{"id":4128,"date":"2026-10-11T06:38:25","date_gmt":"2026-10-11T06:38:25","guid":{"rendered":"https:\/\/nhdbio.com\/?page_id=4128"},"modified":"2026-10-11T07:41:51","modified_gmt":"2026-10-11T07:41:51","slug":"%e6%ae%8b%e7%95%99%e6%ba%b6%e5%89%82-ppm-%e8%ae%a1%e7%ae%97%e7%a4%ba%e4%be%8b","status":"publish","type":"page","link":"https:\/\/nhdbio.com\/cn\/analytical-methods\/residual-solvent-ppm-worked-example\/","title":{"rendered":"\u6b8b\u7559\u6eb6\u5242 ppm\uff1a\u5c06\u62a5\u544a\u8f6c\u6362\u4e3a\u5b9e\u9645\u8d28\u91cf"},"content":{"rendered":"

A report says 100 ppm of a solvent. How much is that in a 10 mg powder sample? First check that ppm is expressed by weight. Then the conversion takes only two steps.<\/p>\n

What does ppm count?<\/h2>\n

For a weight-based result, 100 ppm means 100 parts solvent per one million parts sample by weight. One ppm by weight equals 1 \u00b5g\/g, or 1 mg\/kg.<\/p>\n

The same abbreviation can have a different basis in another setting. Check the solvent name, sample type and method before converting it.<\/p>\n

\"Figure
Figure 1. Weight-based ppm describes a mass ratio.<\/figcaption><\/figure>\n

Convert 100 ppm in a 10 mg sample<\/h2>\n

First convert 10 mg to 0.010 g. The result is 100 \u00b5g solvent per gram of sample. Multiply: 100 \u00d7 0.010 = 1 \u00b5g solvent, or 0.001 mg.<\/p>\n

A shortcut is solvent \u00b5g = ppm by weight \u00d7 sample mg \u00f7 1,000. Forgetting the mg-to-g conversion gives an answer a thousand times too large.<\/p>\n

\"Figure
Figure 2. 100 ppm by weight in 10 mg corresponds to 1 \u00b5g solvent.<\/figcaption><\/figure>\n

Keep the less-than sign<\/h2>\n

If the result is less than 100 ppm, the same 10 mg sample contains less than 1 \u00b5g of that solvent on this basis. It is an upper-bound statement, not an exact measurement of 1 \u00b5g.<\/p>\n

Ask how the reporting limit was established if that upper bound is important to your study.<\/p>\n

To calculate solution concentration, you need volume<\/h2>\n

Suppose all of the example 1 \u00b5g transfers into a final 2 mL solution without loss. The solvent concentration is then 1 \u00f7 2 = 0.5 \u00b5g\/mL.<\/p>\n

Without the final volume and transfer assumptions, powder ppm cannot simply become a solution concentration. ppm is not always interchangeable with mg\/L.<\/p>\n

\"Figure
Figure 3. Powder ppm and solution concentration need different information.<\/figcaption><\/figure>\n

Calculate first, then evaluate the research requirement<\/h2>\n

Suitability depends on the named solvent, material, method and research use. A calculated amount alone does not establish a universal acceptable level.<\/p>\n

A 20 mg powder contains 250 ppm by weight. How much solvent is that?<\/strong><\/p>\n
\nSee the answer<\/summary>\n

250 \u00d7 20 \u00f7 1,000 = 5 \u00b5g, or 0.005 mg.<\/p>\n<\/details>\n<\/div>\n

Asking about GHK-Cu or MOTS-c solvent results<\/h2>\n

For GHK-Cu or MOTS-c, specify which solvent you are investigating and confirm whether that test was performed. A general purity statement does not establish a residual-solvent result.<\/p>\n

GHK-Cu<\/a> \/ MOTS-c<\/a><\/p>\n

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