When you purchase a peptide, it will arrive as a dry powder in an individual vial. You will need to reconstitute it into a solution using the instructions provided in the product data sheet. Once reconstituted the peptide will be at a specific concentration and can be used for your intended experiment.
In order to ensure the purity of the lyophilized peptide it is a good idea to use a compendial HPLC analytical method to determine the mass content of the peptide in each vial (mg/vial). This will also help you to establish an absolute physical standard for your sample.
You should always use the correct peptide storage conditions for long-term stability. Most peptides are stable for a few weeks at room temperature but if you want to ensure that the peptide is still soluble in the future then it is best to store it in a freezer at -20°C.
Keeping your peptides in the right condition will help to prevent contamination during their shelf life. Contamination can cause a number of problems including bacterial degradation and non-linearity in LC-MS analysis. This can lead to poor study performance and false results.
Aside from the storage conditions outlined in the product datasheets you should also pay attention to what type of peptide vials you are using. This is because some materials will adsorb the peptide and decrease its stability.
To reduce this problem you should be using peptide vials made of polypropylene. This type of material will not adsorb the peptide and should provide you with accurate results.
When using a new vial you should sterilize it by wiping the lid with an alcohol prep pad. You should then assemble all of your supplies including the peptide and bacteriostatic water. Be sure to use a large sterile syringe and needle. It is important to sterilize all of these items before you begin because any contaminant that may be introduced will decrease the long term stability of your peptide.
Once you have a clean vial and the correct syringe and needle on hand it is time to start the process of reconstituting your peptide. First, you will need to remove the peptide and bacteriostatic from cold storage and allow them to warm up to room temperature. This will reduce the moisture uptake in the peptide vial and allow it to re-seal itself properly.
Next, you will need to prepare a small volume of the sterile solvent for reconstitution. The amount of sterile solvent that you need to withdraw will be indicated on the instruction sheet in either mg/ml or mcg/mL. Then you will insert the syringe needle into the vial of bacteriostatic water and withdraw the correct amount of solvent.
Once you have the correct amount of sterile solvent in your syringe you will be ready to inject the peptide. Be sure to apply pressure to the plunger to ensure that you get a full injection into the target area. The injection site can be any area of the body that you are comfortable with, however, the most common sites include the abdomen, thigh, and upper arm.