning Injection and Scutellariae Radix extract in bile, urine, and feces of rats, so as to reveal the difference in the excretion process of Shuganning Injection and Scutellariae Radix extract in rats and explore the law of the excretion process of the five components in vivo before and after the compatibility of Scutellariae Radix. Rats were injected with Shuganning Injection and Scutellariae Radix extract(4.2 mL·kg~(-1)), respectively, and the excretion of baicalin, baicalein, oroxylin A, oroxylin A-7-O-ß-D-glucuronide, and scutellarin in bile, urine, and feces of rats in 24 h was observed. The results showed that except for baicalin, the other four index components were excreted as prototype components in a high proportion after intravenous injection of Shuganning Injection and Scutellariae Radix extract in rats, respectively. The excretion of each component was relatively high in urine and less in feces and bile. After the compatibility of Scutellariae Radix extract, the accumulative excretion of five index components in rats all decreased. Among them, the cumulative excretion of baicalein in bile, urine, and feces significantly decreased by 26.67%, 48.11%, and 31.01%. The cumulative excretion of baicalin in bile, urine, and feces decreased significantly by 70.69%, 19.43%, and 31.22%. The result showed that the five index components in Scutellariae Radix extract were mainly excreted by the kidneys, and other components in Shuganning Injection delayed the excretion process and prolonged the residence time. This study is of great significance for elucidating the compatibility rationality of Shuganning Injection.

[Analysis of constituents in different parts of Forsythia suspensa by UPLC-Q-TOF-MS and evaluation of their anti-inflammatory activity].

This study aims to characterize and identify the chemical constituents in 11 parts of Forsythia suspensa by using ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry(UPLC-Q-TOF-MS) combined with a self-established chemical constituent database, including leaves, flowers, fruits, green F. suspensa, old F. suspensa, and seeds. The quality attributes and differences of different parts of F. suspensa were evaluated by principal component analysis, partial least square discriminant analysis, and other stoichiometric methods. A total of 79 compounds were identified, including 13 phenylethanol glycosides, 10 lignans, 12 flavonoids, 10 organic acids, 14 terpenoids, and 20 other types of compounds. Among them, 34 compounds were the main variables of difference between the different parts of F. suspensa, and the content of each component was relatively higher in the leaves and green F. suspensa. The LPS-induced inflammation model of RAW264.7 cells was applied to study the anti-inflammatory activity of the extracts of the different parts of F. suspensa and the main constituents. The results show that the extracts of green F. suspensa, flower, twig, and stem exhibited anti-inflammatory activity, and the constituents such as forsythoside A, phyllyrin, phillygenin, and(+)-pinoresinol-ß-D-glucopyranoside could significantly inhibit anti-inflammatory activity released by NO. The chemical constituent in different parts of F. suspensa is analyzed comprehensively, and the anti-inflammatory activity is evaluated in this study, which provides a reference for the development and comprehensive utilization of F. suspensa resources.

[Determination of 13 chemical components of Epimedii Folium in pharmacopoeia by UPLC method combined with quantitative analysis of multicomponents by single-marker].

The quantitative analysis of multicomponents by single-marker(QAMS) was established for 13 chemical components of Epimedii Folium, including neoglycolic acid, chlorogenic acid, cryo-chlorogenic acid, magnolidine, hypericin, epimedin A, epimedin B, epimedin C, icariin, baohuoside Ⅱ, sagittatoside A, icariin subside Ⅰ, and baohuoside Ⅰ, so as to investigate the feasibility and accuracy of this method in evaluating the quality of Epimedii Folium materials from different origins and different varieties. Through the scientific and accurate investigation of the experimental method, the external standard method was used to determine the content of 13 chemical components in epimedium brevieornu. At the same time, icariin was used as the internal standard, and the relative correction factors of icariin with neoglycolic acid, chlorogenic acid, cryo-chlorogenic acid, magnolidine, hypericin, epimedin A, epimedin B, epimedin C, icariin, baohuoside Ⅱ, sagittatoside A, icariin subside Ⅰ, and baohuoside Ⅰ were established, respectively. The contens of neoglycolic acid, chlorogenic acid, cryo-chlorogenic acid, magnolidine, hypericin, epimedin A, epimedin B, epimedin C, icariin, baohuoside Ⅱ, sagittatoside A, icariin subside Ⅰ, and baohuosideⅠ in Epimedii Folium were calculated by QAMS. Finally, the difference between the measured value and the calculated value was compared to verify the accuracy and scientific nature of QAMS in the determination. The relative correction factor of each component had better repeatability, and there was no significant difference between the results of the external standard method and those of QAMS. With icariin as the internal standard, QAMS simultaneously determining neoglycolic acid, chlorogenic acid, cryo-chlorogenic acid, magnolidine, hypericin, epimedin A, epimedin B, epimedin C, icariin, baohuoside Ⅱ, sagittatoside A, icariin subside Ⅰ, and baohuoside Ⅰ can be used for quantitative analysis of Epimedii Folium.

[Identification and visual analysis of ginsenosides in multi-steamed roots of Panax quinquefolium based on UPLC-Q-TOF-MS/MS and MALDI-MSI].

This study aims to investigate the component variations and spatial distribution of ginsenosides in Panax quinquefolium roots during repeated steaming and drying. Ultra performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry(UPLC-Q-TOF-MS/MS) was employed to identify the ginsenosides in the root extract. Matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI) was employed to visualize the spatial distribution and spatiotemporal changes of prototype ginsenosides and metabolites in P. quinquefolium roots. The UPLC results showed that 90 ginsenosides were identified during the steaming process of the roots, and polar ginsenosides were converted into low polar or non-polar ginsenosides. The content of prototype ginsenosides decreased, while that of rare ginsenosides increased, which included 20(S/R)-ginsenoside Rg_3, 20(S/R)-ginsenoside Rh_2, and ginsenosides Rk_1, Rg_5, Rs_5, and Rs_4. MALDI-MSI results showed that ginsenosides were mainly distributed in the epidermis and phloem. As the steaming times increased, ginsenosides were transported to the xylem and medulla. This study provides fundamental information for revealing the changes of biological activity and pharmacological effect of P. quinquefolium roots that are caused by repeated steaming and drying and gives a reference for expanding the application scope of this herbal medicine.

Phytochemical exploration of Neolitsea pallens leaves using UPLC-Q-TOF-MS/MS approach.

Neolitsea pallens (D. Don) Momiyama & H. Hara (Family: Lauraceae), commonly known as Pale Litsea, is an evergreen small tree, distributed in India at altitudes of 1500-3000 m. Traditionally utilized for various purposes, its leaves and bark are used as spices, and the plant is valued in preparing a hair tonic from freshly pressed juice. Secondary metabolites of the leaves have not comprehensively been analysed so far. The objective of the study was to determine the chemical composition of the leaves by analysing their 25% aqueous methanol extract with the aid of ultra-performance liquid chromatography quadrupole time of flight tandem mass spectrometry. Overall, 56 compounds were identified in the study. Phenolics represented by phenolic acids, phenolic glycosides, proanthocyanidins, and flavonoids were the main components of the extract.

Analysis of the Guanine Nucleotide-Bound State of KRAS by Ion-Pair Reversed-Phase High-Performance Liquid Chromatography.

Guanine nucleotides can be quantitatively analyzed by high-performance liquid chromatography (HPLC). Here we describe an ion-pair reversed-phase HPLC (IP-RP-HPLC)-based method, which enables analyzing GDP and GTP bound to small GTPases immunoprecipitated from cells. The activation status of FLAG-KRAS expressed in HEK293T cells can be investigated with the IP-RP-HPLC method. This method also can be adapted to determine the effects of compounds such as the KRAS/G12C inhibitor sotorasib on the activation status of FLAG-KRAS in the cells.

Determination of trace chelating carboxylic acids in rice by green extraction combined with liquid chromatography-mass spectrometry analysis and its application in the evaluation of old and new rice.

RATIONALE: Accurate identification of old rice samples from new ones benefits their market circulation and consumers. However, the current detection methods are still not satisfactory because of their insufficient accuracy or (and) time-consuming process. METHODS: Chelating carboxylic acids (CCAs) were selectively extracted from rice, by stirring with chelating resin and a dilute Na2CO3 solution. The green analytical chemistry guidelines for sample preparation were investigated by using the green chemistry calculator AGREE prep. The extractant was determined by liquid chromatography-mass spectrometry (LC/MS), and statistical analysis of the analytical data was carried out to evaluate the significance of the difference by ChiPlot. RESULTS: The limit of quantitation for the CCAs is in the range of 1 to 50 ng/mL, with a reasonable reproducibility. The CCAs in 23 rice samples were determined within a wide concentration range from 0.03 to 1174 µg/g. Intriguingly, the content of citric acid, malonic acid, α-ketoglutaric acid and cis-aconite acid in new rice was each found to be distinctively higher than that in old rice by several times. Even mixtures of old and new rice were found to show much difference in the concentration of citric acid and malic acid. CONCLUSION: A green analytical method has been developed for the simultaneous determination of CCAs by LC/MS analysis, and the identification of old rice samples from new ones was easily carried out according to their CCA content for the first time. The results indicated that the described method has powerful potential for the accurate identification of old rice samples from new ones.

Analytical method development, identification, and characterization of stress degradation products of idelalisib by ultrahigh-performance liquid chromatography with photodiode array and ultrahigh-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry studies.

RATIONALE: As per International Council for Harmonization (ICH) drug stability test guideline Q1A(R2), inherent stability characteristics of a drug should be studied. This work was designed to investigate inherent degradation characteristics of the drug idelalisib under ICH prescribed stress conditions, identify its degradation products, and postulate their corresponding degradation pathways. METHODS: Idelalisib was subjected to the ICH prescribed conditions of hydrolytic (neutral, acidic, and alkaline), photolytic, oxidative, and thermal stress according to ICH guideline Q1A(R2). An ultrahigh-performance liquid chromatography with photodiode array (UHPLC-PDA) method was developed to adequately resolve the drug from its degradation products, validated as per the ICH guidelines, and subsequently extended to UHPLC with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOFMS) studies to identify the degradation products. RESULTS: Significant degradation was noted under conditions of acidic/alkaline hydrolysis, acid photolysis, and oxidative stress. The UHPLC/ESI-QTOFMS studies revealed the generation of four degradation products (I-IV), which were satisfactorily resolved from the drug by UHPLC on a Kinetex® C18 (100 × 4.6 mm; 2.6 µm) column by the developed isocratic elution method. Detection wavelength was selected as 270 nm. All the degradation products (I-IV) could be identified and characterized from their mass spectral data. The degradation pathways for the generation of various products from the drug were postulated. CONCLUSIONS: A UHPLC-PDA method was developed and validated for idelalisib. Four degradation products of idelalisib were revealed through UHPLC/ESI-QTOFMS studies, and corresponding degradation pathways were postulated for the same.

Measurements of Ascorbate and Dehydroascorbate in Plants Using High-Performance Liquid Chromatography.

The current concepts emphasize the fundamental role of reactive oxygen species (ROS) as signaling molecules that coordinate defense mechanisms, cell death, and the growth and development processes in plants. However, due to the inherent reactivity of ROS, achieving precise control over their levels within plant cells, both spatially and temporally, becomes important to effectively harness the potential of ROS signaling while concurrently minimizing the risk of oxidative damage. Ascorbate is an exceptional antioxidant and contributes to the antioxidant defense system in plants. Its role is further reinforced by the presence of ascorbate peroxidases and enzymes responsible for recycling ascorbate from its oxidized forms. Ascorbate metabolism plays a pivotal role in averting oxidative damage and facilitates meticulous regulation of ROS signal availability. This chapter outlines the preferred protocol for the measurement of ascorbate.

Simple and rapid determination of tartrazine in fake saffron using the metal organic framework (Fe SA MOF@CNF) by HPLC/PDA.

The present study of a novel metal-organic framework containing Fe single atoms doped on electrospun carbon nanofibers (Fe SA-MOF@CNF) based on dispersive micro solid phase extraction (D-µ-SPE) using HPLC-PDA for detection tartrazine in fake saffron samples was designed. The Fe SA-MOF@CNF sorbent was extensively characterized through various techniques including N2 adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The specific area of surface of the sorbent was 577.384 m2/g. The study variables were optimized via the central composite design (CCD), which included a sorbent mass of 15 mg, a contact time of 6 min, a pH of 7.56, and a tartrazine concentration of 300 ng/ml. Under the optimum condition, the calibration curve of this method was linear in the range of 5-1000 ng/mL, with a correlation coefficient of 0.992. The LOD and LOQ values were ranged 0.38-0.74 and 1.34-2.42 ng/ml, respectively. This approach revealed significant improvements, including high extraction recovery (98.64), recovery rates (98.43-102.72%), and accuracy (RSDs < 0.75 to 3.6%). the enrichment factors were obtained in the range of 80.6-86.4 with preconcentration factor of 22.3. Consequently, the D-µ-SPE method based on synthesized Fe SA-MOF@CNF could be recommended as a sustainable sorbent for detecting tartrazine in saffron samples.

Optimization, validation, and application of a liquid chromatography-tandem mass spectrometry method for the determination of 47 banned drug and related chemical residues in livestock urine using graphitized carboxyl multi-walled carbon nanotubes-based QuEChERS extraction.

The establishment of an efficient method for the analysis of drug residues in animal urine facilitates the real-time monitoring of drugs used in the production of animal-derived food. A modified QuEChERS extraction-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of 47 banned drug and related chemical residues in livestock urine. The sample was extracted with acetonitrile by converting the acid-base environment. The sample cleanup effects of seven solid phase extraction cartridges and two EMR-Lipid products were compared, and three materials, including graphitized carboxyl multi-walled carbon nanotubes (MWCNTs), PSA, and C18, were selected as QuEChERS adsorbents from 24 materials. All analytes showed good linearity, with correlation coefficients (R2) greater than 0.9936. Low limits of quantification could be obtained, ranging from 0.2 to 5.5 ng/mL. The average recoveries at low, medium, and high spiked levels were in the range of 70.8-114.9 %, with intra-day precision ranging from 2.4 % to 11.2 % and inter-day precision ranging from 4.5 % to 16.1 %. Swine urine and bovine urine samples collected from different farms were effectively analyzed using the developed method, and metronidazole was detected in three swine urine samples.