On-line monitoring of the transesterification reaction carried out in microreactors using near infrared spectroscopy

► The biodiesel produced from sunflower oil and ethanol is of 100% renewable origin. ► EtONa is used as a homogeneous catalyst. ► The transesterification reaction was carried out in continuous systems: microreactors. ► On-line monitoring of the transesterification reaction was developed by using near infrared spectroscopy. ► A multivariate approach is used to establish calibration models.