University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Cows Milk

Classification: Agricultural -> dairy -> milk -> cow

Citations 10

"Amperometric Determination Of Lactose In Human And Cow's Milk Using A Flow Injection System With Some Immobilized Enzyme Reactors"
Electroanalysis 1989 Volume 1, Issue 4 Pages 413-416
Toshio Yao*, Reina Akasaka, Tamotsu Wasa

Abstract: A bioelectrochemical flow-injection system is proposed for the determination of lactose in milk from humans and cows. The system includes an amperometric flow-through platinum electrode to measure hydrogen peroxide, which was enzymatically generated by injecting a 10-L sample into the packed-bed reactors of immobilized -galactosidase and glucose oxidase that are incorporated in series in the flow line. Because the presence of glucose interfered with the measurement of lactose, a precolumn packed with coimmobilized glucose oxidase and catalase was positioned just before the two immobilized enzyme reactors to remove the glucose from the milk. The peak current was linearly related to the lactose concentration between 0.01 and 2.0 mM. The determinations of lactose in milk could be performed at a rate of 60 samples/h with satisfactory precision (less than 0.8% RSD) and no pretreatment except for the sample dilution.
Lactose Amperometry Reactor Injection technique Immobilized enzyme

"Flow Injection Spectrophotometric Catalytic Determination Of Iodine In Milk"
Anal. Sci. 1998 Volume 14, Issue 3 Pages 559-564
Ana Rita de Araujo NOGUEIR), Fabiana MOCKIUTI), Gilberto Batista de SOUZ) and Odo PRIMAVESI

Abstract: A flow injection method based on the catalytic action of iodide on the color-fading reaction of the FeSCN2+ complex was proposed and applied to the determination of iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbance of Fe(III)-SCN (0.10 and 0.0020 mol L-1) in the presence of NO2- (0.3 mol L-1) is proportional to the concentration. of iodide, with linear response up to 100.0 µg I- L-1. The detection limit was determined as 0.99 µg I- L-1 (3s blank/slope); and the system handles 48 samples h-1. Organic matter was destroyed by a dry procedure carried out under alkaline conditions. Alternatively, the use of Schoeninger combustion after milk dehydration was evaluated. The residue was taken up in 0.12 mol L-1 KOH solubilization. For typical samples, recoveries varied from 94.5 to 105%, based on the amounts of both organic matter destroyed. The accuracy of the method was established by using a certified reference material (IAEA A-11, milk powder) and a manual method.
Iodine Spectrophotometry Reference material Method comparison Indirect

"Feeding Of Silage Effluent To Dairy Cows"
Acta Agri. Scand. A 1997 Volume 47, Issue 1 Pages 20-30
Ashild T. Randby

Abstract: Three feeding experiments, each with 24 cows, were performed to evaluate the use of effluent from grass silage as feed. The quality of silages produced in open-drainage silos and closed-drainage silos was also compared. Silage and effluent were fed ad libitum with concentrate supplements. Animals readily consumed effluent at 30 kg day-1 on average, equivalent to 2.2 kg dry matter (DM) day-1. Silage intakes decreased by 1 kg DM day-1 when silage plus effluent was fed as compared with silage alone, while total roughage intake (silage plus effluent) increased by 1.2 kg DM day-1. Milk yields and fat, protein, and lactose contents (analyzed by FIA) tended to increase for cows receiving effluent. Increases in milk yield were small, however, relative to the increases in DM intake, indicating reduced feed conversion efficiency when effluent was fed. Intakes of silage stored in the presence of effluent tended to be lower than those of silage from which effluent had been drained, but milk yield and milk composition were unaffected.
Fatty acids, free Protein Lactose

"Flow Injection Analysis For The Determination Of Urea In Cows Milk"
Acta Vet. Scand. 1985 Volume 26, Issue 3 Pages 396-404
Oltner R, Bengtsson S, Larsson K.

Abstract: An inexpensive and easily automated flow injection method for determination of urea in cow's milk was evaluated. Urea is hydrolyzed by urease and in a gas diffusion cell the ammonia formed passes a membrane into an indicator solution. The resulting color change of the indicator is measured at 590 nm. The repeatability of the analysis, expressed as the coefficient of variation (C.V.), was between 0.5 and 1.2%. Measured (y) and expected (x) milk urea concentrations after addition of known amounts of urea were related according to the equation y = 1.00x - 0.12 with a C.V. for the regression of 1.8%. Recommended amounts (0.02%) of the preservative bronopol (2-bromo-2-nitropropane-1,3-diol) added to the milk did not affect the results (P > 0.05).
Urea Spectrophotometry Enzyme Gas diffusion Tecator

"The Diurnal Variation Of Urea In Cow's Milk And How Milk Fat Content, Storage And Preservation Affects Analysis By A Flow Injection Technique"
Acta Vet. Scand. 1994 Volume 35, Issue 1 Pages 67-77
Carlsson J, Bergström J.

Abstract: Six Swedish Red and White dairy cows, producing 20-39 kg of 4% fat- corrected milk were given a ration balanced in energy and protein. They had access to feed from 05.15 to 09.00 and from 13.00 to 16.30 and were milked at 06.15 and 15.30. The milk was analyzed for urea with a FIA technique. There was a significant diurnal variation in milk urea. The highest values were found 3-5 h after the beginning of the morning feeding and the lowest values (down to 60% of the max. values) during late night. Within 1 h after the start of the morning feeding the urea values had increased significantly, but they had decreased within the same time after the start of the afternoon feeding. Since there was a pronounced diurnal variation in the milk fat content, the urea concentration was also recalculated to concentration in the water phase of the milk. It was higher in that phase, but the pattern of the diurnal variation was not changed significantly. However, analyzes on milk with a very high fat content may give misleading results. There were no important differences in the milk urea concentration of different udder quarters. When calculated as concentration in the water phase of the milk, no differences in urea concentration were found between the beginning and the end of milking. The analytical method had a good precision (coefficient of variation max. 3%). The milk urea concentration was not changed significantly after storage during 10 days at 4°C when no preservative was added; but after 17 days the milk had turned sour and the urea value had increased. When a preservative (bronopole) was added the urea concentration remained unchanged during 17 days. Deepfreezing did not influence the urea concentration.
Urea Spectrophotometry

"FIA System With Urease Reactor For The Determination Of Urea In Food"
Dtsch. Lebensm. Rundsch. 1994 Volume 90, Issue 6 Pages 178-181
Schwedt, G.;Shi, R.;Stein, K.

Abstract: Urease, immobilized on 150 mg of VA Epoxy resin (Riedel-de Haen), was packed in a glass column (4.5 cm x 2 mm i.d.), which was mounted in a flow injection system. Meat, fish and milk were extracted with HClO4 or trichloroacetic acid, the extracts were neutralized and portions of the extract (0.1 ml) were injected into a carrier stream of water. After passing through the urease reactor the stream was mixed with alkaline EDTA solution. The mixture passed over a gas diffusion membrane, where the NH3 formed diffused into an absorber solution, which contained bromocresol violet, bromothymol blue and cresol red. The absorbance of the resulting solution was measured at 590 nm; linear calibration graphs for 50-800 ppm of urea were obtained. Regular calibration was required as the reactor lost 25% of its activity after 24 days storage at 60°C. Corrections were required for the ammonia content of some samples; these were obtained by allowing the sample to bypass the reactor. Results were similar to those obtained by the Boehringer UV test and by the official photometric method of the food industry.
Urea Spectrophotometry Gas diffusion Immobilized enzyme

"Automation Of Iron And Copper Determination In Milks Using FIA Systems And Colorimetric Detection"
Food Chem. 1998 Volume 62, Issue 1 Pages 117-121
José L. F. C. Lima, Cristina Delerue-Matos* and M. Carmo V. F. Vaz

Abstract: This paper describes a flow injection manifold with a colorimetric detection system that enables the determination of iron and copper in different types of milks, namely cow milk and infant formula powd. milks. The methodology used is based on the formation of colored complexes produced by the reaction of iron (II) with 1,10-phenanthroline and copper(II) with 1,5-diphenylcarbazide. The samples were digested with nitric and sulfuric concentrated acids and inserted in the FIA system without additional treatment. The pH adjustment was carried out inside the manifold including the addition of the reagents needed to form the absorbing species. The sample rate of both species was never lower than 120 determinations h-1. The results obtained were compared with those given by the reference methods, and the relative deviation was less than 5 and 4% for the determinations of iron and copper respectively. The precision of the results evaluated by the relative standard deviation (RSD%) was less than 0.5% for iron and 2% for copper determinations
Iron(2+) Copper(II) Spectrophotometry Sample preparation Complexation pH Method comparison

"Conductometric Measurement Of Sugar Content Of Food With Flow Injection Analysis System. Study On Electrochemical Measurement Of Sugar Content Of Food, Part VIII"
Nippon Shokuhin Kagaku Kogaku Kaishi 1985 Volume 32, Issue 12 Pages 916-919
Takakazu NOMURA, Hiroyuki UKEDA, Kiyoshi MATSUMOTO, Yutaka OSAJIMA

Abstract: The rapid and convenient methods based on conductometric flow injection analysis (FIA) were proposed for measuring sugar content of apple juice and juice of sugar beet root and for measuring total solids content of cow's milk. With the FIA system, all measurements were able to carry out under the same operational conditions of the system, by use of each calibration curve for each sample -apple juice, juice of sugar beet root and cow's milk, respectively. For apple juice and clarified juice of sugar beet root with tannic acid, sugar content estimated from the proposed mehtods agreed with that obtained from phenol-sulfuric acid method with an error of 0.24%. For cow's milk homogenate, the total solids content estimated from the proposed method agreed with that obtained from gravimetric method (method of A.O.A.C.) with an error of 0.19%.
Sucrose Total soilds Conductometry

"Potentiometric Determination Of Chloride Ion In Milk And Dairy Products By FIA Titration"
Quim. Anal. 1995 Volume 14, Issue 2 Pages 121-124
Alegret, S.;Alonso, J.;Bartroli, J.;Garcia Raurich, J.;Martinez Fabregas, E.;Sanchez Rodriguez, J.

Abstract: A 100 µL portion of milk was injected into a carrier stream (1 ml/min) of 0.1 M KNO3 and passed into a 0.55 mL variable-volume dilution chamber. The stream then passed through a ground electrode to a flow-through reference electrode as previously described (Alegret et al., Ibid. 1987, 6, 278) and a tabular flow-through Ag25 heterogeneous membrane all-solid-state electrode for the detection of the end point of the titration. The calibration graph was linear for 0.4-0.8 M chloride. Results are discussed.
Chloride Potentiometry Electrode Titrations