{'fraction_non_alphanumeric': 0.04871259568545581, 'fraction_numerical': 0.023660403618649965, 'mean_word_length': 4.89344262295082, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Nanostructured gemini-based supramolecular solvent coupled with ultrasound-assisted back extraction as a preconcentration step before GC-MS.

Liquid-phase microextraction based on gemini-based supramolecular solvent was successfully applied as a preconcentration step before gas chromatography with mass spectrometry. To eliminate the interferences of gemini surfactant, the analytes were back-extracted into an immiscible organic solvent in the presence of ultrasonic sound waves. Three phthalate esters (di-n-butyl-, butylbenzyl-, bis(2-ethylhexyl)-, and di-n-octyl phthalatic esters) were used as target analytes. The effective parameters on extraction efficiency of the target analytes (i.e., the amount of surfactant and volume of propanol as major components making up the supramolecular solvent, ionic strength, hexane volume, and ultrasound time) were investigated and optimized by a one-variable-at-a-time method. Under the optimum conditions, the preconcentration factors of the analytes were in the range of 95-182. The linear dynamic range of 0.05-200.00 μg/L with a correlation of determination of (R2 ) ≥ 0.9935 was obtained. The proposed method had an excellent limit of detection (S/N = 3) of 0.01 for di-n-octyl and 0.02 μg/L for butylbenzyl- and di-n-butyl-phthalatic ester. Good relative recoveries in the range of 85.7-105.2% guaranteed the accuracy of the amount of phthalates distinguished in the nonspiked samples.