Procurement teams often receive quotations that call two materially different molecules “CJC-1295.” That shorthand is risky. A CJC-1295 with DAC vs without DAC bulk peptide comparison must start with the declared sequence, terminal chemistry, Drug Affinity Complex modification, salt form, and theoretical molecular mass. If the supplier’s quotation lists only a product name and a purity percentage, it is not specific enough to issue a purchase order.
The DAC modification changes more than the name
CJC-1295 is a growth hormone-releasing hormone analogue developed with substitutions intended to improve stability. The DAC form contains a reactive maleimidopropionyl group designed for covalent attachment to albumin in biological research systems. Material sold as “without DAC” generally refers to a shorter-acting GHRH analogue commonly associated with Mod GRF(1-29) terminology. Suppliers do not use these names consistently, so buyers should never infer identity from the catalogue title.
Request the full amino-acid sequence in one-letter or three-letter format and a structural description of every terminal modification. Then calculate the expected molecular mass independently. With-DAC and without-DAC materials should not share the same theoretical mass. If two COAs show identical mass values, identical chromatograms, or identical peak tables, treat that as a document-control failure or possible report reuse.
Identity testing must reflect the modification
LC-MS is the practical first-line identity check. The observed deconvoluted mass should match the declared structure within the instrument and method tolerance. For the DAC form, examine the spectrum for unmodified precursor, hydrolyzed or side-reacted species, and incomplete conjugation-related impurities from synthesis. A main mass alone does not tell you where a modification is located; peptide mapping or tandem MS may be required when site confirmation is important.
HPLC purity should be evaluated with a method capable of resolving closely related deletion sequences and modification variants. The DAC group increases hydrophobic character and may alter retention, peak shape, and recovery. Applying the same gradient and sample preparation to both variants without method suitability work can create misleading comparisons. Ask for system suitability, diluent composition, injection concentration, detection wavelength, column chemistry, and the unedited integration table.
Purity is not net peptide content
A 99% area-purity result can coexist with substantially lower peptide content by weight. Water, counterion, residual solvents, and nonchromophoric material are not represented faithfully by UV area normalization. Bulk formulation work requires a defined basis: gross powder mass, anhydrous peptide, or peptide as the stated salt. The COA should identify that basis and the purchaser’s calculation should use the same one.
Salt form is frequently omitted in international quotations. Trifluoroacetate may remain after preparative purification; acetate conversion may be offered but must be verified. Counterion level affects formula weight, pH after reconstitution, and compatibility with downstream buffers. A vague statement such as “TFA free” should be supported by a quantitative method and acceptance limit, not merely a change in the product name.
Stability and handling are not interchangeable
DAC does not make the dry raw material universally stable. Both variants can be affected by moisture, oxidation, repeated warming, and inappropriate pH after reconstitution. The modified form may also show surface adsorption or aggregation behavior that depends on concentration and excipients. Supplier stability data should identify the exact sequence, salt form, container, residual moisture, storage temperature, and analytical method.
For reconstitution development, begin at small scale. Evaluate the intended aqueous buffer, pH, ionic strength, concentration, container material, and mixing method. Vigorous vortexing may foam or accelerate surface-related losses for some peptides. Visual clarity is necessary but not sufficient; measure recovery and related substances after preparation and at defined hold times. Do not transfer a protocol from the without-DAC material to the DAC form without confirmation.
A specification comparison procurement can use
- Identity: full sequence, terminal groups, DAC presence, theoretical and observed mass.
- Purity: validated or suitable RP-HPLC method, complete chromatogram and integration.
- Content: peptide-content basis, water, counterion and residual solvents.
- Physical state: appearance, solubility method and reconstitution recovery.
- Packaging: bulk container, fill size, closure, light and moisture protection.
- Traceability: one batch identifier across raw material, filled units and reports.
Which form should a laboratory buy? That is determined by the research design, not by a claim that one is “better.” A study requiring the DAC modification must use structurally verified DAC material. A protocol specifying the shorter analogue should not accept the modified molecule as a substitute. Procurement should preserve the exact molecular identity used in the approved protocol and analytical reference.
Common supplier red flags
Watch for a generic COA template that changes only the product title; the same HPLC retention time across unrelated peptides; an MS screenshot without charge-state interpretation; missing salt form; and a specification that says “white powder” but gives no content basis. Another problem is quoting with-DAC material, then sending a proforma invoice that drops “with DAC.” Resolve the identity on the purchase order, commercial invoice, labels, packing list, and COA before shipment.
When comparing suppliers, ask each one to return a completed specification table rather than answer a general request for “99% CJC.” A useful quotation identifies the exact structure and testing basis. If your laboratory needs a current-lot comparison, provide the intended analytical and packaging requirements and request matched raw HPLC and MS files before approving the bulk quantity.
Reference-material strategy should be agreed before routine receipt testing. A previous supplier lot can help trend retention time and impurity pattern, but it is not automatically a qualified identity standard. Preserve a characterized reference under controlled storage, document its preparation and expiry, and run a system-suitability sample with every sequence-specific method. This separates a genuine lot change from column aging, instrument drift, or preparation error.