ELECTRONIC TONGUE

BY R.PAVAN KUMAR, RIPER-ANANTAPUR.

WHAT IS ELECTRONICTONGUE? The electronic tongue is an instrument that measures and compares tastes. It is an analytical instrument comprising an array of non-specific, low selective chemical sensors with cross-sensitivity to different components in solution, and an appropriate method of pattern recognition and/or multivariate calibration for the data processing.

MAIN NEED IN PHARMACY FIELD Assessment of the taste of oral drug the preparation-Major interest To date, only method employed for determination of taste intensity was human sensory test. To facilitate the work and address the difficulties associated with human panel test, a safe, reliable, fast analyzing objective instrument was developed called

Electronic Tongue .

PRINCIPLEUtilization of non-specific or lowselective potentiometric chemical sensors with enhanced crosssensitivity to as many different components in solution as possible.

CORRELATION WITH HUMAN TONGUE Mechanism involved for taste recognition shows the same three levels in both. Taste buds in human. Lipid membrane of sensors. Nerve transmission transducers Cognition in thalamus Statical analysis

The receptor level

The circuit level

The perceptual level

INSTRUMENTATION Liquid Autosampler

Chemical Sensor or Sensor array Acquisition System Data Processing System

CHEMICAL SENSOR ????Chemical sensors are small devices that perform transformation of chemical or biochemical information of a qualitative or quantitative type into an analytical useful signal by the process of chemical

interaction between sample and sensors. Currently these technologies are based on electrochemical sensors(POTENTIOMETRIC). Other sensing methods applied is voltammeter.

The detecting sensor part consist of lipid/polymer membranes and act as the working electrodes.

The reference electrodes -Ag/AgCl.

Electrode charge density of the lipid/polymer membrane surface and ion distribution near the surface of the membrane is changed due to sample. Therefore the total electrical charge on the lipid membrane gives the response membrane electric potential for the substances.

ACQUISITION SYTEM The acquisition system establishes the communication between the sensor array and data processing system.

Converts the electrical signals from sensorarray to digital distortion.

signals with less

Amplifier must be present as the electrical signals from the sensors are always small.

DATA PROCESSING SYSTEMSChemometric techniques a type of multivariate statistic used in the analytical field provide data processing, which consist of recognition, classification and identification and multivariate calibration.

Statistical analysis

Broad use

Application

Principal component analysis (PCA)

Qualification, exploration and discrimination

Initial formulation studies

Discrimination factorial analysis (DFA)

Discrimination and identification

Recognition of unknown sample

Soft independent modeling of class analogy (SIMCA)

Good/bad modeling

Quality control against reference good product

Partial least square (PLS)

Quantification

Quantification of bitterness against sensory panel

APPLICATIONS Quantify taste masking efficiency of formulations. Analyze medicines stability in terms of taste. Benchmark target products. Analyze flavor ageing in beverages. Quantify bitterness or spicy level of drinks or dissolved compounds.

CONCLUSIONElectronic tongues are emerging, promising and proved to be a valuable tool for assessment and prediction of the taste of pharmaceuticals and related products.

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