AssayIndex

AX-2026-043356

L-Glutathione (reduced) · 600 mg declared · WuXi TIDES (WuXi AppTec Testing Division) · lot WXT-2512-P2820

FAILMETHOD LIMITED
Report ID
AX-2026-043356
Compound
L-Glutathione (reduced)
Compound class
Short bioregulator peptides
Supplier
WXT — WuXi TIDES (WuXi AppTec Testing Division)
Batch / lot
WXT-2512-P2820
Declared label claim
600mg
Laboratory
Janoshik Analytical
Assay date
10 May 2026
Submitted
21 May 2026
Quarter
2026-Q2
Submitter
Contributor #R-8813
Sample provenance
Buyer-sourced
Section 1

Results

Measured against the index acceptance specification for the short bioregulator peptides class. A specification is a decision the index made; a result is a measurement. See where each threshold came from.

ParameterMethodResultUnitIndex spec
PurityRP-HPLC, 30 min gradient, 214 nm98.29% area≥ 98.5FAIL
Total impuritiesRP-HPLC, sum of reported peaks1.71% area≤ 1.5FAIL
Largest single impurityRP-HPLC — γ-Glu-Cys (−57 Da)0.89% area≤ 1.00PASS
Identity — theoretical monoisotopic masscalculated from molecular formula307.0838Da—NOT TESTED
Identity — observed monoisotopic massLC-MS, high resolution (ESI-TOF/QTOF)307.0840Da—NOT TESTED
Mass accuracyobserved vs theoretical+0.7ppm± 20PASS
Total peptide contentby difference from the gravimetric mass balance91.06%w/w—NOT TESTED
Target-compound contenttotal peptide content × purity89.50%w/w—NOT TESTED
Gross fill (as weighed)five-place balance, under nitrogen675.14mg600 mg declaredNOT TESTED
Recovered target peptidegross fill × target content604.250mg600 mg claimNOT TESTED
Recovery against label claimrecovered ÷ claim100.7%90.0 – 110.0PASS
Water contentKarl Fischer, coulometric, duplicate8.58%≤ 12.0PASS
Counter-ionno ionisable counter-ion expectedN/A—not applicableNOT TESTED
Residual solvent + inorganic residueestimated — see /methods/residual-solvents-q3c/0.36%—NOT TESTED
Endotoxinnot ordered on this submissionnot determined—≤ 5.0NOT TESTED
Sterilitynot ordered on this submissionnot determined—no growthNOT TESTED
Appearancevisual, diffuse light, black and white backgroundWhite lyophilised cake, intact—white to off-white intact cakePASS
Reconstitution clarityreconstituted per submitter procedureClear, colourless, no visible particulates—clear, no visible particulatesPASS
pH (reconstituted, 1 mg/mL)potentiometric, two-point calibration7.45—2.5 – 8.0PASS
Retention time (observed)RP-HPLC, 30 min gradient4.33min4.28 ± 0.20 (normalised)PASS
Peak asymmetry (10 % height)Ph. Eur. 2.2.460.93—0.80 – 1.50PASS
Plate count, main peakN = 5.54 (t/w½)²85,343—≥ 20,000PASS
Resolution to nearest impurityvs S-sulfonate adduct (+80 Da)2.30—no index criterionREPORTED
Section 2

Chromatogram and peak integration

The figure is drawn from the table. It is not an independent illustration — if a number in the table changed, the trace would change with it.

07955159092386431819 L-Glutathione (reduced)4.33 min · 98.29 % 4.15 same trace · ×50 vertical expansion, baseline-corrected · main peak off-scale reporting threshold 0.05 % area 05101520253035 Retention time (min) Response (mAU)
Figure 1. RP-HPLC trace, 30 min gradient, 214 nm. Drawn from the peak-integration table below: peak positions are the reported retention times, peak areas are the reported area percentages, peak widths follow the reported plate count of 85,343, and skew follows the reported asymmetry factor of 0.93. Baseline noise is seeded from the report ID and is illustrative. The lower panel is the same trace at a stated vertical expansion with the slow gradient drift subtracted, because at full scale a 0.89 % impurity against a 98.29 % main peak is a line two pixels tall; the main peak runs off-scale there by design.
#PeakRTArea (µV·s)% areaΔ mass (Da)
1L-Glutathione (reduced) — main peak4.334,777,19998.29—
2γ-Glu-Cys (−57 Da)4.1543,2570.89-57.021
3S-sulfonate adduct (+80 Da)4.1922,8430.47+79.957
4glutathione disulfide (GSSG, +305 Da)4.8510,6930.22+304.984
5cysteinyl-glycine (−129 Da)4.096,3180.13-129.043
Closure check — purity + Σ impurities 100.00CLOSES

Reporting threshold 0.05 % area. Peaks below it are not reported and are therefore excluded from the total, which overstates purity by their sum — see peak integration.

Section 3

Mass spectrum and identity

Theoretical monoisotopic mass 307.0838 Da, computed from C10H17N3O6S. All ppm figures on this site are against monoisotopic values — see why that matters.

0255075100275300325350375400 [M+1H]1+308.09 m/z Relative abundance (%)
Figure 2. ESI charge-state envelope, high-resolution instrument. Sticks are placed at m/z = (M + z × 1.007276)/z for the observed neutral mass of 307.0840 Da. Sodium (+21.982/z) and potassium (+37.956/z) adducts are shown where the parent charge state exceeds 25 % relative abundance; they are adducts of the same molecule and are not impurities.
ChargeTheoretical m/zObserved m/zΔ m/zRel. abundance (%)
1+308.0911308.09130.0002100.0
Section 4

Gravimetric mass balance

Water, counter-ion, residual and total peptide content are exhaustive and mutually exclusive categories. They must account for 100 % of the cake mass. The index closes this to within 0.02 pp and the build asserts it.

ComponentDetermination%w/w of cake
WaterKarl Fischer8.58
Counter-ionnone expected0.00
Residual solvent + inorganic residueestimated0.36
Total peptide contentby difference91.06
Total100.00 CLOSES

Supplier certificate, as declared

The supplier's own figures for this lot, beside the independent measurement. Divergence is assessed against the batch median, not against this single report — see rule AX-R05.

FigureSupplier COAThis reportIndex note
Purity (% area)98.2498.29divergence +0.14 pp vs batch median
Total impurities (% area)1.761.71
Largest single impurity (% area)0.840.89
Water (%)not stated8.58
Counter-ion (%)not statedN/A
Peptide content (%w/w)91.791.06
Endotoxin (EU/mg)not statednot determined
Method stated on certificateNO—no method section — the result cannot be reconciled against any other
Section 5

Provenance and caveats

Where a sample came from changes the weight of the evidence. The index treats it as a first-class field.

Sample provenance
Buyer-sourced
Evidentiary weight
Strongest available evidence in this index.
Chain of custody
Retail purchase → submitter (2–8 °C, 15 d) → laboratory (courier, ambient, 11 d) → assay.
Assay date
10 May 2026
Submitted to the index
21 May 2026
Laboratory
Janoshik Analytical, Ostrava, Czechia
Method basis
30 min gradient · high-resolution MS
Verification status
METHOD LIMITED
Section 6

Annotations 2

Signed technical comments from index contributors. Not a discussion forum — annotations question or contextualise the result, and the data team replies where a reply is warranted.

regression_mean
Retests after a low first result tend to come back higher, and most of that is regression to the mean rather than a different vial. Worth remembering before treating a confirmatory retest as a refutation.
spec_vs_result
Purity 98.29 %, water 8.58 %, counter-ion 0.00 % counter-ion. Read together these say the cake is what it claims to be and the chromatographic homogeneity is the limiting property. That narrows the question usefully.
Section 7

Related records

Same batch — lot WXT-2512-P2820 n=12

ReportLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043357WXT-2512-P2820Janoshik2026-Q298.778.85—Supplier-supplied0PASS
AX-2026-043358WXT-2512-P2820Kestrel2026-Q298.688.5797.6Buyer-sourced0PASS
AX-2026-043359WXT-2512-P2820VendorInvestigate2026-Q297.768.32—Buyer-sourced0FAIL
AX-2026-043360WXT-2512-P2820Janoshik2026-Q297.999.16—Buyer-sourced0FAIL
AX-2026-043361WXT-2512-P2820Medutest2026-Q298.108.47106.1Buyer-sourced0FAIL
AX-2026-043362WXT-2512-P2820Janoshik2026-Q298.108.92—Buyer-sourced0FAIL
AX-2026-043363WXT-2512-P2820Janoshik2026-Q298.048.90105.6Buyer-sourced0FAIL
AX-2026-043364WXT-2512-P2820Janoshik2026-Q297.888.77—Buyer-sourced0FAIL
AX-2026-043365WXT-2512-P2820PeptideMeter2026-Q298.338.2498.9Buyer-sourced0FAIL
AX-2026-043366WXT-2512-P2820Nordanalyt2026-Q298.189.0089.0Buyer-sourced1FAIL
AX-2026-043367WXT-2512-P2820VendorInvestigate2026-Q297.878.4992.9Buyer-sourced0FAIL

Cross-sections

Other recent L-Glutathione (reduced) records in the index.
ReportSupplierLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043429WXTWXT-2605-B3833Nordanalyt2026-Q398.486.5896.9Supplier-supplied1FAIL
AX-2026-043424WXTWXT-2605-B3833PeptideMeter2026-Q398.376.86—Buyer-sourced0FAIL
AX-2026-043166GL BiochemGLBI-2606-S7352Janoshik2026-Q399.018.84105.4Laboratory-retained1MARGINAL
AX-2026-043423WXTWXT-2605-B3833Janoshik2026-Q397.866.6693.4Buyer-sourced0FAIL
AX-2026-043426WXTWXT-2605-B3833Kestrel2026-Q398.836.32—Supplier-supplied1MARGINAL
AX-2026-043425WXTWXT-2605-B3833Janoshik2026-Q398.776.35—Supplier-supplied1MARGINAL
AX-2026-043431WXTWXT-2605-B3833Nordanalyt2026-Q397.946.18—Buyer-sourced0FAIL
AX-2026-043427WXTWXT-2605-B3833Medutest2026-Q397.676.08—Buyer-sourced1FAIL
Other recent WXT records in the index.
ReportCompoundLotLabQuarterPurity %Water %Recovery %ProvenanceFlagsResult
AX-2026-043376SemaglutideWXT-2604-C3248Janoshik2026-Q397.084.22—Buyer-sourced1MARGINAL
AX-2026-043429L-Glutathione (reduced)WXT-2605-B3833Nordanalyt2026-Q398.486.5896.9Supplier-supplied1FAIL
AX-2026-043347LeuprolideWXT-2604-K2596PeptideMeter2026-Q399.165.9993.6Buyer-sourced0PASS
AX-2026-043353LeuprolideWXT-2604-K2596Janoshik2026-Q399.194.9095.3Laboratory-retained0PASS
AX-2026-043345LeuprolideWXT-2604-K2596Janoshik2026-Q398.935.28—Buyer-sourced0PASS
AX-2026-043424L-Glutathione (reduced)WXT-2605-B3833PeptideMeter2026-Q398.376.86—Buyer-sourced0FAIL
AX-2026-043374SemaglutideWXT-2604-C3248Janoshik2026-Q397.003.56—Buyer-sourced1MARGINAL
AX-2026-043377SemaglutideWXT-2604-C3248PeptideMeter2026-Q397.204.08—Buyer-sourced1MARGINAL