An Overview of the Kjeldahl Method of Nitrogen Determination. Part II. Sample Preparation, Working Scale, Instrumental Finish, and Quality Control

Sáez-Plaza, Purificación; Navas, M.J.; Wybraniec, Sławomir; Michałowski, Tadeusz; Asuero, Agustín G.

doi:10.1080/10408347.2012.751787

Cited by 250 publications

(104 citation statements)

References 274 publications

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“…The preparation of NH 4 + followed the basic principle of a Kjeldahl distillation(Saez- Plaza et al 2013). The resulting ammonium sulfate was homogenized and weighed into tin capsules that were combusted in an elemental analyzer Vario ISOTOPE Cube (Elementar Analysensysteme GmbH, Hanau) connected to an isotope ratio mass spectrometer Isoprime 100 (Isoprime Ltd,…”

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confidence: 99%

Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater

Coban

Kuschk

Hipsey

et al. 2014

Environ Sci Pollut Res

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Pathways of ammonium (NH4 (+)) removal were investigated using the stable isotope approach in constructed wetlands (CWs). We investigated and compared several types of CWs: planted horizontal subsurface flow (HSSF), unplanted HSSF, and floating plant root mat (FPRM), including spatial and seasonal variations. Plant presence was the key factor influencing efficiency of NH4 (+) removal in all CWs, what was illustrated by lower NH4 (+)-N removal by the unplanted HSSF CW in comparison with planted CWs. No statistically significant differences in NH4 (+) removal efficiencies between seasons were detected. Even though plant uptake accounted for 32-100 % of NH4 (+) removal during spring and summer in planted CWs, throughout the year, most of NH4 (+) was removed via simultaneous nitrification-denitrification, what was clearly shown by linear increase of δ(15)N-NH4 (+) with decrease of loads along the flow path and absence of nitrate (NO3 (-)) accumulation. Average yearly enrichment factor for nitrification was -7.9 ‰ for planted HSSF CW and -5.8 ‰ for FPRM. Lack of enrichment for δ(15)N-NO3 (-) implied that other processes, such as nitrification and mineralization were superimposed on denitrification and makes the stable isotope approach unsuitable for the estimation of denitrification in the systems obtaining NH4 (+) rich inflow water.

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confidence: 99%

Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater

Coban

Kuschk

Hipsey

et al. 2014

Environ Sci Pollut Res

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“…All KM steps must be verified and controlled using quality control methods recommended for Kjeldahl analyses (Persson et al, 2008;Saez-Plaza et al, 2013a, 2013b), such as: analyze a pure substance with known N-content, analyze certified RM and participate in proficiency testing schemes with other RLs, and prepare own reference sample and verify it versus other RLs. From all the given possibilities, only a pure substance is now available.…”

Section: Basic Performance Parameters Of Direct Analysismentioning

confidence: 99%

“…We employed for calculation statistical methods (Clinical Laboratory Standards Institute, 2012a, 2013bFraser, 2009;Montgomery, 2009) and metrological terms presented in BIPM (2012).…”

Section: Basic Performance Parameters Of Direct Analysismentioning

confidence: 99%

The Kjeldahl Method as a Primary Reference Procedure for Total Protein in Certified Reference Materials Used in Clinical Chemistry. II. Selection of Direct Kjeldahl Analysis and Its Preliminary Performance Parameters

Vinklárková

Chromý

Šprongl³

et al. 2015

Critical Reviews in Analytical Chemistry

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To select a Kjeldahl procedure suitable for the determination of total protein in reference materials used in laboratory medicine, we reviewed in our previous article Kjeldahl methods adopted by clinical chemistry and found an indirect two-step analysis by total Kjeldahl nitrogen corrected for its nonprotein nitrogen and a direct analysis made on isolated protein precipitates. In this article, we compare both procedures on various reference materials. An indirect Kjeldahl method gave falsely lower results than a direct analysis. Preliminary performance parameters qualify the direct Kjeldahl analysis as a suitable primary reference procedure for the certification of total protein in reference laboratories.

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“…[64]. The titration of ammonia in the final step of the Kjeldahl method of nitrogen determination [105,106] was discussed in Ref. [107].…”

Section: Other Examplesmentioning

confidence: 99%

Principles of Titrimetric Analyses According to Generalized Approach to Electrolytic Systems (GATES)

Michałowska-Kaczmarczyk¹,

Spórna‐Kucab²,

Michałowski³

2017

Advances in Titration Techniques

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The generalized equivalent mass (GEM) concept, based on firm algebraic foundations of the generalized approach to electrolytic systems (GATES), is considered and put against the equivalent "weight" concept, based on a "fragile" stoichiometric reaction notation still advocated by IUPAC. The GEM is formulated a priori, with no relevance to a stoichiometry. GEM is formulated in a unified manner, and referred to systems of any degree of complexity with special emphasis put on redox systems, where generalized electron balance (GEB) is involved. GEM is formulated on the basis of all attainable (and preselected) physicochemical knowledge on the system in question, and resolved with use of iterative computer programs. It is possible to calculate coordinates of the end points taken from the vicinity of equivalence point. This way, one can choose (among others) a proper indicator and the most appropriate (from analytical viewpoint) color change of the indicator. Some interpolative and extrapolative methods of equivalence volume V eq determination are recalled and discussed. The GATES realized for GEM purposes provides the basis for optimization of analytical procedures a priori. The GATES procedure realized for GEM purposes enables to foresee and optimize new analytical methods, or modify, improve, and optimize old analytical methods.

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An Overview of the Kjeldahl Method of Nitrogen Determination. Part II. Sample Preparation, Working Scale, Instrumental Finish, and Quality Control

Cited by 250 publications

References 274 publications

Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater

Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater

The Kjeldahl Method as a Primary Reference Procedure for Total Protein in Certified Reference Materials Used in Clinical Chemistry. II. Selection of Direct Kjeldahl Analysis and Its Preliminary Performance Parameters

Principles of Titrimetric Analyses According to Generalized Approach to Electrolytic Systems (GATES)

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