Collaborative Evaluation of a Fluorometric Method for Measuring Alkaline Phosphatase Activity in Cow's, Sheep's, and Goat's Milk

2005 ◽  
Vol 68 (5) ◽  
pp. 1047-1053 ◽  
Author(s):  
FRANK HARDING ◽  
EILEEN GARRY
Keyword(s):  
Alkaline Phosphatase ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Dairy Products ◽  
Test System ◽  
Plant Performance ◽  
Alp Activity ◽  
Goat’S Milk ◽  
Relative Standard ◽  
Goat's Milk

Pasteurization of raw milk was introduced to extend product shelf life and destroy pathogens. The measurement of alkaline phosphatase (ALP) activity has been used as an indicator of proper pasteurization in dairy products for more than 65 years. This study was undertaken to evaluate six different fluid dairy products at lower phosphatase levels than previously verified using the Fluorophos Test System, a sensitive and precise method for ALP activity detection. Thirteen laboratories participated in this collaborative, international study to evaluate the fluorometric test at 20, 40, 100, 350, and 500 mU/liter and extend the scope of the method to include milk from not only cows but also goats and sheep. Initially, the statutory level of ALP measured fluorometrically was set to equivalent levels of colorimetric test standards (500 mU/liter). The European Union recently announced its intention of lowering the legal limit from 500 to 350 mU/liter and, in addition, setting a target value of 100 mU/liter, which if exceeded would trigger an investigation into the pasteurizer plant performance. At 500 mU/liter of ALP, this trial generated relative standard deviation of repeatability values of 6.48, 5.69, and 1.74% and relative standard deviation of reproducibility values of 14.66, 13.30, and 5.33% for all cow's, sheep's, and goat's milk samples, respectively. Data from this study are comparable to data from previous studies and indicate the suitability of the Fluorophos Test System method for measuring ALP activity in milk from cows, sheep, and goats not only at the current European statutory level of 500 mU/liter but also at much lower levels.

Evaluation of Spectrophotometric and Fluorometric Methods for Alkaline Phosphatase Activity Determination in Ewe's Milk

2000 ◽  
Vol 63 (9) ◽  
pp. 1258-1261 ◽  
Author(s):  
M. F. SCINTU ◽  
E. DAGA ◽  
A. LEDDA
Keyword(s):  
Alkaline Phosphatase ◽  
Standard Deviation ◽  
Raw Milk ◽  
Cow’S Milk ◽  
Official Method ◽  
Cow's Milk ◽  
Alp Activity ◽  
Relative Standard ◽  
Ewe's Milk ◽  
European Method

The alkaline phosphatase (ALP) activity test has been used since 1935 to assess the effectiveness of pasteurization. Different analytical methods exist for detecting ALP in milk. Unfortunately, there is little information about ALP activity in ewe's milk. The aim of this study was to assess and compare the official European method (spectrophotometric method) and the Fluorophos method (fluorometric method) regarding their use in ewe's milk. Bulk ewe's milk samples were taken from a flock and from three different dairies. A portion of the original sample was pasteurized at 63°C for 30 min in a circulating bath; another portion was heated to and kept at 95°C for about 2 min, and 0.1% (vol/vol) of raw milk was added. The samples obtained were analyzed in duplicate using the spectrophotometric and fluorometric methods. The relation between ALP activity determined by the two methods was characterized by the following equation: Y = 1.34 + 0.0039X (where Y = ALP in μg of phenol per ml of milk and X = ALP in mU/liter; R2 = 91.5%). Precision parameters (repeatability [r], standard deviation of repeatability [sr], and relative standard deviation of repeatability [RSDr]) for both methods were calculated. The values of RSDr for the Fluorophos method were 4.30 for pasteurized milk and 2.96 for 0.1% raw milk, close to the value indicated by Rocco in whole cow's milk (RSDr = 4.4). The repeatability for the official method (r = 2.16) was close to that indicated for whole cow's milk (r = 2).

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.

scholarly journals Evaluation of a Chemiluminescence Method for Measuring Alkaline Phosphatase Activity in WholeMilk of Multiple Species and Bovine Dairy Drinks: Interlaboratory Study

2006 ◽  
Vol 89 (4) ◽  
pp. 1061-1070 ◽  
Author(s):  
Robert S Salter ◽  
John Fitchen ◽  
B Bain ◽  
M Bella ◽  
S Bergman ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Limit Of Detection ◽  
The United States ◽  
Buffalo Milk ◽  
The European Union ◽  
Chemiluminescence Method ◽  
Relative Standard ◽  
Multiple Species

Abstract Alkaline phosphatase (ALP) is a ubiquitous enzyme in milk with timetemperature destruction similar to that of certain pathogens destroyed in pasteurization. Measurement of ALP to indicate proper pasteurization is a common practice. Recently the public health level for ALP was decreased to 350 mU/L, a level below the sensitivity of older colorimetric ALP methods. This study was conducted within the structure of the International Dairy Federation and the International Organization for Standardization to evaluate the reproducibility of the chemiluminescence method (Charm PasLite) for ALP at 50, 100, 350, and 500 mU/L in whole milk of multiple species to meet new regulations in the United States and proposed regulations in the European Union (EU). Fifteen laboratories from 8 countries evaluated bovine, goat, sheep, and buffalo milk, bovine skim milk, 20% fat cream, and 2% fat chocolate milk. At ALP levels of 350 and 500 mU/L, the average relative standard deviation for repeatability (RSDr) was 7.5%, and the average relative standard deviation of reproducibility was (RSDR) 15%. For ALP at 100 and 50 mU/L, the average RSDr values were 10.5 and 12.6%, respectively, and the average RSDR values were 18 and 25%, respectively. The limit of detection was 20 mU/L. Results are comparable to those obtained with other enzymatic photo-activated system methods such as the fluorometric method. Results indicate that the method is suitable for measuring ALP in the milk of multiple species and in dairy drinks at U.S. and proposed EU levels.

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>

Estimation of Aflatoxin M1 Levels in Some Dairy Products Manufactured from Raw Milk Experimentally Inoculated with Toxin

2019 ◽  
Vol 43 (1) ◽  
pp. 50-58
Author(s):  
H. S. Alnaemi
Keyword(s):  
Dairy Products ◽  
Raw Milk ◽  
Aflatoxin M1 ◽  
Consumer Health ◽  
Goat’S Milk ◽  
White Cheese ◽  
Elisa Technique ◽  
Permissible Levels ◽  
Goat's Milk

     Fate of AflatoxinM1 in soft white cheese and its by-product (whey) and in yogurt locally made from raw sheep's and goat's milk experimentally inoculated with 0.05 and 0.5 µg/l AflatoxinM1 were investigated using ELISA technique. Results reported that AflatoxinM1 was concentrated in cheese at levels significantly higher than that recorded in the raw milk that used for its processing, with a significant decrease in AflatoxinM1 levels in its by-product (whey) comparable to the raw milk used in manufacturing at both inoculated levels. Yogurt produced from raw sheep's milk at second inoculated level exerted AflatoxinM1concentration significantly lower than that present in the milk. Significant differences in AflatoxinM1distribution in cheese and whey produced from sheep's milk comparable to their counterparts produced from goat's milk were recorded. Finally, results revealed the efficacious role of the various dairy manufacturing processes in AflatoxinM1 distribution and the necessity to issue of local legislations concerning the maximum permissible limits for AflatoxinM1 in milk in order to stay within the universal permissible levels for AflatoxinM1 in dairy products to provide greater protection for consumer health. 

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.

scholarly journals A computer-controlled potentiometric/spectrophotometric titrator

1988 ◽  
Vol 10 (2) ◽  
pp. 95-100
Author(s):  
John D. Stong
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Bromophenol Blue ◽  
System Control ◽  
Data Format ◽  
Relative Standard ◽  
Spectrophotometric Titrations ◽  
Computer Controlled ◽  
Major Attention ◽  
Diode Array Spectrophotometer

A laboratory computer controlled potentiometric titrator interfaced to a diode array spectrophotometer is described. The titrator consists of widely used, commercially available components; therefore, major attention is given to modes of interconnection and software implementation in data format and system control. Replicate potentiometric titrations of glycines gave a relative standard deviation in titre of 1.035% and a relative standard deviation in pH of 0.745%. Replicate spectrophotometric titrations of bromophenol blue were analysed at three wavelengths to yield pKa= 3.898 ± 0.075 (1.9% rsd).Methods of data presentation and manipulation are presented.

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