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. 2021 Nov 4;13(11):1860.
doi: 10.3390/pharmaceutics13111860.

Utilization of Pharmaceutical Technology Methods for the Development of Innovative Porous Metasilicate Pellets with a Very High Specific Surface Area for Chemical Warfare Agents Detection

Jiří Zeman  1 , Sylvie Pavloková  1 , David Vetchý  1 , Adam Staňo  1 , Zdeněk Moravec  2 , Lukáš Matějovský  3 , Vladimír Pitschmann  4   5
Affiliations

Utilization of Pharmaceutical Technology Methods for the Development of Innovative Porous Metasilicate Pellets with a Very High Specific Surface Area for Chemical Warfare Agents Detection

Jiří Zeman et al. Pharmaceutics. .

Abstract

Pharmaceutical technology offers various dosage forms that can be applied interdisciplinary. One of them are spherical pellets which could be utilized as a carrier in emerging second-generation detection tubes. This detection system requires carriers with high specific surface area (SSA), which should allow better adsorption of toxic substances and detection reagents. In this study, a magnesium aluminometasilicate with high SSA was utilized along with various concentrations of volatile substances (menthol, camphor and ammonium bicarbonate) to increase further the carrier SSA after their sublimation. The samples were evaluated in terms of physicochemical parameters, their morphology was assessed by scanning electron microscopy, and the Brunauer-Emmett-Teller (BET) method was utilized to measure SSA. The samples were then impregnated with a detection reagent o-phenylenediamine-pyronine and tested with diphosgene. Only samples prepared using menthol or camphor were found to show red fluorescence under the UV light in addition to the eye-visible red-violet color. This allowed the detection of diphosgene/phosgene at a concentration of only 0.1 mg/m3 in the air for samples M20.0 and C20.0 with their SSA higher than 115 m2/g, thus exceeding the sensitivity of the first-generation DT-12 detection tube.

Keywords: BET method; chemical warfare agent; detection tube; extrusion; metasilicate; phosgene; porous pellets; spheronization; volatile substance.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Graphical representation of the results (average values from several measurements) of evaluation of pellets with error bars depending on the volatile substance (VS) used and its concentration in the original powder mixture, where the initial concentration of 0.0% always corresponds to the results of sample N: (a) specific surface area, (b) hardness, (c) friability, (d) loss of drying, (e) interparticular porosity, (f) intraparticular porosity.
Figure 2
Figure 2
SEM images of selected samples, where 1 is a sample without Neusilin® US2 (N0), 2 is a sample with 25% (w/w) of Neusilin® US2 (N). The remaining samples had a specific surface area modified by the addition of volatile substances, which sublimed during drying: samples 3 (M7.5) and 4 (M20.0) originally contained 7.5% and 20.0% (w/w) menthol, similarly samples 5 (C7.5) and 6 (C20.0) contained camphor and samples 7 (AB7.5) and 8 (AB20.0) contained ammonium bicarbonate. In addition, (a–c) denote the whole pellet, the surface detail and the cross-section detail, respectively.
Figure 3
Figure 3
(a) PCA scores plot—objects included in the model: pellets differing in type and concentration of the volatile substance. (b) PCA loadings plot—variables included in the model: selected pellet characteristics. Bulk and tapped density were excluded from the PCA due to the strong correlation of the respective vectors with the Hausner ratio vector.
Figure 4
Figure 4
Reaction of o-phenylenediamine-pyronine (PY-OPD) with phosgene and comparison of the impregnated sample C20.0/PY-OPD under UV light at 366 nm before and after the reaction.
Figure 5
Figure 5
Comparison of the appearance of selected samples before impregnation with the detection reagent PY-OPD, after their impregnation and after their reaction with diphosgene in the visible light spectrum.
See this image and copyright information in PMC

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