CURRENT TECHNOLOGY AND

FUTURE PROSPECT FOR DETECTION

OF ALCOHOL

By: Phurpa Dema Thungon

146106001

DETECTION OF ALCOHOL

Accurate and rapid measurement of alcohol in order to analyze human body fluids for checking ethanol content

The food, beverage and pulp industries require simple, fast and economic analytical methods in order to control fermentation processes and the quality of products

In agricultural and environmental analysis, e.g. for the assessment of ethanol at a spill site or in groundwaters

Screening for alcohol problems: Drivers and alcoholics

Major work on Ethanol

NON-ENZYMATIC TECHNIQUES FOR

QUANTIFICATION OF ETHANOL

GC= gas chromatography; FID = flame-ionisation detection; MS= mass spectroscopy; HPLC = high performance liquid chromatography; IR = infrared; NIR = near infrared; FT = Fourier transform

However: Complex, time consuming and require

previous separations processes (distillation..)

Expensive instrumentation and trained operators

Overcome by the use of enzymatic methods

ENZYMES FOR ETHANOL BIOSENSORS

Alcohol Oxidase (AOX) and Alcohol Dehydrogenase (ADH)

ALCOHOL OXIDASE

Produced by methylotrophic yeasts during growth

on methanol

Cofactor- flavin adenine dinucleotide (FAD)

Biosensors based on

Decrease in O2

Increase in H2O2 concentration

BIOSENSORS DEVELOPED USING ALCOHOL

OXIDASE

O2 Probe- Electrochemical Detection and Optical

Detection

H2O2 Probe

a) Direct (First generation biosensor)

b) Indirect method

(Second and Third generations)

THIRD GENERATION ALCOHOL BIOSENSOR

(2014)

• Ferrocene molecules entrapped in the AOX protein matrix

• Detection limit of 2.3 uM

VISUAL ETHANOL BIOSENSOR (2014)

Dip Stick Test

Polyaniline (PANI) is a polymer that changes

conductivity and colour with changes in pH or redox

reactions

The colour change of the films towards ethanol has

been scanned and analyzed using image analysis

software (i.e., ImageJ)

PROPOSED REACTION MECHANISM

Reduction of the PANI film from its emeraldine salt

form (green) to the emeraldine base form (blue)

ALCOHOL DEHYDROGENASE

Co-enzyme nicotinamide adenine dinucleotide(NAD+)

NAD+ to be added externally

ELECTROCHEMILUMINESCENCE ETHANOL

BIOSENSOR (2013)

Electrochemiluminescence (ECL) is a process of

converting electrochemical energy into radiative

energy on the surface of electrode

Based on tris(2,2′-bipyridine) ruthenium(II)

[Ru(bpy)32+ ] : good electrochemical stability, high

ECL efficiency, and the convenience to couple with

various separation techniques

Alcohol Dehydrogenase

FORMATION OF ECL ETHANOL BIOSENSOR BASED

ON GRAPHENE/BSA COMPOSITE FILM

The CVs of the biosensor at the different scan rate in 100 mM PBS (pH 7.0).

a–g Correspond to scan rate: 20, 60, 100, 200, 400, 500 and 600 mV/S respectively.

(B) CVs of 100 mM PBS (pH 7.0) on the bare GCE (Curve b) and

the ECL ethanol biosensor (Curve a), and ECL–potential curve of bare GCE (Curve b′)

and the ECL ethanol biosensor (Curve a′) to 500 μM ethanol. Scan rate: 100 mV/s.

DISPOSABLE BIOSENSOR STRIP(2011)

Alcohol dehydrogenase

Screen-printed electrode modified with Meldola’sBlue (MB) absorbed on Nafion

A) print conductive sliver strip

B)carbonic working counter electrodes

C)Ag/AgCl reference electrode

D) insulating layer (D)

PHOTOGRAPH OF THE BIOSENSOR

CONCLUSION AND FUTURE

Keys features needed for alcohol biosensors

portability, low cost and potential for fabrication

immobilization of alcohol oxidase (AOD) or alcohol

dehydrogenase or any other enzyme

ADH more popular in recent disposable ethanol

biosensors than AOX as it’s dry enzyme

preparation has low shelf life

Disposable biosensor

Majority of work done in Ethanol but not Methanol

which is considered as toxic

THANK YOU