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  • Residual Solvents Testing

    The residual solvents in drugs refer to the organic volatile compounds used in the production of APIs, excipients and preparations, but can not be completely removed in the process. In the process of APIs synthesis, the selection of appropriate solvent can increase the yield or determine the properties of the drug, such as crystal form, purity, dissolution rate and so on. Therefore, organic solvents are essential and critical substances in drug synthesis. However, if they are not removed correctly, the residual solvent can damage the quality or safety of the product. Residual solvent testing is a way to solve potential quality problems and ensure product safety. T,C&A Lab runs strictly in accordance with GMP and GLP standards to meet the relevant requirements of compliance, quality, efficiency, etc. We can perform residual solvents testing according to USP Residual Solvents <467> method. Welcome to contact our experts for consultation.

    Classification of residual solvents

    • Class 1 residual solvents (should not be employed in the manufacture of drug substances, excipients, and drug products), including:
    BenzeneCarbon tetrachloride1,2-Dichloroethane
    • Class 2 residual solvents (should be limited in drug substances, excipients, and drug products), including:
    Chlorobenzene2-EthoxyethanolMethylene chloride
    ChloroformEthylene glycolN-Methylpyrrolidone
    • Class 3 residual solvents (solvents of low toxicity, limited by GMP or other quality-based requirements in drug substances, excipients, and drug products), including:
    Acetic acidHeptaneAcetone
    Isobutyl acetateAnisoleIsopropyl acetate
    1-Butanol2-ButanolMethyl acetate
    3-Methyl-1-butanolButyl acetateMethylethylketone
    tert-Butylmethyl etherMethylisobutylketoneCumene
    2-Methyl-l-propanolDimethyl sulfoxidePentane
    Ethanol1-PentanolEthyl acetate
    1-PropanolEthyl ether2-Propanol
    Ethyl formatePropyl acetateFormic acid

    The residual solvents testing method we used

    Our laboratory uses headspace gas chromatography to analyze drug solvent residues. This method has the following advantages:

    • First of all, the method is simple and only takes the gas phase for analysis, which greatly reduces the interference of the sample matrix to the analysis.
    • Secondly, there are different modes of headspace analysis, which can be suitable for all kinds of sample analysis by optimizing operation parameters.
    • Third, the sensitivity of headspace analysis can meet the requirements of regulations.
    • Finally, combined with the quantitative ability of GC, headspace GC can be used for accurate quantitative analysis.

    Instruments and data

    Residual Solvents Testing 1
    Residual Solvents Testing 2


    1. Aline, R. H.; et al. Ex vivo real-time monitoring of volatile metabolites resulting from nasal odorant metabolism. Scientific Reports (Nature Publisher Group) 9.1 (2019).

    Note: this service is for Research Use Only and Not intended for clinical use.


    T,C & A LAB is an independent lab providing quality or custom testing, characterization and analysis of a variety of materials. Our engaged experts are ready to help you.

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