Determination of hydrogen peroxide on N95 masks after sanitization using a colorimetric method

Abstract

Hydrogen peroxide is commonly used as a sterilizing agent for medical devices and its use has recently been extended to N95 masks during PPE shortages as a result of the COVID-19 pandemic. The hydrogen peroxide remaining on the masks after sterilization could potentially pose a health hazard to the mask users. In the present study a colorimetric method was optimized for the determination of hydrogen peroxide on N95 masks following chemical sanitizations. The developed analytical method demonstrated an overall recovery of 98% ± 7%. The limit of detection ranged from 0.16 to 0.25 mg/mask, depending on the type of mask. The expanded measurement uncertainty was 13% (at a 95% confidence interval). The sanitization process itself introduced a significant variation in hydrogen peroxide load between masks. The ozone used in the sanitization process had no significant impact on analytical performance. Stamped and printed marks on the mask surfaces could induce biased readings. Hydrogen peroxide decomposes quickly on the mask surfaces so timing of analysis is an important factor in method standardization.•The validation data demonstrated that the in-house method is reliable and fit for the intended purpose, offering a sensitive, simple, rapid, and inexpensive method of residue monitoring.

Keywords: Colorimetry; Extraction; FFP2; Filtering facepiece respirator; H2O2; KN95; Method validation; Ozone; Photometry; Uncertainty.

Graphical abstract

Fig. 1

Three sampling areas on mask: 1-top, 2-side with a stamped mark and 3-side without a stamped mark were extracted for hydrogen peroxide analysis.

Fig. 2

Absorption profiles of various mask pieces sampled from: 1: top area, 2: side area with stamped and 3: side area without a stamped mark.

Fig. 3

The interference of ozone on hydrogen peroxide analysis on masks, the blue bar is from H₂O₂ and O₃ in a normal sanitization, the orange bar is only O_3, and a grey bar is untreated masks (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).

Fig. 4

The blank readings of various masks and the corresponding hydrogen peroxide concentrations (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.).

Fig. 5

Loss of hydrogen peroxide determination during room temperature storage.

Fig. 6

Recovery (%) of hydrogen peroxide analysis on masks.

Fig. 7

Identify source of uncertainty.

Fig. 8

Uncertainty profile of hydrogen peroxide determination on masks.