Nuclear Magnetic Resonance Metabolomic Analysis of Spent Human Embryo Culture Media: Method Validation and Technical Considerations.

Spent human embryo culture media contains low-molecular-weight metabolites that can provide a non-invasive readout of preimplantation embryo physiology. However, nuclear magnetic resonance (NMR)-based metabolomic analysis of these samples is technically challenging because routine embryo culture conditions involve microliter volumes, protein supplementation, and paraffin oil overlays that generate background signals and compromise spectral quality. Here, we present an optimized NMR metabolomics workflow for spent embryo culture media incorporating controlled droplet collection to minimize oil contamination, fluorinated ethylene propylene (FEP) tube liners to chemically isolate the sample from the external reference (TMSP) while accommodating microliter volumes, and acquisition using a Carr-Purcell-Meiboom-Gill pulse sequence to suppress macromolecular background signals. The protocol enables consistent detection and quantification of low-molecular-weight metabolites from individually cultured human embryos and supports reproducible analysis under routine laboratory conditions. Due to numerous technical challenges, the method must be properly validated before it can be used for research or clinical purposes.