A Method for the Analysis of Total Nitrogen in Natural Waters

1984 ◽  
Vol 41 (5) ◽  
pp. 815-819 ◽  
Author(s):  
J. Kalff ◽  
E. Bentzen
Keyword(s):  
Sample Size ◽  
Total Nitrogen ◽  
Coefficient Of Variation ◽  
Natural Waters ◽  
Sodium Salicylate ◽  
Persulfate Oxidation ◽  
Dissolved Nitrogen

This method for analyzing total nitrogen (TN) in freshwaters is based on the persulfate oxidation of nitrogen to nitrate, followed by the analysis of this nitrate by a modified version of the sodium salicylate method. The method is simpler than other reported techniques for TN in oligotrophy and mesotrophic waters and requires equipment readily available in most laboratories. The method is linear to 1000 μg N/L, with the range extendable by changing the sample size. The variability is lowest (coefficient of variation 6.6%) between 100 and 1000 μg N/L. We have successfully used the method for the determination of TN, as well as dissolved nitrogen (DN) on filtered samples and nitrate on nonoxidized samples.

Modified Automated Determination of 2,3-Diphosphoglycerate in Whole Blood

1972 ◽  
Vol 18 (9) ◽  
pp. 1001-1004 ◽  
Author(s):  
Kenneth F Atkinson
Keyword(s):  
Sample Size ◽  
Coefficient Of Variation ◽  
Whole Blood ◽  
Normal Range ◽  
Blood Samples ◽  
Automated Determination

Abstract A modification is described of the automated determination of 2,3-diphosphoglycerate (DPG) in blood [Grisolia, S., et al., Anal. Biochem. 31, 235 (1969)]. Modifications in the manifold result in a sensitive, noise-free, rapid system and the modifications in the preparations of the reagents ensure stability of the diluted standards and blood samples for at least three weeks. Samples are run at the rate of 60/h and sample size can be as small as 5 µl of whole blood. The coefficient of variation of the overall determination of automated DPG and manual hemoglobin is 3.6% and the SD is ±0.77 µmol/g Hb. The normal range is 14.6 ± 2.2 (SD) µmol/g hemoglobin.

Improved ultraviolet spectrophotometric method for determination of nitrate in natural waters

2002 ◽  
Vol 2 (2) ◽  
pp. 213-221 ◽  
Author(s):  
N. Kishimoto ◽  
I. Somiya ◽  
R. Taniyama
Keyword(s):  
Water Quality ◽  
Spectrophotometric Method ◽  
Standard Error ◽  
Coefficient Of Variation ◽  
Natural Waters ◽  
Uv Light ◽  
Rapid Determination ◽  
The Other ◽  
Extreme Conditions

An improved UV spectrophotometric method for determination of nitrate in natural waters was proposed and the determination accuracy of the method was discussed in this study. As a result of estimation of the proposed method, adoption of 215 and 220 nm for detection of nitrate and interfering substances resulted in decreasing standard error to about a half of that of a conventional spectrophotometric method. One of the reasons was thought that the coefficient of variation of relative absorbance of interfering substances (rs) at 215 nm was smaller and more stable than that at 275 nm, which was used in the conventional method. The other reason inferred was that most of the interfering substances absorbed UV light at wavelengths of 215 and 220 nm. Although rs has to be renewed when targeted water quality is under extreme conditions, the procedure of the proposed method is very simple, namely only measuring two UV absorbances of a filtrated sample, and more accurate than the conventional spectrophotometric method. Consequently, the proposed method is available for rapid determination of nitrate in natural waters.

Determination of Total Nitrogen in Natural Waters

1975 ◽  
Vol 4 (4) ◽  
pp. 465-468 ◽  
Author(s):  
D. W. Nelson ◽  
L. E. Sommers
Keyword(s):  
Total Nitrogen ◽  
Natural Waters

scholarly journals Automated simultaneous determination of total dissolved nitrogen and phosphorus in seawater by persulfate oxidation method

Talanta Open ◽  
2020 ◽  
Vol 2 ◽  
pp. 100016
Author(s):  
Saori Yasui-Tamura ◽  
Fuminori Hashihama ◽  
Hiroshi Ogawa ◽  
Takashi Nishimura ◽  
Jota Kanda
Keyword(s):  
Simultaneous Determination ◽  
Nitrogen And Phosphorus ◽  
Oxidation Method ◽  
Persulfate Oxidation ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen

Turbidimetric Assay of Tylosin in Animal Feeds Containing Urea

1990 ◽  
Vol 73 (6) ◽  
pp. 927-931
Author(s):  
Mark R Coleman ◽  
Daniel H Mowrey
Keyword(s):  
Sample Size ◽  
Coefficient Of Variation ◽  
Phosphate Buffer ◽  
Urea Adduct ◽  
Cattle Feed ◽  
Animal Feeds ◽  
Turbidimetric Method ◽  
Turbidimetric Assay ◽  
Over Time

Abstract A turbidimetric method Is described for determination of tylosin in animal feeds containing urea. This method Includes several modified or new steps to existing turbidimetric and AOAC plate assays that Improve the extraction of tylosin, remove interferences from feeds, free tylosin activity, concentrate tylosin from low-level feeds, and reduce variability of assay results. A larger analytical sample size has been incorporated Into the assay to decrease variability of assay results. A methanol-phosphate buffer extraction solution has replaced the hot buffer and methanol extraction solution. A hydrolysis step, which Is not contained in the AOAC plate assay, was developed to free tylosin from the tylosin urea adduct that forms over time In feeds containing urea. A disposable C18 column was used to concentrate tylosin from feeds at levels less than 15 ppm. By Increasing the analytical sample size from 25 to 100 g, the coefficient of variation for 12 weighings of cattle feed was reduced from 28.4 to 9.3%. Average recoveries from cattle rations containing tylosin at levels of 8,10, and 100 ppm were 94, 94, and 91 %, respectively.

Evaluation of total phosphorus and total nitrogen methods in pulp mill effluents

2004 ◽  
Vol 50 (3) ◽  
pp. 79-86 ◽  
Author(s):  
D.L. Cook ◽  
N.L. Frum
Keyword(s):  
Total Nitrogen ◽  
Total Phosphorus ◽  
Pulp Mill ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Persulfate Oxidation ◽  
Pulp Mill Effluents ◽  
Epa Methods

Under the Clean Water Action Plan, the US Environmental Protection Agency is requiring states to establish numeric criteria for phosphorus and nitrogen. In preparation for the development of nutrient criteria NCASI undertook a research project to conduct a comparative study of methods for the determination of total phosphorus and total nitrogen in pulp and paper mill matrices. This paper presents results of a single laboratory method evaluation and comparative study of digestion techniques and analytical methods for the determination of total phosphorus (TP) and total nitrogen (TN) in pulp and paper mill secondary treated effluents. Analytical methods included EPA Methods 365.2 and 365.4 for TP. TN and total kjeldahl nitrogen (TKN) methods included EPA Methods 351.2, 351.4, and 353.2. Examinations of sample preservation and storage stability were conducted. Substitution of mercuric sulfate with copper sulfate during block digestion resulted in higher blank levels and method detection limits. TP measurements using EPA Method 365.4 (autoanalyzer) were found to be accurate with a positive bias as determined using matrix spike experiments. Sample digestion by acidic persulfate oxidation or mercuric sulfate block digestion in conjunction with EPA Method 365.4 yielded low blank levels (averages of 0.01 and 0.02 mg/L, respectively), precision of 2.1 and 2.4% relative standard deviations, respectively, and accuracy expressed as an average recovery (%R) of 117% for both. EPA Method 351.2 (autoanalyzer) was more precise than EPA Method 351.4 (ammonia probe). Accuracy (%R) for EPA Method 351.2 ranged from 81 to 95%, depending on the digestion technique applied, and was 55% when EPA Method 351.4 was utilized. Investigation of a method utilizing basic to acidic persulfate oxidation for the simultaneous determination of TN and TP using only two analytical techniques was found to be effective at concentrations above 1 mg/L in pulp mill effluents.

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