Multisensor systems for gas analysis: optimization of arrays for classification of pharmaceutical products

Abstract

In the present work, the use of the cluster analysis method in the fuzzy logic concept for the optimization of the cross-selective sensor arrays (electronic nose, EN) is considered. This approach enables to purposefully form the sensor arrays with definite chemical functionality optimized for the solution of the specific applied problems. The criteria of the optimization of the sensor response, number and type of the sensor elements are considered with the goal to improve the classification of widely used pharmaceutical products. The optimization of EN array in the kinetic mode and selection of the most informative part of the sensor response enabled to reduce the analysis time, and also the number of sensors in array, to improve the discriminatory capability of the whole array. Being based on the analysis of response kinetic peculiarities, the physical mechanisms determining the peculiarities of adsorption-desorption processes at the interface have been considered.

Analyte induced water adsorbability in gas phase biosensors: the influence of ethinylestradiol on the water binding protein capacity

“…4). The saturation levels of the typical responses indicate that the increase in mass on the surface of the transducer as a result of the interactions of different organic materials with the vapor ETED did not exceed 40-50 ng (40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50). This is approximately an order of magnitude less than that obtained for ETED solutions.…”

“…40 Briefly, the QCM analyzer contains: (i) a temperature controlled measurement camera with a sensor array of the flowing type; (ii) a quartz generators block; (iii) a block for the frequency measurement and an RS232 interface constructed using a specialized microprocessor (AT89C2051); (iv) a generator of the gas mixtures; (v) system collection and processing of the information on a personal computer. [40][41][42][43] To maximize the correctness of the measurements and prevent possible adsorption of components of gaseous mixtures on construction inside the sampling systems, the simplest possible measurement configuration based on a static headspace procedure was used (Fig. 2).…”

“…For measurements of ETED powders, the same QCM based electronic nose instrument was used with transducers modified with thermally evaporated thin films (100 nm) of annulenes (dibenzotetraazaannylene, H 2 TAA and tetramethyldibenzotetraazaannulene, H 2 TMTAA), calixarenes (tert-butylcalyx [4,6,8]arenes) and polyacenes (tetracene and pentacene), as well as metal free phtalocyanine H 2 Pc. 41…”

Adsorbate Induced Transformations of Ovalbumin Layers in Volatile Organic Solvents: QCM Study of a Potential Bio-Sniffer for Acute Toxicity Assays

“…On the other hand, the non-polar cyclohexane molecule does not possess the capability to penetrate into the protein globule to give rise to the change in hydrophobic domain. The adsorption capacities for both analytes significantly exceed the values typical for conventional organic coatings [12][13][14], which is well explained by the developed surface of the protein layer and the presence of a large number of groups suitable for binding. Approximation of the responses by stretched exponential functions [14][15][16] shows that Sauerbrey's mass loading is due to Langmuir adsorption for ethanol (β~1) (Figure 1b) and a small contribution of the sorption for water (β~0.8) (Figure 1a).…”

“…The instrument contains (i) a temperature-stabilized (21 ± 1 • C) chamber with the 8-sensor array; (ii) quartz generators (10 MHz); (iii) the microprocessor-based frequency meter (AT89C2051); (iv) a generator of the gas mixtures with argon as carrier gas (flow rate c.a. 180 mL/min, dynamic headspace injection through surface evaporation vapor generation [11]); and (v) a data-processing package [12,13]. The measurement procedure includes argon circulation up to the frequency stabilization (3 Hz); circulation of the vapor-argon mixture; purging by carrier gas up to the restoration of the initial frequency value of the QCMs.…”