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(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.

Abstract: In this study, the effect of several factors that govern the partitioning behaviour of three model proteins, such as bovine serum albumin, lysozyme and trypsin was analysed in a two-phase system formed by maltodextrin and a copolymer of ethylene and propylene oxides. The protein partition coefficient (Kr) showed to be very sensitive to temperature changes, protein molecular weight, pH medium and the lyotropic ion presence. The phase diagram obtained for these novel polymer–polymer two-phase systems shows two phases with high polymer concentrations. The maltodextrin is enriched in the bottom phase while the copolymer of ethylene and propylene oxides is found in the upper phase. Since this copolymer is thermoreactive, the upper phase can be removed and heated above the copolymer''s cloud point resulting in the formation of a new two-phase system with a lower water phase, containing the target protein and an upper copolymer-rich phase. Our results show that systems formed by maltodextrin and a copolymer of ethylene and propylene oxides may be considered as an interesting alternative to be used in protein purification due to their low cost, and also because they offer a viable solution to problems of polymer removal and recycling. [Copyright &y& Elsevier]

(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. [ABSTRACT FROM AUTHOR]