Metabolomics FAQ

• • What Are the Key Steps in Serum Metabolomics Analysis?

  Serum metabolomics analysis is a powerful approach for profiling metabolites in serum samples, widely applied in biomarker discovery, disease diagnosis, and biomedical research. The workflow generally consists of the following steps:   1. Sample Collection and Preparation Blood samples are collected from individuals and processed by centrifugation to isolate the serum. To preserve metabolite stability, the serum samples must be stored under controlled conditions, such as low temperatures or in the pre......

• • What Are the Methods for Extracting Bacterial Cell Membrane Lipids?

  The extraction of bacterial cell membrane lipids involves a series of critical steps, including cell disruption, lipid extraction, and purification. The detailed methodology is outlined below.   1. Cell Collection and Preprocessing (1) Bacterial Cultivation: Grow bacterial cultures until they reach the desired growth phase. (2) Cell Harvesting: Collect bacterial cells via centrifugation or filtration. (3) Cell Washing: Wash the collected cells with an appropriate buffer, such as phosphate-buffered sal......

• • What Are the Three Structural Forms of Flavonoids?

  Flavonoids, a diverse class of polyphenolic compounds, primarily occur in three structural forms:   Flavonols Flavonols represent a subclass of flavonoids distinguished by a hydroxyl (-OH) group at the C-4 position. These compounds are abundant in nature and play significant roles in plant defense and human health. Common flavonols include quercetin, rutin, and quercetin-3-O-glucuronide, which are predominantly found in vegetables, fruits, and tea.   Flavonoid Glycosides Flavonoid glycosides are flavo......

• • How to Establish a Polysaccharide Standard Curve via the Phenol-Sulfuric Acid Method? Why No Color or Stable UV Absorbance?

  The phenol-sulfuric acid method is a widely used technique for quantifying polysaccharides by measuring the absorbance of chromogenic products formed through the reaction between polysaccharides and phenol under acidic conditions. A critical aspect of this method is the establishment of a standard curve for accurate quantification. The detailed procedure is outlined below:   1. Selection of Standard Substance A purified monosaccharide or polysaccharide, such as glucose or glycoprotein, is typically us......

• • Are Gut Microbes Detectable in Feces After 3 Years at -80°C? Does Storage Impact Microbial Composition or Serum Metabolomics?

  1. Stability of Fecal Samples for Gut Microbiota Analysis Freezing fecal samples at -80°C is a widely accepted method for preserving bacterial DNA in microbiome research. Even after three years of storage, DNA degradation remains minimal under these conditions, allowing for reliable microbial detection. However, prolonged storage may influence microbial composition, particularly for taxa sensitive to freeze-thaw cycles, potentially affecting downstream analyses.   2. Stability of Serum Samples for Unt......

• • What Methods Can Be Used to Completely Remove Starch from Yam Polysaccharides?

  To completely remove starch from yam and ensure the extraction of only yam polysaccharides, the following methods can be employed:   Enzymatic Degradation Amylases, such as α-amylase, can selectively degrade starch without affecting other polysaccharides. Incubate the sample under suitable temperature and pH conditions to allow the amylase to act for a specified period, after which the degradation products can be removed through centrifugation and filtration.   Alcohol Precipitation Polysaccharides an......

• • What Are the Key Differences Between Untargeted Lipidomics and Untargeted Metabolomics?

  Untargeted lipidomics and untargeted metabolomics are two distinct global profiling approaches used to comprehensively study lipids and metabolites in biological systems.   Untargeted lipidomics enables qualitative and quantitative characterization of lipid composition and alterations, primarily using mass spectrometry-based techniques to analyze complex lipid mixtures. This approach involves sample extraction, ionization, and spectral analysis. By evaluating differences in spectral data across sample......

• • What Are the Steps for Dialysis-Based Removal of Small Molecules from a Polysaccharide Solution?

  Dialysis is a widely used technique for removing small molecules from polysaccharide solutions by leveraging the size-selective permeability of a semipermeable membrane. The general procedure involves the following steps:   1. Preparation of Dialysis Equipment and Membrane A dialysis membrane, combined with a dialysis bag or tubing, is required. The membrane's pore size should be selected to retain polysaccharide molecules while permitting small molecules to diffuse. Before use, the membrane should be......

• • Which Column Is Best for Fatty Acid Analysis by GC?

  When analyzing fatty acids by gas chromatography (GC), the column of choice is typically one designed for long-chain non-polar or weakly polar compounds. Below are several GC columns commonly used for fatty acid analysis:   Molecular Sieve Column For example, SP-2560, characterized by high polarity and a relatively long column length (typically 100 m), suitable for separating long-chain fatty acids.   Cyanopropyl Silicone Column: Such as CP-Sil 88 or HP-88, which also exhibit high polarity and are spe......

• • Should Protein KEGG Pathway Analysis Prioritize Pathways of Interest or P-Value Rankings?

  When conducting protein KEGG pathway annotation and enrichment analysis, pathways can be selected based on two primary criteria:   Selection Based on P-Value Ranking This is the most widely used approach, where pathways are selected according to statistical significance, typically measured by the P-value. Pathways with lower P-values are considered more statistically significant, indicating a stronger association with the dataset. A common practice is to report and discuss pathways with P-values below......