Analysis of Detergent Residues on Clothing Using DMI-GC/MS

Importance of the Topic

Detergent residues on textiles can affect product quality, user safety, and environmental compliance. Sensitive detection of these trace compounds is vital in forensic, industrial, and quality control contexts. The DMI-GC/MS approach offers a streamlined workflow by minimizing sample pretreatment and preserving volatile analytes, thus improving analytical efficiency.

Objectives and Study Overview

The study aimed to evaluate DMI-GC/MS for detecting residual detergent compounds in cotton fabrics. It compared un-rinsed and rinsed samples, identified key volatile components, and assessed method precision and workflow simplicity.

Methodology

Sample Preparation:

• Cotton swatches (3×1 cm) washed in aqueous detergent for 1 h, rinsed three times, dried, and cut into 5–10 mg pieces.

DMI Procedure:

• Sample fragments placed in micro vials inserted into a PTV liner.
• PTV injector ramped from 35 °C to 250 °C at 5 °C/min to volatilize analytes directly into the GC column.
• Non-volatile matrix components remain in the liner, minimizing column contamination.

Used Instrumentation

• GC-MS: GCMS-QP2010 Ultra (Shimadzu)
• PTV Injector: OPTIC 4 with DMI liner (ATAS GL International BV)
• Column: InertCap WAX 60 m × 0.32 mm, 0.5 µm (GL Sciences)
• Autosampler: AOC-5000 Plus (Shimadzu)
• Carrier Gas: Helium at 1.0 mL/min

Results and Discussion

Chromatograms revealed detergent volatiles such as tetrahydrolinalool, citronellol, benzyl alcohol, butyl glycol, hexadecanol, and α-isomethylionone. Both un-rinsed and rinsed fabrics showed these peaks, with reduced intensities after rinsing. Method repeatability (%RSD) was 4% for retention time and 13% for peak area, demonstrating reliable performance for trace-level analysis.

Practical Benefits and Applications

• Significant reduction in sample preparation time and cost.
• Lower risk of volatile analyte loss enhances detection sensitivity.
• Suitable for rapid screening of detergent residues in textiles, food packaging, and forensic samples.

Future Trends and Potential Applications

Integration with high-resolution mass spectrometry could improve compound identification. Automation of vial handling may enable higher throughput. The DMI-GC/MS approach can be extended to other challenging matrices, including polymers, soils, and biological tissues.

Conclusion

DMI-GC/MS provides an effective, reproducible, and rapid method for detecting trace detergent residues on cotton with minimal pretreatment. It streamlines analytical workflows and offers broad applicability in analytical chemistry.

Reference

Shimadzu Corporation and ATAS GL International BV. Application Datasheet LAAN-J-MS-E035: Analysis of Detergent Residues on Clothing Using DMI-GC/MS. First Edition, November 2011.