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The objective of the study was to mask the unpleasant taste of captopril (CPT). Taste masking was achieved by complexation of CPT with a basic ion exchange resin, Dowex® 66, using the batch...

Electronic tongue technology based on arrays of cross-sensitive chemical sensors and chemometric data processing has attracted a lot of researchers’ attention through the last years. Several so far reported applications dealing with pharmaceutical related tasks employed different e-tongue systems to address different objectives. In this situation, it is hard to judge on the benefits and drawbacks of particular e-tongue implementations for R&D in pharmaceutics. The objective of this study was to compare the performance of six different e-tongues applied to the same set of pharmaceutical samples. For this purpose, two commercially available systems (from Insent and AlphaMOS) and four laboratory prototype systems (two potentiometric systems from Warsaw operating in flow and static modes, one potentiometric system from St. Petersburg, one voltammetric system from Barcelona) were employed. The sample set addressed in the study comprised nine different formulations based on caffeine citrate, lactose monohydrate, maltodextrine, saccharin sodium and citric acid in various combinations. To provide for the fair and unbiased comparison, samples were evaluated under blind conditions and data processing from all the systems was performed in a uniform way. Different mathematical methods were applied to judge on similarity of the e-tongues response from the samples. These were principal component analysis (PCA), RV′ matrix correlation coefficients and Tuckeŕs congruency coefficients.

The aim of this work was to investigate the effect of ultrasound (US) pre-treatment on endogenous metabolic activity of kiwifruits slices subjected to osmotic dehydration (OD), measured by metabolic heat production in isothermal calorimeter, respiration rate, structure changes and cell viability. Moreover, the overall changes on minimally processed kiwifruit were also studied by means of electronic tongue system. Kiwifruit slices (10 mm thick) were treated with US in the bath at a frequency of 35 kHz for 10, 20 and 30 min. The OD process was conducted in a 61.5% sucrose solution at 25 °C for pre-established contact period of 0, 10, 20, 30, 60 and 120 min. The results showed that the application of US pre-treatment and OD process promoted the reduction of metabolic heat as a consequence of a partial loss of vitality. Moreover, US and US + OD treatment specifically impacted the structure and the chemical picture of kiwifruit samples. Industrial relevance Ultrasound treatment coupled with osmotic dehydration could be applied at industrial level in order to save time and energy for a further dehydration process. Moreover, fruit tissue treated with ultrasound treatment promoted structural modifications and chemical changes in the kiwifruit tissue, as resulted from the present study, which could be useful for the industries to design novel products with intermediate moisture content.

This work reports a critical evaluation of performance of various pattern recognition techniques applied to the classification of pharmaceutical taste-masked samples. Data obtained by potentiometric electronic tongue equipped with 16 ion-selective electrodes (ISEs) were processed by the most frequently used techniques in the analysis of electronic tongue data. Principal component analysis, partial least squares discriminant analysis, soft independent modelling of class analogy, principal component regression, support vector machine − discriminant analysis, 3-way partial least squares, K-nearest neighbours as well as combination of principal components analysis and back propagation neural networks were tested. In order to compare their ability to estimate class affinity of pharmaceutical samples, sensitivity, precision, percent of correct classification (%cc) and root mean square error (RMSE) were calculated. Additionally, 4 different kinds of data matrices: dynamic responses, stationary responses, combinations of them both, CPA values (change of the membrane potential caused by adsorption) were processed by pattern recognition techniques for the determination of the influence of the extraction of the data on the classification results. SVM-DA is proved to exhibit the best performance for the most commonly applied data extraction i.e. the steady-state response of the sensor array. Furthermore, it is shown, that including dynamic responses in the data matrix better classification abilities of the majority of the studied pattern recognition techniques are obtained. It must be underlined, that the presented findings are based on studying 399 models for whom all performance factors (sensitivity, precision, %cc, RMSE) were determined for both train and test sets to obtain reliable and repeatable results.

This work reports a critical evaluation of the results of the release of active substances (APIs) from novel pharmaceutical formulations provided by an electronic tongue system (ET). Detailed dissolution studies of modified-release granules used in pharmacotherapy containing metamizole sodium and pseudoephedrine sulphate were carried out. The impact of the dissolution-modifying excipients (carmellose sodium and hypromellose) on the dissolution process as well as on the outcomes of the sensor array of ion-selective electrodes was investigated. The obtained dissolution profiles were compared and correlated with those registered during the reference studies performed according to the pharmacopoeial method. It was pointed out that the proper evaluation of the efficiency of the release modification requires the examination of dosage forms as well as physical mixtures of API and excipient. Moreover, the results obtained using potentiometric ET were complementary to the classical methodology. Their partial inconsistency, remarked during several experiments, should be interpreted with caution owing to simultaneous sensing of APIs and excipients by the sensors and their various performances (i.e. selectivity and sensitivity) towards these components.

The overall performance of a potentiometric electronic tongue (ET) as well as the sensitivity and selectivity pattern of particular ion-selective electrodes forming the array towards exemplary APIs (metamizole sodium, pseudoephedrine sulphate) and excipients (hypromellose, carmellose, Eudragit E) was determined. Simultaneous sensing of both API and the encapsulating excipient in their physical mixture was noticed using potentiometric sensors. Usually, such altering of chemical image is treated as an evidence of taste masking/modified release effect (linked with chemical entrapment of API in polymer matrix), while the observed "mixture effect" can also take place which may complicate the interpretation of ET results. Moreover, the influence of the same excipients on chemical images of various APIs was compared and related to sensor array performance. The presented considerations should be taken into account in the case of ET assessment of drug dissolution profiles and detection of modified release effect, especially when novel drug delivery systems are considered.

Nowadays electronic tongues are used for the recognition of variety of samples, but most popular application area is pharmaceutical analysis, including mainly taste masking effects detection and estimation. However, it is noticeable, that among various pharmaceutical formulations still simple masking with the use of sweeteners plays the key role in such investigation. In this work we conduce electronic tongue study of novel drug delivery system—microspheres containing cetirizine. Microspheres prepared with the use of two coating agents with different drug to polymer ratio are applied for the observation of change in taste masking and release properties (in vivo and in vitro study) and these results are compared with changes in chemical images recorded by the developed electronic tongue system. High correlation of the electronic tongue results and “compromise scores” of human panel is presented.

In this work a potentiometric electronic tongue based on classical ion-selective electrodes (6 types) and solid contact electrodes (2 types) was applied. The classical electrodes based on PVC membrane with other plasticizers exhibited cation-, anion-, amine-, and carbonate sensitivity, while the solid contact electrodes based on different lipophilic salts established diclofenac sensitivity. These sensors were used to assess the taste masking efficiency of diclofenac using selected sweeteners and cyclodextrin. Various amounts of four sweeteners (namely: sucrose, lactose, acesulfame K, sodium saccharin) as well as 2-hydroxypropyl-β-cyclodextrin were applied to mask the bitter taste of diclofenac. The signals of the sensor array registered during the experiments were processed by the Principal Component Analysis. The results obtained i.e. the chemical images of the samples indicated that the taste masking effect was the most pronounced for cyclodextrin, acesulfame K, sodium saccharin and for sucrose at higher concentration, whereas was almost negligible in the case of the presence of lactose in solution.

Research funding: National Science Centre. Grant Numbers: DEC-2013/09/B/ST4/00957, LIDER/17/202/L-1/09/NCBiR/2010 An advanced potentiometric electronic tongue and Sequential Injection Analysis (SIA) measurement system was applied for the quantitative analysis of mixtures containing three active pharmaceutical ingredients (APIs): acetaminophen, ascorbic acid and acetylsalicylic acid, in the presence of various amounts of caffeine as interferent. The flow-through sensor array was composed of miniaturized classical ion-selective electrodes based on plasticized PVC membranes containing only ion exchangers. Partial Least Squares (PLS) analysis of the steady-state sensor array responses, measured in API mixtures prepared by the SIA system permitted a correct quantitative analysis of acetylsalicylic acid and ascorbic acid. Further optimization using multiway PLS fed by dynamic responses without additional feature extraction did not improve significantly the resolution of acetaminophen. Lastly, the chemometric treatment, involving the extraction of dynamic components of the transient response employing the Wavelet transform, the removal of less-significant coefficients by means of Causal Index pruning and training of an Artificial Neural Network (ANN) with the selected coefficients, allowed the simultaneous determination of all the three studied APIs, while counterbalancing any interference due to caffeine.

The learning process (calibration) of electronic tongue (ET) systems involves the acquisition of a large number of data. The introduction of continuous-flow methods, including flow-through and flow injection analysis, can significantly streamline and simplify the calibration process. However, the performance characteristics of the sensors based on the same receptor layers differ in various modes of measurements. In this work, the performances of the potentiometric sensors working in various sensor array configurations i.e. classical, batch set-up, flow-through set-up and flow injection analysis (FIA) set-up were determined. Moreover, the classification capabilities of the designed ET systems were compared on the basis of the differentiation between pharmaceutical samples of pure Ibuprofen and Ibuprofen modified with various co-spray dried excipients.

The aim of this paper is to use hybrid electronic tongue in the qualitative and quantitative analysis of extracts obtained from raw and dried apples prepared by different food processing techniques (drying techniques). The system is based on potentiometric and voltammetric sensors, moreover data recorded by spectrophotometry, amperometry and conductometry techniques were applied to enhance the classification ability of the device. The combination of the data from various measurement techniques (hybrid electronic tongue) leads to improved differentiation of the dried apple extracts samples comparing to separate techniques. Appropriate chemometric techniques were used to the recognition and classification of samples, whereas the efficiency of the qualitative and quantitative analysis was evaluated on the basis of Root Mean Squared Error (RMSE), determination coefficient ( R 2 ), slope ( a ), and intercept ( b ) parameters.

Novel drug delivery systems, which facilitate swallowing and improve patient adherence due to bitter taste masking of Active Pharmaceutical Ingredient (API), gain an increasing interest in recent years. Usually, studies on the taste of pharmaceutical products are conducted by human taste panel, but it concerns ethical doubts. Electronic tongue is one of the candidate tools allowing for fast, repeatable, and objective analysis of pharmaceuticals. In this work a sensor array composed of cross-selective electrodes was coupled with Principal Component Analysis in order to assess the taste-masking efficiency of the microencapsulated API (cetirizine dihydrohloride) formulated in lyophilisates. The obtained results show that presented electronic tongue can be used for the recognition of the studied pharmaceutical formulations and evaluation of the taste-masking effect.

A potentiometric electronic tongue was applied to study the release of valsartan from pharmaceutical formulations, i.e., minitablets uncoated and coated with Eudragit E. Special attention was paid to evaluate the influence of medium temperature and composition, as well as to compare the performances of the sensor arrays working in various hydrodynamic conditions. The drug dissolution profiles registered with the ion-sensitive electrodes were compared with standard dissolution tests performed with USP Apparatus 2 (paddle). Moreover, the signal changes of all sensors were processed by principal component analysis to visualize the release modifications, related to the presence of the coating agent. Finally, the importance and influence of the experimental conditions on the results obtained using potentiometric sensor arrays were discussed.