Shelf life is typically 1?3 years with proper storage conditions.

13C and 15N labels do not affect chromatography; deuterium may cause slight retention shifts.

No, they are internal standards and cannot replace reference standards.

Yes, some compounds may degrade over time depending on stability and storage.

Yes, they improve precision in detecting pollutants, pesticides, and residues.

Ideal isotopic enrichment is typically above 95% for clear MS separation.

These are standards where isotopes are inserted at exact molecular positions.

Used in proteomics for protein quantification and metabolic profiling.

Yes, many drugs are available in deuterated or 13C-labeled versions.

Synthesized using isotope-enriched precursors through controlled organic chemistry.

Yes, labeled molecules show predictable mass shifts for easier identification.

Yes, they are used in both LC-MS/MS and GC-MS assays.

The concentration depends on assay requirements and calibration design.

Solubility varies but many dissolve in methanol, water, or acetonitrile.

They improve quantification but are not used as calibrators.

A COA includes purity, isotopic enrichment, MS data, and storage conditions.

Premixed SIL standards used for multi-analyte testing.

They help compensate for variations in ionization efficiency.

FDA and EMA strongly recommend their use for accuracy in validated methods.

Yes, widely used in metabolic flux and tracer studies.