CJC-1295 Without DAC and Ipamorelin in One Vial
The CJC-1295 without DAC and ipamorelin blend puts a 29-residue peptide and a 5-residue peptide in the same vial. The mass ratio between them is nearly five to one, which makes the pair straightforward to characterise and creates one specific reading trap in the mass spectrum.
What is in the vial
The 10 mg vial is 5 mg of each component, blended in solution before lyophilisation.
- CJC-1295 without DAC, also written Mod GRF 1-29 — [D-Ala2, Gln8, Ala15, Leu27]-GRF(1-29) amide, C152H252N44O42, 3367.9 g/mol, CAS 863288-34-0.
- Ipamorelin — Aib-His-D-2-Nal-D-Phe-Lys-NH2, C38H49N9O5, 711.9 g/mol, CAS 170851-70-4.
Both are C-terminally amidated. The version without the drug-affinity complex is a different molecule from CJC-1295 with DAC, which is larger at roughly 3,647 g/mol; that distinction is covered in CJC-1295 with and without DAC.
Two different structural classes
These are not variations on a theme. Mod GRF 1-29 is a modified fragment of a 44-residue endogenous releasing hormone, with four deliberate substitutions and a terminal amide, all intended to resist the degradation routes the native sequence is subject to. Ipamorelin is a designed pentapeptide built largely from non-proteinogenic residues and bearing no resemblance to anything endogenous.
The structural distinction between the two families, and why they are often conflated, is set out in GHRH analogs versus growth hormone secretagogues.
The charge-state trap
Ipamorelin is small enough that electrospray produces mainly the singly protonated ion, near m/z 712.9. Mod GRF 1-29 at 3367.9 daltons produces a charge envelope: the five-plus ion sits near m/z 674.6, the four-plus near 843.0 and the three-plus near 1123.6.
So ipamorelin’s only significant ion lands between two of the larger peptide’s charge states, in a region of the spectrum where a narrow scan window might catch an unexpected neighbour. The two are still trivially distinguishable, but by isotope spacing rather than by position: a singly charged ion shows isotope peaks 1.0 m/z apart, a five-plus ion shows them 0.2 apart.
This is a useful habit generally. Charge state is read from isotope spacing, not from where a peak happens to sit, and a spectrum reported without enough resolution to show the isotope envelope has left that information out.
Both components absorb at 280 nanometres
Mod GRF 1-29 carries tyrosines at positions 1 and 10. Ipamorelin carries D-2-naphthylalanine, whose naphthalene ring absorbs strongly in the same region, along with histidine and D-phenylalanine.
That means a chromatogram of this blend can usefully be recorded at 280 nm as well as 214 nm, and the ratio of the two areas for each peak is additional identity evidence. This is unusual: most peptide blends contain at least one component invisible at 280 nm, which makes dual-wavelength comparison useless.
Area percentage still does not give the ratio
At 214 nm the response scales with the number of backbone amide bonds. Mod GRF 1-29 has 28 and ipamorelin has 4. Equal masses do not produce equal areas, and the larger peptide is heavily over-represented on the chromatogram.
A 50:50 blend by mass will not look like a 50:50 blend by area at any wavelength, and converting between them requires response factors from reference standards. The general problem is covered in what one vial of several compounds can and cannot tell you.
The stereochemistry neither measurement addresses
Ipamorelin contains D-2-naphthylalanine and D-phenylalanine. Mod GRF 1-29 contains D-alanine at position 2. In all three cases a D-to-L substitution produces a diastereomer of identical formula and identical mass.
Amino acid analysis after hydrolysis returns the composition but not the configuration. Mass spectrometry is blind to it. Only a chiral analysis, or a separation that resolves diastereomers, addresses the question, and it is rarely on a routine certificate. This is discussed further in racemisation and chiral purity.
What confirms a blend lot
Both masses observed, 3367.9 and 711.9, with charge states assigned from isotope spacing rather than inferred. A chromatogram with both peaks identified against standards, ideally at two wavelengths since both components permit it. A composition stated per component in milligrams. Both compounds are also stocked individually — CJC-1295 without DAC and ipamorelin — for work that needs one without the other.
