“Not detected” (ND) on a heat transfer fluid test report should not be rewritten as “completely absent.” It describes a result for a particular sample under specified analytical and decision conditions—not a guarantee that the true amount of the target substance is exactly zero. Buyers, quality teams and suppliers should establish how the laboratory uses the term before deciding what the result supports.
1. Start with the report’s definition of ND
ND generally indicates that the test did not produce a result meeting the applicable detection criterion. Laboratories and methods may use different reporting conventions. Read the footnotes and ask the laboratory for clarification rather than assigning ND a fixed concentration.
EPA’s data quality assessment guidance treats non-detects as a specific data-evaluation issue.[1] Keeping the method and reporting boundary is more informative than replacing ND with “0.” This does not authorize a reader to relabel any value below a boundary as ND: the laboratory’s reporting definitions still apply.
2. Detection, quantification and reporting limits are different
A detection limit concerns the method’s ability to distinguish a low-level analyte signal. A quantification limit concerns the level at which acceptable quantitative performance can be achieved under stated conditions. Definitions, estimation procedures and conditions must come from the applicable method and laboratory explanation.[2]
Detecting a substance does not necessarily mean that its amount can be reported reliably. “Detected below the quantification limit” must not be changed to “not detected,” and extra decimal places should not be invented. A “less than” value may identify a reporting limit or another boundary; matching units do not make it a detection limit.
3. Method capability must support the decision
If an agreed specification limit is lower than the reporting level the method can support, ND alone may be insufficient to demonstrate compliance. The laboratory should assess method capability, the meaning of the reported result, the applicable requirement and the decision rule before issuing a conformity statement.
For example, “below the reporting limit” does not automatically establish whether a separate purchase requirement below that reporting limit has been met. Insufficient evidence to decide is also different from proof of nonconformity. There is no universal detection, reporting or acceptance limit for every heat transfer fluid in this article.
4. Keep the sample and analyte scope intact
A non-detect for one target substance does not establish the absence of every contaminant. A submitted sample does not automatically represent every location in a system or all future delivered batches. Verify the grade, batch or system identification, sample ID, sampling information and full test-item name.
A new-fluid purchasing report and a used-fluid investigation report have different sample backgrounds. The same grade name does not make them interchangeable. When quoting a result, retain the qualification “for this sample, this analyte and this method”; do not extend it into a batch-wide, system-wide or permanent guarantee without supporting evidence.
5. Align conditions before explaining differences
One report may show a numerical result while another shows ND because samples, methods, units, reporting levels or other conditions differ. The result format alone does not establish that either laboratory is wrong. Compare those fields and ask the laboratory to explain whether the results are comparable.
Do not automatically replace ND with zero when calculating an average or select only the report that appears more favorable. If statistical treatment is needed, use an appropriate plan and state its assumptions. Preserve changes in sampling and methods as part of the evaluation.[1]
6. Request the complete report—not an isolated screenshot
When consulting SCHULTZ or another heat transfer fluid supplier, explain the decision you need to make and check four groups of information:
What was tested: the full analyte or test-item name.
What it represents: sample identity, batch and new- or used-fluid background.
How it was tested: method, units, reporting boundaries and notes.
What it supports: the relevant specification, contract requirement and decision rule.
A supplier’s summary should preserve the analytical scope. Without sufficient evidence, ND for a specified item should not become a claim of “absolute zero content” or “no contamination of any kind.” Formal acceptance must follow applicable requirements and the laboratory’s conformity statement, not a marketing interpretation.
Conclusion
Not detected does not mean zero. Read the reporting definition, distinguish detection from quantification, and confirm method capability and sample scope before turning a laboratory result into a product claim.
References and scope
[1] EPA QA/G-9R — Data Quality Assessment: A Reviewer’s Guide. Appendix F, printed page 52 (PDF page 58). Background on non-detect data and data evaluation, not a heat transfer fluid acceptance standard.
[2] Eurachem/CITAC — Guide to Quality in Analytical Chemistry (2026). Sections 17.4–17.8 and 21.10–21.11 (printed pages 27 and 35). Background on analytical capability, detection, quantification and decision rules. Specific limits must be interpreted according to the applicable method.
[3] NIST OSAC Lexicon — Limit of Detection. This forensic toxicology entry is a terminology reference for distinguishing an analyte from a blank matrix and identifying it, not a heat transfer fluid test method or acceptance requirement.
Source check: 3 October 2026. The cited sections and glossary entry were reviewed; they are not evidence of brand-specific test performance.
This article provides general report-reading guidance. It does not replace the laboratory’s method explanation, conformity statement or contractual acceptance decision. No brand-specific test results or universal acceptance values are provided.
