Background:
An Ionic Liquid-based based Dispersive Liquid-Liquid Microextraction
(IL-DLLME) method was not applied to preconcentration and determination of bilirubin. Ionic
Liquids (ILs) are new chemical compounds. In recent years, Ionic Liquids (ILs) have been employed
as alternative solvents to toxic organic solvents. Due to these perfect properties, ILs have already
been applied in many analytical extraction processes, presenting high extraction yield and selectivity
for analytes.
Methods:
In this study, IL-DLLME was applied to biological samples (urine and serum) for the spectrophotometric
detection of bilirubin. For bilirubin analysis, the full-color development was based on
the reaction with periodate in the presence of hydrochloric acid. The high affinity of bilirubin for the
ionic liquid phase gave extraction percentages above 98% in 0.3 M HCl solution.
Results:
Several IL-extraction parameters were optimized and room temperature ionic liquid 1-butyl-
1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and ethanol were used as extraction and
disperser solution. The linear range was found in the range of 0.5-6.0 μM (0.3-3.5 μg mL-1) and the
limits of detection of the proposed method was 0.5 μM (0.3 μg mL-1). The proposed method was applied
for the preconcentration and separation of trace bilirubin in real urine samples. Also, the recoveries
for bilirubin in spiked biological samples (urine and serum) were found to be acceptable, between
95-102%.
Conclusion:
The proposed IL-DLLMEapproach was employed for the enrichment and determination
of trace levels of bilirubin in urine samples using NaIO4 as an oxidizing agent and Uv-vis spectrophotometric
detection. The periodate oxidation of bilirubin is rapid, effective, selective, and simple to
perform. The method contains only HCl, NaOI4, and an anionic surfactant. The method may be useful
for economizing in the consumption of reagents in bilirubin determining. The IL-DLLMEmethod
ensures a high yield and has a low toxicity no skin sensitization, no mutagenicity and no ecotoxicity in an
aquatic environment since only very low quantities of an IL is required. For full-color formation, no
any extra auxiliary reagents are required. Besides, the IL-DLLME technique uses a low-cost instrument
such as Uv-vis which is present in most of the medical laboratories.