The estimation of ammonia using the indophenol blue reaction
ABSTRACT The addition of sodium hypochlorite solution of pH 12.5 to an ammonia solution before the addition of sodium phenate has been shown to increase the sensitivity and accuracy of the indophenol blue reaction. This reaction is not temperature-dependent over the range −5° to +25°. The pH of the phenate solution is much less critical when it is added after the hypochlorite; a reagent with a pH in the range 10.6–11.2 is quite suitable.This modified method may be applied to the later stages of Fenton's1 method of estimating plasma ammonia and while it increases the sensitivity and accuracy it does not impair the specificity.
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- "Treatments are: CK=control, NN=high N, CC=high CO 2 , CN=high CO 2 +high N. and Mg 2+ concentrations in leachates using inductively coupled plasma atomic emission spectroscopy. NO − 3 -N was determined by the phenol disulfonic acid spectrophotometric method (Nicholas and Nason, 1957) and NH + 4 -N by the indophenol blue spectrophotometric method (Horn and Squire, 1966). The P concentration was measured by the stannous chloride method (APHA Standard Methods, 20th ed., 4–145, Method 4500-P D, 1998). "
ABSTRACT: The effect of high atmospheric CO 2 concentra-tions on the dynamics of mineral nutrient is not well doc-umented, especially for subtropical China. We used model forest ecosystems in open-top chambers to study the effects of CO 2 enrichment alone and together with N addition on the dynamics of soil cations and anions. Two years of ex-posure to a 700 ppm CO 2 atmospheric concentration resulted in increased annual nutrient losses by leaching below 70 cm soil profile. Compared to the control, net Mg 2+ losses in-creased by 385%, K + by 223%, Ca 2+ by 167% and NO − 3 -N by 108%, respectively. Increased losses following exposure to elevated CO 2 were related to both faster weathering of minerals/organic matter decomposition and greater amounts of leaching water. Net annual nutrient losses in the high CO 2 concentration chambers reached 22.2 kg ha −1 year −1 for K + , 171.3 kg ha −1 year −1 for Ca 2+ , 8.2 kg ha −1 year −1 for Mg 2+ and about 2 kg ha −1 year −1 for NO − 3 -N. The N addition alone had no significant effect on the mineral nutrient leaching losses. However, addition of N together with the high CO 2 treatment significantly reduced mineral nutrient losses.We hypothesize that forests in subtropical China might suffer from nutrient limitation and reduction in plant biomass under elevated CO 2 concentration due to mineral leaching losses in the future.
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- "For the determination of total N and P content in plants, dried samples were digested with 4 mL H 2 SO 4 and 300 g L –1 H 2 O 2 in a Kjeldahl flask. Nitrogen was determined by spectrophotometer using the Indophenol blue method (Horn and Squire 1966) and P was determined by colorimeter using the vanadomolybdate yellow method (Bertramson 1942). "
ABSTRACT: We studied the effects of the application of organic matter (OM) and chemical fertilizer (CF) on soil alkaline phosphatase (ALP) activity and ALP-harboring bacterial communities in the rhizosphere and bulk soil in an experimental lettuce field in Hokkaido, Japan. The ALP activity was higher in soils with OM than in soils with CF, and activity was higher in the rhizosphere for OM than in the bulk soil. Biomass P and available P in the soil were positively related to the ALP activity of the soil. As a result, the P concentration of lettuce was higher in OM soil than in CF soil. We analyzed the ALP-harboring bacterial communities using polymerase chain reaction based denaturing gradient gel electrophoresis (DGGE) on the ALP genes. Numerous ALP genes were detected in the DGGE profile, regardless of sampling time, fertilizer treatment or sampled soil area, which indicated a large diversity in ALP-harboring bacteria in the soil. Several ALP gene fragments were closely related to the ALP genes of Mesorhizobium loti and Pseudomonas fluorescens. The community structures of the ALP-harboring bacteria were assessed using principal component analysis of the DGGE profiles. Fertilizer treatment and sampled soil area significantly affected the community structures of ALP-harboring bacteria. As the DGGE bands contributing to the principal component were different from sampling time, it is suggested that the major bacteria harboring the ALP gene shifted. Furthermore, there was, in part, a significant correlation between ALP activity and the community structure of the ALP-harboring bacteria. These results raise the possibility that different ALP-harboring bacteria release different amounts and/or activity of ALP, and that the structure of ALP-harboring bacterial communities may play a major role in determining overall soil ALP activity.Soil Science and Plant Nutrition 01/2008; 54(1):62 - 71. DOI:10.1111/j.1747-0765.2007.00210.x · 0.73 Impact Factor
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ABSTRACT: The catalytic action of both sodium nitroprusside and acetone on the indophenol blue reaction for the estimation of ammonia nitrogen has been investigated. It was shown that the reaction is catalysed by sodium ferrous nitritopentacyanide and not by sodium nitroprusside as previously thought. The sensitivity of the reaction is greatly improved by omitting acetone and converting the sodium nitroprusside to ferrous nitritopentacyanide by the action of alkali.Clinica Chimica Acta 08/1967; 17(1):99-105. DOI:10.1016/0009-8981(67)90102-7 · 2.82 Impact Factor