Determination of steroid sex hormones in real matrices by bar adsorptive microextraction (BAμE)

• A new analytical methodology using a downsized BAµE device.
• The comparison of the selectivity of different sorbent phases.
• A reduced solvent volume at the microliter level for the back-extraction step.
• The development and validation for trace level analysis of nine steroid sex hormones.
• The application of the novel analytical approach to real matrices.

In the present work, the development of a novel analytical approach which combines a miniaturized bar adsorptive microextraction device with a micro-liquid desorption in one single step, followed by high performance liquid chromatography with diode array detection (BAµE-µLD/HPLC–DAD), is proposed for the determination of trace levels of nine steroid hormones (estriol, 17ß-estradiol, 17α-estradiol, 19-northisterone, 17α-ethynylestradiol, estrone, d-(-)-norgestrel, progesterone and mestranol) in environmental and biological matrices. From the comparison of ten different coating phases (five polymeric and five activated carbon sorbents), the modified pyrrolidone polymer (P2) showed the best compromise between selectivity and efficiency. Assays performed through BAµE(P2, 1.3 mg)-µLD(100 µL)/HPLC–DAD on 25 mL of ultrapure water samples spiked at the 6.0 μg/L level, yielded recoveries ranging from 93±9% to 101±8%, under optimized experimental conditions. The analytical performance showed convenient detection (50.0–100.0 ng/L) and quantification limits (165.0–330.0 ng/L), as well as good linear dynamic ranges (0.2–24.0 µg/L) with remarkable determination coefficients (r2>0.9968). Excellent repeatability were also achieved through intraday (RSD<14%) and interday (RSD<12%) experiments. The application of the proposed analytical approach on environmental water and urine samples, using the standard addition methodology (SAM), revealed good linearity and sensitivity at trace level, with the detection of some of the target compounds. In short, the miniaturization of the analytical device for microextraction combined with the minimization of the solvent volume for back-extraction in one single step demonstrated remarkable performance, increasing the enrichment factor, being simultaneously more easier to implement and environment friendly.

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