Perfluorinated alkyl substances in Spanish adults: Geographical distribution and determinants of exposure.

Per- and polyfluoroalkyl substances (PFAS) are widely found in humans and the environment. Their persistence, bioaccumulation and toxicity make them a source of increasing public health concern. In this study, we analyzed the concentrations and geographical distribution of six PFAS in the serum of 755 Spanish adults aged 18-65. The geometric mean concentrations (and P95 values) for PFOS (perfluoroctane sulfonate), PFOA (perfluorooctanoic acid), PFHxS (perfluorohexane sulfonate), PFNA (perfluorononanoic acid) and PFDA (perfluorodecanoic acid) were 7.67 (19.3), 1.99 (5.48), 0.91 (2.84), 0.96 (2.44) and 0.42 (0.99) µg/L, respectively. N-Methylperfluorooctane sulfonamide (N-MeFOSAA) was detected in only 3.3% of samples. Residents in northeast (Catalonia) and northwest of Spain (Galicia) were found to have the highest serum values, whereas residents in the Canary Islands had the lowest values for almost all PFAS. Men presented higher levels than women, and we confirm that lactation (breastfeeding) contributes to a reduced body burden for all PFAS in women. Our data provide new information on exposure to PFAS in a national cross section sample of Spanish adults, thus providing a proxy for reference values for the Spanish population and forming the base for following temporal trends in the future.

On-line flow injection molecularly imprinted solid phase extraction for the preconcentration and determination of 1-hydroxypyrene in urine samples.

New analytical strategies tend to automation of sample pre-treatment and flow analysis techniques provided a number of enhanced analytical methods allowing high throughput. Flow techniques are usually faster, more robust and more flexible than their batch equivalents. In addition, flow methods use less sample and reagent amounts and reduce analytical costs and waste. A flow injection solid-phase extraction pre-concentration system using a molecularly imprinted polymer (MIP) packed micro-column was developed for the determination of 1-hydroxypyrene in human urine with fluorescence detection. The pre-concentration of 1-hydroxypyrene on the MIP was carried out based on the specific retention of analyte by on-line introducing the sample into the micro-column system. Methanol and dichloromethane mixture was used to elute the retained analyte for fluorometric analysis. Important influencing factors were studied in detail, in batch and in flow (MISPE procedure optimisation, sample and eluent volumes, flow rate, dimensions of MIP micro-column and amounts of packing material, etc). To the best of our knowledge, this is the first on-line flow injection molecularly imprinted solid phase extraction for the pre-concentration and determination of hydroxylate PAH metabolite in urine samples. The optimised method was successfully applied to the determination of 1-Hydroxypyrene in spiked urine samples, with recoveries in the range of 74-85% and RSD<4.6%. Under optimum experimental conditions, the linearity concentration range used was 10-400µgL-1, R2>0.996. We obtained limit of detection and quantification of 3.1µgL-1 and 10.5µgL-1, respectively.

A fast method for analysing six perfluoroalkyl substances in human serum by solid-phase extraction on-line coupled to liquid chromatography tandem mass spectrometry.

We have developed and validated an on-line TurboFlow solid-phase extraction procedure coupled to high-performance liquid chromatography with tandem mass spectrometry for the analysis of six perfluoroalkyl substances (PFAS), two sulfonates (perfluorooctane sulfonate and perfluorohexane sulfonate), three carboxylates (perfluorooctanoic acid, perfluorononanoic acid and perfluorodecanoic acid), and one sulfonamide (N-methylperfluorooctane sulfonamide), in human serum samples. This method requires only 100 µL of sample and involves a short pre-treatment with acetonitrile followed by addition of a labelled internal standard for quantification and ultracentrifugation. All PFAS were detected with a run time of 8.5 min. Linearity ranges stay between 0.1 and 20 µg L(-1) (R (2) > 0.9960). Recoveries were determined by spiking blank serum samples with a mixture of six PFAS and found to be in the range 96-110 % for all compounds. Isotopic dilution was used to quantify the selected analytes. The low limits of quantification obtained, between 0.16 and 0.34 µg L(-1), small volume of sample required and short run time used (from two to three times shorter than any other described method), make this validated method highly recommended for human biomonitoring studies.

Evaluation of a molecularly imprinted polymer for determination of steroids in goat milk by matrix solid phase dispersion.

A molecularly imprinted polymer-matrix solid-phase dispersion methodology for simultaneous determination of five steroids in goat milk samples was proposed. Factors affecting the extraction recovery such as sample/dispersant ratio and washing and elution solvents were investigated. The molecularly imprinted polymer used as dispersant in the matrix solid-phase dispersion procedure showed high affinity to steroids, and the obtained extracts were sufficiently cleaned to be directly analyzed. Analytical separation was performed by micellar electrokinetic chromatography using a capillary electrophoresis system equipped with a diode array detector. A background electrolyte composed of borate buffer (25mM, pH 9.3), sodium dodecyl sulfate (10mM) and acetonitrile (20%) was used. The developed MIP-MSPD methodology was applied for direct determination of testosterone (T), estrone (E1), 17ß-estradiol (17ß-E2), 17α-ethinylestradiol (EE2) and progesterone (P) in different goat milk samples. Mean recoveries obtained ranged from 81% to 110%, with relative standard deviations (RSD)≤12%. The molecularly imprinted polymer-matrix solid-phase dispersion method is fast, selective, cost-effective and environment-friendly compared with other pretreatment methods used for extraction of steroids in milk.

High-performance liquid chromatography with diode-array detection cotinine method adapted for the assessment of tobacco smoke exposure.

Smoking is considered to be one of the main risk factors for cancer and other diseases and is the second leading cause of death worldwide. As the anti-tobacco legislation implemented in Europe has reduced secondhand smoke exposure levels, analytical methods must be adapted to these new levels. Recent research has demonstrated that cotinine is the best overall discriminator when biomarkers are used to determine whether a person has ongoing exposure to tobacco smoke. This work proposes a sensitive, simple and low-cost method based on solid-phase extraction and liquid chromatography with diode array detection for the assessment of tobacco smoke exposure by cotinine determination in urine. The analytical procedure is simple and fast (20 min) when compared to other similar methods existing in the literature, and it is cheaper than the mass spectrometry techniques usually used to quantify levels in nonsmokers. We obtained a quantification limit of 12.30 µg/L and a recovery of over 90%. The linearity ranges used were 12-250 and 250-4000 µg/L. The method was successfully used to determine cotinine in urine samples collected from different volunteers and is clearly an alternative routine method that allows active and passive smokers to be distinguished.