Refinement of a Quantitative Technique for Estimating Alkaline Phosphatase Activity in Milk

Abstract A procedure for determining alkaline phosphatase activity in milk and chocolate milk, based upon the dialysis of phenolphthalein monophosphate and subsequent measurement of absorbance of the dialysate at 550 nm, has been refined. The modified procedure specifies 3 ml milk, 3 drops (0.04 ml/drop) of substrate, and a 3 hr incubation period. These changes have resulted in a decrease in the cost of reagents and higher, more suitable absorbance values. The Scharer modified Spectrophotometric method was used as a reference. The modified method showed an apparent linear relationship which was verified by calculating correlation coefficients, 0.996 for milk and 0.992 for chocolate milk; both of these values are significant at the 1% level.

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UTILIZATION OF PHENOLPHTHALEIN MONOPHOSPHATE TO TO DETERMINE THE PHOSPHATASE ACTIVITY OF MILK1

Journal of Milk and Food Technology ◽

10.4315/0022-2747-35.7.405 ◽

1972 ◽

Vol 35 (7) ◽

pp. 405-409 ◽

Cited By ~ 2

Author(s):

Dick H. Kleyn

Keyword(s):

Alkaline Phosphatase ◽

Phosphatase Activity ◽

Rapid Method ◽

Alkaline Phosphatase Activity ◽

Collaborative Study ◽

Correlation Coefficients ◽

Raw Milk ◽

New Method ◽

Chocolate Milk ◽

Positive Correlations

The properties of alkaline phosphatase as it exists in milk are considered. The more common methods of measuring alkaline phosphatase activity in milk are briefly reviewed, especially those employing substrates possessing “built-in” indicators which produce a chromogen directly upon hydrolysis. The visual procedure employing phenolphthalein monophosphate as the substrate is given. The sensitivity of this method is shown to be far greater than that of the Scharer I (Rapid) method. Results of an AOAC Collaborative study demonstrated that the method yields results that are as precise and either as accurate as or more accurate than those obtained by the Scharer I (Rapid) method. The quantitative spectrophotometric procedure employing the above substrate is presented. Comparison of this method with the Scharer modified spectrophotometric method on milk revealed correlation coefficients (Scharer method: 0.998 and modified new method 0.991) showing very little difference in the positive correlations of absorbance values and % raw milk. For chocolate milk, the values were 0.990 and 0.990 for the respective methods. Collaborative study of this method has demonstrated that the random error of the modified new method is almost twice that of the Scharer technique while the systematic error is only about one-fourth of the latter method.

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Influence of Brand of Dialysis Tubing on a Quantitative Technique for Determining Alkaline Phosphatase Activity of Milk

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/57.3.710 ◽

1974 ◽

Vol 57 (3) ◽

pp. 710-712

Author(s):

Dick H Kleyn ◽

Joseph Jakubowski

Keyword(s):

Alkaline Phosphatase ◽

Phosphatase Activity ◽

Analysis Of Variance ◽

Alkaline Phosphatase Activity ◽

Raw Milk ◽

Regenerated Cellulose ◽

Dialysis Tubing ◽

Quantitative Technique ◽

Modified Method

Abstract A study was conducted to determine the influence of brand of dialysis tubing on the official first action method for alkaline phosphatase activity of milk, 16.B01—16.B05. Two brands of tubing were compared: seamless regenerated cellulose tubing and membrane tubing. Analyses were performed in quintuplet on 8, 5, and 5 samples of milk containing about 0.10, 0.25, and 0.50% raw milk, respectively. Two trials were also conducted to compare the rates of dialysis, using about 0.25% raw milk. An analysis of variance of the data showed that the brand of tubing did have a significant ( P< 0.05) influence on resulting absorbance values, particularly at the higher levels of phosphatase activity. Rates of dialysis were found to agree within ± 0.07 μg phenolphthalein/hr during the 3 hr incubation specified. The modified method has been adopted as official final action.

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LEUCOCYTE METABOLISM IN PREGNANCY

Acta Endocrinologica ◽

10.1530/acta.0.xxxv0575 ◽

1960 ◽

Vol XXXV (IV) ◽

pp. 575-584 ◽

Cited By ~ 2

Author(s):

C. Borel ◽

J. Frei ◽

A. Vannotti

Keyword(s):

Alkaline Phosphatase ◽

Oxygen Consumption ◽

Pregnant Women ◽

Phosphatase Activity ◽

Alkaline Phosphatase Activity ◽

Lactate Production ◽

Glucose Consumption ◽

In Pregnancy

ABSTRACT Enzymatic studies, on leucocytes of pregnant women, show an increase of the alkaline phosphatase activity and a decrease of the glucose consumption and lactate production, as well as of proteolysis. The oxygen consumption, with succinate as substrate, does not vary.

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