Emprego da microextração líquido-líquido dispersiva na determinação da tafenoquina em amostras de plasma humano

Abstract

Tafenoquine (TQ) is an 8-aminoquinolone, synthetic analogue of primaquine which is in fase III tests for the treatment of human malaria. It shows better antimalarial activity than primaquine in vitro and is usually well tolerated in patients. There are some methods for TQ quantification in human plasm, but none uses Dispersive-Liquid-Liquid Microextraction (DLLME), an extraction technique that shows as mean advantages: miniaturization, low cost, high efficiency of extraction and pre-concentration and high potential for routine application. The aim of this study was to evaluate the use of DLLME to determine tafenoquine in human plasma. After protein precipitation, TQ was extracted from plasma by DLLME using chloroform and acetonitrile as extraction solvents and dispersants, respectively. The mobile phase consisted of methanol/acetonitrile/sodium acetate (10 mmol L-1, pH 6.7, 25oC)/acetic acid (50:30:20:0.1 v/v/v) and a C18 column (15 x 4.6mm, 5m) was used. The UV detection was performed at 262 nm and 1 mL/min as flow rate. The following factors that influences extraction efficiency were evaluated and optimized: dispersing solvent, solvent extractor, extractor solvent volume, pH and extraction time. During optimization, chloroform and acetonitrile showed higher recovery as an extractor and dispersant solvent, respectively. For evaluation of solvent extractor volume, the best result was obtained by adding 1 mL of a solution containing 30% of solvent extractor. For pH evaluation, greater extraction was observed by adding 100 L of 0.5 mol L- 1 NaOH solution in the sample. Finally, 2 min was the greater recovery extraction time. After optimized conditions, the method recovery was 78,3% and the lower limit of quantification was 50 ng mL-1. This method was considered linear over the range 50-1500 ng mL-1 (r2 = 0,99), with satisfactory accuracy and precision, and also may be useful in routine analyses specially because of the simplicity of this tecnique, rapidity and low use of solvents, presented features by DLLME tecnique