Ultrasound-assisted emulsification microextraction for rapid determination of unmetabolized synthetic polycyclic and nitro-aromatic musks in human urine.

An effective method to rapidly determine the presence of seven unmetabolized synthetic musks in human urine samples is developed. The target musks are five synthetic polycyclic musks (i.e., celestolide (ADBI), phantolide (AHMI), traseolide (ATII), galaxolide (HHCB), tonalide (AHTN)), and two nitro-aromatic musks (i.e., musk xylene (MX) and musk ketone (MK)). The method involved an ultrasound-assisted emulsification microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS). The factors that affect USAEME efficiency were optimized in detail, and the optimized procedure involved the rapid injection of 50 µL of carbon tetrachloride into 1.0 mL of urine sample (contained 0.1-g of sodium chloride) in a conical bottom glass tube. After 1.0 min ultrasonication and 3 min centrifugation (at 7000 rpm), the sedimented extract 10 µL was directly injected into the GC-MS system. The limits of quantitation (LOQs) varied from 0.1 to 0.5 ng/mL. The precisions for both repeatability and reproducibility were <8%. The trueness varied from 79 to 96% with the RSD ranging from 2 to 8%. The total concentrations of the seven unmetabolized target musks in collected human urine samples were in the range from 0.93 to 3.74 ng/mL. HHCB and AHTN were detected in all the collected samples, and the daily excretion doses were evaluated.

Determination of parabens in human urine by optimal ultrasound-assisted emulsification microextraction and on-line acetylation gas chromatography-mass spectrometry.

An effective and solvent-less method for the rapid determination of four commonly detected parabens (methyl-, ethyl-, propyl- and butyl-) in human urine samples is described. This method employed ultrasound-assisted emulsification microextraction (USAEME) before identification and quantitation of the parabens via on-line acetylation gas chromatography-mass spectrometry (GC-MS). Urine samples were enzymatically de-conjugated with ß-glucuronidase and then extracted by an optimal USAEME procedure for the measurement of total concentrations of target analytes. The optimal USAEME parameters for one mL of urine sample (containing 0.1-g of sodium chloride), according to the Box-Behnken design method, are thus described: extractant of 200-µL of ethyl acetate, and ultrasonication for 1.0min and centrifugation at 7000rpm (3min). The supernatant was collected and evaporated until dry. Then the residue was re-dissolved in methanol (100-µL), and the extract was subjected to on-line acetylation GC-MS analysis. The limits of quantitation (LOQs) were less than 0.06ng/mL. Precisions for both intra- and inter-day analysis were calculated, and were less than 8%. Mean extraction recovery (known as trueness) was between 83 and 101% on three concentration levels. In human urine, the total concentrations of the four selected parabens, according to preliminary results, range from 0.3 to 124.5ng/mL for male, and from 27.2 to 246.3ng/mL for female. Female urine samples showed higher concentrations for the target parabens, which may indicate higher exposure due to lifestyle. This method permits accurate and high-throughput analysis of parabens for epidemiological studies.