The indophenol method
with some modifications was used to measure the urease inhibitory activity of the extracts (9).
The indophenol method
was used for the determination of urease activity by measuring ammonia production as defined by Weatherburn .
Kiyota, "Estimation of L-glutaminase and L-asparaginase activities in soils by the indophenol method
," Soil Science and Plant Nutrition, vol.
Water quality of the tanks was monitored by determination of the following variables: (1) pH (pH meter mPA210--MS Tecnopon), (2) temperature and specific conductance at 0800 and 1500 (conductivity meter CD-4303--Lutron), (3) dissolved oxygen (0800; dissolved oxygen meter YSI 55), (4) total ammonia nitrogen (TAN; indophenol method
), (5) nitrite (sulfanilamide method), (6) nitrate (Cd reduction technique), (7) reactive phosphorus (molybdenum blue method), (8) total alkalinity (titration with H2SO4 standard solution), (9) total hardness (titration with EDTA standard solution), (10) organic matter (consumed KMn[O.sub.4]) and (11) settleable solids (sedimentation in Imhoff cones).
Ammonia was determined by the indophenol method
, and measured using a spectrophotometer (Biospectro; SP220; Curitiba, PR, Brazil; [lambda] = 640nm) according to the American Public Health Association (APHA, 1998).
Standard indophenol method
was used as described by Ranganna (1986) .
Preparation of aerosol and air samples for the determination of ammonia by the indophenol method
. Oceanologia 46:175-184.
Ammonium ions were analyzed through Indophenol Method
using UV/Visible spectrophotometer.
Urease inhibition activity was determined by measuring ammonia production using the indophenol method
as described by Weatherburn (Weatherburn 1967).
Ammonium concentration was determined using the indophenol method
, while glucose concentration was determined using a glucose oxidase GOD-PERID test kit (Boehringer Mannheim) according to the manufacture's instruction.
Ammonia production was measured as a urease activity by indophenol method
as described earlier .
Total ammonia nitrogen in water samples were determined weekly by the indophenol method