Pesticide residue rapid test reagent which has the characteristic of well stability and high sensitivity, and could be used on various types of pesticide detecting instrument.

1. Principle

Pesticide of organophosphorus and carbamate could inhibit the activity of cholinesterase under certain conditions. Whether the samples contain organophosphorus or carbamate could be determined through the calculation of inhibition rate, which has positive correlation with pesticide concentration .  

2. Reagents preparation

2.1 Buffer solution: Dissolve one pack of buffer powder with 1000mL pure water or distilled water, store at room temperature. 

2.2 Cholinesterase: Dissolve one bottle of cholinesterase with 16ml buffer solution, store at 4℃.

2.3 Chromogenic agent: Dissolve one bottle of chromogenic powder with 27.5mL buffer solution , store at 4℃. 

2.4 Substrate: Dissolve one bottle of substrate with 12mL pure water or distilled  water, store at 4℃

3. Sample preparation

3.1 Weigh 1g vegetable samples (1cm shape) . 

3.2  Soak the samples with 5mL buffer solution, shake it for 2~3mins. Stand it for 1-2mins.

4. Add solution on 96 holes plate

4.1 Add 50μL chromogenic reagent and cholinesterase respectively into corresponding poles on 96 holes plate.

4.2 Add 150μL buffer solution as contrast sample in Column 1 .

4.3 Add 150μL testing sample respectively in other holes.

4.4 Stand for 10-15mins

4.5 Add 20μL substrate respectively in the holes in which there are contract sample and testing sample. 

5. Starting instrument

Connect the instrument with power, press the “enter” button allowing the instrument to self-checking which will take about 1min, instrument is ready to use after self-checking process. 

6. Results:

Inhibition rate could be calculated by formula: [( ΔΑ 0 －ΔΑ t )/ ΔΑ 0 ]×100%;

Normally, Inhibition rate could be calculated by pesticide detecting instrument automatically. 

Inhibition rate≥50%: Positive result, it is recommended to detect again with gas chromatography.

Inhibition rate≤50%: Negative result.

Remark : If the inhibition rate is near 50%, the test should be repeat again to make sure whether the testing sample is OK or not. 

Attention:

In actual production, the lowest limit maybe fluctuate due to the variation of products types and activity of enzyme. And it needs to be adjusted according to customers’ requirement. 

7. Retention Period 

This kind of pesticide residue rapid test reagent is very stable, and it can be transported in room temperature. For long term storage, it should be stored at 4℃, and the expiration time is 12 months. If it is stored in room temperature or normal temperature, the expiration time is 3-6 months. 

8. Matters need attention

8.1 Pesticide residue test reagent include 12 packages of buffer powder, 6 bottles of cholinesterase, 4 bottles of Chromogenic reagent, and 4 bottles of substrates.

8.2 When using any reagent , please exhaust the open one before reopening a new one in case they go bad. 

8.3 Biochemical reaction will occur immediately when enzyme, substrate and chromogenic reagent meet together. So pipette and container should be labeled ,used alone in order to avoid cross-contamination . 

8.4 When sucking the reagent from the bottle, it is strictly forbidden to inject the reagent back to the bottle.