CN110927078A - Method for detecting vitamin A in blood - Google Patents

Abstract

Vitamin A interacts with antimony trichloride in chloroform to produce a blue substance, the shade of which is proportional to the amount of vitamin A contained in the solution. Although the blue substance is unstable, its absorbance at a wavelength of 620nm can be measured with a spectrophotometer for a certain period of time. The invention discloses a method for detecting vitamin A in blood, which comprises the steps of grinding, extracting, concentrating and the like. The method is simple and convenient in operation, high in analysis speed and good in effect, and provides accurate and reliable serum vitamin A detection results for clinic.

Description

Method for detecting vitamin A in blood

Technical Field

The invention relates to a method for detecting vitamin A in blood.

Background

Vitamin A is one of essential nutrients in the growth and development process of human bodies, and vitamin A deficiency can cause the occurrence of nyctalopia and also cause immune dysfunction, so that a plurality of infectious diseases such as measles and the like can occur. There are many methods for detecting vitamin A in blood, but there are problems of reagent instability and interference of phytofluene.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a method for detecting vitamin a in blood, comprising the steps of:

(1) diluting vitamin A standard application solution with chloroform;

(2) grinding: accurately weighing 2-5 g of sample, putting the sample into a mortar containing 3-5 times of anhydrous sodium sulfate by weight, grinding until the water in the sample is completely absorbed, and homogenizing;

(3) extraction: carefully transferring the ground substance into a conical flask with a plug, accurately adding 50-100 mL of diethyl ether, covering the plug, vigorously shaking for 2 minutes to dissolve the vitamin A in the diethyl ether, and placing the conical flask in ice water for 1-2 hours until the ethyl ether solution is clear.

(4) Concentration: taking 2-5 mL of clear ether extract, putting the clear ether extract into a colorimetric tube, evaporating the clear ether extract to dryness in a water bath at 70-80 ℃ by air suction, immediately adding 1mL of chloroform to dissolve residues, adding 1 drop of acetic anhydride and 9mL of antimony trichloride, uniformly mixing, and measuring the light absorption value within 6 seconds.

(5) And finding out the international unit number of the vitamin A in the tube to be detected from the standard curve according to the detected light absorption value, and obtaining the content of the vitamin A in the sample according to the dilution relation.

Further, vitamin E or lecithin is added in the step (4).

The method is simple and convenient to operate, high in analysis speed and good in effect, and provides accurate and reliable serum vitamin A detection results for clinic. In the step (4), the vitamin E or lecithin is beneficial to stabilizing the vitamin A, increasing the stability of the chemical reaction, prolonging the light absorption time and improving the detection precision.

Detailed Description

The water used in the invention is distilled water. Preparing a reagent of trichloromethane, wherein the trichloromethane does not contain decomposition products, otherwise, the trichloromethane can destroy the vitamin A. The reagent should be tested for the presence of decomposition products, and if so, the reagent should be washed several times with water in a separating funnel, dehydrated by adding anhydrous sodium sulfate or calcium chloride, and then distilled.

Instruments and devices: common laboratory equipment, a spectrophotometer, and a reflux condenser.

The operation steps are as follows:

vitamin A is extremely vulnerable to light, and experimental procedures should be performed under weak light or with a brown glass instrument.

(1) Diluting vitamin A standard application solution with chloroform;

(2) grinding: accurately weighing 2-5 g of sample, putting the sample into a mortar containing 3-5 times of anhydrous sodium sulfate by weight, grinding until the water in the sample is completely absorbed, and homogenizing;

(3) extraction: carefully transferring the ground substance into a conical flask with a plug, accurately adding 50-100 mL of diethyl ether, covering the conical flask, vigorously shaking for 2 minutes to dissolve the vitamin A in the diethyl ether, and placing the conical flask in ice water for 1-2 hours until the diethyl ether solution is clear;

(4) concentration: taking 2-5 mL of clear ether extract, putting the clear ether extract into a colorimetric tube, evaporating the clear ether extract to dryness in a 70-80 ℃ water bath by air suction, immediately adding 1mL of chloroform to dissolve residues, adding 1 drop of acetic anhydride and 9mL of antimony trichloride, adding 1 drop of vitamin E or lecithin, uniformly mixing, and measuring the light absorption value within 6-8 seconds;

(5) and finding out the international unit number of the vitamin A in the tube to be detected from the standard curve according to the detected light absorption value, and obtaining the content of the vitamin A in the sample according to the dilution relation.

And (3) vitamin E or lecithin is added in the step (4), so that the stability of vitamin A is facilitated, the stability of the chemical reaction of the vitamin A is improved, the light absorption time is prolonged, and the detection precision is improved.

Preparation of a standard curve: a certain amount of vitamin A standard solution is accurately taken and put into 4-5 volumetric flasks, and a standard series is prepared by trichloromethane. And sequentially taking 1mL of trichloromethane and 1mL of standard serial use solution from the colorimetric tubes with the same quantity, and adding 1 drop of acetic anhydride into each colorimetric tube to prepare a standard colorimetric column. At the wavelength of 620nm, trichloromethane is used for adjusting the absorbance to zero, and 9mL of antimony trichloride-trichloromethane solution is quickly added before the standard colorimetric arrays are sequentially moved into the light path. And measuring the absorbance within 6s, and drawing a standard curve graph by taking the absorbance as the ordinate and the vitamin A content as the abscissa.

And (3) sample determination: 10mL of chloroform was added to a colorimetric tube, and 1 drop of acetic anhydride was added as a blank solution. And adding 1mL of trichloromethane into the other colorimetric tube, and respectively adding 1mL of sample solution and 1 drop of acetic anhydride into the other colorimetric tube. The other steps are the same as the preparation of the standard curve.

And (3) calculating: x = C/m V100/1000

In the formula: x — amount of vitamin a in the sample, mg/100g (e.g. 0.3 μ g vitamin a per 1 international unit);

c, checking the content of vitamin A in the sample by a standard curve, namely mu g/mL;

m is sample mass, g;

v is the volume of chloroform added after extraction, mL;

100-per hundred grams of sample.

Claims (2)

1. The detection method of vitamin A in blood is characterized in that: the method comprises the following steps:

(1) diluting vitamin A standard application solution with chloroform;

(2) grinding: weighing 2-5 g of sample, putting the sample into a mortar containing 3-5 times of anhydrous sodium sulfate by weight of the sample, grinding until the water in the sample is completely absorbed, and homogenizing;

(3) extraction: transferring the ground substance into a conical flask with a plug, adding 50-100 mL of diethyl ether, covering the plug, shaking vigorously for 2 minutes to dissolve the vitamin A in the diethyl ether, and placing the conical flask in ice water for 1-2 hours until the diethyl ether liquid is clear;

(4) concentration: taking 2-5 mL of clear ether extract, putting the clear ether extract into a colorimetric tube, evaporating the clear ether extract to dryness in a water bath at 70-80 ℃ by air suction, immediately adding 1mL of chloroform to dissolve residues, adding 1 drop of acetic anhydride and 9mL of antimony trichloride, uniformly mixing, and measuring the light absorption value within 6 seconds;

(5) and finding out the international unit number of the vitamin A in the tube to be detected from the standard curve according to the detected light absorption value, and obtaining the content of the vitamin A in the sample according to the dilution relation.

2. The method for detecting vitamin A in blood according to claim 1, wherein: adding vitamin E or lecithin in the step (4).