Assessment of the Naphthylazo-naphthylamine Method for the Determination of Nitrate and Nitrite

1968 ◽  
Vol 51 (1) ◽  
pp. 140-147
Author(s):  
Len Kamm ◽  
D F Bray ◽  
D E Coffin
Keyword(s):  
Reproducibility Of Results ◽  
Statistical Data ◽  
Collaborative Study ◽  
Food Samples ◽  
Experimental Designs ◽  
Dye Reduction ◽  
Nitrate And Nitrite

Abstract The 1-naphthylazo-naphthylamine method for nitrate and nitrite, reported in 1965, was subjected to specific experiments statistically designed to determine more precisely the precision of the method. Experimental designs included the following: standard nitrite curve, stability of 1-naphthylazo- naphthylamino dye, reduction of nitrate to nitrite by the cadmium column, reproducibility of results comparing natural foodstuffs with pure solutions, and collaborative study on food samples. The statistical data obtained indicate that the method is consistent and precise

Experimental Designs for Interlaboratory Precision Experiments: Comparison of ISO 5725 with Draft NEN 6303

1989 ◽  
Vol 72 (1) ◽  
pp. 34-37 ◽  
Author(s):  
J Zaalberg
Keyword(s):  
Standard Deviation ◽  
Edible Oils ◽  
Collaborative Study ◽  
Experimental Designs ◽  
Interlaboratory Experiments ◽  
Interlaboratory Studies ◽  
Repeatability Standard Deviation ◽  
Level Design ◽  
Iso 5725

Abstract To determine the precision of standardized analytical methods, interlaboratory experiments are carried out in which several laboratories analyze identical samples from well homogenized batches of material. From the test results, estimates of the standard deviations under repeatability as well as under reproducibility conditions are calculated. In the present work, the experimental designs recommended in the International Standard ISO 5725 have been compared with a design proposed in the draft Netherlands Standard NEN 6303. This has been done by comparing their mathematical models as well as by applying them to the results of a recent collaborative study on the determination of heavy metals in edible oils and fats. The reproducibility standard deviation is estimated equally well with both Standards, but it appeared that the designs given in ISO 5725 can lead to serious underestimation (uniform-level design) or overestimation (split-level design) of the repeatability standard deviation. By using the design proposed in NEN 6303, these biases can be avoided. Hence, it is recommended that interlaboratory studies be organized according to the design of NEN 6303.

Liquid Chromatographic Determination of Bendiocarb in Technical Materials and Wettable Powder Formulations: Collaborative Study

1986 ◽  
Vol 69 (5) ◽  
pp. 908-911
Author(s):  
Peter L Carter ◽  
Keith C Overton ◽  
◽  
P G Baker ◽  
O O Bennett ◽  
...  
Keyword(s):  
Statistical Data ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Liquid Chromatograph ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method for determination of bendiocarb in technical materials and wettable powders was tested by 12 collaborators. Bendiocarb is dissolved in acetonitrile containing 0.1% propiophenone as internal standard. This solution is analyzed on a liquid chromatograph utilizing a reverse phase (C18) column. The compound is detected at 254 nm and peak area is used for quantitation. The 3 different materials studied contained 20, 80, and nominally 100% bendiocarb. Each was examined in duplicate to provide the necessary matched pairs. Collaborators approved of the ease and simplicity of the method and, in particular, the way the method can be applied to automatic injection assemblies. The statistical data show acceptable precision of the method: Reproducibility coefficients of variation were 20% material, 2.04%; 80% material, 1.02%; and nominal 100% material (technical product), 0.64%. The method has been adopted official first action.

Gas Chromatographic Determination of Trans Unsaturation in Margarine: Collaborative Study

1985 ◽  
Vol 68 (1) ◽  
pp. 46-51 ◽  
Author(s):  
Lawrence Gildenberg ◽  
David Firestone
Keyword(s):  
Methyl Ester ◽  
Statistical Data ◽  
Methyl Esters ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Infrared Analysis ◽  
Trans Unsaturation ◽  
Coefficients Of Variation ◽  
International Collaborative Study

Abstract An international collaborative study of a gas chromatographic (GC) method for the determination of trans unsaturation in margarine was conducted in 1980. Thirteen collaborators analyzed a set of 2 of 3 known mixtures of methyl esters and 4 margarine methyl ester samples. Two of the margarine methyl ester samples were blind duplicates. The experimental data were subjected to statistical analysis to determine within- and between-laboratory variation. The statistical data were in excellent agreement with data from a collaborative study of the AOACIUPAC GC method for the determination of methyl esters of fatty acids. Coefficients of variation (CVs) for components in the range of 4-40% were comparable (CV 2-6% for soybean oil methyl esters (AOAC-IUPAC study) as well as for margarine methyl esters (this study)). Good recoveries of total trans acids were obtained and betweenlaboratory as well as within-laboratory CVs were consistently better for the determination of total trans acids by GC vs infrared analysis. The GC method for determining trans unsaturation in margarine has been adopted official first action.

scholarly journals Determination of Methylcellulose and Hydroxypropyl Methylcellulose Food Gums in Food and Food Products: Collaborative Study

2007 ◽  
Vol 90 (3) ◽  
pp. 786-793 ◽  
Author(s):  
Robert G Harfmann ◽  
Balasaheb K Deshmukh ◽  
Jerry Conklin ◽  
Maciej Turowski ◽  
Stephanie Lynch ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Hydroxypropyl Methylcellulose ◽  
Collaborative Study ◽  
Food Samples ◽  
Size Exclusion ◽  
Official Method ◽  
Relative Standard ◽  
Aoac Official

Abstract A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.43. Digestate solutions must be refrigerated to fully hydrate MC or HPMC. The chilled solutions are filtered and analyzed by size-exclusion liquid chromatography. Collaborating laboratories received 28 samples containing MC or HPMC in the range of 0100%. The sample set included blind duplicates of 5 food matrixes (bread, milk, fish, potato, and powdered juice drink). Cochran and Grubbs tests were used to eliminate outliers. For food samples containing MC, values for within-laboratory precision, repeatability relative standard deviation (RSDr), ranged from 4.2 to 16%, and values for among-laboratories precision, reproducibility relative standard deviation (RSDR), ranged from 11 to 20%. For HPMC samples, RSDr values ranged from 6.4 to 27%, and RSDR values ranged from 17 to 39%. Recoveries of MC and HPMC from the food matrixes ranged from 78 to 101%. These results show acceptable precision and reproducibility for the determination of MC and HPMC, for which no Official AOAC Methods exist. It is recommended that this method be adopted as AOAC Official First Action.

Collaborative Study of the Automatic Carbon, Hydrogen, and Nitrogen Determination

1972 ◽  
Vol 55 (4) ◽  
pp. 676-679
Author(s):  
La Verne H Scroggins
Keyword(s):  
Stearic Acid ◽  
Nicotinic Acid ◽  
Simultaneous Determination ◽  
Methyl Palmitate ◽  
Statistical Data ◽  
Collaborative Study ◽  
Nitrogen Determination ◽  
Acid Methyl

Abstract A method for t h e simultaneous determination of per cent carbon, hydrogen, and nitrogen, employing automatic instrumentation, was tested by 10 collaborators. The samples analyzed were acetanilide, nicotinic acid, stearic acid, methyl palmitate, and ethyllaurate . Evaluation of the statistical data and overall consideration indicate satisfactory results for all types of compounds studied. The method was adopted as official first action.

Collaborative Study of the Colorimetric Determination of Nitrate and Nitrite in Cheese

1976 ◽  
Vol 59 (2) ◽  
pp. 284-288
Author(s):  
James E Hamilton
Keyword(s):  
Azo Dye ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Sulfanilic Acid ◽  
Zinc Hydroxide ◽  
Colorimetric Determination ◽  
Standard Curve ◽  
Nitrite Nitrate ◽  
Nitrate And Nitrite

Abstract A quantitative colorimetric method for the determination of nitrate and nitrite in cheese has been subjected to collaborative study. The method includes clarification of an aqueous extract of cheese with zinc hydroxide, reduction of nitrate to nitrite via a spongy cadmium column (the nitrite originally present is unaltered), diazotization of sulfanilic acid with the nitrite, and coupling with 1-naphthylamine hydrochloride to form a pink azo dye whose absorbance is measured at 522 nm. The spectrophotometric responses are compared to a standard curve. In samples containing both nitrate and nitrite, nitrate is determined by difference. A standard deviation of 5.5 was obtained (5 of 6 collaborators) when a cheese sample spiked with 276 ppm sodium nitrate was analyzed by the method. The method has been adopted as official first action.

Collaborative Study of the Determination of Tar and Nicotine in Cigarette Smoke: 1970 Study

1971 ◽  
Vol 54 (5) ◽  
pp. 1011-1018
Author(s):  
C L Ogg ◽  
E Fred Schultz
Keyword(s):  
Cigarette Smoke ◽  
Statistical Data ◽  
Collaborative Study

Abstract A collaborative study was made to evaluate the effects of (1) reducing the number of cigarettes per port, (2) using sleeves vs. dams for sealing the cigarette in the holders, and (3) pooling filter pads before water and nicotine analyses. None of these variables had a significant effect on the precision of the method. The statistical data obtained from this study agreed closely with those reported last year.

scholarly journals Multiple Mycotoxins Determination in Food by LC-MS/MS: An International Collaborative Study

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 658 ◽  
Author(s):  
Thomas Bessaire ◽  
Claudia Mujahid ◽  
Pascal Mottier ◽  
Aurélien Desmarchelier
Keyword(s):  
Collaborative Study ◽  
Milk Powder ◽  
Food Samples ◽  
Relative Standard ◽  
Liquid Chromatography Tandem Mass ◽  
Mycotoxin Analysis ◽  
Repeatability And Reproducibility ◽  
Iso 5725 ◽  
Infants And Young Children

An intercollaborative study was organized to evaluate the performance characteristics of a liquid chromatography tandem mass spectrometry procedure for the simultaneous determination of 12 mycotoxins in food, which were ochratoxin A, aflatoxins B1, B2, G1, G2, and M1, deoxynivalenol, zearalenone, fumonisins B1 and B2, and T-2 and HT-2 toxins. The method combined the simplicity of the QuEChERS (Quick, Easy, Cheap, Efficient, Rugged and Safe) approach with the efficiency of immunoaffinity column cleanup (the step used to enhance sensitivity and sample cleanup for some matrices only). Twenty-three entities were enrolled and were European reference laboratories for mycotoxin analysis, U.S. and European service laboratories, and Nestlé laboratories. Each participant analyzed 28 incurred and/or spiked blind samples composed of spices, nuts, milk powder, dried fruits, cereals, and baby food using the protocol given. Method performances were assessed according to ISO 5725-2. Relative standard deviations of repeatability and reproducibility and trueness values for each of the 115 mycotoxin/sample combinations ranged from 5% to 23%, 7% to 26%, and 85% to 129%, respectively, in line with requirements defined in EC 401/2006. The overall set of data gathered demonstrated that the method offered a unique platform to ensure compliance with EC 1881/2006 and EC 165/2013 regulations setting maximum limits for mycotoxins in food samples, even at low regulated levels for foods intended for infants and young children. The method was applicable regardless of the food, the regulated mycotoxin, and the concentration level, and thus is an excellent candidate for future standardization.

scholarly journals Development and Validation of a Quantitative Method for Determination of Carmine (E120) in Foodstuffs by Liquid Chromatography: NMKL Collaborative Study

1997 ◽  
Vol 80 (5) ◽  
pp. 1044-1051 ◽  
Author(s):  
Leonardo Merino ◽  
Ulla Edberg ◽  
Hakan Tidriks ◽  
I Berndtsson ◽  
K Blomberg ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Quantitative Methods ◽  
Solid Phase ◽  
Collaborative Study ◽  
Food Samples ◽  
Carminic Acid ◽  
Enzymatic Reactions ◽  
Solid Phase Extraction Cartridge ◽  
Relative Standard

Abstract ThimA liquid chromatographic method for quantitative determination of carmine (E120) in different foodstuffs is described. Qualitative and semiquantita- tive methods for analysis of carmine and other related dyes are well established. However, quantitative methods available are based mainly on enzymatic reactions that are time-consuming or specific for analysis of carminic acid in yoghurt. In the method developed and validated here, carminic acid is extracted by boiling the sample with HCI, purified on a solid-phase extraction cartridge, and injected on a Cis analytical column. The method was evaluated by an internal analytical quality control and a collaborative study in which 11 laboratories from the Nordic countries participated. The food samples analyzed were fruit jelly, liqueur, juice, yoghurt, and ice cream. Materials were distributed to participants as uniform level and split level. Validation showed that the proposed method is well suited for quantitative determination of carmine. The detection limit is 0.1 mg/L. The mean relative standard deviation for reproducibility varies from 7.9 to 11.7%. The proposed method is simple and relatively fast compared with previously published methods.

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