Chemometric tools applied to optimize a fast solid-phase microextraction method for analysis of polycyclic aromatic hydrocarbons in produced water.

Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase microextraction procedure, which was used for the analysis of polycyclic aromatic hydrocarbons (PAHs) in oil-based produced water using a Headspace-Solid Phase Microextraction technique (HS-SPME/GC-MS). This optimization was achieved with a 24 factorial design approach, where the final conditions for this extraction procedure were 10 µg L-1, 1 h, 92 °C (at headspace), and 0.62 mol L-1 for PAHs concentration, fiber exposition to headspace, temperature, and NaCl concentration, respectively. The limit of detection (LOD) in this protocol ranged from 0.2 to 41.4 ng L-1, while recovery values from 67.65 to 113.10%. Besides that, relative standard deviation (RSD) were lower than 8.39% considering high molecular weight compounds. Moreover, the proposed methodology in this work does not require any previous treatment of the sample and allows to quantify a higher number of PAHs. Notably, naphthalene was the major PAHs compound quantified in all samples of the produced water at 99.99 µg L-1. Altogether, these results supported this methodology as a suitable analytical strategy for fast determination of PAHs in produced water from oil-based industry.

Multivariate Classification of Original and Fake Perfumes by Ion Analysis and Ethanol Content.

The increased marketing of fake perfumes has encouraged us to investigate how to identify such products by their chemical characteristics and multivariate analysis. The aim of this study was to present an alternative approach to distinguish original from fake perfumes by means of the investigation of sodium, potassium, chloride ions, and ethanol contents by chemometric tools. For this, 50 perfumes were used (25 original and 25 counterfeit) for the analysis of ions (ion chromatography) and ethanol (gas chromatography). The results demonstrated that the fake perfume had low levels of ethanol and high levels of chloride compared to the original product. The data were treated by chemometric tools such as principal component analysis and linear discriminant analysis. This study proved that the analysis of ethanol is an effective method of distinguishing original from the fake products, and it may potentially be used to assist legal authorities in such cases.