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. 2021 Jul 26;26(15):4490.
doi: 10.3390/molecules26154490.

Characteristics of the Molecular Weight of Polyhexamethylene Guanidine (PHMG) Used as a Household Humidifier Disinfectant

Dong-Uk Park  1 , Kee Won Yang  2 , Jiwon Kim  1 , Ju-Hyun Park  3 , So-Yeon Lee  4 , Kyung Ehi Zoh  5 , Jung-Hwan Kwon  6 , Soyoung Park  7 , Han Bin Oh  2
Affiliations

Characteristics of the Molecular Weight of Polyhexamethylene Guanidine (PHMG) Used as a Household Humidifier Disinfectant

Dong-Uk Park et al. Molecules. .

Abstract

(1) Background: Household humidifier disinfectant (HD) brands containing polyhexamethylene guanidine (PHMG) have been found to cause the most HD-associated lung injuries (HDLIs) in the Republic of Korea. Nevertheless, no study has attempted to characterize the potential association of the health effects, including HDLI, with the physicochemical properties of PHMG dissolved in different HD brands. This study aimed to characterize the molecular weight (MW) distribution, the number-average molecular weight (Mn), the weight-average molecular weight (Mw), and the structural types of PHMG used in HD products. (2) Methods: Quantitative measurements were made using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The Mn, Mw, and MW distributions were compared among various HD products. (3) Results: The mean Mn and Mw were 542.4 g/mol (range: 403.0-692.2 g/mol) and 560.7 g/mol (range: 424.0-714.70 g/mol), respectively. The degree of PHMG oligomerization ranged from 3 to 7. The MW distribution of PHMG indicated oligomeric compounds regardless of the HD brands. (4) Conclusions: Based on the molecular weight distribution, the average molecular weight of PHMG, and the degree of polymerization, the PHMG collected from HDLI victims could be regarded as an oligomer. PHMG, as used in household humidifiers, should not be exempted from toxic chemical registration as a polymer. Further study is necessary to examine the association of PHMG oligomeric compounds and respiratory health effects, including HDLI.

Keywords: humidifier-disinfectant-associated lung injury (HDLI); molecular mass; number-average molecular weight (Mn); oligomer; polyhexamethylene guanidine (PHMG); polymerization; weight-average molecular weight (Mw).

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Structures of four isomeric types of PHMG oligomers in HD products, as identified in the MALDI-TOF MS spectra.
Figure 2
Figure 2
Distribution of molecular types of polyhexamethylene guanidine (PHMG) among types of humidifier disinfectant products.
See this image and copyright information in PMC

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