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Publication . Restolho, José; Barroso, Mário; Dias, Mário; Afonso, Carlos A. M.; Saramago, Benilde

Room temperature ionic liquids (RTILs) are known to provide efficient extraction media for a variety of systems. In particular, their ability to remove low volatility compounds (including opiate drugs) from the surface of human hair was recently demonstrated by this team. Among many tested ILs, some exhibited high extraction efficiencies for the two studied compounds, morphine and 6-monoacetylmorphine, while others have practically zero efficiency. The aim of the present study was to further understand the special affinity of specific combinations cation/anion towards the opiate drugs, through a systematic study of a limited number of ILs: 1-ethyl-3-methylimidazolium acetate, [C2mim][OAc], 1-butyl-3-methylimidazolium acetate [C4mim][OAc], 1-hexyl-3-methylimidazolium acetate [C6mim][OAc], 1-ethanol-3-methylimidazolium tetrafluoroborate, [C2OHmim][BF4], 1-ethanol-3-methylimidazolium chloride [C2OHmim][Cl], and 1-butyl-3-methylimidazolium tetrafluoroborate, [C4mim][BF4]. Correlations between the efficiency of drug extraction from hair and the water content, surface tension and polarity of the ionic liquids (ILs) were found. The extraction efficiency increased with the IL’s water content, although in a different way for each IL/drug pair. A decrease in the surface tension during the process of drug extraction was detected only for highly efficient ILs. Efficiency was correlated with the polarity parameters defined by Kamlet and Taft: large for ILs of high acidity and low basicity (e.g. [C2OHmim][BF4]) and small for liquids with of low acidity and high basicity (e.g. [C6mim][OAc]).

2015-04Journal article

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Development, optimization, and validation of a novel extraction procedure for the removal of opiates from human hair’s surface

Publication . Restolho, José; Barroso, Mário; Saramago, Benilde; Dias, Mário; Afonso, Carlos A. M.

Room temperature ionic liquids (ILs) have proved to be efficient extraction media for several systems, and their ability to capture volatile compounds from the atmosphere is well established. We report herein a contactless extraction procedure for the removal of opiate drugs from the surface of human hair. The compounds were chosen as a model drug, particularly due to their low volatility. Equal amounts of IL and hair (about 100 mg) were introduced in a customized Y-shaped vial, and the process occurred simply by heating. After testing several ILs, some of them (e.g. 1-methyl-3-ethanol-imidazolium tetrafluoroborate, phenyl-trimethyl-ammonium triflate or bis(dimethyl) diheptylguanidinium iodide) showed extraction efficiencies higher than 80% for the two studied compounds, morphine and 6-monoacetylmorphine. Using the design of experiments (DOE) approach as an optimization tool, and bearing in mind the hygroscopic properties of the ILs (in particular, 1-methyl-3-ethanol-imidazolium tetrafluoroborate), the process was optimized concerning the following variables: temperature (50–120 ºC), extraction time (8–24 h), IL amount (50–200 mg) and water content of the IL (0.01–60%). This study not only provided the optimum conditions for the process (120 ºC, 16 h, 100 mg of IL containing 40% of water), but has also showed that the water content of the IL represents the variable with the most significant effect on the extraction efficiency. Finally, we validated our method through the comparison of the results obtained by treating hair samples with the described procedure to those obtained using a standard washing method and criteria for positivity.

2015-05Journal article

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