1 Introduction

According to related reports, some dairy plants may not be able to withstand the temptation of profit. In the case of cows being ill or infertile, blindly in order to increase the milk production of cows, they will use antibiotics and hormones and other banned drugs. Infants and young children may suffer from precocious puberty after consuming milk powder containing hormones, which may cause serious harm to the infants and young children.

The Ministry of Health entrusted the Beijing Municipal Center for Disease Control and Prevention, China Academy of Inspection and Quarantine, and other testing institutions to adopt internationally accepted testing methods ("Methods for the Detection of Hormone Residues in Animal-derived Foods by Liquid Chromatography-Mass Spectrometry-Mass Spectrometry" GB / T21981-2008) After testing a variety of milk powders, the hormone content did not exceed the standard, but people are thinking deeply about the health protection of infants and young children. Many parents have become a startled bird. They do n’t know what kind of milk powder to buy to let their children grow up healthily, so Establishing a simple test method for related hormones is a matter that has both economic benefits and benefits for humanity.

2 Preparation of samples

2.1 Animal muscle, liver, shrimp

Take a representative sample of about 500 g from all the samples taken, remove the fascia, and remove the head and shell of the shrimp. Use a tissue masher to mash them evenly, divide them into two portions, put them into clean containers, seal them, mark them, and store them frozen below -18 ℃.

2.2 Milk

Take about 500g of representative samples from all the samples taken, shake them well, divide them into two parts, put them in clean containers, seal them, mark them, and store them in the refrigerator below 0 ℃ -4 ℃.

2.3 Eggs

Take a representative sample of about 500 g from all the samples taken. After removing the shell, stir thoroughly with a tissue masher, divide into two parts, put them into clean containers, seal them, and mark them at 0 ℃ -4 Store refrigerated below ℃. Note: The sample preparation operation should prevent the sample from being contaminated or the residues in it from changing.

3 Sample extraction and purification

3.1 Extraction

Weigh 5g sample (accurate to 0.01g) in a 50mL plastic centrifuge tube with stopper, accurately add 100μL of internal standard solution (4.15) and 10mL of acetate-sodium acetate buffer solution, vortex to mix, then add β-glucuronidase 100μL of the solution was shaken at 37 ± 1 ℃ for 12h. Take out and cool to room temperature, add 25mL of methanol for ultrasonic extraction for 30min, centrifuge at 10000r / min for 10min at 0 ℃ ～ 4 ℃, transfer the supernatant to a clean beaker, add 100mL of water, mix and wait for purification.

3.2 Purification

The extract was applied to the activated ENVI-Carb national phase extraction column at a rate of 2 mL / min to 3 mL / min. The small column was dried under reduced pressure, and the activated amino column was connected in series below the ENVI-Carb solid phase extraction column. Elute with 6mL of dichloromethane-methanol solution and collect the eluent, remove the small column, and then wash the amino column with 2mL of dichloromethane-methanol solution, the eluent is blown dry under a weak nitrogen flow, and use 1mL of methanol-water solution The residue was dissolved and measured by the LC-MS / MS method.

4 Products available from Hengao Company

4.1 Internal-cut homogenizer

The experiment first is to homogenize the tested sample. The HFJ series of internal homogenizer produced by Hengao Company adopts 316L stainless steel and is corrosion resistant. The rotating speed is adjustable from 5000 to 35000, and is equipped with different diameter cutter heads, which can be selected according to the difficulty of different sample homogenization.

4.2 Mixer

The experiment requires that the standard solution, acetic acid-sodium acetate buffer solution and the sample to be tested are vortex mixed. The HMV series multi-tube mixer produced by Hengao can be selected according to the experiment and the difficulty of mixing the two substances. Different 500-2400r / min Rotation speed to achieve the best extraction effect. This product also has a timing function, without the need for personnel care, saving a lot of manpower. It can process 50 samples at a time, which is beneficial to the experiment of large-scale sample detection. At the same time, it can increase the RSD% value of the parallel experiment in method verification.

4.3 Constant temperature water bath shaker

The experiment requires enzymatic hydrolysis of the sample in a 37 ± 1 ° C water bath with shaking. HWT series constant temperature water bath shaker produced by Hengao Company is made of high-quality stainless steel, which is corrosion-resistant and has a long service life. The temperature control accuracy is ± 1 ℃, which fully complies with the requirements of the national standard GB / T 21981-208. Different speeds, oscillation ranges, heating capacity, etc. can be selected according to the requirements.

4.4 Ultrasonic cleaner

After enzymatic hydrolysis, methanol is added and ultrasonic extraction is required. The HU series or HS series ultrasonic cleaning equipment and pharmacopoeia-specific ultrasonic cleaning series produced by Hengao Company are made of stainless steel embossed material, and the power, degassing and frequency are adjustable, and they can be heated and electronically timed.

4.5 Solid phase extraction instrument

In the experiment, the solid phase extraction method was used to purify the samples. The traditional solid phase extraction equipment produced by Hengao Company used PTFE and 316L stainless steel materials, which have strong corrosion resistance. In addition to the traditional solid phase extraction, Henghao also produced a multi-energy numerical control solid phase extraction instrument. Its main feature is to upgrade the traditional solid phase extraction to semi-automated, 0.01-7mL / min precise speed control, each channel It is independent to avoid cross-contamination and can process 8 samples at the same time, which improves work efficiency.

4.6 Oil-free vacuum pump

There are two types of HP series oil-free vacuum pumps produced by Hengao, and their flow rates are 10mL / mim and 20mL / min, respectively. The main difference between HPD series and HP series is that the flow rate varies from 25mL / mim to 50mL / min and the flow rate can be adjusted according to the experimental requirements.

4.7 Nitrogen blower

The final step in the experiment is to concentrate the sample. The HAC series nitrogen blower produced by Tianjin Hengao Company can be used. The concentration process is completely visible to ensure the safety of the experiment. The purged material can be directly discharged, and the gas flow can also be according to the experimental requirements For adjustment, HAC-II also has the function of quantitative concentration, which does not require personnel to take care, saving a lot of manpower.

The main feature of the HGC series nitrogen blower is the dry heating method, which has the advantages of fast heating rate, accurate temperature control of ± 1 ℃, and the highest temperature can be increased to 120 ℃.

The HSC series nitrogen blower is a water bath heating type nitrogen blower. Its advantages are safe operation and uniform heating. Different numbers of nitrogen blowing needles can be purchased according to the number of samples.

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