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[Haiyan Lecture Hall] Summary of aseptic sampling knowledge points

[Haiyan Lecture Hall] Summary of aseptic sampling knowledge points

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  • Time of issue:2018-08-29
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[Haiyan Lecture Hall] Summary of aseptic sampling knowledge points

(Summary description)Sampling operation is the first step of the entire laboratory testing process, and it is also an important link that should be guaranteed first. It is often the case that the sample test results are abnormal. We have checked all aspects of the test process, and the result is that the sample has been contaminated during sampling.

  • Categories:Industry News
  • Author:
  • Origin:
  • Time of issue:2018-08-29
  • Views:0
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Sampling operation is the first step of the entire laboratory testing process, and it is also an important link that should be guaranteed first. It is often the case that the sample test results are abnormal. We have checked all aspects of the test process, and the result is that the sample has been contaminated during sampling. In fact, this situation is not uncommon. How to prevent it? We have to start with standardized sampling operations. Since different types of samples should take different sampling operations, in order to make the sampling more scientific, the following is a classification and description of the sampling operations for different samples.

[Haiyan Lecture Hall] Summary of aseptic sampling knowledge points

Liquid sample

In general, it is easier to obtain representative samples for liquid samples. Liquid food is generally placed in a large tank, and can be stirred continuously or intermittently during sampling. For smaller containers, the liquid can be turned upside down before sampling to make it completely mixed. The sample obtained should be placed in a sterilized container and sent to the laboratory. The laboratory should mix the liquid thoroughly before sampling and testing.

Solid sample

According to the different sample materials, the tools used are also different. Common sampling tools for solid samples include scalpel, spoon, cork drill, saw, pliers, etc., which must be sterilized before use. For example, mixed foods such as flour or milk powder have uniform and stable ingredients, and a small amount of samples can be taken for testing. However, bulk samples must be sampled from multiple points, and each point must be processed separately and thoroughly mixed before testing. Meat, fish or similar foods should be sampled both in the epidermis and in the deep layer. Be careful not to be contaminated by the surface when sampling the deep layer. Some foods, such as fresh meat or cooked meat, can be sampled with sterilized scalpels and forceps; frozen foods are not thawed with a saw, wood drill or electric drill, and generally beveled in to obtain deep samples; powdered samples are sampled At this time, a sterile sampler can be inserted into the bottom of the box at an oblique angle, the sample is filled with the sampler and taken out of the box, and then a sterile spoon is used to sample the upper, middle and lower parts of the sampler.

Water sample

When taking water samples, it is best to choose a jar with a dust-proof, ground-top stopper. For chlorine-treated water, add 0.1 mL of 2% sodium thiosulfate solution to 100 mL of water sample after sampling. Special attention should be paid to prevent contamination of the sample when sampling, and the sample should be completely filled with the sampling bottle. If the sample is taken from a faucet, the inside and outside of the faucet mouth should be wiped clean. Turn on the faucet and let the water flow for a few minutes, turn off the faucet and burn with an alcohol lamp, turn on the faucet again and let the water flow for 1-2 minutes, then take the sample and fill the sampling bottle. This sampling method can ensure the quality of the bacteriological analysis of the water supply system. However, if the purpose of the test is to trace the source of microbial contamination, it is recommended that the sample should be sampled before the faucet is sterilized. The sample should be smeared with a cotton swab on the inside and outside of the faucet. Detect the possibility of contamination of the tap itself. When taking water samples from reservoirs, ponds, wells, rivers, etc., use sterile instruments or tools to take the bottle and open the stopper. When taking samples in flowing water, the mouth of the bottle should be directly facing the water flow. The official sampling procedures of most countries have clearly stipulated the equipment used for sampling. If you do not have appropriate sampling equipment or temporary sampling tools, you can only operate by hand. However, when sampling, you should be especially careful to prevent hands from touching water samples or taking samples. Inside the bottle.

Packaged food

Small packages of food for direct consumption should be taken from the original package as much as possible, and do not open the seal to prevent contamination before testing; liquid or solid food packaged in barrels or large containers should be taken from several different parts with an aseptic sampler and put into a sterilized container Don’t get too humid inside to prevent the bacteria inherent in the food from multiplying; for frozen foods packed in barrels or large-volume packaging, samples should be taken from several different parts with sterilization tools to make them fully representative and deliver the samples Before the laboratory, always keep the samples in a frozen state. Once the sample has melted, do not allow it to be frozen again, just keep it cool.

Surface sampling

The inert carrier can transfer the microorganisms on the surface sample to a suitable medium for microbial detection. This inert carrier can neither cause the death of the microorganisms nor make them proliferate. Such carriers include water, swabs and the like. It is difficult to achieve that the microorganisms neither die nor proliferate, so testing should be performed as soon as possible after sampling. The surface sampling technology can only transfer bacteria directly, and cannot do serial dilution. It is only applicable when the number of bacteria is small. Its biggest advantage is that the sampling process does not damage the sample. Commonly used surface sampling techniques include cotton swab, leaching method, tape method, etc. Here, cotton swab method is taken as an example. For qualitative testing, just apply all the surfaces to be tested. For quantitative testing, the sterile sampling frame must be used to determine the area to be tested. Wrap dry cotton around a 4cm long wooden stick or stainless steel stick with a diameter of 1-1.5mm to make a cotton swab (disposable cotton swabs can also be used for convenience), put it into an alloy test tube, close the lid and sterilize it. When sampling, first wet the swab in the diluent, and then slowly rotate the swab on the surface of the sample to be tested twice in parallel. Ensure that the swab is in the sampling frame during application. After sampling, replace the swab back into the test tube containing 10 mL of the sampling solution.

The above are the operational requirements for aseptic sampling in various situations. The standardization of aseptic sampling is the prerequisite to ensure the accuracy of sample testing. Therefore, we should standardize the operation when sampling to ensure that contamination is eliminated from the source.

Transfer from: GMP Industry News

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