Determination of Ammoniacal and Total Nitrogen in Fertilizers by Ammonia-Selective Electrode

1984 ◽  
Vol 67 (5) ◽  
pp. 890-892
Author(s):  
Roberto A Navarro ◽  
Pedro Rojas
Keyword(s):  
Tartaric Acid ◽  
Magnesium Oxide ◽  
Total Nitrogen ◽  
Ammoniacal Nitrogen ◽  
Selective Electrode ◽  
Digestion Procedure ◽  
Acid Recovery ◽  
Aoac Official ◽  
Good For

Abstract A method was studied for determining ammoniacal nitrogen in fertilizers by using an ammonia-selective electrode. Recovery for the method was evaluated with synthetic samples, and the method was also compared with the magnesium oxide method by analyzing 3 Magruder Check Samples. The method was adapted to determine total nitrogen in fertilizers by using the digestion procedure of the modified comprehensive nitrogen method and eliminating metal interferences by forming soluble complexes with tartaric acid. Recovery was evaluated and a comparison with AOAC official methods was made by performing a /-test on results for 3 Magruder Check Samples. Recoveries were good for determinations of both ammoniacal and total nitrogen by the method described, and results were not significantly different from those for AOAC methods.

Ammonia-Selective Electrode Determination of Nitrogen in Fertilizers

1981 ◽  
Vol 64 (5) ◽  
pp. 1096-1099
Author(s):  
Victor M Boy ◽  
Manuel Guijosa
Keyword(s):  
Magnesium Oxide ◽  
Total Nitrogen ◽  
Ammoniacal Nitrogen ◽  
Selective Electrode ◽  
Nitrogen Determination ◽  
Accuracy And Precision ◽  
Routine Work ◽  
Electrode Method ◽  
Aoac Official

Abstract The official AOAC magnesium oxide method (MOM), 2.065, for determining ammoniacal nitrogen in fertilizers not containing urea was compared with an alternative ammonia-selective electrode method (ASEM-1). Likewise, the official AOAC Raney powder method (RPM), 2.063-2.064, for determining total nitrogen in fertilizers, except nitric phosphates containing nonsulfate S, was compared with an ammonia- selective electrode method (ASEM-2). Each comparison included 6 samples. For ammoniacal nitrogen determination, MOM and ASEM-1 showed equivalent precision, although significant statistical differences were obtained in average values for the majority of samples. For total nitrogen determination, RPM and ASEM-2 showed equivalent precision, although significant statistical differences were obtained in 3 samples. The AOAC official methods showed better accuracy than ASEM-1 and ASEM-2. However, the accuracy and precision of ASEM-1 for ammoniacal nitrogen is suitable for routine work.

scholarly journals Determination of titratable acidity in white wine

2007 ◽  
Vol 52 (2) ◽  
pp. 169-184 ◽  
Author(s):  
Milos Rajkovic ◽  
Ivana Novakovic ◽  
Aleksandar Petrovic
Keyword(s):  
Tartaric Acid ◽  
Potentiometric Titration ◽  
Ph Value ◽  
Titratable Acidity ◽  
White Wine ◽  
Selective Electrode ◽  
Alcohol Fermentation ◽  
Standard Methods ◽  
Illegal Acts

The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol) during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.

Comparison of Methods for Determining Sodium in Fertilizers

1981 ◽  
Vol 64 (3) ◽  
pp. 704-708
Author(s):  
Luis F Corominas ◽  
Víctor M Boy ◽  
Pedro Rojas
Keyword(s):  
Phosphate Rock ◽  
Collaborative Study ◽  
Ammonium Oxalate ◽  
Selective Electrode ◽  
Accuracy And Precision ◽  
Flame Emission ◽  
Aoac Method ◽  
Aoac Official ◽  
Aas Method

Abstract The AOAC official first action method, 2.147-2.150, for flame emission spectrophotometry (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Ammonium oxalate, which was previously compared with water, H2SO4, HC1, and HNO3, was used to extract the sample for all 3 methods. Three synthetic NPK samples, 3 commercial samples (urea, normal superphosphate, and neutrophos), 1 phosphate rock, and 2 Magruder check samples were used for the study. Statistically significant differences were obtained in averages for most of the samples, but few differences were found in standard deviations. The AAS method showed the best accuracy and precision. Accuracy of the AOAC method is acceptable. The SSE method showed the highest deviations from the theoretical values. A collaborative study is recommended to compare the AOAC with the AAS method.

Preliminary Comparison of Methods for Determining Sodium in Fertilizers

1980 ◽  
Vol 63 (3) ◽  
pp. 551-553
Author(s):  
Luis F Corominas ◽  
Victor M Boy ◽  
Manuel Guijosa
Keyword(s):  
Atomic Absorption ◽  
Experimental Work ◽  
Check Sample ◽  
Comparison Of Methods ◽  
Selective Electrode ◽  
Flame Emission ◽  
Aoac Method ◽  
Aoac Official ◽  
Aas Method

Abstract The AOAC official first action method 2.147–2.150 for the flame emission spectrophotometric (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Two synthetic NPK samples, 3 commercial samples (urea, DAP, and superphosphate), 2 Magruder NPK check samples, and one Magruder muriate check sample were used for the study. Statistically significant differences were obtained in both averages and standard deviations for all samples. In general, the precision for all methods was acceptable; the AAS method seems to be the more accurate; the AOAC method needs to be revised; and the SSE method has the tendency to give higher values. Additional experimental work is necessary to define which method is the most convenient.

An Unforeseen Problem in the Use of Kel-Paks

1968 ◽  
Vol 51 (6) ◽  
pp. 1290-1295
Author(s):  
T C Woodis ◽  
J A Brabson ◽  
W G Burch
Keyword(s):  
Salicylic Acid ◽  
Nicotinic Acid ◽  
Organic Compounds ◽  
Total Nitrogen ◽  
Ammoniacal Nitrogen ◽  
Powder Method ◽  
Catalyst Powder ◽  
Possible Cause ◽  
Digestion Step

Abstract In Kjeldahl methods for the determination of nitrogen in fertilizers, the digestion temperature must be above 370°C to mineralize the nitrogen in refractory organic compounds such as nicotinic acid. In total nitrogen determinations by the Raney catalyst powder method, temperatures during the digestion step were investigated as a possible cause of occasional low results. Decomposition of the polyethylene envelopes of Kel-Paks in the presence of salts of metallic reductants caused rapid fluctuations and excessive rise in temperature with consequent loss of ammoniacal nitrogen. Complete Kel-Paks can be used without difficulty in methods such as 2.044 (for nitrate-free samples) or 2.045 (salicylic acid) that do not use metallic reductants, but only the contents of the Kel-Paks without the envelopes should be used when Raney catalyst or chromium powders have been used to reduce nitrates.

Flow-based method for the determination of biomarkers urea and ammoniacal nitrogen in saliva

Bioanalysis ◽  
2020 ◽  
Author(s):  
Yanisa Thepchuay ◽  
Carolina FA Costa ◽  
Raquel BR Mesquita ◽  
Benedita Sampaio-Maia ◽  
Duangjai Nacapricha ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Ammoniacal Nitrogen ◽  
Sequential Injection ◽  
Ammonium Ions ◽  
Selective Electrode ◽  
Ammonia Gas ◽  
Ammonium Determination ◽  
Potential Biomarkers

Aim: Salivary urea and ammonium levels are potential biomarkers for chronic kidney disease. A fast and efficient assessment of these compounds in the saliva of healthy and diseased individuals may be a useful tool to monitor kidney function. Materials & methods: Ammonium ions were measured with an ammonia selective electrode after conversion to ammonia gas. A urease reactor was incorporated in the manifold to hydrolyze urea to ammonium, thereby providing values of ammonia from both urea and ammonium ions in the sample. The accuracy of the method was assessed by comparison with a commercially available kit for urea and ammonium determination. Conclusion: A sequential injection method for the biparametric determination of salivary urea and ammonium employing a single sequential injection manifold was successfully applied to samples collected from both healthy volunteers and chronic kidney disease patients.

Determination of Ammoniacal Nitirogen in the Presence of Urea

1980 ◽  
Vol 63 (6) ◽  
pp. 1248-1253
Author(s):  
T S Viswanathan ◽  
M Nagarajan ◽  
B Haribabu
Keyword(s):  
Quality Control ◽  
Spectrophotometric Method ◽  
Ammonium Phosphate ◽  
Ammoniacal Nitrogen ◽  
Distillation Method ◽  
Selective Electrode ◽  
Reduced Pressure ◽  
Electrode Method ◽  
Precision And Accuracy

Abstract There is no approved AOAC procedure for determining ammoniacal nitrogen in the presence of urea, which is required for the quality control of urea-ammonium phosphate-based fertilizers. A comparative study has been made of various methods available for this estimation. We found that the automated spectrophotometric method, the ion selective electrode method, and the reduced pressure distillation method all furnish results of comparable precision and accuracy. The MgO distillation method, even though not recommended for the above type of sample, still yields results of satisfactory accuracy when certain precautions are taken.

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