Abstract
A disposable electrochemical test strip for the quantitative point-of-care (POC) determination of acetaminophen (paracetamol) in plasma and finger-prick whole blood was fabricated. The industrially scalable dry transfer process of single-walled carbon nanotubes (SWCNTs) and screen printing of silver were combined to produce integrated electrochemical test strips. Nafion coating stabilized the potential of the Ag reference electrode and enabled the selective detection in spiked plasma as well as in whole blood samples. The test strips were able to detect acetaminophen in small 40 μL samples with a detection limit of 0.8 μM and a wide linear range from 1 μM to 2 mM, well within the required clinical range. After a simple 1:1 dilution of plasma and whole blood, a quantitative detection with good recoveries of 79% in plasma and 74% in whole blood was achieved. These results strongly indicate that these electrodes can be used directly to determine the unbound acetaminophen fraction without the need for any additional steps. The developed test strip shows promise as a rapid and simple POC quantitative acetaminophen assay.
Highlights
Acetaminophen is one of the most widely used analgesics with antipyretic properties.[1]
We have recently shown that by combining carbon electrodes with thin-film Nafion coatings, we can virtually eliminate the interference from anions, such as AA and uric acid (UA), and significantly reduce the matrix effect in the electrochemical determination of opioids in human plasma.[29,30]
The observation of an singlewalled carbon nanotubes (SWCNTs)/Nafion composite layer is in agreement with a previous study by us,[29] suggesting that the SWCNTs are Nafion-functionalized
Summary
Acetaminophen (paracetamol) is one of the most widely used analgesics with antipyretic properties.[1]. While the susceptibility of the Nafion-coated electrode is lower than that predicted by the Nernst equation for an Ag/AgCl electrode,[47] these results suggest that the use of the test strip is limited to applications where the sample Cl− concentration is known For this reason, all dilutions are carried out with PBS to avoid changes in the ionic strength. This result is in line with a similar passivation study carried out with a Nafion-coated SWCNT electrode in previous research.[29] the electrodes used to measure 50 μM acetaminophen in whole blood (see Table 1) were used to measure 50 μM acetaminophen in PBS. Even in fatal cases of morphine and tramadol poisoning, the concentrations remain below the tested concentrations at approximately 1.75 and 3.8 μM, respectively.[52]
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