Solventless Microextration Techniques for Pharmaceutical Analysis: The Greener Solution

Extensive efforts have been made in the last decades to simplify the holistic sample preparation process. The idea of maximizing the extraction efficiency along with the reduction of extraction time, minimization/elimination of hazardous solvents, and miniaturization of the extraction device, eliminating sample pre- and posttreatment steps and reducing the sample volume requirement is always the goal for an analyst as it ensures the method’s congruency with the green analytical chemistry (GAC) principles and steps toward sustainability. In this context, the microextraction techniques such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), fabric phase sorptive extraction (FPSE), in-tube extraction dynamic headspace (ITEX-DHS), and PAL SPME Arrow are being very active areas of research. To help transition into wider applications, the new solventless microextraction techniques have to be commercialized, automated, and validated, and their operating principles to be anchored to theory. In this work, the benefits and drawbacks of the advanced microextraction techniques will be discussed and compared, together with their applicability to the analysis of pharmaceuticals in different matrices.

RP-HPLC enantioseparation of β-adrenolytics using micellar mobile phase without organic solvents

Enantioseparation of a few commonly administered racemic β-adrenolytics (namely, carvedilol, betaxolol, salbutamol and bisoprolol) has been achieved using a water micellar mobile phase containing surfactants (sodium dodecyl sulphate and Brij-35) without organic solvents as a new approach in RP-HPLC. Two chiral derivatizing reagents based on enantiomerically pure (S)-(-)-levofloxacin were synthesized using N-hydroxysuccinimide and N-hydroxybenzotriazole as the activation auxiliaries. Diastereomeric derivatives of the chosen β-adrenolytics were synthesized under microwave irradiation in a very short reaction time. The (S)-(-)-levofloxacin moiety enhanced molar absorbance of the diastereomeric derivatives resulting in very low limit of detection (1.618 and 4.902 ng/mL, respectively, for diastereomeric derivatives of (RS)-betaxolol and better resolution with lower retention times (for all the analytes), in comparison to literature reports. There was 15-20 times less consumption of mobile phase because of lower retention time.