{"id":3026,"date":"2026-10-03T16:08:47","date_gmt":"2026-10-03T16:08:47","guid":{"rendered":"https:\/\/nhdbio.com\/?p=3026"},"modified":"2026-10-15T03:53:29","modified_gmt":"2026-10-15T03:53:29","slug":"%e8%82%bdcoa%e6%9c%aa%e6%a3%80%e6%b5%8b%e5%88%b0%e6%a3%80%e6%b5%8b%e5%ae%9a%e9%87%8f%e9%99%90","status":"publish","type":"post","link":"https:\/\/nhdbio.com\/cn\/peptide-coa-not-detected-detection-quantitation-limits\/","title":{"rendered":"\u201c\u672a\u68c0\u51fa\u201d\u4e0d\u7b49\u4e8e\u96f6\uff1a\u4e86\u89e3\u68c0\u6d4b\u9650\u4e0e\u5b9a\u91cf\u9650"},"content":{"rendered":"

A report says \u201cnot detected.\u201d Can you write that the sample contains none of that substance? Not quite. Every method has a limit to what it can see and measure. The report needs to tell you that limit.<\/p>\n

Seeing something and measuring it accurately are different<\/h2>\n

The detection limit concerns whether a low-level substance can be identified by the method. The quantitation limit concerns whether its amount can be measured with suitable performance. A faint signal may be recognizable before its quantity is reliable.<\/p>\n

A reporting limit may be separately defined by the procedure. Ask which limit the report actually uses.<\/p>\n

\"Figure
Figure 1. Detection and reliable quantity measurement answer different questions.<\/figcaption><\/figure>\n

Follow one example from low to high<\/h2>\n

In this teaching example, the detection limit is about 0.2 \u00b5g\/g and the quantitation limit is 0.6 \u00b5g\/g. Below the detection capability, presence cannot be reliably established by these rules.<\/p>\n

Above detection but below 0.6, there may be evidence of presence without a reliable numerical amount. In the established quantitative range, the method can support a quantity result.<\/p>\n

\"Figure
Figure 2. Example detection and quantitation limits of 0.2 and 0.6 \u00b5g\/g.<\/figcaption><\/figure>\n

Does the limit answer your requirement?<\/h2>\n

Suppose you require less than 0.1 \u00b5g\/g, but the result only supports less than 0.2 \u00b5g\/g. It does not settle whether the sample meets the stricter requirement.<\/p>\n

Both numbers may look small. The gap between them still matters. Compare the same substance, units and sample basis.<\/p>\n

A blank box is not \u201cnot detected\u201d<\/h2>\n

A blank field may mean no result was supplied. \u201cNot tested\u201d means the test was not performed. \u201cNot detected\u201d describes an outcome under a method\u2019s reporting rules. None automatically means an exact zero.<\/p>\n

A displayed 0.000 can also be rounded or processed. Ask how it was generated before treating it as an exact value.<\/p>\n

\"Figure
Figure 3. Read \u201cnot detected\u201d together with the method, unit and reporting limit.<\/figcaption><\/figure>\n

Ask one complete question<\/h2>\n

Ask: which substance was tested, by which method, in what units, and with what reporting limit? Endotoxin and residual solvent tests, for example, investigate different substances.<\/p>\n

A report states less than 1 \u00b5g\/g. Does that establish less than 0.5 \u00b5g\/g?<\/strong><\/p>\n
\nSee the answer<\/summary>\n

No. The range from 0.5 to 1 \u00b5g\/g has not been excluded.<\/p>\n<\/details>\n<\/div>\n

Requesting results for LL-37 or GHK-Cu<\/h2>\n

For LL-37 or GHK-Cu, name the substance you want measured and the reporting capability you need. Confirm which tests were actually performed. HPLC purity does not provide an endotoxin result.<\/p>\n

LL-37<\/a> \/ GHK-Cu<\/a><\/p>\n

Discuss material and document requirements with NHD<\/a> \u00b7 Continue with the analytical guide<\/a><\/p>\n