A novel, simple, low-cost, and user-friendly potentiometric surfactant sensor based on the new 1,3-dihexadecyl−1H-benzo[d]imidazol−3-ium-tetraphenylborate (DHBI–TPB) ion-pair for the detection of cationic surfactants in personal care products and disinfectants is presented here. The new cationic surfactant DHBI-Br was successfully synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectrometry, liquid chromatography–mass spectrometry (LC–MS) and elemental analysis and was further employed for DHBI–TPB ion-pair preparation. The sensor gave excellent response characteristics for CTAB, CPC and Hyamine with a Nernstian slope (57.1 to 59.1 mV/decade) whereas the lowest limit of detection (LOD) value was measured for CTAB (0.3 × 10−6 M). The sensor exhibited a fast dynamic response to dodecyl sulfate (DDS) and TPB. High sensor performances stayed intact regardless of the employment of inorganic and organic cations and in a broad pH range (2−11). Titration of cationic and etoxylated (EO)-nonionic surfactant (NSs) (in Ba2+) mixtures with TPB revealed the first inflexion point for a cationic surfactant and the second for an EO-nonionic surfactant. The increased concentration of EO-nonionic surfactants and the number of EO groups had a negative influence on titration curves and signal change. The sensor was successfully applied for the quantification of technical-grade cationic surfactants and in 12 personal care products and disinfectants. The results showed good agreement with the measurements obtained by a commercial surfactant sensor and by a two-phase titration. A good recovery for the standard addition method (98–102%) was observed.
This study characterizes and compares the parameters of the quality reproduction of fine elements in flexography on coated and uncoated paper as well as on OPP film (oriented polypropylene). A monochrome test form was created and printed using cyan UV ink. The analysis of results confirms the importance of interaction between the printing substrate and ink; it also indicates identical line and text deformations on the print. Quality reproduction on coated paper is higher in relation to OPP film for all the research parameters. The ink penetrates significantly more and with more irregularity into the pores and throats of the uncoated paper, which results in less homogeneous elements, and in such way that it loses its original shape. In coated paper and OPP film, the ink spreads more on the substrate area which gives it a significantly more homogeneous shape. However, due to the surface spread of the ink, the biggest changes in the size of fine elements are noticeable in the OPP film. The scientific contribution of this paper is based on the comparison of print quality parameters of fine elements, which can contribute to the optimization of the production process and quality of the final graphical product.
A 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-tetraphenylborate (DHBI-TPB) ion-pair implemented in DHBI-TPB surfactant sensor was used for the potentiometric quantification of anionic surfactants in detergents and commercial household care products. The DHBI-TPB ion-pair was characterized by FTIR spectroscopy and computational analysis which revealed a crucial contribution of the C–H∙∙∙π contacts for the optimal complex formation. The DHBI-TPB sensor potentiometric response showed excellent analytical properties and Nernstian slope for SDS (60.1 mV/decade) with LOD 3.2 × 10−7 M; and DBS (58.4 mV/decade) with LOD 6.1 × 10−7 M was obtained. The sensor possesses exceptional resistance to different organic and inorganic interferences in broad pH (2–10) range. DMIC used as a titrant demonstrated superior analytical performances for potentiometric titrations of SDS, compared to other tested cationic surfactants (DMIC > CTAB > CPC > Hyamine 1622). The combination of DHBI-TPB sensor and DMIC was successfully employed to perform titrations of the highly soluble alkane sulfonate homologues. Nonionic surfactants (increased concentration and number of EO groups) had a negative impact on anionic surfactant titration curves and a signal change. The DHBI-TPB sensor was effectively employed for the determination of technical grade anionic surfactants presenting the recoveries from 99.5 to 101.3%. The sensor was applied on twelve powered samples as well as liquid-gel and handwashing home care detergents containing anionic surfactants. The obtained results showed good agreement compared to the outcomes measured by ISE surfactant sensor and a two-phase titration method. The developed DHBI-TPB surfactant sensor could be used for quality control in industry and has great potential in environmental monitoring.
Original scientific paper The paper explores the influence of the background effect of induction or simultaneous contrast on a specific type of media during the reproduction of a constructed design solution. The lightness of the background that surrounds the primary stimulus (rectangle) on a specifically constructed design was varied in ten ways. The intensity and direction of variations in the manifestation of lightness was determined with the help of the technique of simultaneous binocular harmonization on a certain number of respondents (10). The ANOVA analysis determined the existence of differences between arithmetic means (F = 132,50; p = 0,000), and the post-hoc analysis by Fisher classified three groups of samples: samples on which simultaneous contrast reflects more strongly (a very dark background); samples on which the effect is weaker (a light background); and samples on which the effect is manifested in the opposite direction (a very bright background). Keywords: achromatic reproduction; ANOVA; psychophysics; simultaneous contrast Intenzitet efekta simultanog kontrasta u ovisnosti o promjeni svjetline pozadineIzvorni znanstveni članak U radu je istražen utjecaj pozadinskog efekta indukcije ili simultanog kontrasta na određenoj vrsti medija prilikom reprodukcije konstruiranog dizajnerskog rješenja. Pritom je na 10 načina varirana svjetlina pozadine koja okružuje primarni stimulus (pravokutnik) na specifično konstruiranom dizajnu. Utvrđen je intenzitet i smjer odstupanja u pojavnosti svjetline pomoću tehnike simultanog binokularnog usuglašavanja na određenom broju ispitanika (10). ANOVA analizom utvrđeno je postojanje razlika među aritmetičkim sredinama (F = 132,50; p = 0,000) te su post-hoc analizom po Fisheru klasificirane tri grupe uzoraka: uzorci na kojima se simultani kontrast očituje jače (vrlo tamna pozadina); uzorci na kojima je efekt slabiji (svjetlija pozadina); te uzorci na kojima se efekt manifestira u suprotnom smjeru (vrlo svijetla pozadina).
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