L-Carnitine (LC600): preparation and storage
Intended for research use only. Not a medicinal product.
Contents (9 sections)
Start with form, not water volume
Establish whether the vial contains dry L-carnitine, a specific salt, a mixture with excipients or a ready-made aqueous solution. Powder needs mass, chemical form and dissolution data. A prepared solution needs concentration, total volume, full composition and conditions after opening. Do not reconstitute a prepared solution again; any dilution changes its original concentration.
The 600 mg designation on a dry vial describes total declared quantity. It does not establish whether content is expressed as free L-carnitine or mass of a particular salt. Check the batch certificate. L-carnitine, acetyl-L-carnitine and L-carnitine tartrate are not one calculation form. Do not automatically use the same molecular weight for all three.
What is supported for free L-carnitine?
The MedChemExpress L-Carnitine page lists CAS 541-15-1, formula C7H15NO3 and molecular weight 161.20 g/mol. It lists water solubility at ≥50 mg/mL. The ≥ sign means dissolution occurs at that concentration but saturation was not established. It does not mean that the solubility limit equals 50 mg/mL.
These data concern that manufacturer's material and the free form. They do not prove identical composition in every LC600 vial or that 600 mg dissolves in an arbitrarily small volume. For the chosen concentration, check batch specification, water quality, pH and compatibility with the eventual matrix. Without data, begin with a small trial.
A mass concentration example
Making a confirmed 600 mg material up to a final volume of 12.0 mL gives nominal mass concentration 50.0 mg/mL. A final volume of 20.0 mL gives 30.0 mg/mL. These are arithmetic examples, not recommended reconstitution volumes. They do not establish that either volume meets specification, container capacity or experimental requirements.
Do not automatically add 12.0 mL to a small vial: it may lack capacity, and added volume is not final volume. Follow the laboratory's quantitative preparation procedure in compatible containers. When using only part of a vial, check powder sampling accuracy and material homogeneity. Do not assume a randomly sampled portion of a mixture has identical composition.
Molarity requires a confirmed form
For free L-carnitine with molecular weight 161.20 g/mol, 50.0 mg/mL corresponds to approximately 310.2 mM. Do not transfer this conversion to tartrate, an acetylated form or an unknown mixture. If the certificate does not establish quantitative content, label concentration nominal. HPLC peak-area purity does not replace an absolute material assay.
As a dilution example, 20.0 µL of a 50.0 mg/mL aqueous stock made up to a final volume of 1.00 mL gives 1.00 mg/mL. For confirmed free L-carnitine, that is approximately 6.20 mM. This is not a recommended experimental concentration. Define whether the method counts salt mass, free carnitine or total material, and maintain one basis across comparisons.
Preparation and initial checks
Before opening a cold dry vial, let it reach room temperature while closed. Use water of the method's required quality, clean compatible containers and a measured volume. Mix according to specification. Do not arbitrarily add acid, alkali or organic solvent just to remove particles faster. Each additive changes the experimental matrix.
After preparation, check appearance, particles and, where required, pH and osmolality. Clarity does not establish sterility or exact concentration. Do not call the liquid sterile merely because sterile water was used: powder, container and process also affect the result. Cell work separately needs appropriate endotoxin and microbiological quality requirements.
Matrix matters in metabolic studies
A concentrated aqueous stock can change medium composition, volume fraction, pH and osmolality. Check the final mixture at the actual incubation temperature and duration. Do not automatically attribute precipitate, cloudiness or colour changes to carnitine behaviour: medium-component interactions or contamination may be responsible. Assess before continuing.
The control receives the same water or other vehicle volume and the same excipients without carnitine. If a stock does contain an organic solvent, calculate its final fraction: 10 µL of stock containing 10% DMSO in a final volume of 1 mL gives 0.10% DMSO. This conditional example does not establish a need for DMSO with L-carnitine.
For fatty-acid oxidation, respiration or viability studies, account for carnitine already present in medium and supplements. Added concentration is not always total system concentration. Increased ATP or altered signal does not itself establish mechanism. A quantitative carnitine method should distinguish free carnitine from acylcarnitines when relevant to the research question.
Storage depends on package and form
Lyophilization does not automatically establish a long shelf life. Dry LC600 needs batch-specific conditions, moisture protection and sealed storage. Use a long-term freezer or short-term refrigerator scheme only under a confirmed specification. Do not transfer another manufacturer's free-carnitine conditions to a product with unknown excipients or different packaging.
Prepared solutions separately need temperature, container and a supported period for the relevant concentration and composition. Freezing can change component behaviour, so assess thawed portions before use. Do not give an aqueous working dilution the dry vial's shelf life. Label date, concentration, calculation basis, lot and freeze–thaw cycles; compare stored and fresh material in critical series.
Common questions
Does LC600 mean ready-made 600 mg/mL? No: the current product card describes 600 mg dry material per vial. Can free carnitine be replaced with the same mg of tartrate? Not correctly without conversion and form verification. Does bacteriostatic water remove process-cleanliness requirements? No. Is there a universal dissolution volume? No: it depends on specification and method.
End of article
L-Carnitine
for laboratory research
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