After placing an order by filling in your contact information, no payment is required. We will contact you within 3 days.

Chemical purity: Usually refers to chromatographic purity (e.g., HPLC, GC), which needs to reach 98% or above. Isotopic abundance: Refers to the relative proportion of a specific isotope in the total amount of all stable isotopes, i.e., absolute abundance. It is generally determined by mass spectrometry, and the purity value also needs to reach 98% or above. Certification date and expiration date: The selected internal standard must be used within its validity period.

Isotopes refer to different nuclides of the same element with the same number of protons but different numbers of neutrons. They are divided into radioactive isotopes and stable isotopes based on radioactivity. Stable isotope-labeled compounds have similar structures to their corresponding unlabeled compounds, so their physicochemical properties are also very similar. If stable isotope-labeled compounds and their unlabeled counterparts are detected using the same chromatographic method, their retention times are almost identical and cannot be distinguished. Moreover, stable isotopes are non-radioactive, so there are no special protection requirements during the synthesis, separation, purification, and application of labeled compounds.

Chemical purity: Usually determined by chromatography (GC, HPLC); Isotopic abundance: Usually determined by mass spectrometry.