Net content testing

Apex Labs Pty Ltd determines content gravimetrically or volumetrically, depending on the sample form, and compares the measured amount with the labelled strength you enter on the order form. The certificate reports the measured amount alongside the label claim.

Net content complements the other two results in the panel: identity by mass spectrometry confirms what the main component is, and HPLC purity describes how clean the chromatographic profile is. A sample can be high purity yet under-filled, or correctly filled but impure, which is why all three are reported together.

• Fill variation: small differences in how much powder or liquid was dispensed into each vial.
• Counter-ions and water: peptides are often supplied as salts (for example trifluoroacetate or acetate) and lyophilised powders hold some residual moisture, so powder weight is not the same as peptide weight.
• Degradation or loss: poor storage or handling over time can reduce the amount of intact compound.
• Labelling errors: the strength printed on the vial may simply be wrong.

1. Send an unopened vial where possible, so the result reflects the vial as supplied.
2. Enter the labelled strength exactly as printed (for example “10 mg”) on the order page.
3. Include the batch number so the certificate can be matched to other vials from the same lot.

A certificate describes only the sample tested on the test date. It is not medical advice, not a recommendation to use any substance, and not a guarantee for other vials or batches.