Combined liquid phase microextraction and fiber-optics-based cuvetteless micro-spectrophotometry for sensitive determination of ammonia in water and food samples by the indophenol reaction.
Food Chem
; 340: 128156, 2021 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-33011465
ABSTRACT
The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (6040, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2-3 mg kg-1, 0.14 mg kg-1 and 38, respectively, measuring red species for milk, cheese and beer (4.9-5.5% error; 4.8-6.3% RSD; n = 5); and 5-400 µg L-1, 0.4 µg L-1 and 137, respectively, measuring blue species for water samples (3.3-5.7% error; 3.6-6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Espectrofotometria
/
Água
/
Amônia
/
Indofenol
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
Food Chem
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Índia