Chapter

    How the Lab Tests 251 Substances: Instruments and What N.D. Means

    The direct answer

    A 251-substance SVHC screen is not one test - it is a battery of instrument methods chosen by chemical family: ICP-OES for metals, GC-MS and LC-MS/MS for organics, HPLC-PDA and UV-Vis for specific substance groups. The lab pretreats each sample, runs the appropriate instruments, and reports each substance as not-detected (N.D.) at a stated reporting limit - in our report, 0.010%. N.D. does not mean "zero"; it means "below the limit the method can reliably report," and a report without a limit is a report without a meaning.

    The instrument map

    Instrument

    What it measures

    Why it is in the battery

    ICP-OES

    Metals and inorganics

    Lead, cadmium, arsenic, chromium, cobalt, borates

    UV-Vis

    Colored complexes, certain anions

    Specific inorganic screenings

    HPLC-PDA

    UV-absorbing organics

    Certain dyes and aromatic substances

    GC-MS

    Volatile and semi-volatile organics

    Phthalates, flame retardants, solvents

    LC-MS/MS

    Non-volatile organics at low levels

    Polar and thermally unstable substances

    No single instrument can measure all 251 substances. The scope of the report is only as good as the method map behind it - which is why the method line (ours lists all five) matters as much as the result line.

    The metal/non-metal split

    Our report tests two sample categories:

    Sample

    Scope

    Result

    Non-metal (mixed)

    All 251 SVHCs

    N.D. for all

    Metal (mixed)

    The 73 SVHCs applicable to metal matrices

    N.D. for all

    Not every substance can exist in a metal matrix - many organic SVHCs are irrelevant to a zinc alloy zipper head. The lab applies the full list to non-metal materials and the applicable subset to metals. That is efficiency without compromise: the substances that can be there are tested; the ones that cannot are correctly excluded.

    The reporting limit: the number that makes N.D. honest

    The report shows an RL (reporting limit) of 0.010% for the substance list. Three things to understand:

    1. N.D. means below the RL - not "absent," but "below the lowest concentration the method can reliably report."
    2. The RL is far below the 0.1% threshold - 0.010% is ten times lower than the REACH trigger, so even a substance at the reporting limit would be nowhere near the duty threshold.
    3. Without the RL, N.D. is meaningless - a report that says "not detected" and hides the limit is a report that hides its own standards.

    Factory data: When we review a lab's methods, we ask three questions: which instruments were used, what is the reporting limit, and how were the samples split. Our Model 8404 report answers all three - five instruments, 0.010% RL, non-metal and metal split - and that is the level of detail we recommend buyers demand from any factory.

    How the test runs

    1. The product is disassembled into material categories - non-metal and metal.
    2. Each sample is cut or prepared, then weighed.
    3. The sample goes through pretreatment suited to the substance family being tested.
    4. The prepared extract runs on the appropriate instruments.
    5. Results are compared to the reporting limit and the 0.1% threshold, and recorded per substance.

    FAQ

    Can one machine test all 251 SVHCs?

    No. The screen uses a battery of methods - ICP-OES for metals, GC-MS and LC-MS/MS for organics, HPLC-PDA and UV-Vis for specific groups - each chosen for the chemical family it can measure.

    What does N.D. mean in a REACH report?

    Not detected - the substance is below the method's reporting limit. With the RL stated (0.010% in our report), N.D. is the strongest result available.

    Why does the metal sample test only 73 substances?

    Because only 73 of the 251 SVHCs are applicable to metal matrices. The full list applies to non-metal materials; the applicable subset applies to metals.

    What is a reporting limit (RL)?

    The lowest concentration the method can reliably report. It matters because N.D. only means "below the RL" - and in our report the RL (0.010%) is ten times lower than the 0.1% REACH threshold.

    Do I need to understand the instruments to trust the report?

    Not in detail - but you should see them listed. A report with no method line, no RL and no sample split cannot be evaluated, and that is itself the answer.

    Can a REACH screen miss a substance?

    Every screen is scoped to the list version and the methods used. Substances added to the list later, or families outside the method map, are outside the screen - which is why the list date and method list are part of the evidence.

    About this report

    The method analysis in this article comes from report No. S260120016001-1 for our Model 8404 - five instruments, non-metal and metal split, 0.010% reporting limit, all results below threshold. We share the method and substance-list pages with buyers so the scope can be verified line by line. Ask for them at clkbusiness@clkluggage.com or WhatsApp +86-18879628221.

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