Determination of Biuret in Urea and Mixed Fertilizers by Cupric Ion Selective Electrode

1986 ◽  
Vol 69 (1) ◽  
pp. 119-122
Author(s):  
Luis F Corominas ◽  
Roberto A Navarro ◽  
Pedro Rojas ◽  
José L Cruz
Keyword(s):  
Atomic Absorption ◽  
Copper Complex ◽  
Confidence Level ◽  
Collaborative Study ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Cupric Ion ◽  
Excess Copper ◽  
Aas Method

Abstract A method for determining biuret in urea and mixed fertilizers by using a cupric ion selective electrode (CISE) has been developed to take advantage of the simplicity of the apparatus. The method is based on the same principle as the atomic absorption spectrophotometric (AAS) method, 2.091-2.093: formation of a biuret-copper complex, elimination of excess copper, and determination of complexed copper. However, some changes were needed to eliminate starch and alcohol interferences. The method was tested for ruggedness and then compared with the AAS method for 4 fertilizer samples. Averages and variances were equivalent at the 99% confidence level according to t- and F-tests. A collaborative study is recommended to compare behavior of both methods in different laboratories.

Determination of Vitamin Bi in Pharmaceutical Preparations Using a Lead Ion Selective Electrode and Atomic Absorption Spectroscopy

1979 ◽  
Vol 62 (2) ◽  
pp. 315-319
Author(s):  
Saad S M Hassan ◽  
Mohamed T Zaki ◽  
Mohamed H Eldesouki
Keyword(s):  
Standard Deviation ◽  
Atomic Absorption ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Pharmaceutical Preparations ◽  
Ion Selective Electrode ◽  
Lead Ion ◽  
Fluorometric Method ◽  
Selective Electrode

Abstract Simple, rapid, and accurate methods have been developed for determining vitamin Bx in pharmaceutical preparations without prior separation of the vitamin. The methods are based on the desulfurization reaction with potassium plumbite and measurement of the unreacted lead (II) ions at 217 nm using atomic absorption spectroscopy (AAS), or by titration with EDTA at pH 4.5 with the lead ion selective electrode and Gran's plot. The results compare favorably with those obtained using the USP fluorometric method. Recoveries of pure vitamin Bx averaged 99.1%, with a standard deviation of 0.8%, and 99.0%, with a standard deviation of 0.7%, for the AAS and ion selective electrode procedures, respectively.

Atomic Absorption Spectrophotometric Method for Determination of Water-Soluble Copper in Water-Insoluble Copper Fungicides: CIPAC Collaborative Study. Comparison with Bathocuproine Method

1981 ◽  
Vol 64 (1) ◽  
pp. 75-78
Author(s):  
F Sánchez Rasero ◽  
◽  
P G Balayannis ◽  
H P Beyers ◽  
E Celma ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
The United States ◽  
Atomic Absorption Spectrophotometry ◽  
Water Soluble ◽  
Absorption Spectrophotometry ◽  
Aas Method ◽  
Standard Deviations ◽  
The Difference

Abstract An atomic absorption spectrophotometric (AAS) method was collaboratively studied by 8 laboratories from Africa, the United States, Australia, and Europe. The samples were dispersed in deionized water. After centrifuging and filtering, the water-soluble copper in the filtrate was acidified and measured by atomic absorption spectrophotometry, in an airacetylene flame, at 324.7 nm. The results from 7 laboratories were satisfactory and no unfavorable comments were received. Repeatability standard deviations ranged from 0.005 to 0.023, and reproducibility standard deviations ranged from 0.012 to 0.062. When compared with the bathocuproine method, the difference in bias between both methods is not significant. They were both adopted as full CIPAC methods, with the bathocuproine method as the referee method. Both methods have been adopted official first action.

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.

scholarly journals Determination of Volatile Bases in Seafood Using the Ammonia Ion Selective Electrode: Collaborative Study

2000 ◽  
Vol 83 (4) ◽  
pp. 933-943 ◽  
Author(s):  
P Christopher Ellis ◽  
Lori F Pivarnik ◽  
Mamadou Thiam ◽  
L Berger ◽  
S Field ◽  
...  
Keyword(s):  
Ammonium Chloride ◽  
Atlantic Cod ◽  
Collaborative Study ◽  
Ion Selective Electrode ◽  
Atlantic Halibut ◽  
Matched Pairs ◽  
Selective Electrode ◽  
Atlantic Mackerel ◽  
Standard Deviations

Abstract Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively.

Collaborative Study of Ion Selective Electrode Method for the Direct Determination of Fluoride in Feeds

1975 ◽  
Vol 58 (3) ◽  
pp. 477-481 ◽  
Author(s):  
Laszlo Torma
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Ion Selective Electrode ◽  
Official Method ◽  
Selective Electrode ◽  
Standard Curve ◽  
Electrode Method ◽  
Aoac Method

Abstract A rapid and precise method for the determination of fluoride in feeds employs HC1 extraction of the sample. Acetate buffer and sodium citrate are added to control pH and ionic strength. The amount of fluoride is calculated from a standard curve after measuring the potentials of standard and sample solutions. Eight collaborators participated in the study of the method. Statistical values on 3 pairs of samples were calculated. The standard deviation, precision, coefficient of variation, and bias, respectively, were: Pair 1, 0.005071, 0.001763, 3.09, 0.0034; Pair 2, 0.037122, 0.006475, 1.82, 0.0258; Pair 3, 0.034587, 0.013021, 2.63, 0.0227. The results from the proposed method agreed favorably with the values obtained by using the official final action AOAC method, 7.089. The average and standard deviation, respectively, for individual samples by the proposed method were: Sample 3, 0.049, 0.0029; Sample 4, 0.059, 0.0021; Sample 5, 0.334, 0.0114; Sample 6, 0.341, 0.0101; Sample 7, 0.511, 0.0219; Sample 8, 0.492, 0.0237. By the official method the values were: Sample 3, 0.049, 0.0041; Sample 4, 0.058, 0.0029; Sample 5, 0.334, 0.0055; Sample 6, 0.331, 0.0082; Sample 7, 0.517, 0.0183; Sample 8, 0.499, 0.0175. The ion selective electrode method has been adopted as official first action.

Atomic Absorption Spectrophotometric Determination of Chelated Iron in Iron Chelate Concentrates: Collaborative Study

1983 ◽  
Vol 66 (4) ◽  
pp. 952-955
Author(s):  
James R Silkey ◽  
◽  
S G Angell ◽  
K Bartunek ◽  
L W Clark ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
Ferric Hydroxide ◽  
Disodium Edta ◽  
Iron Chelate ◽  
Iron Citrate ◽  
Coefficients Of Variation ◽  
Chelated Iron ◽  
Aas Method

Abstract An atomic absorption Spectrophotometric (AAS) method for determining chelated iron in iron chelate concentrates was collaboratively studied by 13 laboratories. Nonchelated iron was selectively precipitated as ferric hydroxide from an aqueous solution of the sample by adjusting to pH 8.5 with sodium hydroxide. A filtered portion of the sample solution was diluted with 0.5N HC1, and the iron was determined by AAS using standards containing disodium EDTA. Six pairs of iron chelate materials (12 samples) were analyzed and the average coefficients of variation were iron EDTA 3.52%, iron HEDTA 4.16%, iron DTPA 3.55%, iron EDDHA 3.52%, iron citrate 2.86%, and iron DPS 8.47%. The method has been adopted official first action.

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.

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