Molecular Structure Explorer
L-Carnitine
Structure of the compound covered in this guide.
Last reviewed: October 2026 · Cleared Peptides research team
Research use only. L-Carnitine: Research Guide is supplied for laboratory research. It is not a drug, food, cosmetic, or dietary supplement. It is not FDA-approved. It is not for human or veterinary administration. This page does not give a dose or a method of administration. A study cited on this page describes that study’s own test article. It does not make this lot an approved medicine. To check a fact, open the PubMed or DOI link, confirm the authors and year, and match the paper’s compound name, CAS number, or sequence to the specification table. The full method is on the research desk page. Identity and purity for a lot are only what that lot’s certificate of analysis reports. An HPLC percentage is not a sterility result and not an endotoxin result unless the certificate prints those tests.
L-Carnitine (levocarnitine) is a quaternary-ammonium compound synthesized from lysine and methionine. It carries long-chain fatty acids across the inner mitochondrial membrane as acyl-carnitine esters — the carnitine shuttle.
L-Carnitine Structure and Identifiers
| Name | L-Carnitine |
|---|---|
| Synonyms | Levocarnitine |
| CAS number | 541-15-1 |
| PubChem CID | 10917 |
| Molecular formula | C7H15NO3 |
| Molecular weight | ≈161.2 g/mol |
| Type | Amino-acid derivative (not a peptide) |
The Carnitine Shuttle
Carnitine palmitoyltransferase I (CPT1) on the outer mitochondrial membrane converts acyl-CoA to acyl-carnitine; a translocase moves it inward; CPT2 regenerates acyl-CoA in the matrix for β-oxidation.
Laboratory Applications
- Fatty-acid-oxidation assays
- CPT1/CPT2 enzyme studies
- Acyl-carnitine LC-MS reference standards
This summary describes laboratory research only and makes no claim about effects in humans or animals.
Purity Testing and Storage
Every lot of L-Carnitine supplied by Cleared Peptides is tested by an independent laboratory for identity and purity (or composition, for multi-component preparations), and the lot Certificate of Analysis is published on our COA page. Store at room temperature, tightly sealed and protected from moisture. Handle according to your institution’s chemical-hygiene procedures.
Research materials referenced in this guide
Analytical testing notes for L-Carnitine
L-Carnitine is identified in this guide as CAS 541-15-1, formula C7H15NO3, listed mass ≈161.2 g/mol. An identity test compares a measurement with those values. A mass spectrum is the usual measurement for a peptide. FTIR, when a certificate uses it, is a supporting infrared fingerprint and is less specific for closely related sequences.
L-Carnitine is not a peptide. Identity and purity may be chromatographic (HPLC or GC) or spectroscopic, depending on the method named on the certificate. The peptide-specific notes below — sequence mass, 214 nm peptide-bond detection, and net peptide content — should not be assumed. Sterility and endotoxin still apply only when those lines are on the report.
Read the method named on the certificate before treating a purity percentage as an HPLC area-percent result. Small molecules in this library may be assessed by HPLC, gas chromatography, or spectroscopy. The instrument named on the report is the one that applies. A purity result still does not measure sterility, endotoxin, or a labeled fill weight.
A sterility test and an endotoxin test are not included in a chemical purity result. The compendial sterility test is a culture method (USP <71>): membrane filtration or direct inoculation into fluid thioglycollate medium and soybean-casein digest medium, incubated for 14 days. A PCR sterility screen uses a thermal cycler to detect microbial DNA and is a different method. The endotoxin test (USP <85> LAL, or USP <86> recombinant Factor C) reports endotoxin units with an incubating reader or a cartridge reader. Use a result only when that method is printed on the lot certificate. One published example in this catalog states that the report does not cover microbial contamination or endotoxins. The full description of equipment, standards, and how US laboratory accreditation works is in peptide analytical testing. Lot records are on the COA page.
Frequently Asked Questions
Is L-carnitine a peptide?
No. It is an amino-acid-derived quaternary-ammonium compound.
Is L-Carnitine for human use?
No. Cleared Peptides supplies L-Carnitine for laboratory research use only; it is not for human or veterinary use.
Selected References
Peer-reviewed literature on the compounds discussed in this guide, listed as scientific background for laboratory researchers. Citation does not imply endorsement by the authors or any use other than in-vitro research.
- Sweeney JD, et al. L-carnitine and its possible role in red cell and platelet storage. Transfus Med Rev. 2004;18(1):58-65. PubMed 14689378 · DOI
Laboratory note: solubility depends on salt form and solvent. This guide does not state a single solubility figure. Handling of lyophilized material is described in the peptide storage guide.
Research Use Only Notice
This guide is provided for educational and laboratory reference purposes. It summarizes published, primarily in-vitro and structural research literature and does not describe, recommend or imply any use in humans or animals. Products sold by Cleared Peptides are for laboratory research use only; they are not drugs, foods, cosmetics or dietary supplements, are not FDA-approved, and are not intended to diagnose, treat, cure, mitigate or prevent any disease. No dosing, administration or therapeutic information is provided.
