Direct Methanol (or Ethanol) Fuel Cell as Enzymatic or Non-Enzymatic Device, Used to Check Ethanol in Several Pharmaceutical and Forensic Samples

Abstract

It was already demonstrated by our research group that a direct catalytic methanol (or ethanol) fuel cell (DMFC) device can be used also for analytical purposes, such as the determination of ethanol content in beverages. In the present research we extended the application to the analysis of several ethanol-based pharmaceutical products, i.e., pharmaceutical tinctures (dyes) and disinfectants. In recent work we have also shown that the use of alcohol dehydrogenase enzyme as a component of the anodic section of a direct catalytic methanol (or ethanol) fuel cell significantly improves the performance of a simple DMFC device, making it more suitable to measure ethanol (or methanol) in real samples by this cell. At the same time, we have also shown that DMFC can respond to certain organic compounds that are more complex than methanol and ethanol and having R(R’)CH-OH group in the molecule. Firstly, pharmaceutical dyes were analyzed for their ethanol content using the simple catalytic DMFC device, with good accuracy and precision. The results are illustrated in the present paper. Additionally, a detailed investigation carried out on commercial denatured alcoholic samples evidenced several interferences due to the contained additives. Secondly, we hypothesized that by using the enzymatic fuel cell it would be possible to improve the determination, for instance, of certain antibiotics, such as imipenem, or else carry out determinations of ethanol content in saliva and serum (simulating forensic tests, correlated to drivers “breath test”); even if this has already been hypothesized in previous papers, the present study is the first to perform them experimentally, obtaining satisfactory results. In practice, all of the goals which we proposed were reached, confirming the remarkable opportunities of the enzymatic (or non-enzymatic) DMFC device.

Direct Catalytic Fuel Cell Device Coupled to Chemometric Methods to Detect Organic Compounds of Pharmaceutical and Biomedical Interest

“…However, the latter was found to be only between 0.07% and 0.4%, for example, for the determination of ethanol in alcoholic drinks [ 26 ]. On the other hand, as far as the accuracy, estimated by recovery tests (i.e., using the standard addition method), is concerned, it is obvious that it also depends on the compound under examination, given the different sensitivities of the fuel cell towards them; for example, for Imipenem, it was found to be between −3.9% and −4% [ 28 ], for Chloramphenicol between −7% and −8% [ 41 ], while, for ethanol, from −0.3% to +8% [ 26 ]. The LOD value also varies between about 10 −6 mol L −1 and 10 −4 mol L −1 , according to the different compounds examined.…”

“…The LOD value also varies between about 10 −6 mol L −1 and 10 −4 mol L −1 , according to the different compounds examined. This means that, generally, there is no difficulty, for example, in analyzing antibiotics tested in pharmaceutical specialties [ 28 , 41 ] or to determine ethanol in wines, beers or hard liquor drinks [ 25 , 26 ]. On the other hand, it is clear that it would be difficult to apply the method to real samples containing concentrations of antibiotics considered to be lower than about 10 −6 mol L −1 , or of ethanol, methanol and propanol lower than about 10 −4 mol L −1 , without a preliminary preconcentration step.…”

“…However, our research group recently performed new researches of analytical-quantitative types by using a simple and suitable direct methanol fuel cell (DMFC) [ 25 , 26 , 27 ]. In some of the works already published [ 27 , 28 ], we have also observed that the cells (DMFC) developed, used or marketed essentially for analytical purposes in the quantitative determination of methanol or ethanol are able to respond, even if with different sensitivities and different response times, to organic compounds other than the simplest aliphatic alcohols, provided that, in their molecule, there is a –OH group having (at least partly) alcoholic properties. This circumstance has prompted us to investigate an idea that we had been trying to develop for some time using other types of sensors; our research team, in fact, has developed many other classic electrochemical sensors and biosensors in the past years, which have generally proven very useful for the quantitative analyses of different compounds, while they have not been so successful in qualitative analyses, both because this analytical aspect has generally been poorly investigated and because some practical difficulties often arise using classic sensors or biosensors and, finally, because modern mathematical methods, such as chemometric ones, have not been applied to this problem.…”

The Applications of Sensors and Biosensors in Investigating Drugs, Foods, and Nutraceuticals

“…The fifth paper is from an Italian team and reports a study in which a direct methanol fuel cell is proposed to find ethanol in several pharmaceuticals and forensic samples [5]. The paper refers, extending its application, to an alcoholmeter, where breath samples are received and, due to the catalytic properties of the electrode material, are transduced into an electric current, the intensity of which is proportional to the alcohol concentration in the breath sample.…”

In Situ Tracking of Wetting‐Front Transient Heat Release on a Surface‐Mounted Metal–Organic Framework

“…Introduction of such an inclusive approach should lead to a widespread integration of MOFs on flexible and low-cost paper substrate, affording cheap and portable thin film devices (Table S3, Supporting Information) for liquid content determination, e.g., water, methanol, and ethanol from fuel oil, liquor, and alcoholic beverages. [26][27][28] In essence, this portable method enables easier operation and faster detection versus currently reported Karl Fischer titration, chromatography, and other MOF sensors based signal transduction (Table S4, Supporting Information).…”