After continuous experimentation and debugging, our technicians carefully developed and produced four kinds of immunoassay kits of four kinds of metabolites of furan (furancillin, nitrofurantoin, furantone, furazolidone): tissue (chicken, duck / liver, fish, Shrimp) Honey and other pre-treatment four-in-one test kits have been successfully launched. The sensitivity is 0.05PPB, the detection limit is 0.1PPB, the recovery rate can reach about 90%, and all of them are in the 25 degree reaction. All the operation steps before the point plate are the same, and it is the first in China to develop the true meaning of "four in one." A "factory. This improvement will greatly shorten the working hours of the experimenter .
1. Preparation of the solution
Sample preparation should be prepared :
Solution 1 : 0.1M K 2 HPO 4 solution
Weigh 22.8g K 2 HPO 4 · 3H 2 O with deionized water to dissolve and dissolve to 1L
Dosing 2 : 1M HCL
8.6mL concentrated HCL plus deionized water to a volume of 100mL
Dosing 3 : 1M Â NaOH solution
        Weigh 4g NaOH , add deionized water to make up to 100ml .
Solution 4 : complex solution 1 ×
2 × complex solution should be diluted 1 : 1 before use ( 1 part concentrated solution + 1 part deionized water)
Dosing 5 : washing solution
The 4 0ml concentrated detergent solution (20-fold concentrated) was diluted with deionized water
20 × washings were concentrated before use 1: 19 dilution (washing solution + 1 part Deionized water 19 parts of concentrate) (configurable on demand)
2. Sample pretreatment method
Before the sample processing
When handling any sample, you must pay attention to:
( 1 ) Disposable tips must be used in the experiment, and the tips should be replaced when taking different reagents.
( 2 ) Before the experiment, it is necessary to check whether the various experimental instruments are clean. Clean test equipment must be used to avoid contamination and interference with the experimental results.
Sample processing steps :
( A ) Tissue, honey (chicken, duck / liver, liver, fish, shrimp, etc.)
1. Weigh 1 ± 0.05g homogeneous sample in centrifuge tube;
2 , adding 4ml deionized water, 0. 5 ml  1M hydrochloric acid solution and 100 μl of derivatization reagent fully oscillate ;
3 , incubate overnight at 37 ° C ( about 16 hours ) or 5 6 ° C water bath for 2 hours ;
4 , add 5 ml respectively  0.1M  K 2 HPO 4 solution, 0.4ml  1M NaOH solution and 5 ml of ethyl acetate, shaking for 5 minutes ;
5, at room temperature under 4000 r / min, centrifuged for 10 minutes;
6, 2.5 ml of the supernatant was taken into another centrifuge tube, 50 deg.] C water bath, blown dry with nitrogen;
7, the residue dissolved with 1ml of n-hexane was reconstituted by adding 1 ml working solution shaken sufficiently mixed for 30 seconds; RT 4000 r / min, and centrifuged for 5 min;
8, take 50μl lower for analysis.
( sample dilution factor is 2 )
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