RESUMEN
Monitoring biological samples at trace levels of chemicals from anthropogenic actions such as pesticides, pharmaceuticals, and hormones has become a very important subject. This work describes a method for the determination of eight compounds of different chemical classes in human urine samples. Dispersive liquid-liquid microextraction based on magnetic ionic liquids was used as the sample preparation procedure. The main parameters of the method, such as sample dilution, type, and volume of disperser solvent, amount of magnetic ionic liquids, extraction time, and pH were optimized by univariate and multivariate procedures. Validation was performed using a urine sample of a male volunteer in order to obtain a calibration curve and the main analytical parameters of merit such as limits of detection and quantification. Values varied from 3.0 to 7.5 µg/L and from 10 to 25 µg/L, respectively. Satisfactory precisions of 21% for intraday (n = 3) and 16% for interday (n = 9) were achieved. Accuracy was evaluated by relative recovery assays using different urine samples and ranged from 75 to 130%. Robustness was assured by the Lenth method. The validated procedure was applied to five urine samples from different volunteers and the hormone estrone was found in one sample.
Asunto(s)
Diclofenaco/orina , Estrona/orina , Etinilestradiol/orina , Líquidos Iónicos/química , Microextracción en Fase Líquida , Plaguicidas/orina , Adulto , Calibración , Cromatografía Líquida de Alta Presión , Femenino , Humanos , Concentración de Iones de Hidrógeno , Fenómenos Magnéticos , Masculino , Adulto JovenRESUMEN
In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extraction phases and dispersive liquid-liquid microextraction (DLLME) was developed to analyze the hormones estriol, 17-ß-estradiol, 17-α-ethynylestradiol, and estrone in human urine samples. This is the first report of an application of manganese-based MILs compatible with HPLC to extract compounds of biological interest from urine samples. The hydrophobic MILs trihexyltetradecylphosphonium tetrachloromanganate (II) ([P6,6,6,14+]2[MnCl42-]) and aliquat tetrachloromanganate (II) ([Aliquat+]2[MnCl42-]) were employed and the optimized extraction conditions were comprised of 5 mg of MIL ([P6,6,6,14+]2[MnCl42-]), 5 µL of methanol (MeOH) as disperser solvent, and an extraction time of 90 s at sample pH 6. The analytical parameters of merit were determined under optimized conditions and very satisfactory results were achieved, with LODs of 2 ng mL-1 for all analytes, determination coefficients (R2) ranging from 0.9949 for 17-ß-estradiol to 0.9998 for estrone. In addition, good results of method precision were achieved with the intraday (n = 3) varying from 4.7% for 17-ß-estradiol to 19.5% for estriol (both at 5 ng mL-1) and interday precision (evaluated at 100 ng mL-1) ranging from 11.4% for estrone to 17.7% for 17-α-ethynylestradiol and analyte relative recovery evaluated in three real samples ranged from 67.5 to 115.6%. The proposed DLLME/MIL-based approach allowed for a reliable, environmentally friendly and high-throughput methodology with no need for a centrifugation step. Graphical abstract An overview of the rapid and straightforward extraction procedure using DLLME/MIL-based approach.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Estrógenos/orina , Líquidos Iónicos/química , Microextracción en Fase Líquida/métodos , Imanes/química , Adulto , Estradiol/orina , Estrona/orina , Etinilestradiol/orina , Femenino , Humanos , Límite de Detección , Magnetismo/métodos , MasculinoRESUMEN
This work describes the preparation of an electrochemical immunosensor for ethinylestradiol (EE2) based on grafting of diazonium salt of 4-aminobenzoic acid onto a glassy carbon electrode modified with silver nanoparticles/SiO2/graphene oxide hybrid followed by covalent binding of anti-ethinylestradiol (anti-EE2) to activated carboxyl groups. A competitive immunoassay was developed for the determination of the hormone using peroxidase-labeled ethinylestradiol (HRP-EE2) and measurement of the amperometric response at -200mV in the presence of hydroquinone (HQ) as redox mediator. The calibration curve for EE2 exhibited a linear range between 0.1 and 50ng/mL (r(2)=0.996), with a detection limit of 65pg/mL. Interference studies with other hormones related with EE2 revealed the practical specificity of the developed method for the analyte. A good reproducibility, with RSD=4.5% (n=10) was also observed. The operating stability of a single bioelectrode modified with anti-EE2 was maintained at least for 15 days when it was stored at 4°C under humid conditions between measurements. The developed immunosensor was applied to the analysis of spiked urine with good results.