Difference between revisions of "Team:SSHS-Shenzhen/Human Practices/4"

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Internship of how to detect vegetables’ pesticide residue in the Food Inspection Center of Shenzhen
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Learning to quickly detect pesticide residues
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Date: April 4, 2018
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<p id="para"> In order to survey the problems, existent or potential, of pesticide residue on the market, 5 members from our SSHS-Shenzhen team bought several kinds of common vegetables (Choy sum and Pakchoi) from the supermarket to the Food Inspection Center of Shenzhen. With the help of officers, we learned to accurately detect the pesticide residue and even conducted our own experiments.<br><br>
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During the experiment, we firstly sampled the vegetables we bought and turned them into a semi-solid mixture. After that, we took samples from the mixture and started the distill phase, by combining the mixture with ethyl solution and distilling evenly. Then we put it in the fridge with a temperature of -30 Celsius for 5 minutes. After that, we put the mixture into the centrifugal machine to divide them into three layers: a layer of vegetable juice, a layer of water and a layer of ethyl. Then we used the PSA (to pure) and centrifugate for a second time, and finally use the Gas Chromatography-Tandem Mass Spectrometry to inspect the results. <br><br>
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Date: August 18, 2018<br><br>
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After analyzing the data, we found out that the Pakchoi contains three types of pesticide residue which are fliorosilazole 0.057mg/kg, worm nitrile 0.124mg/kg and cypermethrin 0.188mg/kg.<br><br>
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Location: Research lab at Shenzhen University
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According to scientific information, those pesticide residues can induce not only cancer but can also hurt your skin. In conclusion, we found that the pesticides are deleterious to humans. This statement formed a concept that links up the processes towards further investigations.
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We wanted to find out the situation of food safety in small farmer’s markets, where food safety control is less strict. We also want to find a simple pesticide residue detection method, which people can use at home. Thus, we performed another round of pesticide residue detection using quick pesticide detection method. Five of our iGEM team members gathered at the laboratory of Shenzhen University to find out methods for quickly detecting pesticide residues on vegetable leaves. We bought three groups of vegetables from three different places to detect pesticide residues. They are from a small farmer's market, a farmer's market and a supermarket (Renrenle supermarket). The three vegetables are Pak Choi, Chinese flowering cabbage, and Water spinach. Arriving at the lab, everyone appeared to be a little overwhelmed. At first glance, detecting residues emerged as a complicated matter.<br> <br>
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But when we really got started, we found that the method of quickly detecting pesticide residues is rather simple and convenient. Generally, there are two methods for detecting pesticide residues on vegetable leaves: one is to use a pesticide residue detector; the other is to employ test strips. We chose the second method, thus ordering test strips online and completing our pesticide residue test under the guidance of Deng Zihan's father.<br> <br>  
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Let's take a look at the process of using those pesticide residue test strips:</p>
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Unpack the pesticide residue test strip, take out the eluent and the pesticide residue test strips. Drop 3-5 drops of eluent on one leaf and gently rub it with another leaf. Transfer the eluent onto the white tablet on the test strip and wait for 10 minutes. Fold the test strip in half and press it tightly for 3 minutes. Unfold the strip and interpret the results based on the color change on the white tablet. Compare the strip to a blank control strip. If the white tablet remains uncolored or turns slightly blue, the results are positive. A white color shows a strong positive result, indicating high pesticide residue. A light blue color shows a weak positive result, indicating low pesticide residue. A sky-blue color is identical to the blank control strip, showing a negative result. Our final results are carefully documented. Based on our test results, there were small amount of pesticide residues in the samples we tested.<br> <br>  
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Although the test strips may not have the precision and accuracy of a pesticide residue detector, they are very convenient and practical as a measure of purchasing food in daily life.<br> <br>  
 
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Latest revision as of 08:43, 15 October 2018

2018.igem.org/Team:SSHS-Shenzhen) Title

Title

Learning to quickly detect pesticide residues

Date: August 18, 2018

Location: Research lab at Shenzhen University

We wanted to find out the situation of food safety in small farmer’s markets, where food safety control is less strict. We also want to find a simple pesticide residue detection method, which people can use at home. Thus, we performed another round of pesticide residue detection using quick pesticide detection method. Five of our iGEM team members gathered at the laboratory of Shenzhen University to find out methods for quickly detecting pesticide residues on vegetable leaves. We bought three groups of vegetables from three different places to detect pesticide residues. They are from a small farmer's market, a farmer's market and a supermarket (Renrenle supermarket). The three vegetables are Pak Choi, Chinese flowering cabbage, and Water spinach. Arriving at the lab, everyone appeared to be a little overwhelmed. At first glance, detecting residues emerged as a complicated matter.

But when we really got started, we found that the method of quickly detecting pesticide residues is rather simple and convenient. Generally, there are two methods for detecting pesticide residues on vegetable leaves: one is to use a pesticide residue detector; the other is to employ test strips. We chose the second method, thus ordering test strips online and completing our pesticide residue test under the guidance of Deng Zihan's father.

Let's take a look at the process of using those pesticide residue test strips:







Unpack the pesticide residue test strip, take out the eluent and the pesticide residue test strips. Drop 3-5 drops of eluent on one leaf and gently rub it with another leaf. Transfer the eluent onto the white tablet on the test strip and wait for 10 minutes. Fold the test strip in half and press it tightly for 3 minutes. Unfold the strip and interpret the results based on the color change on the white tablet. Compare the strip to a blank control strip. If the white tablet remains uncolored or turns slightly blue, the results are positive. A white color shows a strong positive result, indicating high pesticide residue. A light blue color shows a weak positive result, indicating low pesticide residue. A sky-blue color is identical to the blank control strip, showing a negative result. Our final results are carefully documented. Based on our test results, there were small amount of pesticide residues in the samples we tested.

Although the test strips may not have the precision and accuracy of a pesticide residue detector, they are very convenient and practical as a measure of purchasing food in daily life.