title: Development of a polydimethylsiloxane-thymol/nitroprusside composite based sensor involving thymol derivatization for ammonium monitoring in water samples.
abstract: This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a PDMS support that contains the Berthelot's reaction reagents. To prepare the PDMS-thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the PDMS matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS-thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4(+) could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LOD<0.4 mg L(-1)) and reproducibility (RSD <10%) for the rapid detection of ammonium. The PDMS-NH4(+) sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter PM10 samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS-NH4(+) sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods.
authors.affiliation: Grupo QANAP, Departamento de Química Analítica, Facultade de Ciencias, Universidade da Coruña, Campus de A Coruña, 15071 A Coruña, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Prieto-Blanco
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Jornet-Martínez
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: Y
authors.initials: Y
authors.lastname: Moliner-Martínez
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Molins-Legua
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Herráez-Hernández
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Verdú Andrés
authors.affiliation: Departmento de Química Analítica Grupo MINTOTA, Facultad de Química, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. Electronic address: pilar.campins@uv.es.
authors.forename: P
authors.initials: P
authors.lastname: Campins-Falcó
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis*; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D009599:Nitroprusside / Q000737:chemistry; D015203:Reproducibility of Results; D013943:Thymol / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D064751:Ammonium Compounds; D004129:Dimethylpolysiloxanes; D014874:Water Pollutants, Chemical; D009599:Nitroprusside; D013943:Thymol; C013830:baysilon
keywords: Ammonium sensor; Delivery PDMS composite; Thymol derivatization; Water samples