Peptide blend testing: why each peptide in the vial needs its own identity and mg

What a peptide blend test has to show

A blend test asks the same two questions as any peptide test, once for each peptide in the vial. Is the peptide there? How many mg of it are there? For a vial labelled BPC-157 and TB-500, that means two identity results and two content results, each tied to its own peak in the chromatogram.

Question	Single-peptide vial	Blend
Is it the right peptide?	One mass match by LC-MS	One mass match per component, each tied to a labelled peak
How much is in the vial?	mg against one reference standard	mg per component, each against its own reference standard
Does it match the label?	% of label claim	% of label for each component, plus the measured ratio
How clean is it?	Main peak as % of UV area	Area share of each assigned peak, plus the peaks that belong to no component

Many blends are sold under trade names, so the first step is to know what should be inside. Lab menus spell them out. Janoshik lists GLOW as GHK-Cu, TB-500 and BPC-157, and KLOW as the same three plus KPV. Finnrick calls TB-500 with BPC-157 the “Wolverine” blend. CagriSema is cagrilintide with semaglutide.

Why one purity number does not fit a blend

HPLC purity is the main peak’s share of all UV peak area. Our guide to HPLC peptide purity explains the method. A blend has several main peaks on purpose, so a single purity figure has no clear meaning. If the lab counts the second peptide as an impurity, a good blend looks impure. If it adds the components together, the number hides which one is short.

Peak area shares are also different from shares by weight. UV absorbance at 214 nm depends on the number of peptide bonds and on certain amino acids. A 2007 study measured tryptophan at about 30 times the absorbance of one peptide bond, and phenylalanine, tyrosine and histidine at about 6 times. So two peptides at the same mg can give very different peak areas. A split of, say, 90/10 by area does not show a 90/10 split by weight.

Buyers meet this problem in group tests. In one Reddit group test of a CJC-1295 and ipamorelin blend, the organiser left content in mg off the order. The report gave each peptide as a percentage of the whole, so the group could not tell whether the vials were under-filled (r/PeptidePathways).

What helps instead is a component table: each peak, the peptide it belongs to and its area share, plus the total of the peaks that belong to no component. Some labs also print a purity for each component. That needs every impurity peak assigned to its parent peptide, usually by mass, and the report should show how this was done.

Identity for each component

Each peptide in the blend needs its own mass match. An LC-MS identity test compares the observed mass with the mass calculated from the formula. Our guide to LC-MS identity explains why retention time alone is not proof.

Two common blend ingredients carry names that cover more than one molecule:

• TB-500 is used for full-length thymosin β4 and for short fragments. The TB-500 testing guide shows how far apart their masses are.
• CJC-1295 is sold with and without DAC, and the two are different molecules, as our CJC-1295 page notes. Janoshik lists separate blend tests for CJC-1295 DAC with ipamorelin and for CJC no DAC (Mod GRF 1-29) with ipamorelin.

A blend report should name the exact molecule it looked for in each case.

It should also label which peak is which. ICH Q2(R2), the guideline on validating analytical methods, asks that the chromatograms used to show a method’s specificity label the relevant components. For chromatography, it says specificity can be shown by the resolution of the two components that elute closest to each other. A blend report can follow both habits: label every peak, and show that the component peaks are apart.

Our September 2026 review of public COAs from 25 labs shows why labels matter. One public record for a two-peptide blend printed a purity of 99.93, while its own peak list showed a 90.55% main peak and an unassigned 8.77% peak. Without labels, a reader cannot tell whether that second peak was the other peptide or an impurity.

mg for each component

Each peptide should be measured against its own reference standard, on its own calibration line, because each gives a different detector response. The result for each component should state its basis, such as free base, and its % of the label claim. Our guide to net peptide content explains why the basis matters, and the content per vial page shows how a single-peptide result is reported.

The ratio matters too. A vial labelled 5 mg plus 5 mg that holds 5 mg plus 2 mg has a problem that a total figure cannot show.

A public example shows one format. SideChain Analytics’ sample certificate for a KLOW blend, labelled 50 mg GHK-Cu and 10 mg each of TB-500, BPC-157 and KPV, lists net content in mg, chromatographic purity and fill accuracy for each peptide. It then gives the total net content and each peptide’s share of that total. Those shares come from mg, so they are shares by weight, unlike a split of peak areas.

GHK-Cu adds one more question: whether the mg counts the copper or only the peptide. The report should say which. Copper itself is a separate measurement.

Form matters as well. Freedom Diagnostics accepts blends of two or more named peptides, each with its own mg claim, but does not offer purity for liquid blends.

Which labs list blend tests

Many labs test blends, and they describe the service in different ways. These are the facts each one publishes, checked in September and October 2026.

Lab or platform	What it publishes about blends
Janoshik	Named blend tests, including BPC-157/TB-500, CJC-1295 (DAC and no DAC) with ipamorelin, CagriSema, GLOW and KLOW
Krause Analytical	KLOW, GLOW, Wolverine, Selank + Semax, CJC-1295 + ipamorelin and ipamorelin + tesamorelin; other blends “if all the compounds are on this list”
SideChain Analytics	Net content, purity and fill accuracy for each component on one certificate
Horizon Analytical	2-, 3- and 4-component blend panels, with “validated LC-MS/MS quantitative methods” stated for a listed set
Freedom Diagnostics	Blends of two or more named peptides, each with its mg claim; no purity for liquid blends
TrustPointe Analytics	Ten named blend tests, from BPC-157 + TB-500 to KLOW and cagrilintide with retatrutide
Finnrick (testing platform)	Blend testing since January 2026, such as CJC-1295 + ipamorelin and TB-500 + BPC-157

Blend tests usually cost more than single-peptide tests, since each component adds its own identity and content measurement. Horizon prices blends by the number of components. TrustPointe’s 2025 price list stated that blends are priced at the cost of each individual active test.

What public blend results show so far

Blends are a small share of public testing. Finnrick’s public data summary, with tests to 25 September 2026, lists these blends:

Blend	Tests	Passed	Failed	Incomplete
KLOW	19	9	6	4
Wolverine (TB-500 + BPC-157)	9	0	6	3
CJC-IPA	8	3	4	1
GLOW	4	1	1	2

For scale, the same summary lists 4,367 retatrutide tests. Finnrick’s blend pages show its default standard: purity of 99.5% or more and a dose within ±35% of the label. Its methodology page does not say how a purity threshold applies to a mix of peptides. Read the COA behind a blend rating before you draw a conclusion. Our guide to how Finnrick rates vendors explains the standards.

Lab reports vary too. In our COA review, three labs printed a single purity figure for a blend, one of them for a four-peptide blend.

Questions to ask before you send a blend

1. Will you confirm each component by mass, and which molecule will you look for, such as full-length TB-500 or a fragment?
2. Do you hold a qualified reference standard for every component?
3. Will the report give mg for each component, with its basis and % of label?
4. Will the chromatogram label which peak belongs to which peptide?
5. What do you report in place of a single purity number?
6. How many vials do you need? Endotoxin and sterility each need their own sealed vials, as our guide on how many vials to send explains.

What HK Analytical does for blends

HK Analytical does not offer per-component blend analysis, so we do not report identity and mg for each peptide in a blend. For single peptides, one order can combine identity (LC-MS), purity (HPLC), content per vial, endotoxin (LAL), Sterility (USP <71>, 14 days) and the other tests on our list, in any mix per sample. Results within days of receipt. Sterility (USP <71>, 14 days) is the one test that takes 14 days, because the method incubates for 14 days. Every number comes with its raw data, as the example report shows. If you hold a blend and want to know what we can test on it, list its components on the quote form and ask.