Fast In Vivo Microextraction: A New Tool for Clinical Analysis

Abstract

Background:We sought to develop a technique with the potential to partly replace current methods of analysis based on blood draws. To achieve this goal, we developed an in vivo microextraction technique that is faster than conventional methods, interferes minimally with the investigated system, minimizes errors associated with sample preparation, and limits exposure to hazardous biological samples. Methods: Solid-phase microextraction devices based on hydrophilic polypyrrole and polyethylene glycol coatings were used for direct extraction of drugs from the flowing blood of beagle dogs, over a period of 8 h. The drugs extracted on the probes were subsequently quantified by liquid chromatography coupled to tandem mass spectrometry. Two calibration strategies-external and standard on the fiber-were used to correlate the amount extracted with the in vivo concentration. Results: Diazepam and its metabolites were successfully monitored over the course of a pharmacokinetic study, repeated 3 times on 3 beagles. The fast microextraction technique was validated by comparison with conventional plasma analysis, and a correlation factor of 0.99 was obtained. In addition to total concentrations, the method was useful for determining free drug concentrations. Conclusions:The proposed technique has several advantages and is suitable for fast clinical analyses. This approach could be used not only for drugs, but for any other endogenous or exogenous compounds.

Use of a novel technique, solid phase microextraction, to measure tranexamic acid in patients undergoing cardiac surgery

“…They introduced SPME fibres directly into a catheter in the carotid artery. 21 Their results correlated well with those of a standard analytical method using protein precipitation of blood samples obtained at preselected time points.…”

“…This validation of the SPME extraction technique for TXA results in adding another medication to the long list of analytes that have been investigated previously. 2,[18][19][20][21] It demonstrates potential of this analytical method to be applied for measurements of other agents of interest in clinical medicine.…”

Making biosamples compatible with instrumental analysis

“…Prof. Pawliszyn`s group is the pioneer of in-vivo microextraction that solves this shortcoming [20]. As the name well indicates, this approach consists on the integration of sampling and microextraction and presents the following advantages: a) is faster than con-ventional approaches; b) minimizes error associated to sample treatment and c) minimizes the error associated to sample storage since the analysis is performed after the in-vivo extraction [21]. In addition, the microextraction does not change the system equilibrium since the amount of extracted analyte is very low.…”

Low invasive in vivo tissue sampling for monitoring biomarkers and drugs during surgery

“…12,13 Recently, the feasibility of the method was also shown for global screening purposes. [14][15][16][17] The main advantages of in vivo SPME, being a low invasive and nondisturbing method to the system under study, were demonstrated for pharmacokinetics and metabolomics in blood, [18][19][20][21][22][23] whereas in vivo tissue analyses were conducted for analysis of pharmaceuticals in living fish. 24,25 In addition, with the SPME technique, blood sampling can be performed directly from a vein by using a hypodermic needle-assembled SPME probe (Figure 1) or by insertion of the probe to the vein through the i.v.…”

“…In addition, to control blood flow through the interface and increase the rate of extraction, a syringe or pump can be connected to the interface. [19][20][21][22][23] For tissue sampling, the SPME fiber can be placed in the studied tissue either by using the needleassembled device, as it is proposed in this work, or by using specially designed tissue samplers, as reported for fish muscle sampling. 25 In order to provide fully quantitative results, a Figure 1 The SPME probe with no assembly (a) and assembled in hypodermic needle (b, c).…”