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.

A tandem giant magnetoresistance assay for one-shot quantification of clinically relevant concentrations of N-terminal pro-B-type natriuretic peptide in human blood

We report a microfluidic sandwich immunoassay constructed around a dual-giant magnetoresistance (GMR) sensor array to quantify the heart failure biomarker NT-proBNP in human plasma at the clinically relevant concentration levels between 15 pg/mL and 40 ng/mL. The broad dynamic range was achieved by differential coating of two identical GMR sensors operated in tandem, and combining two standard curves. The detection limit was determined as 5 pg/mL. The assay, involving 53 plasma samples from patients with different cardiovascular diseases, was validated against the Roche Cobas e411 analyzer. The salient features of this system are its wide concentration range, low detection limit, small sample volume requirement (50 μL), and the need for a short measurement time of 15 min, making it a prospective candidate for practical use in point of care analysis.

Evaluation of determination of uric acid in serum and whole blood with the Reflotron.

The performance of the Reflotron system (Boehringer Mannheim) for the determination of urate in whole blood and serum was evaluated. Within-run and day-to-day imprecision of the system were comparable with those for a solution-chemistry enzymatic method (overall CVs in the range 2.2-2.5%). Results for 100 individual specimens with urate concentrations ranging from 16 to 134 mg/L agreed well with the comparison method, both for serum and whole blood. We saw no significant interference from lipemia or hemoglobin. Bilirubin interfered at concentrations greater than 100 mg/L. Hematocrit variation between 25% and 55% did not affect results for whole blood; variation of the applied sample volume from 28 microL to 35 microL (stated sample volume requirement: 30 microL) did not significantly influence the measured value. We consider results produced by the system to be of the same analytical quality as those obtained by the more conventional solution-chemistry methods that are currently available.