Determinación cuantitativa de diisobutil ftalato en líquidos mediante ATR-FTIR: estudio inicial

Abstract

Los ftalatos son compuestos utilizados como plastificantes; su presencia está regulada, sin embargo, el diisobutil ftalato (DiBP) aún no está sujeto a prohibición en la UE. Aquí, se aborda su determinación cuantitativa en líquidos mediante espectroscopia infrarroja con transformada de Fourier en el modo reflexión total atenuada (ATR-FTIR). Se utilizan la regresión de componentes principales (PCR) y por mínimos cuadrados parciales (PLS). Se estudia el análisis directo de DiBP en ciclohexano. Se evalúa qué efecto tienen usar ciclohexano o aire para registrar el espectro del fondo, el número de barridos que se registran, y el pretratamiento de los datos espectrales. Se calculan algunas figuras de mérito; encontrando capacidades de detección sobre 2.000-3.000 ppm ( =  = 0.05). Se incluye una etapa de preconcentración para incrementar la sensibilidad; se estudia la influencia del número de depósitos. Se alcanzan capacidades de detección de hasta 52 ppm ( =  = 0.05).

Phthalates are a group of synthetic compounds widely used as plasticizers, mainly used to increase plastic flexibility, resistance and durability. These substances may be found in toys, cosmetics, plastic bottles, etc. Their presence in some fields is regulated to avoid risks to the health. Diisobutyl phthalate (DiBP) is among these phthalates, many of which are banned in toys, childcare articles or cosmetics; however, DiBP has so far not been subjected to EU ban. The determination of DiBP in liquid samples by means of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is approached in this work. Soft multivariate regression models, principal component regression (PCR) and partial least squares regression (PLS), are used for the quantitative analysis. The level of concentration for the direct analysis of DiBP in cyclohexane is studied. It is assessed what effect the use of cyclohexane or air to collect the background spectrum, the number of scans to be collected in the sample measurement, and the pretreatment of spectral data have on the analytical determination. Some figures of merit are calculated to establish the performance of the analytical method. Values of the capability of detection around 2.000-3.000 ppm are achieved (a = b = 0.05). A preconcentration step is included in the method in order to increase its sensitivity. The influence of the number of depositions on the performance of the analytical method is studied. Capabilities of detection down to 52 ppb are reached (a = b = 0.05).