Colorimetric Determination of Melamine in Dairy Products by Fe3O4Magnetic Nanoparticles−H2O2−ABTS Detection System

2010 ◽  
Vol 82 (13) ◽  
pp. 5897-5899 ◽  
Author(s):  
Ning Ding ◽  
Na Yan ◽  
Cuiling Ren ◽  
Xingguo Chen
Keyword(s):  
Dairy Products ◽  
Detection System ◽  
Colorimetric Determination

Sensitive Colorimetric Determination of Cholesterol in Dairy Products

1976 ◽  
Vol 59 (5) ◽  
pp. 1146-1149 ◽  
Author(s):  
Kermit C Bachman ◽  
Jan-Hai Lin ◽  
Charles J Wilcox
Keyword(s):  
Dairy Products ◽  
Skim Milk ◽  
Raw Milk ◽  
Colorimetric Determination ◽  
Hexane Extraction ◽  
Color Development ◽  
Fat Extraction ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract Cholesterol can be determined colorimetrically in dairy products at levels of ≥10 μg (coefficient of variation = 5.3%) with an o-phthalaldehyde reagent when non-cholesterol lipids arc eliminated prior to color development. Absorbance for 2 mg tripalmitin was found to be equivalent to about 20 μg cholesterol. Saponification followed by hexane extraction removed interfering lipids. Using the described procedure, 238 individual raw milk samples were found to contain 144.4±37.9 μg cholesterol/ml, while their skim milk portions had 26.5±6.4 μg cholesterol/ml (mean ± standard deviation). The o-phthalaldehyde cholesterol estimates agreed with those obtained by a gas-liquid chromatographic procedure when cheese and ice cream were analyzed by the colorimetric procedure with and without prior fat extraction.

Colorimetric Determination of Total Iodine in Foods by Iodide-Catalyzed Reduction of Ce+4

1986 ◽  
Vol 69 (4) ◽  
pp. 687-689 ◽  
Author(s):  
Peter W F Fischer ◽  
Mary R L’Abbé ◽  
Alexandre Giroux
Keyword(s):  
Detection Limit ◽  
Reference Material ◽  
Standard Reference Material ◽  
Dairy Products ◽  
Colorimetric Method ◽  
Colorimetric Determination ◽  
Acid Digestion ◽  
Total Iodine ◽  
Relative Standard

Abstract An earlier acid digestion determination of iodine in foods was modified to provide an improved detection limit and to allow for the analysis of a greater variety and larger amounts of foods. The organic material in the sample was oxidized overnight by concentrated nitric acid, followed by digestion in a mixture of concentrated sulfuric and 70% perchloric acid. The iodine was determined by an automated colorimetric method based on the iodide-catalyzed reduction of Ce+4 by As+3. The method had an average relative standard deviation of 3.1% for the samples analyzed, and a detection limit of 0.1 ng/mL in the digested solution and 5 ng/g in a 2 g sample prior to digestion. The recovery of added iodine ranged from 90.3 to 101.3%, using external standards. Samples analyzed included NBS Standard Reference Material 1549, and composites of a variety of dairy products, meat, eggs and fish, cereals, and potatoes. The iodine detected in these samples ranged from 9 ng/g for the potato group to 3360 ng/g for the standard reference material.

31. The Determination of Copper and Iron in Dairy Products

1931 ◽  
Vol 3 (1-2) ◽  
pp. 93-100 ◽  
Author(s):  
W. Williams
Keyword(s):  
Dairy Products ◽  
Colorimetric Determination ◽  
Ferric Thiocyanate ◽  
Iron Contamination ◽  
Wet Ashing ◽  
High Degree ◽  
Very High ◽  
Determination Of Copper ◽  
Colorimetric Methods

1. Two colorimetric methods for determination of copper have been described, viz. the xanthate and the sodium diethyl-dithio-carbamate. Both methods have given satisfactory results but the carbamate method has proved to be more sensitive and less liable to error from possible contamination than the xanthate method.2. The colorimetric determination of iron by the modification of the ferric thiocyanate method has been proved to give a very high degree of accuracy and excellent results have been obtained.3. A method of wet ashing has been described whereby organic matter is oxidised by the use of concentrated sulphuric acid and sodium nitrate and copper and iron extracted from the fat.4. A number of results are given showing the amount of copper and iron contamination that the cream is subjected to during the course of butter manufacture, and the distribution of copper and iron in the cream, butter and buttermilk.

scholarly journals Analytical Microsystem for the Monitoring and Analysis of Cobalt in Aqueous Solutions Using LTCC Technology

2017 ◽  
Vol 58 (4) ◽  
Author(s):  
Olga Natalia Bustos López ◽  
Francisco Valdés Perezgasga ◽  
Héctor Aurelio Moreno Casillas ◽  
Julián Alonso Chamarro ◽  
Hesner Coto Fuentes
Keyword(s):  
Aqueous Solutions ◽  
Continuous Flow ◽  
Flow System ◽  
Detection System ◽  
Light Emitting Diode ◽  
Colorimetric Determination ◽  
Light Emitting ◽  
Design And Implementation ◽  
Optical Detection System

<p>This work is focused on the design and implementation of a microsystem for continuous colorimetric determination of cobalt in aqueous solutions in real time.  The main goal is the colorimetric determination of cobalt by adapting colorimetric methodologies used in discontinuous analysis systems to a continuous flow system and its subsequent miniaturization using the LTCC (Low Temperature Co-fired Ceramics) technology. The measure absorbance was recorded using an optical detection system based on a LED (Light Emitting Diode) with a wavelength of 540 nm. </p>

scholarly journals Hydrogen-Bonding Recognition-Induced Colorimetric Determination of Hydrazine Based on the Tryptophan Capped Gold Nanoparticles

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Wenhua Gao ◽  
Jing Xi ◽  
Yunsheng Chen ◽  
Song Xiao ◽  
Xingqing Wang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
Detection System ◽  
Colorimetric Method ◽  
Cost Effective ◽  
Colorimetric Determination ◽  
Chloroauric Acid ◽  
Sample Analysis ◽  
Higher Temperature

A simple, cost-effective, and rapid colorimetric method for hydrazine detection using tryptophan-caped gold nanoparticles (Trp-AuNPs) has been developed. Tryptophan (Trp) is a protein with reducibility and amino group which can reduce chloroauric acid (HAuCl4) to AuNPs and modify the surface of AuNPs simultaneously. The Trp-AuNPs could be used to quantitatively detect hydrazine and showed different responses to vary concentration of hydrazine in an aqueous solution based on the aggregation-induced color change of Trp-AuNPs. The real water sample analysis verified the conclusion. The sensitivity of the detection system was influenced by the size of AuNPs which is determined by the pH of the detection system, the concentration of Trp, and the react time. We found that higher temperature contributed to more rapidly results. The detection system can detect as low as 1 μM hydrazine. We expect our approach to have wide-ranging applications in the developing region for monitoring water quality in some areas.

scholarly journals Use of Flow InjectionMultisite Detection as a Novel Approach for Blank Signal Correction in a Spectrophotometric Determination

2005 ◽  
Vol 88 (5) ◽  
pp. 1511-1515
Author(s):  
Teresa A C Oliveira ◽  
Raquel B R Mesquita ◽  
José L F C Lima ◽  
António O S S Rangel
Keyword(s):  
Detection System ◽  
Sampling Rate ◽  
Flow Cell ◽  
Colorimetric Determination ◽  
Soil Extracts ◽  
Novel Approach ◽  
Relative Standard ◽  
Color Reagent ◽  
Colored Product

Abstract A flow injection multisite detection system was developed for correction of the sample blank in a colorimetric determination. By using detector relocation, a single spectrophotometer is used for the sequential reading of the sample blank and of the colored product; the sample crosses the flow cell to measure intrinsic absorption, the color reagent is subsequently added, and the flow cell is relocated to provide the reading of the resulting plug. The subsequent detector relocation immediately after peak maximum increases the determination frequency. This strategy was tested in the colorimetric determination of iron in soil samples based on the reaction of Fe (II) with 1,10-phenanthroline after reduction of Fe (III) to Fe (II) by ascorbic acid. The results obtained for 15 soil extracts were in good agreement with those obtained by the reference procedure. Relative standard deviations better than 4% were obtained, with a sampling rate of 30/h.

Review: Determination of Vitamin D in Dairy Products by High Performance Liquid Chromatography

2005 ◽  
Vol 11 (6) ◽  
pp. 451-462 ◽  
Author(s):  
S. Perales ◽  
A. Alegría ◽  
R. Barberá ◽  
R. Farré
Keyword(s):  
Vitamin D ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Dairy Products ◽  
High Performance ◽  
Detection System ◽  
Chromatographic Determination ◽  
Sample Treatment ◽  
Cold Saponification

This work reviews the methods used for the determination of vitamin D in some dairy products (milk and infant formulas) by high performance liquid chromatography (HPLC). The low vitamin D contents and the presence of interfering compounds require sample treatment and purification of the extract. The advantages and drawbacks of hot and cold saponification, direct extraction and different types of extract purification are also discussed, taking into account the lack of vitamin D stability by heating, exposure to light and oxidation. With respect to chromatographic determination, the mode (normal or reverse phase), type of column (microcolumn or conventional) and detection system (UV, electrochemical and mass spectrometry) are overviewed, considering the vitamers to be determined.

scholarly journals Lab on a Chip for the Colorimetric Determination of Nitrite in Processed Meat Products in the Jordanian Market

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 36 ◽  
Author(s):  
Mohammad F. Khanfar ◽  
Nour J. Abu Eisheh ◽  
Loiy Al-Ghussain ◽  
Ala’aldeen T. Al-Halhouli
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Meat Products ◽  
Processed Meat ◽  
Colorimetric Determination ◽  
Statistical Parameters ◽  
Photometric Detection ◽  
Limit Of Quantitation ◽  
High Concentrations

Nitrite and Nitrate have been used extensively as additives in various meat products to enhance flavor, color, and to preserve the meat from the bacterial growth. High concentrations of nitrite can threat human health since several studies in the literature claim that nitrite is associated with cancer incidences, leukemia, and brain tumors. Therefore, it is vital to measure the nitrite concentrations in processed meat products. In this study, an in-lab miniaturized photometric detection system is fabricated to inspect the nitrite concentration in processed meat products in Jordan. The analytical performance of nitrite detection is evaluated based on three key statistical parameters; linearity, limit of detection, and limit of quantitation. Respectively, for the fabricated system, the three values are found to be equal to 0.995, 1.24 × 10−2 ppm, and 4.12 × 10−2 ppm. Adherence to Beer’s law is found over the investigated range from 2.63 ppm to 96.0 ppm. The developed system is utilized for photometric detection of nitrite in processed meat products available in the Jordanian market like pastrami, salami, and corned beef. In all of the analyzed samples, the nitrite content is found to be lower than 150 ppm, which represents the maximum allowable nitrite limit.

A Method for the Colorimetric Determination of β-Glucuronidase in Urine, Serum, Tissue; Assay of Enzymatic Activity in Health and Disease

1959 ◽  
Vol 36 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Julius A. Goldbarg ◽  
Esteban P. Pineda ◽  
Benjamin M. Banks ◽  
Alexander M. Rutenburg
Keyword(s):  
Enzymatic Activity ◽  
Colorimetric Determination ◽  
Health And Disease ◽  
Urine Serum

Colorimetric Determination of Fluoride in Drinking Groundwater using a Polymeric Zirconium Complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline

2013 ◽  
Vol 12 (7) ◽  
pp. 460-465
Author(s):  
Sameer Amereih ◽  
Zaher Barghouthi ◽  
Lamees Majjiad
Keyword(s):  
Drinking Water ◽  
Detection Limit ◽  
Complex Formation ◽  
Molar Absorptivity ◽  
Colorimetric Determination ◽  
Zirconium Complex ◽  
Reliable Determination ◽  
Percentage Recovery ◽  
Quantitation Limit

A sensitive colorimetric determination of fluoride in drinking water has been developed using a polymeric zirconium complex of 5-(2-Carboxyphenylazo)-8-Hydroxyquinoline as fluoride reagents. The method allowed a reliable determination of fluoride in range of (0.0-1.5) mg L-1. The molar absorptivity of the complex formation is 7695 ± 27 L mol-1 cm-1 at 460 nm. The sensitivity, detection limit, quantitation limit, and percentage recovery for 1.0 mg L-1 fluoride for the proposed method were found to be 0.353 ± 0.013 μg mL-1, 0.1 mg L-1, 0.3 mg L-1, and 101.7 ± 4.1, respectively.

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