Determination of multi-residue pesticides in dairy products using single-step emulsification/demulsification clean-up strategy combined with low-pressure gas chromatography-tandem mass spectrometry.

In this study, a simple, sensitive, and rapid method was developed for the simultaneous determination of 99 kinds of pesticides in fatty milk samples. This novel emulsification-demulsification clean-up approach, coupled with an automatic demulsification-dehydration cartridge, allowed rapid single-step clean-up operation and high throughput. It also achieved effective and selective removal of lipids. The analysis was performed using low-pressure gas chromatography-tandem mass spectrometry (LPGC-MS/MS). Based on the optimal conditions, the targeted pesticides showed good linearity in the range of 5-250 µg/kg, with recoveries of 70-120% at spiking levels of 5, 10, and 20 µg/kg in cow milk, goat milk, and almond milk, respectively. The limit of quantification for most pesticides was 5 µg/kg, and the RSDs were lower than 20%. Analysis of real dairy products obtained from local markets revealed a potential risk in plant-derived almond milk, but no significant risks were found for cow and goat milk.

Development and validation of an LC-MS/MS method for quantifying NAD+ and related metabolites in mice sciatic nerves and its application to a nerve injury animal model.

Recent studies highlight the pivotal roles of Nicotinamide adenine dinucleotide (NAD+) and its metabolites in aging and neurodegeneration. Accurate quantification of NAD+ and its metabolite levels in cells or tissues is crucial for advancing biochemical research and interventions targeting aging and neurodegenerative diseases. This study presents an accurate, precise, and rapid LC-MS/MS method using a surrogate matrix to quantify endogenous substances NAD+, nicotinamide mononucleotide (NMN), nicotinamide (NAM), adenosine diphosphate ribose (ADPR), and cyclic adenosine diphosphate ribose (cADPR) concentrations in mice sciatic nerves. Considering the properties of the phosphate groups in the analytes, the column and mobile phase were systematically optimized. These five polar analytes exhibited excellent analytical performance and baseline separation within 5 min on an Atlantis Premier BEH C18 AX column, with methylene phosphonic acid as a mobile phase additive. Enhanced sensitivity addressed the challenges posed by the small sample size of mice sciatic nerve and low NMN and cADPR detection. The method was fully validated, with linear correlation coefficients exceeding 0.992, precision (%relative standard deviation, RSD) values within 8.8%, and accuracy values between 92.2% and 107.3%, suggesting good reproducibility. Analytical recoveries in spiked and diluted matrix ranged from 87.8% to 104.7%, indicating the suitability of water as a surrogate matrix. Application of the method to quantify NAD+ and its metabolite levels in normal and injured mice sciatic nerve identified cADPR as a sensitive biomarker in the nerve injury model. This method is anticipated to deepen our understanding of the connections between NAD+ and its metabolites in health and disease, potentially improving diagnoses of various neurological disorders and aiding drug development for aging and neurodegenerative diseases.

Molecular imprinting of glycoproteins: From preparation to cancer theranostics.

Glycoprotein imprinted polymers have rapidly grown as excellent receptors for cancer targeting, diagnostics, inhibition, and nanomedicines as they specifically target glycans and glycosites overexpressed in various tumors. Compared to natural antibodies, they are easy to synthesize, stable, and cost-efficient. Currently, no study specifically discusses glycoproteins imprinting strategies for cancer theranostics. In this review, firstly we explored various factors involved in designing and synthesis of glycoprotein imprinted materials, including, the characteristics and choice of monomers for imprinting, types of templates and their interactions involved, and the imprinting methods. Secondly, the integration of these MIPs with different probes that have been applied for in vitro and in vivo targeting for cancer diagnostics including biosensing and bioimaging, and image-guided therapeutic applications as nanomedicines. These Glycoprotein imprinted polymers have been found to specifically target the glycoprotein biomarkers and glycosylated cell receptors overexpressed in different cancers and have been reported as excellent diagnostic tools. As nanomedicines, they have been potentially employed in various modes of cancer therapy such as targeted drug delivery, photodynamic therapy, photothermal therapy, and nanoMIPs themselves as therapeutics for locally killing tumor cells. Although the research is still in its early stages and no real-world clinical trials on humans have been conducted, nanoMIPs have a promising future in this field. We believe these findings will pave the way for MIPs in advanced diagnostics, antibody treatment, and immunotherapy as future nanomedicine for real-world cancer theranostics.

Efficient ofloxacin degradation via photo-Fenton process over eco-friendly MIL-88A(Fe): Performance, degradation pathways, intermediate library establishment and toxicity evaluation.

The high-throughput production of the eco-friendly MIL-88A(Fe) was achieved under mild reaction conditions with normal pressure and temperature. The as-prepared MIL-88A(Fe) exhibited efficient photo-Fenton catalytic ofloxacin (OFL) degradation upon visible light irradiation with good stability and reusability. The OFL (20.0 mg/L) was completely degraded within 50 min under visible light with the aid of MIL-88A(Fe) (0.25 g/L) and H2O2 (1.0 mL/L) in aqueous solution (pH = 7.0). The hydroxyl radicals (·OH) are the main active species during the photo-Fenton oxidation process. Meanwhile, the degradation intermediates and the corresponding degradation pathways were identified and proposed with the aid of both ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and density functional theory (DFT) calculations. Finally, the degradation product library was firstly established to identify intermediate transformation products (TPs) with their variation of concentration, and their corresponding toxicologic activities were assessed via Toxtree and T.E.S.T software as well. Finally, the MIL-88A is efficient and stable with four cycles' catalysis operations, demonstrating good potential for water treatment.

The effects of heat treatment and fermentation processes on the formation of furfurals in milk-based dairy products using a QuEChERS technique followed by gas chromatography coupled with triple quadrupole mass spectrometry.

A method based on gas chromatography coupled with triple quadrupole mass spectrometry (GC-MS/MS) combined with QuEChERS extraction was developed to detect furfurals, including furfural, 2-acetylfuran, 5-methyl-2-furfural, and 5-hydroxymethyl-2-furfural, in milk-based dairy products. Under the optimized conditions, good linearity was obtained with correlation coefficients (R2) above 0.999, and the recovery values from the spiked samples were 79.0%-115.0% with relative standard deviations (RSDs) less than 13.1%. The limits of detection (LODS) were in the range of 0.002-0.02 mg/kg. To investigate the effects of the production process on milk-based dairy products, 55 real samples were analysed. The higher contents of furfurals were observed when higher temperatures were used during heat treatment and fermentation. In addition, the Toxtree and T.E.S.T. software programs were used to predict the risks associated with these four furfurals. Ultimately, safe dairy intake levels were determined.

Solid-phase microextraction based on nickel-foam@polydopamine followed by ion mobility spectrometry for on-site detection of Sudan dyes in tomato sauce and hot-pot sample.

Sudan dyes are one kind of synthetic azo dyes that are forbidden to use in foodstuffs according to the European Union Rule. In this work, considering the structure of Sudan dyes, nickel-foam@polydopamine (NF@PDA) was prepared through the self-polymerization of dopamine on the nickel-foam surface under weak alkaline conditions and used as SPME material to selectively extract the Sudan dyes. With the feature of three dimension (3D) cross-linked grid structure, large porosity and specific surface area, Ni-foam was selected as carrier material which can increase mass adsorption capacity. The primary parameters affecting extraction efficiency such as extraction time, extraction temperature, stirring speed, pH value, ionic strength and desorption time were investigated and optimized. After the Sudan dyes were eluted from the NF@PDA, the eluate was detected by IMS with a corona discharge (CD) ionization source. Thus, an innovative and rapid screening method coupling the NF@PDA to ion mobility spectrometry (IMS) was developed. Under the optimal extraction conditions, the detection limits for Sudan dyes were in the range from 0.005 µg g-1 to 0.25 µg g-1. The spiked recoveries were in the range from 81% to 91.3% by testing tomato sauce and hot-pot sample and validated by the UPLC-MS. Based on the results, the PDA coating has great ability for the extraction of Sudan dyes, mainly due to the catechol structure, electron-deficient quinones and amine groups on its surface. Thus, the developed method has great potential for on-site rapid screening of the Sudan dyes in food quarantine field.

Determination of fipronil and its metabolites in chicken egg, muscle and cake by a modified QuEChERS method coupled with LC-MS/MS.

An easy-to-use method for determining the levels of fipronil and its metabolites (fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide) in chicken egg, muscle and cake was developed and validated using a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) approach coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The samples were extracted using acetonitrile, salted out with sodium chloride at -20°C, and then purified by combined PSA and C18 phases and anhydrous magnesium sulphate. The recoveries were 80.4-119% with relative standard deviations (RSDs) < 10% for the different matrixes. The validated method was used to analyse the target compounds in 214 real samples collected in Beijing. The metabolite fipronil-sulfone was detected in most of the samples and was identified as the main residue in the egg and cake. The method was validated using a proficiency test for fipronil in products of animal origin published by Wageningen University & Research in 2017.

Toxicity assessment of the extractables from multi-layer coextrusion poly ethylene bags exposed to pH=5 solution containing 4% benzyl alcohol and 0.1 M sodium acetate.

A non-target analysis was developed for the analysis of extractables from multi-layer coextrusion bags exposed to 4% benzyl alcohol solution and 0.1 M sodium acetate at pH = 5 for defined periods (15 day, 45 day and 90 day) according to manufacturer instructions based on the ultra-performance liquid chromatography (UPLC) quadrupole-time of flight mass spectrometry (Q-TOF MS). In order to confirm the extractables, principal component analysis (PCA) was used to indicate the differences among samples of different periods. Then, the extractables were identified based on searching the self-built library or online searching. The total content of extractables of 90 day samples was 589.78 µg/L, and the content was in the range of acceptable levels for pharmaceutical manufacturers. The risk assessment of the extractables were evaluated by Toxtree and T.E.S.T. software to avoid the animals bioexperiment.

Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods.

Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

Prediction of biomarkers of therapeutic effects of patients with lung adenocarcinoma treated with gefitinib based on progression-free-survival by metabolomic fingerprinting.

Lung carcinoma is one of the most frequently diagnosed malignancy and threats human life and health. In clinical practice, gefitinib, one of the most well-known epidermal growth factor receptor tyrosine kinase inhibitors, was frequently used in the treatment of non-small cell lung carcinoma. However, this drug is not useful for all non-small cell patients. In this study, the biomarkers were found out to predict the therapeutic effects of gefitinib for lung carcinoma patients. Serum samples were collected from patients with advanced lung adenocarcinoma. The ultra-high performance liquid chromatography (UHPLC)-quadrupole-time of flight mass spectrometry (Q-TOF MS) was conducted to obtain the metabolic data for each patient. Partial least squares-discriminate analysis (PLS-DA) was performed to indicate the differences between metabolites of patients, and Cox proportional hazards regression analysis was used to eliminate the interference of the patient's gender, age, smoking history and disease stage. Thus, differential biomarkers were found. The combination of these biomarkers was statistically significant predictors based on progression-free survival. If these biomarkers can be further confirmed by the clinic, it could suggest the proper therapeutic schedule, and help to reduce patients' economic burden and medication side effects.

Rapid identification of polymer additives by atmospheric solid analysis probe with quadrupole time-of-flight mass spectrometry.

RATIONALE: A method using an atmospheric solid analysis probe (ASAP) combined with quadrupole time-of-flight mass spectrometry (QTOFMS) assisted by a pre-built MS library was found to be efficient in fast and direct analysis of additives for polymers. By this method, sample pretreatment could be eliminated from the additives identification process. METHODS: Some crucial parameters, such as desolvation gas temperature, corona current, sample cone voltage and collision energy, should be optimized. A MS library of 100 polymer additives, including phenols (Irganox 1010, Irganox 1076), hydroxyl phenyl benzotriazole derivatives (Tinuvin 326, Tinuvin 327, Tinuvin 328), hindered amines (Tinuvin 944, Tinuvin 770) and plasticizers, was built based on the optimized conditions. To verify the application of the MS library, the ASAP-QTOFMS method was applied to identify complex additives, a simulated polypropylene (PP) sample and a real polymethylmethacrylate (PMMA) sample purchased from a local market. RESULTS: By searching the exact mass, and comparing the MS and MS/MS spectra of samples with standards in the MS library, complex additives such as Irganox GX 2921, as well as additives in PP and PMMA samples, could be identified quickly and easily. The determination of mass accuracy increased the confidence of peak identification as well. Moreover, the results also provided information of the characterization for PP and PMMA polymers. CONCLUSIONS: A rapid identification method has been developed for polymer additives by ASAP-QTOFMS. A MS library of 100 polymer additives was built by this method. Using ASAP-QTOFMS assisted by the pre-built MS library, polymer additives can be quickly identified. This method was found to be a promising tool in the rapid analysis of additives in polymers and polymer matrices.

Effect of ammonium on liquid- and gas-phase protonation and deprotonation in electrospray ionization mass spectrometry.

The electrospray ionization (ESI) is a complex process and there has been a long debate regarding the gas-phase effect on ion generation in the process. In this paper we investigated the effect of liquid chromatographic mobile phase additives (formic acid, aqueous ammonia and their combination) on the ESI signal intensities for a wide variety of compounds. The addition of a trace amount of aqueous ammonia to the common formic acid-methanol mobile phase significantly enhances the ESI signals of protonated molecules and suppresses the formation of sodium adduct ions. This effect is well observed for the compounds containing the -N-C=O group but not for those without N or O atoms. The ESI signal intensity of deprotonated molecules increases with increase in pH of the mobile phase for neutral compounds, such as substituted urea, whereas this trend is not observed for acidic compounds such as phenoxy acids. The mechanistic analysis regarding liquid- and gas-phase protonation and deprotonation is discussed.

Detection of seven pesticides in cucumbers using hollow fibre-based liquid-phase microextraction and ultra-high pressure liquid chromatography coupled to tandem mass spectrometry.

A liquid-phase microextraction (LPME) methodology based on the use of porous polyvinylidene fluoride (PVDF) hollow fibres was developed for extracting seven pesticides from cucumbers. The seven pesticides include propoxur, carbofuran, atrazine, cyanatryn, metolachlor, prometryn and tebuconazole. The PVDF hollow fibre provides higher extraction efficiency due to its higher porosity and better solvent compatibility. A new desorption methodology was developed since some pesticides were absorbed by the wall pore of the PVDF. Ultra-high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was used for pesticide analysis. In order to obtain high recoveries and enrichment factors of the analytes, several parameters such as method of sealing, acceptor phase (organic solvents), stirring speed, extraction time, salting out effect, desorption mode and time were optimized. A fast, simple method for closing fibre ends was practiced by using mechanical crimping. Pesticides were extracted from the sample to the organic solvent and then desorbed in a mixture of methanol:water (1:1 v/v) prior to chromatographic analysis. Limits of detection (LOD) for the multi-reaction-monitoring (MRM) mode of the method varies from 0.01 to 0.31 µg/kg with optimized sample preparation. Calibration curves are linear with R² ≥ 0.991. Enrichment factor of the hollow fibre LPME ranges from 100 to 147. Matrix effect has been considered and is in the range of 76-122%. The relative recoveries from cucumber samples are between 63% and 119% with the relative standard deviation (RSD, n=6) lower than 20%.