Hydroxylamine Hydrochloride in Automated and Manual Methods for Riboflavin Determination

1977 ◽  
Vol 60 (1) ◽  
pp. 147-150
Author(s):  
Barabara S Jacobson
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Flow System ◽  
Hydroxylamine Hydrochloride ◽  
Automated System ◽  
Relative Standard ◽  
Aoac Method ◽  
Manual Methods ◽  
Oxygen Gas

Abstract The AOAC method for riboflavin determination has been modified to improve the precision of the manual method and greatly simplify its automation. In the AOAC method, permanganate oxidation is used for sample cleanup, and hydrogen peroxide is used to reduce excess permanganate. By substituting hydroxylamine. HCl for the hydrogen peroxide, the generation of oxygen gas, which can be troublesome, is eliminated without otherwise changing the assay. The resulting manual assay has a relative standard deviation of 1% as opposed to 2.5% for the same assay with hydrogen peroxide. This method is simple to automate, using a continuous flow system. The automated system performs 40 determinations per hour with a 1% relative standard deviation and results agree with those from the AOAC method at the 98% confidence level.

Comparison of Automatic and Manual Turbidimetric Analyses of Tylosin in Feeds with the Plate Method

1973 ◽  
Vol 56 (2) ◽  
pp. 363-366
Author(s):  
Hussein S Ragheb ◽  
H Latham Breunig ◽  
Robert E Scroggs
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Plate Method ◽  
Relative Standard ◽  
Significant Difference ◽  
Aoac Method ◽  
Turbidimetric Assay ◽  
The Mean ◽  
The Difference ◽  
Feed Samples

Abstract Two laboratories participated in a comparison of a manual turbidimetric assay with the AUTOTURB® System and the AOAC method of analysis of tylosin in 4 feed samples. Results showed no significant difference between the 2 turbidimetric assays. When the AOAC method was considered, the difference between laboratories was significant. On an overall basis the turbidimetric methods were significantly higher than the plate method. The relative standard deviation was higher (6.72%) for the plate assay versus turbidimetric assay (4.5%). The mean recovery in both laboratories was significantly less than the labeled amount of tylosin by all 3 methods.

Simplified Spectrophotometric Curcumin Method for the Determination of Boron in Marine Shellfish

1975 ◽  
Vol 32 (6) ◽  
pp. 813-816 ◽  
Author(s):  
R. E. Drew
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Acetic Anhydride ◽  
Sulphuric Acid ◽  
Relative Standard Deviation ◽  
Tissue Sample ◽  
Total Error ◽  
Relative Standard ◽  
Wet Weight

The method involves a sulphuric acid–hydrogen peroxide digestion of the tissue sample at 100 C, dehydration of the digest with acetic anhydride, formation of the boron–curcumin complex (rosocyanin), followed by buffering of the solution and measurement of the absorbance at 545 nm. Data are presented to show that a mean relative standard deviation of approximately 5% and a mean total error of approximately 12% can be expected for shellfish in the concentration range of 1.0–10.0 μg B/g wet weight tissue (ppm).

Kinetic Spectrophotometric Determination of Selenium (IV) by its Catalytic Effect on the Oxidation of Acid Chrome Blue K by Hydrogen Peroxide

2012 ◽  
Vol 538-541 ◽  
pp. 2358-2363 ◽  
Author(s):  
Zhi Rong Zhou ◽  
Li Zhen Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Limit Of Detection ◽  
Fixed Time ◽  
Relative Standard ◽  
Kinetic Spectrophotometric ◽  
Acid Chrome Blue K ◽  
Good Agreement

Based on the oxidation of acid chrome blue K (ACBK) by hydrogen peroxide in 0.002 mol/L sulfuric acid solution, while 1,10-phenanthroline (phen) acts as an activator, a simple kinetic spectrophotometric method was developed for the determination of trace amounts of Se(IV).The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of ACBK at 524 nm with a fixed-time method. The decrease in the absorbance of ACBK is proportional to the concentration of Se (IV) in the range 0.06–1.0 µg/L with a fixed time of 4–10 min from the initiation of the reaction. The limit of detection is 0.018 µg/L Se (IV). The influence of the factors such as acidity, concentration of reactants, reaction time, temperature and co-existing ions on the reaction is discussed. The optimum conditions of reaction are established and some kinetic parameters are determined. The apparent activation energy of catalytic reaction is 62.30 kJ/mol. The relative standard deviation for 11 replicate determination of 0.01 and 0.02 µg/25mL selenium (III) was calculated to be 2.3 % and 2.0 %, respectively. Combined with sulphydryl dextrane gel (SDG) separation and enriching, the method has been successfully applied to the determination of Se (IV) in foodstuff samples with the relative standard deviation of 1.1 %–3.7 % and the recovery of 99.0 %–104.0 %, the results are in good agreement with those provided by HG-AAS method.

Automated Photometric Microbiological Assay for Monensin in Poultry Rations

1972 ◽  
Vol 55 (1) ◽  
pp. 114-118 ◽  
Author(s):  
F W Kavanagh ◽  
Mary Willis
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Aqueous Acetone ◽  
Microbiological Assay ◽  
Maximum Sensitivity ◽  
Automated System ◽  
Polysorbate 80 ◽  
Standard Curve ◽  
Relative Standard ◽  
Feed Samples

Abstract A new photometric microbiological assay is described for the coccidiostat monensin in poultry feeds and premixes. The crucial steps in the assay are performed by an automated system. Samples are extracted with acetone and diluted in 50% aqueous acetone to appropriate levels for assay by Streptococcus faecalis ATCC 8043. A special pH 5.2 medium, low in potassium, and polysorbate 80 are used to obtain maximum sensitivity without interference. The range of applicability of the standard curve is 0.10–0.4 μg monensin/ml sample. The assay is free from bias. A relative standard deviation of 1.7% was obtained when 10 feed samples were extracted and assayed 5 times each.

Enzymatic Determination of Sulfite in Foods: NMKL Interlaboratory Study

1993 ◽  
Vol 76 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Ulla Edberg ◽  
◽  
Maija-Liisa Anttonen ◽  
Karen Berg-Nilsen ◽  
Karin Blomberg ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Study Data ◽  
Relative Standard ◽  
Full Study ◽  
Potato Flakes ◽  
Reduced Nicotinamide Adenine Dinucleotide

Abstract An enzymatic method for the determination of sulfite in foods was collaboratively studied in Nordic industry and government laboratories. The sulfite in liquid foods or extracts of solid foods is analyzed according to the following principle: Sulfite ions are oxidized to sulfate ions by oxygen in the presence of sulfite oxidase, thereby forming hydrogen peroxide. Hydrogen peroxide is transformed to water by reduced nicotinamide adenine dinucleotide (NADH) in the presence of NADH peroxidase. In this reaction, NAD+ is formed (and NADH is consumed) in amounts proportional to the sulfite concentration. Consumption of NADH can be measured spectro photo metrically at 340 nm. The method was collaboratively tested in 2 separate studies with high and low levels of sulfite tested. Results of both studies are reported here. The study samples consisted of potato flakes, wine, juice, and dried apples containing between 0 and about 960 mg SCVkg. Eleven laboratories participated in the full study and analyzed 12 samples. Six laboratories analyzed 8 samples in the complementary study. Before statistical evaluation of the collaborative study data, results were adjusted for the time-dependent decrease of sulfite in the case of materials with high sulfite content (dried apples and wine). For 2 blind duplicate samples of wine containing 75 mg S02/kg, the relative standard deviation for repeatability (RSDR, within-laboratory variation) was 3.9%. Relative standard deviation for reproducibility (RSDR, between-laboratory variation) was 7.6%. For 2 samples of dried apples containing 800 and 960 mg S02/kg, an RSDr value of 13.3% and an RSDR value of 13.9% were calculated. The corresponding parameters for 2 juice samples containing about 270 mg S02/kg were 4.8 and 10.4% for repeatability and reproducibility, respectively.

scholarly journals Determination of the Total Nitrogen Content of Hard, Semihard, and Processed Cheese by the Kjeldahl Method: Collaborative Study

2002 ◽  
Vol 85 (2) ◽  
pp. 445-455 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming ◽  
◽  
◽  
...  
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Total Nitrogen ◽  
Crude Protein ◽  
Collaborative Study ◽  
Processed Cheese ◽  
Relative Standard ◽  
Aoac Method

Abstract The objective of this collaborative study was to determine interlaboratory performance statistics for a modified and optimized version of AOAC Method 920.123 for the determination of the total nitrogen content of hard, semihard, and processed cheese by Kjeldahl analysis. Details included addressing the issues of material homogeneity, test portion size (1 g), quantitative transfer (weighing on to filter paper), ensuring system suitability (nitrogen recoveries), and using AOAC Method 991.20 as the basis for nitrogen analysis. Fifteen laboratories tested 18 pairs of blind duplicate cheese materials with a crude protein content between 18 and 36%. Materials represented hard, semihard, and processed commercial cheeses with a wide range of composition. Statistical performance parameters expressed as crude protein (nitrogen × 6.38), g/100 g, with invalid and outlier data removed were mean = 26.461, repeatability standard deviation (Sr) = 0.111, reproducibility standard deviation (SR) = 0.153, repeatability relative standard deviation (RSDr) = 0.42%, reproducibility relative standard deviation (RSDR) = 0.58%, repeatability (r) = 0.312, and reproducibility (R) = 0.428. The interlaboratory study results were acceptable and comparable to those for the milk Kjeldahl nitrogen method on a relative nitrogen basis. The Study Directors recommend that this modified method for the determination of total nitrogen in hard, semihard, and processed cheese by Kjeldahl analysis be adopted First Action as an improved method to replace Method 920.123.

An Automated Procedure for the Determination of Ammonia in Tobacco

1972 ◽  
Vol 6 (4) ◽  
Author(s):  
P.F. Collins ◽  
W.W. Lawrence ◽  
J.F. Williams
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Distillation Method ◽  
Relative Standard ◽  
Tobacco Sample ◽  
Automated Determination

AbstractA procedure for the automated determination of ammonia in tobacco has been developed. Ammonia is extracted from the ground tobacco sample with water and is determined with a Technicon Auto Analyser system which employs separation of the ammonia through volatilization followed by colourimetry using the phenate-hypochlorite reaction. The procedure has been applied to a variety of tobaccos containing from 0.02 to 0.5 % ammonia with an overall relative standard deviation of 2 %. The accuracy of the procedure as judged by recovery tests and by comparison to a manual distillation method is considered adequate

How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

2020 ◽  
Author(s):  
Saneyuki Ohno ◽  
Tim Bernges ◽  
Johannes Buchheim ◽  
Marc Duchardt ◽  
Anna-Katharina Hatz ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Ionic Conductivity ◽  
Relative Standard Deviation ◽  
Solid Electrolytes ◽  
Ionic Conductivities ◽  
Ionic Conductors ◽  
Energy Storage Devices ◽  
Activation Barriers ◽  
Storage Devices ◽  
Relative Standard

<p>Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an <i>interlaboratory reproducibility</i> of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm<sup>-1</sup> in the measured total ionic conductivity (1.3 – 5.8 mScm<sup>-1</sup> for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.</p>

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

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