RESUMEN
Carbon paste based biosensors for the determination of creatine and creatinine have been integrated into a sequential injection system. Applying the multi-enzyme sequence of creatininase (CA), and/or creatinase (CI) and sarcosine oxidase (SO), hydrogen peroxide has been detected amperometrically. The linear concentration ranges are of pmol/L to nmol/L magnitude, with very low limits of detection. The proposed SIA system can be utilized reliably for the on-line simultaneous detection of creatine and creatinine in pharmaceutical products, as well as in serum samples, with a rate of 34 samples per hour and RSD values better than 0.16% (n=10).
Asunto(s)
Técnicas Biosensibles/instrumentación , Creatina/análisis , Creatinina/análisis , Análisis de Inyección de Flujo/instrumentación , Sistemas en Línea/instrumentación , Amidohidrolasas/química , Carbono/química , Creatina/sangre , Creatinina/sangre , Enzimas Inmovilizadas/química , Peróxido de Hidrógeno/química , Sarcosina-Oxidasa/química , Ureohidrolasas/químicaRESUMEN
A sequential injection analysis (SIA) is proposed for the simultaneous determination of L- and D-methotrexate (Mtx) using amperometric biosensors as detectors. A SIA system is proposed due to the highest precision and accuracy and lower consumption of sample and buffer. The amperometric biosensors used as detectors in SIA system were based on L-amino acid oxidase (L-AAOD) or/and L-glutamate oxidase (L-Glox) and horseradish peroxidase (HRP) for the assay of L-Mtx and D-amino acid oxidase (D-AAOD) and HRP for the assay of D-Mtx were selected. The linear concentration ranges are of pmol/l to nmol/l magnitude order, with very low limits of detection. The SIA/biosensors system can be used reliably on-line in synthesis process control, for the simultaneous assay of L- and D-Mtx with a frequency of 34 samples per hour.
Asunto(s)
Aminoácido Oxidorreductasas/química , Técnicas Biosensibles/instrumentación , Electroquímica/instrumentación , Análisis de Inyección de Flujo/instrumentación , Peroxidasa de Rábano Silvestre/química , Metotrexato/análisis , Metotrexato/química , Técnicas Biosensibles/métodos , Mezclas Complejas/análisis , Mezclas Complejas/química , Electroquímica/métodos , Enzimas Inmovilizadas , Diseño de Equipo , Análisis de Falla de Equipo , Análisis de Inyección de Flujo/métodos , Peróxido de Hidrógeno/análisis , Peróxido de Hidrógeno/química , L-Aminoácido Oxidasa , Microquímica/instrumentación , Microquímica/métodos , Sistemas en Línea , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , EstereoisomerismoRESUMEN
A sequential injection analysis (SIA) system is described for the simultaneous determination of L-and D-carnitine using amperometric biosensors as detectors. The SIA system was used, because of its high precision, accuracy and low sample and buffer consumption. The biosensors were designed using physical and chemical immobilization of L-amino acid oxidase and horseradish peroxidase (HRP) for the assay of L- carnitine, and D-amino acid oxidase and HRP for the assay of D-carnitine. The linear concentration ranges are in the pmol/l to nmol/l magnitude order, with very low limits of detection. The biosensors/SIA system was used reliably for on-line process control of the enantiopurity of carnitine with a frequency of 34 samples per hour.
Asunto(s)
Carnitina/análisis , Técnicas Biosensibles , Cápsulas , D-Aminoácido Oxidasa/química , Electroquímica , Enzimas Inmovilizadas , Análisis de Inyección de Flujo , Indicadores y Reactivos , EstereoisomerismoRESUMEN
An amperometric immunosensor, based on diamond paste (diamond powder and paraffin oil), has been constructed for the assay of azidothymidine (AZT). The diamond paste is impregnated with anti-AZT. The immunosensor can be used reliably for the assay of azidothymidine in its pharmaceutical formulations. The potential used for azidothymidine assay was + 240 mV vs. Ag/AgCl electrode. The surface of the immunosensor can be regenerated by simply polishing, thereby obtaining fresh immunocomposite ready to be used in a new assay. The new amperometric immunosensor, based on diamond paste, gives reliable results for the assay of AZT as raw material and from its pharmaceutical formulation.
Asunto(s)
Inmunoensayo/métodos , Zidovudina/análisis , Diamante , Electroquímica , Electrodos , Zidovudina/inmunologíaRESUMEN
In order to determine ortho-acetyl-L-carnitine, two biosensors were proposed. The biosensors were designed using physical immobilization of L-amino acid oxidase (L-AAOD) and horseradish peroxidase (HRP). Electrode characteristics were obtained and compared for the two carbon paste (graphite powder and paraffin oil) biosensors. The linear concentration ranges for the proposed biosensors were in the ranges of fmol/L to nmol/L, magnitude order with low limits of detection. Due to their reliability, the biosensors were used as detectors in a sequential injection analysis system, and gave reliable results for on-line assay of ortho-acetyl-L-carnitine in synthesis process control with a frequency of 75 samples per hour.
Asunto(s)
Acetilcarnitina/análisis , Técnicas Biosensibles/métodos , Análisis de Inyección de Flujo/métodos , Acetilcarnitina/química , Técnicas Biosensibles/instrumentación , Electroquímica , Análisis de Inyección de Flujo/instrumentación , EstereoisomerismoRESUMEN
An amperometric immunosensor based on graphite paste (graphite powder and paraffin oil) has been constructed for the assay of azidothymidine (AZT). The graphite paste is impregnated with anti-AZT. The immunosensor can be reliably used for the assay of AZT in its pharmaceutical formulation. The potential used for AZT assay was 435 mV vs Ag/AgCl electrode. The surface of the immunosensor can be regenerated by simply polishing, obtaining fresh immunocomposite ready to be used in a new assay. Due to its reliability, the immunosensor was successfully used as a detector in a sequential injection analysis system, and gave reliable results for on-line assay of AZT purity in raw material and AZT contents in pharmaceutical formulations.
RESUMEN
In order to determine the enantiopurity of methotrexate (Mtx), seven biosensors were proposed for the assay of L-Mtx and three biosensors for the assay of D-Mtx. The biosensors were designed using physical and chemical immobilization of glutamate oxidase and/or L-amino acid oxidase (L-AAOD) and/or horseradish peroxidase (HRP) for the assay of L-methotherexate, and D-amino acid oxidase (D-AAOD) and HRP for the assay of D-Mtx. Electrode characteristics were obtained and compared for the different carbon paste based biosensors. The linear concentration ranges for the proposed biosensors were in the ranges of fmol l(-1) to pmol l(-1), magnitude order with limits of detection in the fmol l(-1) to nmol l(-1) concentration range. All biosensors were successful for the determination of the enantiopurity of Mtx as raw material, and in its pharmaceutical formulations (tablets and injections).
RESUMEN
In order to determine creatine and creatinine amperometric biosensors were proposed. A bienzymatic biosensor based on creatinase (CI) and sarcosine oxidase (SO) was used for the assay of creatine and a trienzymatic biosensor based on CI, SO and creatininase (CA) for the assay of creatinine. The linear concentration ranges are of pmol l(-1) to nmol l(-1) magnitude order, with very low limits of detection. The biosensors proved high reliability for determination of creatine and creatinine as raw material, and in the pharmaceutical formulation.
