RESUMO
The results reported in this paper regard the setting up of a polymeric membrane ISE that is selective for cholic acids (CA) and able to work in a flow system, especially in flow injection analysis (FIA), based on the exchanger (tetrakisdecylammoniumcholate, TDACh), which has proved effective, is of very simple but suitable structure and is above all easy to synthesise starting from commercially available chemicals. A complete analytical characterisation of the sensor was performed working both in batch conditions and in FIA, using in the latter case a 'wall jet' type of flow cell. The response toward different bile acid sodium salts such as the CA, deoxycholic (DCA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA), taurocholic (TCA) sodium salts was checked. The application to the analysis of different commercial drugs by FIA was also performed to determine the UDCA or CDCA acid content of several pharmaceutical formulations. Lastly, a preliminary study is presented concerning the use of the investigated electrochemical sensor as high performance liquid chromatography (HPLC) detector.
Assuntos
Ácidos Cólicos/análise , Membranas Artificiais , Cromatografia Líquida de Alta Pressão , Eletroquímica , Análise de Injeção de Fluxo , Polímeros , Reprodutibilidade dos TestesRESUMO
An extraction protocol and a reversed-phase high-performance liquid chromatographic method for the simultaneous determination of cysteine, cystine and 18 other amino acids in biological and vegetable samples are described. Among the different methods proposed for amino acid determination, phenylisothiocyanate was used as the reagent for derivatization. Chromatograms obtained in the analysis of standard solutions and actual samples are reported, together with regression equation, correlation coefficient (> 0.999 for all), limit of detection and recoveries (between 86 and 102% for all the examined matrices) for each amino acid. Practical protocol and method applications in normal patients and patients affected by different pathologies, and in algal products are discussed.
Assuntos
Aminoácidos/análise , Cromatografia Líquida de Alta Pressão/métodos , Cisteína/análise , Cistina/análise , Aminoácidos/sangue , Aminoácidos/urina , Cisteína/sangue , Cisteína/urina , Cistina/sangue , Cistinúria/urina , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta , Glândula Tireoide/química , Verduras/químicaRESUMO
Aminoethylcysteine ketimine is a sulfur-containing cyclic compound produced by the enzymatic alpha-deamination of the parent aminoethylcysteine that has been detected in bovine brain and cerebellum. Aminoethylcysteine ketimine is known to dimerize spontaneously and easily lose one carboxyl group. This decarboxylated compound, simply named the dimer, has been recently detected in normal human urine. In this article we provide evidence on the occurrence of the dimer in the bovine cerebellum.
Assuntos
Cerebelo/química , Inibidores Enzimáticos/análise , Morfolinas/análise , Animais , Bovinos , Dimerização , Cromatografia Gasosa-Espectrometria de Massas , HumanosRESUMO
A salicylate ISFET for the analysis of salicylic and acetylsalicylic acid in drugs is described. It is based on a salicylate ion selective membrane coated on the surface of the Si3N4 gate of the FET. The sensitive membrane consists of tetra-dodecylammonium salicylate, polyvinyl chloride and a proper plasticizer. The linearity range of the sensor is 5 x 10(-5)-1.5 x 10(-2) M for the salicylic acid, and 7 x 10(-5)-1.5 x 10(-2) M for the acetylsalicylic acid, respectively. The detection limit for the two compounds is 5 x 10(-5) M while the response time is < or = 20 s. The effect of pH and different interfering ions was also studied. The sensor was used to analyse the content of acetylsalicylic and salicylic acid in some drugs, and the accuracy of the method was evaluated through recovery tests. The results obtained with this method are well correlated either with those obtained with a classical ISE employing the same sensitive membrane or with the classical volumetric method.
Assuntos
Aspirina/análise , Eletrodos Seletivos de Íons , Salicilatos/análise , Transistores Eletrônicos , Membranas Artificiais , Pomadas , Cloreto de Polivinila , Potenciometria , Ácido Salicílico , ComprimidosRESUMO
A simple and rapid method for the determination of ATP, ADP, AMP, NADP+, NAD+, NADPH, and NADH in human erythrocytes is described. A single-step extraction procedure employing alkaline medium and CF 50A Amicon ultrafiltration membranes allows a simultaneous and total recovery of the compounds of interest. Analysis is performed by reverse-phase high-performance liquid chromatography on a 5-micron Supelcosil LC-18 column and uv detection. Extraction and analysis require about 30 min. Levels of adenine and pyridine nucleotides in normal adults are also presented.
Assuntos
Nucleotídeos de Adenina/sangue , Eritrócitos/análise , NADP/sangue , NAD/sangue , Difosfato de Adenosina/sangue , Monofosfato de Adenosina/sangue , Trifosfato de Adenosina/sangue , Fenômenos Químicos , Química , Cromatografia Líquida de Alta Pressão , HumanosRESUMO
A method for the accurate determination of ATP, ADP, AMP, NADP and NAD in 20 min in red blood cell extracts by reversed-phase high-performance liquid chromatography is described. Experimental parameters affecting the separation are discussed.
Assuntos
Eritrócitos/análise , Nucleotídeos/sangue , Difosfato de Adenosina/sangue , Monofosfato de Adenosina/sangue , Trifosfato de Adenosina/sangue , Adulto , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Concentração de Íons de Hidrogênio , NAD/sangue , NADP/sangue , Fatores de TempoRESUMO
Problems connected with the analysis of ultra-trace amounts of halocarbons in air are discussed in terms of trapping procedures, interferences and chromatographic columns. A suitable column for the qualitative and quantitative analysis of C1-C2 halocarbons is described, and examples of applications are given. High-efficiency micropacked columns have been used for the analysis of hydrocarbons in the open atmosphere.