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Merck

Fast determination of antibiotics in whole blood.

Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases (2012-11-30)
Q Chen, A Andersson, M Mecklenburg, B Xie
ABSTRACT

There is a need for analytical methods capable of monitoring blood antibiotic levels in real time. Here we present a method for quantifying antibiotic levels in whole blood that does not require any sample pretreatment. The tests employ the enzyme penicillinase to assay for penicillin G, penicillin V and ampicillin using a flow-injected biosensor, the Enzyme Thermistor. Optimal flow rates, sample volumes and pH were determined to be 0.5 mL/min, 100 μL and 7.0, respectively. Analysis of the antibiotics diluted in buffer gave a linear range of 0.17-5.0 mM. Calibration curves prepared using blood spiked with the antibiotics gave a linear range of 0.17-2.0 mM. Linear regression values for all of the calibration curves were 0.998 or higher. Assay cycle time was 5 min. The relative standard deviation value for 100 determinations of a mock blood sample spiked with penicillin G was 6.71%. Despite the elimination of sample pretreatment, no detectable clogging or signal drift was observed. The assay provides a fast, simple, reliable analytical method for determining antibiotic concentrations in blood without the need for any sample pretreatment. This is an important first step towards developing a device capable of real-time monitoring of antibiotic levels in whole blood. The technology has the potential to significantly improve the outcomes of patients undergoing critical care.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ampicillin trihydrate, 900-1050 μg/mg anhydrous basis (HPLC)
Sigma-Aldrich
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Sigma-Aldrich
Penicillin G sodium salt, powder, BioReagent, suitable for cell culture
Supelco
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Sigma-Aldrich
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Sigma-Aldrich
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Supelco
Penicillin G potassium salt, VETRANAL®, analytical standard
Supelco
Penicillin V potassium salt, VETRANAL®, analytical standard
Sigma-Aldrich
Ampicillin, anhydrous, 96.0-102.0% (anhydrous basis)
Sigma-Aldrich
Penicillin G potassium salt, powder, BioReagent, suitable for cell culture
Sigma-Aldrich
Penicillin G potassium salt, 95.0 - 102.0%
Phenoxymethylpenicillin, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Ampicillin sodium salt, powder or crystals, BioReagent, suitable for cell culture
Sigma-Aldrich
Ampicillin sodium salt
Supelco
Ampicillin, analytical standard