ICP-MS explained

How ICP-MS works, step by step

1. DigestionAcid breaks down the sample’s organic material.
2. IntroductionThe solution is sprayed into the instrument.
3. PlasmaArgon plasma at thousands of degrees ionises the elements.
4. Mass separationIons are separated by their mass.
5. DetectionEach element is counted and quantified.

Strengths

• SensitivityVery low detection limits, often well below legal maximums.
• Multi-elementLead, cadmium, mercury, arsenic, thallium and more in one run.
• Wide rangeFrom trace to higher concentrations.
• EstablishedWidely used for food and supplement testing.

Limits

Speciation: going beyond total arsenic

To measure inorganic arsenic specifically, laboratories combine a separation technique, such as liquid chromatography, with ICP-MS. This is called speciation. It costs more than a total arsenic test, which is why many reports show total arsenic only; see arsenic in shilajit.

ICP-MS vs ICP-OES

ICP-OES uses the same plasma but measures the light emitted by elements rather than their mass. It is robust and suits higher concentrations, but its detection limits are generally higher than ICP-MS. For toxic metals at trace levels, such as mercury against a 0.1 mg/kg limit,^[1] ICP-MS is usually preferred; see laboratory methods.

What it means on a report

A report may name the method as ICP-MS or cite a standard method reference. Results should include units and detection limits. If the method isn’t stated, ask; see reading a COA and detection limits.

Quality control in the laboratory

Accredited laboratories run blanks, calibration standards and reference materials alongside samples to check accuracy. Accreditation to ISO/IEC 17025 covers this kind of quality control for the methods in scope.^[2]

Why a plasma is used

Atoms need to be turned into charged ions before a mass spectrometer can sort and count them. The argon plasma, running at thousands of degrees, does this efficiently for most elements in the periodic table. That is why one ICP-MS run can measure lead, cadmium, mercury, arsenic, thallium and many minerals together.

Sample preparation for shilajit

Shilajit is a complex organic-mineral material, so complete acid digestion is important before analysis. Laboratories often use closed-vessel microwave digestion to break down the organic matrix and keep volatile elements, such as mercury, in solution. Incomplete digestion could lead to underestimated results, which is one reason accredited methods matter.

Units you will see

ICP-MS results are usually reported in mg/kg or µg/kg (equivalent to ppm and ppb). Make sure you know which unit a report uses before comparing with limits; see units on lab reports.

Why some brands use other methods

ICP-MS instruments are expensive and testing costs more than some older methods. Some laboratories use ICP-OES or atomic absorption for certain elements, which can be appropriate at higher concentrations, but trace-level toxic metals are best measured by ICP-MS.

Putting it into practice

When you read a metals report, look for “ICP-MS” or a method reference, check the units and detection limits, and note whether arsenic was measured as total or inorganic. If the report doesn’t name a method, ask the brand which one was used. Knowing the method helps you judge how much weight to give a “not detected” result, especially for mercury.

In short

ICP-MS measures how much of each element is present, very sensitively, but not which chemical form it is in.

An everyday analogy

Think of ICP-MS as a very precise sorting machine. It breaks a sample down into its individual elements, sorts them by weight, and counts how many of each it finds. It can tell you how much lead is there, but not whether that lead is bound up in one compound or another. Speciation methods add that extra layer when it matters, as with arsenic. For buyers, the key point is simply to know which kind of result you are looking at. That one distinction clears up most confusion. Keep it in mind.

The bottom line

ICP-MS is the workhorse method for measuring metals in shilajit: sensitive, multi-element and well established. It measures total elements, so inorganic arsenic needs speciation, and it isn’t an identity test. On a report, look for the method, units and detection limits.

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