Simplex Optimized Acetylacetone Method for Formaldehyde

1973 ◽  
Vol 56 (6) ◽  
pp. 1496-1502
Author(s):  
Fred P Czech
Keyword(s):  
Standard Deviation ◽  
Experimental Design ◽  
Design Process ◽  
Analytical Methods ◽  
High Sensitivity ◽  
Fold Increase ◽  
Chromotropic Acid ◽  
High Quality ◽  
Relative Standard ◽  
Aoac Method

Abstract The AOAC colorimetric acetylacetone method for formaldehyde in sugar products is optimized by means of the simplex experimental design process. The resultant method is almost 4 times as sensitive as the original AOAC method. It is about 33% more sensitive than the simplex optimized J-acid procedure and 45% more sensitive than the simplex optimized chromotropic acid method and, thus, represents one of the most sensitive methods now available. The average relative standard deviation is about ±2.7%. The limit of detectability is estimated to be 30 ppb. The didactic exposition of the simplex optimization process reported earlier is applied to the AOAC acetyl-acetone method. Further insights into simplex operations are provided and certain advantages of simplex application are pointed out. It is shown that, by sacrificing the high sensitivity of the optimized method the parameters of the new method result in about a 10-fold increase in analytical speed. Further application of kinetic considerations and the advantages of high quality, productivity, and economy in chemical analytical methods by means of the simplex experimental design process are described.

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.

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.

Synthesis and Application of p-Carboxyarsenazo for Spectrophotometric Determination of Cu(II) in Environment Water

2013 ◽  
Vol 830 ◽  
pp. 298-301 ◽  
Author(s):  
Lin Gao ◽  
Yan Hua Li ◽  
Sheng Jie Chen ◽  
Fang Chen ◽  
Yuan Fang Zhang ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Water Samples ◽  
Absorption Maximum ◽  
High Sensitivity ◽  
Molar Absorptivity ◽  
Buffer Solution ◽  
Relative Standard ◽  
Sensitivity And Selectivity ◽  
Color Reagent

p-Carboxyarsenazo (CASA) color reagent was synthesized by simple diazotization reaction, and the chromomeric reaction between CASA with Cu(Ⅱ) has been studied by spectrophotometry. In pH=4.6 NaAc-HAc buffer solution, Cu(Ⅱ) reacted with CASA to form a red complex and exhibits an absorption maximum at 614 nm, Beer’s law is obeyed for 0-160 μg/L of copper in solution, the apparent molar absorptivity obtained is 1.57×104 L/(mol.cm), and the relative standard deviation (R.S.D.) is 1.6%. The proposed method exhibited high sensitivity and selectivity for Cu(Ⅱ). The results obtained by this method in the determination of environment water samples were accurate, sensitive and repeatable

scholarly journals Comparison of Some ELISA Kits for Aflatoxin M1 Quantification

2019 ◽  
Vol 102 (2) ◽  
pp. 677-679 ◽  
Author(s):  
Nida Imtiaz ◽  
Agha Waqar Yunus
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Dairy Products ◽  
High Sensitivity ◽  
Aflatoxin M1 ◽  
Comparable Efficacy ◽  
Assigned Value ◽  
Elisa Kit ◽  
Whole Milk ◽  
Relative Standard

Abstract Background: ELISA is a widely used method for aflatoxin M1 (AFM1) quantification in dairy products. This study was conducted to compare ELISA kits from different manufacturers for AFM1 quantification inmilk. Methods: High sensitivity ELISA kits (for up to 250 ng AFM1/L), including AgraQuant (Romer Labs), Bioshield M1ES (Prognosis Biotech), Helica 96 (Helica Biosystems), Veratox (Neogen, Inc.), and the medium sensitivity kit Immunolab AM1E01 (Immunolab GmbH; for 10–1000ng AFM1/L) were tested against a certified reference AFM1 whole milk having 44 ng AFM1/L and its 10-fold dilution, and a50 ng AFM1/L standard. In another experiment, Prognosis Bioshield M1UF (70–1000 ng AFM1/L), Romer’s AgraquantPlus (10–2000 ng AFM1/L), and Immunulab’s AM1E01 kits were compared totest a 500 ng AFM1/L solution. Results: In both of the experiments, the quantification ofthe tested AFM1 levels did not differ (P ≥ 0.310) between the kitsfrom various manufacturers. In the case of 4.4 ng AFM1/L, recovery of the toxin wasclose to the assigned value under the kit by Neogen, Inc. Incase the of 44 ng level, better recoveries were seen under the kits by Immunolab and Prognosis Biotech. In both the cases, low relative standard deviation (RSD) values were obtained only for the kit by Prognosis Biotech. In the case of the 50 and 500 ng AFM1/L solutions, the kits by Prognosis Biotech and Romer Labs provided recoveries close tothe assigned values as well as low RSD. Conclusions: These data indicate that all thestudied ELISA kit brands had comparable efficacy forAFM1 quantification. Recovery of the toxin and RSD may, however, differ between kits fromvarious manufacturers.

Spectrophotometric Method for Microdetermination of Nitrogen in Kjeldahl Digest

1989 ◽  
Vol 72 (6) ◽  
pp. 953-956 ◽  
Author(s):  
Muljibhai B Devani ◽  
Chamanlal J Shishoo ◽  
Shailesh A Shah ◽  
Bhanubhai N Suhagia
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Spectrophotometric Method ◽  
Acidic Medium ◽  
Molar Absorptivity ◽  
Nitrogen Compounds ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Aoac Method

Abstract A new spectrophotometric method for the determination of nitrogen in Kjeldahl digest has been developed. The method is based on the reaction of ammonia with acetylacetone-formaldehyde reagent in aqueous medium to yield yellow 3,5-diacetyl- 1,4-dihydrolutidine with a characteristic absorption maxima at 412 nm. The effect of several experimental variables on the determination of nitrogen was studied. The method was suitable for determination of nitrogen in acidic medium without interference from the usual catalysts employed for the digestion in Kjeldahl method. Lambert-Beer’s law is obeyed in the concentration range of 0.5-6.0 ng nitrogen/mL in the reaction mixture. The molar absorptivity in terms of nitrogen was 1.4 X 103L mol-1 cm-1. The standard deviation and relative standard deviation were ±0.0447 and ±0.896% (n = 10), respectively. The method is simple, rapid, and precise. A variety of carbocyclic and heterocyclic nitrogen compounds have been analyzed for nitrogen content. The results are comparable with those obtained by AOAC method, 47.021.

Simplex Optimized J-Acid Method for the Determination of Formaldehyde

1973 ◽  
Vol 56 (6) ◽  
pp. 1489-1495
Author(s):  
Fred P Czech
Keyword(s):  
Standard Deviation ◽  
Rapid Determination ◽  
Chromotropic Acid ◽  
Colorimetric Analysis ◽  
Simplex Optimization ◽  
Highly Sensitive ◽  
Relative Standard ◽  
Basic Concepts ◽  
Sensitive Method

Abstract This paper is the first in a number of didactic reports on the application of simplex optimization to analytical methods and instruments. The use of simplex optimization allows rapid determination of the best conditions for analytical purposes. Some basic concepts used in simplex optimization operations are introduced, described, and exemplified. A rapid and highly sensitive method for the colorimetric analysis of formaldehyde via J-acid is derived by means of simplex optimization. The method is over 5 times as sensitive as the original J-acid procedure and almost 10% more sensitive than the simplex optimized chromotropic acid procedure. The average relative standard deviation is about ±1.6%. The limit of detectability is estimated to be 70 ppb.

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.

Turbidimetric Microbiological Determination of Oxytetracycline Hydrochloride in Finished Feeds and a Feed Premix: Collaborative Study

1980 ◽  
Vol 63 (5) ◽  
pp. 1038-1043
Author(s):  
Dorothy L Mueller-Brennecke ◽  
Shirley J Reed ◽  
Debra L Waisner ◽  
◽  
S Ahrens ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Plate Method ◽  
Relative Standard ◽  
Significant Difference ◽  
Aoac Method ◽  
Assay Methods ◽  
The Mean ◽  
Feed Premix

Abstract New automated and manual turbidimetric microbiological assay methods for oxytetracycline (OTC) in finished feeds and a feed premix were submitted to 17 collaborating laboratories for comparison with the official AOAC method. Six finished feeds of 50 and 100 g/ton levels and one premix containing 20 g OTC/lb were sent to the collaborators. Results were received from 12 laboratories. Six laboratories provided results derived from the Autoturb System and 7 laboratories performed the turbidimetric analyses manually. All 12 laboratories assayed the samples by the AOAC cylinder-plate method. Ranges of recoveries expressed as percent were 89.5–102.0, 91.2–97.0, and 91.4–96.0 for the AOAC, Autoturb turbidimetric, and manual turbidimetric methods, respectively. Average recoveries were 96.3, 93.4, and 93.6%, respectively. The mean relative standard deviation values were 5.7, 6.3, and 7.2, respectively. There was little significant difference between the turbidimetric methods and the AOAC method; however, the turbidimetric methods were faster.

Application of Imaging Plate to High-Voltage Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 168-169
Author(s):  
Seiji Isoda ◽  
Kimitsugu Saitoh ◽  
Sakumi Moriguchi ◽  
Takashi Kobayashi
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
High Sensitivity ◽  
Imaging Plate ◽  
High Quality ◽  
Electron Dose ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Recording Material

On the observation of structures by high resolution electron microscopy, recording materials with high sensitivity and high quality is awaited, especially for the study of radiation sensitive specimens. Such recording material should be easily combined with the minimum dose system and cryoprotection method. Recently a new recording material, imaging plate, comes to be widely used in X-ray radiography and also in electron microscopy, because of its high sensitivity, high quality and the easiness in handling the images with a computer. The properties of the imaging plate in 100 to 400 kV electron microscopes were already discussed and the effectiveness was revealed.It is demanded to study the applicability of the imaging plate to high voltage electron microscopy. The quality of the imaging plate was investigated using an imaging plate system (JEOL EM-HSR100) equipped in a new Kyoto 1000kV electron microscope. In the system both the imaging plate and films can be introduced together into the camera chamber. Figure 1 shows the effect of accelerating voltage on read-out signal intensities from the imaging plate. The characteristic of commercially available imaging plates is unfortunately optimized for 100 to 200 keV electrons and then for 600 to 1000 keV electrons the signal is reduced. In the electron dose range of 10−13 to 10−10 C/cm2, the signal increases linearly with logarithm of electron dose in all acceralating volatges.

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

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