Multiresidue analysis of glucocorticoids in milk by LC-MS/MS with low-temperature purification and dispersive solid-phase extraction

Aptamer-modified paper-based analytical devices for the detection of food hazards: Emerging applications and future perspective

Food analysis plays a critical role in assessing human health risks and monitoring food quality and safety. Currently, there is a pressing need for a reliable, portable, and quick recognition element for point-of-care testing (POCT) to better serve the demands of on-site food analysis. Aptamer-modified paper-based analytical devices (Apt-PADs) have excellent characteristics of high portability, high sensitivity, high specificity, and on-site detection, which have been widely used and concerned in the field of food safety. The article reviews the basic components and working principles of Apt-PADs, and introduces their representative applications detecting food hazards. Finally, the advantages, challenges, and future directions of Apt-PADs-based sensing performance are discussed, to provide new directions and insights for researchers to select appropriate Apt-PADs according to specific applications.

Development of a broad-spectrum one-step immunoassay for detection of glucocorticoids in milk using magnetosome-based immunomagnetic beads

Immunomagnetic beads provide novel tools for high-throughput immunoassay techniques. In this study, protein G (PG) was immobilized onto bacterial magentic particles (BMPs) using an additional cysteine residue at the C-terminus. A broad-spectrum monoclonal antibody against glucocorticoids (GCs) was attached to BMPs through PG-Fc interaction, generating BMP-PG-mIgG immunomagentic beads. A sensitive one-step immunoassay was developed for GCs based on combination of BMP-PG-mIgG and dexamethasone-horseradish peroxidase tracer (DMS-HRP). The developed assay exhibited half inhibitory concentrations (IC50) for dexamethasone (DMS), betamethasone (BMS), prednisolone (PNS), hydrocortisone (HCS), beclomethasone (BCMS), cortisone (CS), 6-α-methylprednisone (6-α-MPNS), fludrocortisone acetate (HFCS) of 0.98, 1.49, 2.42, 9.29, 1.63, 6.13, 7.3, and 4.89 ng/mL, respectively. The method showed recoveries ranging rates from 86.5 % to 117 % with a coefficient of variation less than 12.3 % in milk sample, which showed a good correlation with LC-MS/MS. Thus, the proposed assay offers a rapid and broad-spectrum screening tool for simultaneous detection of GCs in milk.

Simultaneous determination of 58 glucocorticoid residues in milk by ultra-high performance liquid chromatography-tandem mass spectrometry

Abuse of glucocorticoid veterinary drugs in dairy industry can potentially threat milk safety and consequently influence human health. Here a reliable method for determination of 58 glucocorticoid drug residues in milk was established by combining solid phase extraction with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The analytes were extracted with acetonitrile and cleanup with EMR-Lipid lipid removal column. The analytes were chromatographically separated using Poroshell EC-C18 column and acquired by electrospray ionization with multiple-reaction monitoring (MRM) mode. The limit of quantification (S/N ≥ 10) ranged from 0.2 to 2.0 µg/kg and the limit of detection (S/N ≥ 3) ranged from 0.1 to 1.0 µg/kg. Average recoveries were from 71% to 113%, the relative standard deviations (RSDs) were less than 15%, and the correlation coefficients (R2) of calibration curves exceeded 0.99. The method was applied to detect twenty milk products obtained from local supermarkets including ten pasteurized milk and ten UHT milk. Two endogenous glucocorticoids, i.e. hydrocortisone and cortisone were detected but not exceed the maximum residue limits (MRLs).

Gold immunochromatographic strip assay for the detection of triamcinolone acetonide and budesonide in milk

A monoclonal antibody against triamcinolone acetonide (TCA) and budesonide (BUD) was prepared using a hapten that was generated by introducing a carboxyl group into the structure of TCA. Based on the prepared monoclonal antibody, a gold nanoparticle-based lateral-flow immunoassay (GLFA) was developed with the ability to screen TCA and BUD in milk. The visible limits of detection of the GLFA for the analysis of TCA and BUD were 0.1 and 0.5 ng/mL with a cutoff value of 5 and 10 ng/mL, respectively, in milk. Average recoveries of TCA and BUD in milk were 92.0-102.2% and 96.0-98.8% with a good correlation between the results from the GLFA and LC-MS/MS analysis. These results demonstrated that the GLFA method for the rapid detection of TCA and BUD in milk samples is reliable and sensitive.

Based on Unmodified Aptamer-Gold Nanoparticles Colorimetric Detection of Dexamethasone in Food

Residue and illegal addition of Dexamethasone (DEX) in food has received widespread attention over the past few decades. Long-term intake of DEX will have a strong endocrine-disrupting effect, and there is an urgent need to develop highly sensitive and rapid on-site detection methods. In this work, a colorimetric sensor based on an unmodified aptamer and gold nanoparticles (Au NPs) was designed to detect DEX in milk and glucosamine. Under optimized conditions, the absorbance ratio of Au NPs increased linearly with DEX concentration over the range of 10-350 nmol/mL (r² = 0.997), with a limit of detection (LOD) of 0.5 nmol/mL, and the recoveries ranged from 93.6 to 117%. To explore the interaction mechanism between aptamer and DEX, molecular docking and molecular dynamics simulations were applied to probe intermolecular interactions and structures of the complex. The establishment of aptamer-based sensors effectively avoids the antibody screening response, with a cost-efficient, excellent selective and great potential in DEX determination.

A full scale tracing study of "ghost peaks" encountered in impurity analysis of budesonide based on experimental operation inspection-LC/MS fingerprint- mechanism based stress studies integrated strategy

Budesonide is an active pharmaceutical ingredient used in various dosage forms of finished products for the treatment of asthma. During the process of drug development, unbiased analysis of related substances is of utmost significance for both pharmaceutical research and quality control purposes. In this work, official method documented in the United States Pharmacopoeia was selected to determine the related substances of budesonide considering the pros and cons of critical chromatographic parameters, compared to the European Pharmacopoeia. In doing so, several unpredictable interference peaks, namely "ghost peaks", were observed occasionally during analysis. A strategy which integrated information derived from experimental operation inspection, LC/MS fingerprint analysis and mechanism based stress studies was then proposed for comprehensively and quickly exploring those non-degradable and degradable peaks. Some ghost peaks were found to originate from nylon syringe filter, illumination and alkali borosilicate glass HPLC vials. Besides, degradation pathways under alkaline conditions were also unravelled through LC-MS qualitative analysis. Overall, an optimization of the analytical methodology based on the United States Pharmacopoeia for its application in impurity analysis of budesonide and corresponding formulations was carried out with design of experiments, by which "ghost peaks" could be suppressed or prevented. The results obtained herein are not only crucial to studies on budesonide's stability or degradation kinetics but also contribute to clarify the impurity research of other drugs. This article is protected by copyright. All rights reserved.

S. M. Montenegro MC, Rodríguez-Díaz JM. Contaminants in the cow's milk we consume? Pasteurization and other technologies in the elimination of contaminants

Cow's milk is currently the most consumed product worldwide. However, due to various direct and indirect contamination sources, different chemical and microbiological contaminants have been found in cow's milk. This review details the main contaminants found in cow's milk, referring to the sources of contamination and their impact on human health. A comparative approach highlights the poor efficacy and effects of the pasteurization process with other methods used in the treatment of cow's milk. Despite pasteurization and related techniques being the most widely applied to date, they have not demonstrated efficacy in eliminating contaminants. New technologies have appeared as alternative treatments to pasteurization. However, in addition to causing physicochemical changes in the raw material, their efficacy is not total in eliminating chemical contaminants, suggesting the need for new research to find a solution that contributes to improving food safety.

Latex microsphere immunochromatography for quantitative detection of dexamethasone in milk and pork

Dexamethasone (DEX) is a synthetic long-acting glucocorticoid, which can increase the risk of hypertension and diabetes if it is abused or used improperly. In this study, lateral flow immunoassays (LFIA) based on black and blue latex microspheres (LMs), integrated with a strip reader, was developed for quantitative detection of DEX in milk and pork. The results could be achieved within 15 min. The visible limits of detection (vLODs) were 0.3 ng/mL and 0.7 μg/kg for milk and pork, respectively. The quantitative limits of detection (qLODs) were 0.047 ng/mL and 0.087 μg/kg, respectively. The recoveries ranged from 80.0% to 122.8%. 20 milk and 10 pork samples were analyzed to confirm the performance of the on-site application. The detection results were consistent with the data from LC-MS/MS, indicating the practical reliability of our established assay. The developed LMs-LFIA provides a promising technical support for rapid, sensitive, and on-site detection of DEX.

In-situ preparation of porous monolithic polymer inside hollow fiber as a micro-solid phase extraction device for glucocorticoids in cosmetics

Glucocorticoids have a certain whitening effect on the skin. However, frequent and long-term use of cosmetics including glucocorticoids is harmful to health. Herein, we proposed a novel micro-solid phase extraction method for the detection of prednisolone acetate, prednisone, and prednisolone in cosmetics coupled with high-performance liquid chromatography. In this method, porous monolithic polymer micro-extraction bars were prepared by "one-step, one-pot" in situ photopolymerization combined with sacrificial support in hollow fiber under water atmosphere. The crucial factors such as pH of sample solution, extraction, and elution times that influence micro-extraction were optimized and found to be 9.0, 2 h, and 32 min, respectively. Under the optimum experimental conditions, the linear range of the calibration curves were from 5.0 to 2000 µg/L with correlation coefficients (R² ) between 0.9922 and 0.9996. The limit of detection and limit of quantification were 1.5 µg/L and 5.0 µg/L, respectively, and the recoveries were found to be in range of 69.0-113.3%. The analysis of precision for intraday and interday were less than 10.40 and 10.59%. The device has been successfully achieved photopolymerization under water atmosphere. The results indicated that this method is simple, accurate, and satisfactory for the pretreatment and determination of glucocorticoids in complex cosmetics samples.