Ion Chromatographic Fingerprinting of STC-1 Cellular Response for Taste Sensing.

Taste sensing is of great importance in both the pharmaceutical and foodstuff industries, and is currently mainly based on human sensory evaluation. Many approaches based on chemical sensors have been proposed, leading to the development of various electronic tongue systems. However, this approach is limited by the applied recognition methods, which do not consider natural receptors. Biorecognition elements such as taste receptor proteins or whole cells can be involved in the development of taste sensing biosensors usually equipped with various electrochemical transducers. Here, we propose a new approach: intestinal secretin tumor cell line (STC-1) chemosensory cells were applied for taste recognition, and their taste-specific cellular response was decoded from ion chromatographic fingerprints with the use of multivariate data processing by partial least squares discriminant analysis (PLS-DA). This approach could be useful for the development of various non-invasive taste sensing assays, as well as for studying taste transduction mechanisms in vitro.

Selective determination of Fe(III) in Fe(II) samples by UV-spectrophotometry with the aid of quercetin and morin.

Selective UV-spectrophotometric methods for determination of iron(III) in iron(II) samples have been developed. The methods are based on the interaction of Fe(III) with quercetin and morin, compounds of the flavonoid group. Redox reactions occurring between Fe(III) ions and the reagents used make the basis for the detection. Iron(II) does not react with quercetin and morin under the conditions applied [aqueous-methanolic (3:2) soluions, 0.3 mol L(-1) HCl, 1.2 x 10(-4) mol L(-1) quercetin (morin)] and does not interfere with the determination of Fe(III). Iron(III) can be determined up to 15 microg mL(-1) using both the examined systems. The detection limits are 0.06 and 0.38 microg mL(-1) when using quercetin or morin, respectively. The method with quercetin was applied to the determination of Fe(III) (ca. 0.2%) in a Fe(II) pharmaceutical product.

Spectrophotometric studies of the interaction of noble metals with quercetin and quercetin-5'-sulfonic acid.

Results of some studies on the interaction of noble metals with quercetin (Q) and quercetin-5'-sulfonic acid (QSA), the compounds of flavonoid group, are presented. The reactions of chloride complexes of the metals: RuOHCl5(2-), PdCl4(2-), OsCl6(2-), PtCl6(2-) and AuCl4- with both reagents were examined. The redox reactions of ruthenium and gold with Q and QSA have been identified. The reaction of the metals with both reagents results in the formation of the oxidized form of Q that exhibits maximum absorbance at 291 nm. Ruthenium and gold react with the examined reagents under similar conditions: 0.04 M HCl and 1 x 10(-4) M Q (or QSA). The CH3OH + H2O (1:1) (Q) and pure aqueous (QSA) media can be used. The reaction of gold with Q is slow at room temperature. It can be accelerated by heating the solution being examined. The reaction proceeds significantly faster when the water-soluble sulfonic derivative of quercetin, quercetin-5'-sulfonic acid, is used as a reagent. The new species formed can make the basis of spectrophotometric methods for the determination of ruthenium and gold. The molar absorptivities at 291 nm are equal to 5.0 x 10(3) and 2.2 x 10(4) L mol(-1) cm(-1) for Ru and Au, respectively, independently of the reagent used. Some methods for the determination of the content of gold (0.04%) in a cosmetic cream were developed.

Multi-elemental analysis of non-food packaging materials by inductively coupled plasma-time of flight-mass spectrometry.

Commercial non-food packaging materials of four different matrices (paper, low density polyethylene (LDPE), polyethylene-polypropylene (PE-PP) and high density polyethylene (HDPE)) were examined for the content of Cr, Ni, Cu, Zn, As, Mo, Cd, Sb, Ba, Hg, Tl, Pb and U. The examined samples (0.17-0.35g) were digested in HNO(3) and H(2)O(2) (papers, LDPE and PE-PP) and in HNO(3), H(2)SO(4) and H(2)O(2) (HDPE) using microwave assisted high pressure system. The inductively coupled plasma-time of flight-mass spectrometry (ICP-TOFMS) has been employed as the detection technique. All measurements were carried out using internal standardization. Yttrium and rhodium (50ngg(-1)) were used as internal standards. The detection and quantification limits obtained were in the range of 0.005ngg(-1) ((52)Cr ) to 0.51ngg(-1) ((66)Zn ) and 0.015mugg(-1) ((52)Cr ) to 2.02mugg(-1) ((66)Zn ) of dry mass, respectively. The evaluated contents (mgkg(-1)) of particular elements in the examined materials were as follows: 0.22-219; <1.05-9.03; 1.25-112; <2.02-449; <0.98-<1.30; <0.36-2.06; <0.29-113; <0.22-44.1; <0.06-57.4; <0.66-<0.88; <0.08-0.24; <0.13-1222 and <0.08-0.44 for Cr, Ni, Cu, Zn, As, Mo, Cd, Sb, Ba, Hg, Tl, Pb and U, respectively.

An overview of analytical applications of time of flight-mass spectrometric (TOF-MS) analyzers and an inductively coupled plasma-TOF-MS technique.

A brief overview of the applications of time-of-flight mass spectrometry (TOF-MS) for analytical purposes is presented. The performance of TOF-MS combined with an inductively coupled plasma (ICP) ion source is discussed in detail. The advantages of TOF-MS detectors over the quadrupole mass filters for multi-elemental analysis of fast transient signals are discussed. The applications of ICP-TOF-MS for the detection of signals from laser ablation, electrothermal vaporization, gas and liquid chromatography, capillary electrophoresis and flow-injection analysis are reviewed.

Sample digestion methods for the determination of traces of precious metals by spectrometric techniques.

Recent advances in digestion methods used in the analysis of precious metal samples by spectrometric techniques are reviewed. The applicability of a fire assay, a wet acid treatment, chlorination and alkaline oxidizing fusion to a quantitative recovery of metals from various materials is discussed. Data on the precious metal contents obtained by using particular digestion methods as well as UV-VIS spectrophotometry, atomic absorption spectrometry, atomic emission spectrometry and inductively coupled plasma mass spectrometry in the examination of various samples are tabulated.