Abstract:

A novel method for the determination of diisobutyl phthalate (DIBP), dibutyl phthalate (DBP) and butyl benzyl
phthalate (BBP) in white spirits has been developed by using dispersive liquid-liquid microextraction (DLLME) coupled
with high performance liquid chromatography with a DAD detector. Key DLLME experimental parameters including the
type and volume of extractant and disperser solvent, the amount of added salt, extraction time and temperature were examined
and optimized. The optimized extraction conditions were as follows: 2 mL of sample diluted with 7 mL of 0.26 g/mL NaCl solution
and then mixed with a pre-mixed solution consisting of 60 μL of carbon tetrachloride (extractant) and the same volume of
acetonitrile (disperser solvent) by gently shaking for 5 min at room temperature. After centrifugation, the precipitate phase
of carbon tetrachloride was taken and diluted with the same methanol before being injected into the analytical column
for analysis. The method revealed an excellent linearity over the concentration range of 1–500 ng/mL with correlation
coefficient (r) ＞ 0.99. The detection limits were in the range of 0.3–0.8 ng/mL. The enrichment factors varied from 92 to
102. Intra-day and inter-day repeatability values expressed as relative standard deviation were in the range of 1.3%–2.8%,
and 2.0%–4.7% (n = 6), respectively. The developed method was applied to the determination of the phthalate esters in 31
white spirits, and 17 out of the detected samples exceeded the legal limit of DBP. The average recovery rates ranged from
92.5%–111.2%. Compared to previous methods, the new procedure is characteristics of simple sample preparation, less
organic solvent consumption and higher sensitivity.

Key words: dispersive liquid-liquid microextraction, white spirits, phthalate esters (PAEs)