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.

Available in 1 mg, 5 mg, 10 mg vials or custom aliquots.

U-13C means uniformly labeled with ??C; D-labeled means deuterated.

No radiation handling is needed, but standard chemical precautions apply.

Yes, used for accurate quantification of drugs of abuse.

They ensure sensitivity, reproducibility, and precise quantification.

Labeled compounds have isotope shifts but identical chemistry to unlabeled versions.

1?C and ??N labels have minimal effects; deuterium may affect kinetics slightly.

A labeled metabolite used for PK, metabolomics, and drug studies.

They help quantify biomarkers with high accuracy and low variability.

Available through specialized manufacturers offering high-purity SIL standards.