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Mosquito repellent thermal stability, permeability and air volatility
Author(s) -
Mapossa António B,
Sitoe Alcides,
Focke Walter W,
Izadi Homa,
du Toit Elizabeth L,
Androsch René,
Sungkapreecha Chanita,
van der Merwe Elizabet M
Publication year - 2020
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.5623
Subject(s) - deet , diethyl phthalate , chromatography , permeation , chemistry , volatility (finance) , polyethylene , polymer , materials science , toxicology , organic chemistry , phthalate , membrane , biology , biochemistry , financial economics , economics
BACKGROUND The effectiveness of mosquito repellents, whether applied topically on the skin or released from a wearable device, is determined by the evaporation rate. This is because a repellent has to be present in the form of a vapour in the vicinity of the exposed skin that needs protection. Therefore, gravimetric techniques were used to investigate the direct evaporation of selected liquid repellents, their permeation through polymer films, and their release from a microporous polyethylene matrix. RESULTS Evaporation of a repellent into quiescent air is determined by its air permeability. This is a product of the vapour pressure and the diffusion coefficient, i.e.S A = P A sat D A . It was found that repellents could be ranked in terms of decreasing volatility as: ethyl anthranilate > citriodiol > dimethyl phthalate > N , N ‐diethyl‐meta‐toluamide (DEET) > decanoic acid > ethyl butylacetylaminopropionate > Icaridin. Experimental S A values, at 50 °C, ranged from 0.015 ± 0.008 mPa m 2 s −1 for the least volatile repellent (Icaridin) to 0.838 ± 0.077 mPa m 2 s −1 for the most volatile (ethyl anthranilate). The release rate from microporous polyethylene strands, produced by extrusion‐compounding into ice water baths followed a similar ranking. These strands featured an integral skin‐like membrane that covered the extruded strands and controlled the release of the repellent at a low effective rate. CONCLUSION The high thermal and thermo‐oxidative stability together with the low volatility of the mosquito repellents ethyl butylacetylaminopropionate and Icaridin make them attractive candidates for long‐lasting wearable mosquito‐repellent devices. Such anklets/bracelets may have utility for outdoor protection against infective mosquito bites in malaria‐endemic regions. © 2019 Society of Chemical Industry