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Stable storage of chlorine dioxide mouthrinse solutions
Author(s) -
Richter JL,
Kross R
Publication year - 2005
Publication title -
oral diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.953
H-Index - 87
eISSN - 1601-0825
pISSN - 1354-523X
DOI - 10.1111/j.1601-0825.2005.01105_69.x
Subject(s) - high density polyethylene , chlorine , polyvinyl chloride , aqueous solution , polyethylene , chlorine dioxide , chemistry , nuclear chemistry , materials science , organic chemistry
Chlorine dioxide (ClO 2 ) is a highly effective yet non‐toxic malodor counteractant and germicide that is listed as an ingredient in many mouthrinses. It is a water‐soluble gas whose purported chemical instability and permeability through common storage containers has resulted in its inability to be provided as a shelf‐stable, marketable solution of significant concentration. Thus ClO 2 has had to be generated in situ , or shortly before use, which has limited its utility. The object of the present investigation was to evaluate ClO 2 concentrations over time in aqueous, near neutral pH, ClO 2 ‐ClO 2 − (1:1–1:14) solutions (32–40 ppm ClO 2 ) prepared according to the method of Richter in containers made from a variety of materials under ambient, accelerated storage and other conditions. [ClO 2 ] was measured with standard spectrophotometric technique. All containers tested were standard 16 oz. bottles. The materials tested were glass of various colors and opacities, polyvinyl chloride (PVC), high‐density polyethylene (HDPE), fluorinated HDPE, high‐density terephthalate (PETE) of various colors and fluoridated polyolefins. We discovered that certain materials, such as glass, fluoridated HDPE, clear and white PETE and fluorinated polyolefins can maintain relatively constant levels of ClO 2 in pre‐prepared solutions and in some cases for periods of up to several years under ambient and normal shipping conditions. In one series of studies, the mean loss of ClO 2 per day from solutions prepared to approximately 35 ppm was 0.8 ppm (s.d. = 2.9) (2.2%) for HDPE (32 days); 0.8 ppm (s.d. = 2.2)(2.16%) for PVC (30 days); 0.4 ppm (s.d. = 0.71)(1.20%) for fluoridated HDPE (45 days); 0.02 ppm (s.d. = 0.63) (0.045%) for PETE (45 days) and 0.14 ppm gain (s.d. 0.54)(0.31%) for clear glass (31 days). The s.d.s reported here are skewed high because they assume a linear loss of ClO 2 over time when in fact the actual measured loss (or gain) was in all cases nearly perfectly parabolic. In another study, one supplier's white opaque PETE actually showed a 6.2% overall gain in 252 days of storage. These results dispel the popular notion that ClO 2 always decomposes so rapidly that fresh solutions must be made up frequently to maintain effective ClO 2 concentrations. ClO 2 production from the reservoir of ClO 2 − in these solutions is apparently sufficient to equal or exceed losses of ClO 2 from decomposition, diffusion through the container wall, possible reaction with the container material and escape during sampling for some of the materials tested. Previously observed losses of [ClO 2 ] from ClO 2 ‐ClO 2 − solutions were apparently due primarily to diffusion out of the containers rather than from decomposition within the containers. This achievement now allows for the broad distribution of pre‐prepared ClO 2 solutions for a wide range of oral care and other deodorant and germicidal applications.