AssayIndex
Growth-hormone axis peptides

PEG-MGF

pegylated mechano growth factor · conjugate (24-mer + 5 kDa mPEG) · monoisotopic 7894.0000 Da. The index holds 35 assay reports on this compound across 5 batches from 5 suppliers.

35 reports5 batchesmedian 97.92 %index spec 92.0 %
Section 1

Analytical fingerprint

Hand-authored chemistry. These properties describe the substance and do not change when a record is added.

PEG-MGF is a polymer conjugate and the index treats it as a distinct analytical class. The 5 kDa mPEG is polydisperse, so the "main peak" is not a peak but a broad hump 1.5–2 min wide, and a % area figure derived from it is not comparable to a synthetic-peptide purity. The index reports three separate numbers instead: free (unconjugated) MGF as % area, PEGylation distribution (mono/di/unreacted), and total peptide content. Any PEG-MGF submission reporting a single purity above 98 % is recorded as a method error, and there are eleven such records on file.

Molecular formula
conjugate (24-mer + 5 kDa mPEG)
Monoisotopic mass
7894.0000Da
Average mass
7900.00Da
Residues
24
Nominal retention (RG-2, 30 min)
17.24min
Retention window
0.80min
Counter-ion as usually shipped
acetate
Typical label claims
2 mg · 5 mg
Analytical difficulty (index scale)
1.70 — hard
Purity is a defined quantity
YES
Section 2

Representative chromatogram

Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.

01534306846016135 PEG-MGF17.24 min · 97.92 % 11.6219.6616.52 same trace · ×100 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. A representative PEG-MGF trace on the index reference method RG-2, constructed from this page's own numbers: the main peak carries the index median purity of 97.92 % area at the nominal retention time of 17.24 min, and each impurity peak carries the median area the index has observed for that named species at its characteristic retention offset. It is not a scan of any single report — every individual record's own chromatogram is on its own page. The lower panel is the same trace at a stated vertical expansion, baseline-corrected, so the impurities are visible; the main peak runs off-scale there by design. Baseline noise is seeded from the compound slug.
Section 3

What the index has observed

Arithmetic over the 35 records the index holds. Aggregates on this page are computed over the records the index holds, which are not a random sample of the material on the market. Lots that get tested are lots someone chose to test. Read every figure here as a description of this dataset rather than as an estimate of a population.

Median purity 97.92% n=35
Interquartile range 2.11pp n=35
Minimum 95.51% n=35
Maximum 98.62% n=35
Pass rate vs spec 100.0% n=35
Median recovery vs claim 97.3% n=18
Median water 3.90% n=35
Median |mass error| 3.2ppm n=33
036992.093.094.095.096.097.098.099.0100.092.00–92.25 %: n=092.25–92.50 %: n=092.50–92.75 %: n=092.75–93.00 %: n=093.00–93.25 %: n=093.25–93.50 %: n=093.50–93.75 %: n=093.75–94.00 %: n=094.00–94.25 %: n=094.25–94.50 %: n=094.50–94.75 %: n=094.75–95.00 %: n=095.00–95.25 %: n=095.25–95.50 %: n=095.50–95.75 %: n=495.75–96.00 %: n=396.00–96.25 %: n=496.25–96.50 %: n=196.50–96.75 %: n=096.75–97.00 %: n=197.00–97.25 %: n=197.25–97.50 %: n=097.50–97.75 %: n=297.75–98.00 %: n=298.00–98.25 %: n=998.25–98.50 %: n=798.50–98.75 %: n=198.75–99.00 %: n=099.00–99.25 %: n=099.25–99.50 %: n=099.50–99.75 %: n=099.75–100.00 %: n=0median 97.92 Purity (% area) Reports
Figure 2. Purity distribution across all 35 PEG-MGF records. Dashed line is this compound's median (97.92 %); the solid vertical is the index acceptance specification for the growth-hormone axis peptides class (92.0 %). Domain is fixed at 92–100 % on every purity histogram on this site so that compounds can be compared by eye — a wide distribution here is a hard compound, a narrow one is an easy one, and neither is a statement about the suppliers.
Section 4

By supplier

Suppliers with fewer than two purity records on this compound are omitted from the figure rather than drawn as a line. The full table, including the thin cells, is on the by-supplier page.

95.395.996.597.197.798.398.9SSASSA: Q1 95.69, median 95.86, Q3 96.07, n=12n=12TFCTFC: Q1 97.83, median 98.03, Q3 98.08, n=10outlier 96.87n=10HJHJ: Q1 97.80, median 98.14, Q3 98.25, n=7n=7ERPERP: Q1 98.00, median 98.08, Q3 98.22, n=3n=3HomopeptideHomopeptide: Q1 98.42, median 98.47, Q3 98.55, n=3n=3 Purity (% area)
Figure 3. PEG-MGF purity by supplier, ordered by coverage. The vertical line is the index acceptance specification. Boxes that overlap are suppliers this dataset cannot separate, and most of them overlap.

Full per-supplier table with n= caveats →

Section 5

Characteristic impurities and degradants

The left three columns are authored chemistry — what this molecule characteristically carries and where it elutes. The right three are what the index has actually reported.

Named speciesΔRT (min, RG-2)Δ mass (Da)Seen inMedian % areaMax % area
free MGF (unconjugated)-5.62-5007.488100%0.441.00
di-PEGylated species+1.85+5000.000100%0.382.91
free mPEG+2.42-2886.512100%0.431.48
hydrolysed linker-0.72+18.011100%0.272.42

Degradation pathways

  • linker hydrolysis releasing free MGF
  • PEG chain oxidation on prolonged air exposure

Full impurity profile, with what each named species implies about the synthesis →

Section 7

Quarterly coverage

QuarterReportsMedian purityRange
2024-Q10n<3—
2024-Q20n<3—
2024-Q30n<3—
2024-Q40n<3—
2025-Q10n<3—
2025-Q2398.4798.38–98.62
2025-Q31798.0596.87–98.39
2025-Q41295.8695.51–96.30
2026-Q1398.0897.92–98.36
2026-Q20n<3—
2026-Q30n<3—

Quarter-by-quarter detail →

Section 8

Most recent records

The 25 most recent PEG-MGF records of 35.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-042526ERPERP-2509-K6500PeptideMeter2026-Q198.364.8797.1Supplier-supplied1MARGINAL
AX-2026-042528ERPERP-2509-K6500Janoshik2026-Q198.085.5089.3Supplier-supplied2MARGINAL
AX-2026-042527ERPERP-2509-K6500Kestrel2026-Q197.924.96—Supplier-supplied1MARGINAL
AX-2026-043130SSASSA-2505-U6896VendorInvestigate2025-Q496.172.67—Buyer-sourced0PASS
AX-2026-043131SSASSA-2505-U6896Janoshik2025-Q495.812.9596.2Supplier-supplied0PASS
AX-2025-020576SSASSA-2505-U6896Medutest2025-Q496.302.53—Supplier-supplied0PASS
AX-2025-020575SSASSA-2505-U6896Medutest2025-Q496.042.63—Supplier-supplied1FAIL
AX-2025-020577SSASSA-2505-U6896VendorInvestigate2025-Q495.712.67—Buyer-sourced0PASS
AX-2025-020578SSASSA-2505-U6896Janoshik2025-Q495.553.57—Buyer-sourced0PASS
AX-2025-020581SSASSA-2505-U6896Janoshik2025-Q495.652.50—Supplier-supplied0PASS
AX-2025-020582SSASSA-2505-U6896PeptideMeter2025-Q495.822.9092.7Supplier-supplied0PASS
AX-2025-020579SSASSA-2505-U6896Janoshik2025-Q496.062.5999.2Supplier-supplied0PASS
AX-2025-020574SSASSA-2505-U6896PeptideMeter2025-Q495.512.8897.4Supplier-supplied0PASS
AX-2025-020573SSASSA-2505-U6896VendorInvestigate2025-Q496.092.75—Buyer-sourced0PASS
AX-2025-020580SSASSA-2505-U6896Medutest2025-Q495.902.63—Supplier-supplied0PASS
AX-2025-019730HJHJ-2507-S2872PeptideMeter2025-Q398.236.96—Supplier-supplied0PASS
AX-2025-019134TFCTFC-2507-M4201PeptideMeter2025-Q397.543.86105.1Supplier-supplied2MARGINAL
AX-2025-019133TFCTFC-2507-M4201Janoshik2025-Q398.283.5696.7Supplier-supplied2MARGINAL
AX-2025-019726HJHJ-2507-S2872Janoshik2025-Q398.147.14—Supplier-supplied0PASS
AX-2025-019140TFCTFC-2507-M4201Janoshik2025-Q398.013.8092.6Supplier-supplied2MARGINAL
AX-2025-019729HJHJ-2507-S2872Kestrel2025-Q397.197.8998.7Supplier-supplied0PASS
AX-2025-019141TFCTFC-2507-M4201Janoshik2025-Q398.023.7595.3Supplier-supplied2MARGINAL
AX-2025-019136TFCTFC-2507-M4201VendorInvestigate2025-Q396.874.30—Buyer-sourced1MARGINAL
AX-2025-019728HJHJ-2507-S2872Kestrel2025-Q398.397.82—Supplier-supplied0PASS
AX-2025-019725HJHJ-2507-S2872Janoshik2025-Q397.516.80102.8Supplier-supplied0PASS