Heavy Metal Screening (ICP-MS) on a Peptide COA
Published 2026-08-18 · Last updated: 2026-08-21 · By: Index Peptides technical team
Alongside purity and identity, some peptide certificates carry a heavy metals or elemental impurities line, usually measured by ICP-MS. It records whether trace levels of certain metals were detected in the batch, and how those levels sit against a stated limit. This page explains what the screening records, how ICP-MS works as a method, which elements are typically screened, and how the line appears on a certificate — as analytical-method reference only.
Research use only. Not for human or animal consumption. This page describes a laboratory test method and how its results are documented. It does not describe any use, effect, or outcome of any compound.
What heavy metal screening records
Heavy metal screening is a trace-level measurement. Where HPLC purity records the proportion of signal belonging to the target peak, metal screening records the concentration of specific elemental contaminants in the sample, typically expressed in parts per million (ppm) or micrograms per gram. Metals can enter a batch through raw materials, reagents, processing equipment, or containers, and the screening line documents that the batch was checked for them.
The line sits in the same documentary role as the water content or residual solvents lines: not a statement about the compound's identity, but a record that a defined contaminant check was run and reported. Those related lines are covered in water content residual solvents coa.
ICP-MS as a method
ICP-MS (Inductively Coupled Plasma Mass Spectrometry) ionises a digested sample in an argon plasma and passes the ions into a mass spectrometer, which separates and counts them by mass-to-charge ratio. Each element produces signal at its characteristic masses, so one run can quantify many elements at once. Two properties make it the standard method for this line:
- Sensitivity — detection limits in the parts-per-billion range or below, well under typical specification limits.
- Multi-element coverage — a single analysis screens the full panel of elements rather than testing them one at a time.
As with every other line on a certificate, the result only means what the method defines: a reported concentration is tied to the sample preparation, the instrument calibration, and the elements included in the run. The general principle that a figure is method-relative is the same one that applies to HPLC purity figures.
Elements typically screened
The panel varies by laboratory and by the specification the batch is checked against, but screening commonly covers the classic heavy metals and related elemental impurities:
| Element | Typical notation on a certificate |
|---|---|
| Lead | Pb |
| Cadmium | Cd |
| Mercury | Hg |
| Arsenic | As |
Some reports extend the panel to elements such as nickel, chromium, or copper, or present results grouped under a single "heavy metals (as Pb)" figure from an older colorimetric test. Where a single grouped figure is reported, the method named matters more than usual, because a grouped wet-chemistry figure and an ICP-MS panel are recording different things.
How the line appears on a certificate
A complete heavy metals line records the same structural fields as any other result line: the named method, the specification, the measured result, and the units. A typical presentation reads as a table row — method ICP-MS, a limit such as "not more than 10 ppm", and a result either as a measured value or as "conforms" / "below limit". The structure of result lines generally is walked through in anatomy of a peptide coa and what is a coa peptide.
Specification vs result
The line only becomes interpretable when both halves are present. The specification is the threshold the batch was checked against; the result is what was measured. A result with no stated limit cannot be assessed, and a limit with no measured result records intent rather than measurement. When two certificates are compared, compare like with like: the same elements, the same units, and limits drawn from the same specification basis.
As with every other field, the line should be tied to the batch through the lot number and the report date, so the screening record belongs to the vial in hand rather than to the compound in general.
FAQ
What does a heavy metals line on a peptide COA record?
It records the measured concentration of specific elemental contaminants in the batch, typically in parts per million, checked against a stated limit. It documents that a defined contaminant check was run and reported for that lot.
What is ICP-MS?
Inductively Coupled Plasma Mass Spectrometry. The sample is ionised in an argon plasma and the ions are separated and counted by mass-to-charge ratio, allowing many elements to be quantified in a single run at parts-per-billion sensitivity.
Which elements does heavy metal screening usually cover?
Commonly lead, cadmium, mercury, and arsenic, with some panels extending to elements such as nickel, chromium, or copper. The exact panel depends on the laboratory and the specification the batch is checked against, and should be stated on the certificate.
What is the difference between specification and result on this line?
The specification is the threshold the batch was checked against; the result is what was actually measured. Both halves are needed to interpret the line — a result with no stated limit cannot be assessed, and a limit with no measured result records intent rather than measurement.
Does every peptide COA include heavy metal screening?
No. Purity by HPLC and identity by mass spectrometry are the two core lines; heavy metal screening appears on certificates where the testing scope includes elemental impurities. Where it does appear, it should name the method, the elements, the limit, and the measured result, tied to the lot number.
Research use only. Not for human or animal consumption.