Stable-isotope labeled internal standards
Deuterated and 13C-labeled impurities, metabolites and APIs for isotope dilution quantitation — minimizing matrix suppression effects in bioanalysis and nitrosamine confirmatory methods.
D / 13C
label types
±3 Da
MS resolution need
≥98%
isotopic enrichment typical
IDMS
quantitation mode
GMP
grade on request
Isotope dilution mass spectrometry
An isotopically labeled analogue co-elutes or nearly co-elutes with the unlabeled analyte but produces distinct MRM transitions. The response ratio corrects for recovery and ionization efficiency.
Labels are placed to survive the same metabolism and sample prep as the analyte; deuterium at non-exchangeable sites is standard for small molecules, while peptides may use 13C/15N incorporated residues.
Common applications
Bioanalysis
- Internal standards for parent drug and metabolites in plasma
- Glucuronide IS when hydrolysis step is validated
Nitrosamines
- D4 or 13C-labeled nitrosamines for FDA-style confirmatory methods
- NDSRI-specific labels by custom synthesis
Impurities
- Process impurity IS for genomic toxicity studies
- Peptide impurity standards with labeled sequence
Typical specifications
Figures are indicative industry-typical values. Lot- and project-specific data appear on the quotation and certificate of analysis.
Isotopic purity
≥97–99%
By mass spectrometry
Chemical purity
≥95%
Unlabeled impurity profile reported
Position of label
Documented
On COA and structure drawing
Solution
Optional certified concentration
Solvent and stability defined
Figures are indicative industry-typical values. Lot- and project-specific data appear on the quotation and certificate of analysis.
Indicative bioanalytical spike protocol
- 01
Prepare unlabeled calibrators in matrix across the expected range.
- 02
Add fixed amount of labeled IS at a mid-range concentration before extraction.
- 03
Process samples identically; calculate ratio of unlabeled peak area to IS peak area.
- 04
Back-calculate concentration from calibration curve of response ratios.
- 05
Monitor IS recovery; investigate if outside pre-defined acceptance criteria.
Deliverables
- Neat solid or solution with concentration statement
- COA: isotopic and chemical purity
- Recommended MRM transitions (indicative)
- Custom synthesis for non-catalogue labels
- Pairing with unlabeled impurity standard on request
Frequently asked questions
Enough mass shift to avoid isotopic overlap from natural abundance and from the unlabeled analyte M+1. Method-specific; 3–4 amu shift is a common starting point.
Related
Nitrosamine Impurities
Small-molecule nitrosamines and nitrosamine drug substance-related impurities (NDSRIs) as reference materials for confirmatory testing, CPCA categorization and acceptable intake (AI) justification under current FDA, EMA and ICH M7 expectations.
View detailsMetabolites & Glucuronides
Metabolites, oxidative cleavage products and glucuronide conjugates for bioanalytical method development, metabolite identification and stable-label tracing — supplied with structure confirmation suitable for LC-MS/MS workflows.
View detailsCertified Reference Materials
Impurities and API-related CRMs with certified property values, measurement uncertainty and metrological traceability — produced or distributed under principles aligned with ISO 17034 for method validation and lab accreditation.
View detailsCustom Impurity Synthesis
When catalogue search does not return your peak, we design a synthesis or isolation route for deletion peptides, genotoxic alerts, nitrosamines, metabolites and chiral variants — with a documented package for qualification.
View detailsReady to specify this for your program?
Share sequence, scale and documentation needs. We reply with indicative specs and a project-specific quotation.