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The current approaches remain insufficient for measuring chicken egg spoilage or present analytical limitations. This study aimed to complement the existing analyses and identify novel markers using liquid chromatography-high resolution mass spectrometry-based foodomics strategies. In the discovery set, comparative untargeted metabolomics was utilized to identify marker candidates in microbially inoculated chicken eggs. Markers were annotated by spectral matching with authentic standards, experimental libraries, or in silicofragmentation. In the validation set, targeted metabolomics was employed to verify the markers in stored chicken eggs from five farms. Statistical differences at a p-value < 0.001 revealed increases in lactic and 3-hydroxybutyric acids and decreases in phosphocholine, LPE(O-18:1), LPC(16:0), and LPC(18:0) in stored eggs. Receiver operating characteristic curve analysis of the six combined markers yielded an AUC of 0.956 and a sensitivity and specificity of ∼90%. Four phospholipids were highlighted as a novel class of spoilage markers. Our findings may contribute to further industrial implementation, benefiting the quality assurance and food safety of poultry egg production.

The full characterization of nonbiological complex drugs (NBCDs) is not possible, but analytical approaches are of urgent need to evaluate the similarity between different lots and compare with their follow-up versions. Here, we propose a hypothesis testing-based approach to assess the similarity/difference between random amino acid copolymer drugs using liquid chromatography mass spectrometry (LC-MS) analysis. Two glatiramer acetate (GA) drugs, commercially available Copaxone and in-house synthesized SPT, and a negative control were digested by Lys-C and followed by HILIC-MS analysis. After retention time alignment and feature identification, 1627 features matched to m/zvalues in an elemental composition database were considered as derived from active drug ingredients. A hypothesis testing approach, the sum of squared deviations test, was developed to process high-dimensional data derived from LC-MS spectra. The feasibility of this approach was first demonstrated by testing 5 versus 5 lots of Copaxone and Copaxone versus SPT, which suggested a significant similarity by obtaining the estimated 95th percentile of the distribution of the estimator (ρ̂(95%)) at 0.0056 (p-value = 0.0026) and 0.0026 (p-value < 0.0001), respectively. In contrast, the ρ̂ was 0.036 (p-value = 1.00), while comparing Copaxone and the negative control, implying a lack of similarity. We further synthesized nine stable isotope-labeled peptides to validate the proposed amino acid sequences in the database, demonstrating the correctness in sequence identification. The quantitation variations in our analytical procedures were determined to be 6.8–7.7%. This approach was found to have a great potential for evaluating the similarity between generic NBCDs and listed reference drugs, as well as to monitor the lot-to-lot variation.

Electrochemical interfaces determine the performance of electrochemical devices, including energy-related systems. An in-depth understanding of the heterogeneous interfaces requires in situ techniques with high sensitivity and high temporal and spatial resolution. We develop here an electrochemical reflective absorption microscope (EC-RAM) by using the absorption signals of reacting species with a reasonably good spatial resolution and high sensitivity. We systematically study the response of absorbance (A) and its derivative, i.e. dA/dt, at different positions of the electrode surface and at electrodes with different sizes (50 μm, 500 μm, and 2 mm) both experimentally and theoretically. We find that the derivative cyclic voltabsorptometry (DCVA) frequently used to obtain the local current response in conventional electrochemical optical microscopy techniques is only applicable to reactions of surface species or solution species under linear diffusion control. For processes when the radial diffusion cannot be ignored, as in the case of a microelectrode or the edge of a large electrode, the DCVA curves show distinct diffusion behaviors for the electroactive species in different regions of the electrode, which cannot be directly related to the CV curves. When the radial diffusion dominates the reaction, CVA curves follow the same shape as the CV curves. The developed EC-RAM technique can be applied to extract in situ the local response of an electrochemical system during the dynamic reaction processes.