Ractopamine ELISA Test Kit
Catalog No. LSY-10013
The test kit is based on the competitive enzyme immunoassay for the
detection of Ractopamine in the sample. The conjugated antigens is
pre-coated on the micro-well stripes. The Ractopamine in the sample
and the coupling antigens pre-coated on the micro-well stripes
compete for anti-Ractopamine antibodies. After the addition of the
enzyme conjugate, the TMB substrate is added for coloration. The
optical density (OD) value of the sample has a negative correlation
with the Ractopamine concentration in the sample. The value is
compared to the standard curve and the Ractopamine concentration is
2. Technical specifications
Sensitivity: 0.05 ppb
Incubator temperature: 25℃
Incubator time: 30min～15min
Tissue……………………………………………………………………… 0.2 ppb
Urine, tissue 60~120%
- Micro-well strips: 12 strips with 8 removable wells each
- 6× standard solution (1 mL each): 0ppb, 0.05ppb, 0.15ppb, 0.45ppb,
- Enzyme conjugate (7 mL) red cap
- Antibody working solution (7 mL) blue cap
- Substrate A solution (7 mL) white cap
- Substrate B solution (7 mL) black cap
- Stop solution (7 mL) yellow cap
- 20× concentrated washing buffer (15 mL) white cap
- 2× concentrated extracting solution (50 mL X 2) transparent cap
4. Materials required but not provided
- Equipments: microplate reader, printer, homogenizer, nitrogen-drying device,
oscillator, centrifuge, measuring pipets, balance ( a reciprocal
sensibility of 0.01 g)
- Micropipettors: single-channel 20-200 µL and 100-1000 µL, and multi-channel 30-300
- Reagents: NaOH, HCl
5. Sample pre-treatment
Instructions (The following points must be dealt with before the pre-treatment
- Only the disposable tips can be used for the experiments and the
tips must be changed when used for absorbing different reagents;
- Before the experiment, each experimental utensil must be clean and
should be re-cleaned if necessary, in order to avoid the
contamination that interferes with the experimental results.
Solution preparation before sample pre-treatment:
Solution I 0.2M HCl:
Take 17.2mL HCl, add deionized water to 1L.
Solution II 1M NaOH:
Take 4g NaOH, add deionized water to 100mL.
Solution Ⅲ Sample extracting solution:
Dilute 2× concentrated extracting solution with deionized water at
Take 50 µL clear urine, directly detect it (If urine is muddy, must
filter or centrifuge at 4000 r/min for 10 min, then take clear
urine). Store at frozen environment if don’t use.
Fold of dilution of sample: 1
- Weigh 2±0.05 g homogenized tissue sample into 50ml centrifuge tube,
add 3 mL 0.2M HCl, shake thoroughly for 3 min.
- Then add 600ul 1M NaOH and 2.4ml Sample extracting solution, shake
thoroughly for 3 min, centrifuge at above 4000 r/min at room
temperature (20-25 ℃) for 10 min.
- Take 50 µL clear up-layer liquid for analysis. (Note: if there is
fat, remove fat or separate fat, take clear liquid for analysis)
Fold of dilution of sample: 4
6. ELISA procedures
- Bring all reagents and micro-well strips to the room temperature
(20-25 ℃) before use.
- Return all reagents to 2-8 ℃ immediately after use.
- The reproducibility of the ELISA analysis, to a large degree,
depends on the consistency of plate washing. The correct operation
of plate washing is the key points in the procedures of ELISA.
- For the incubation at constant temperatures, all the samples and
reagents must avoid light exposure, and each microplate should be
sealed by the cover membrane.
6.2 Operation procedures
- Bring test kit to the room temperature (20-25 ℃) for at least 30
min, note that each liquid reagent must be shaken to mix evenly
- Put the required micro-well strips into plate frames. Re-sealed the
unused microplate, stored at 2-8 ℃, not frozen.
- Washing buffer prepare: dilute 15ml 20× concentrated washing buffer
with deionized water at 1:19 (1 part 20× concentrated washing
buffer + 19 parts deionized water ), or prepare as quantity needed.
- Numbering: number the micro-wells according to samples and standard
solution; each sample and standard solution should be performed in
duplicate; record their positions.
- Add 50 µL of the sample or the standard solution into separate
duplicate wells; add 50 µL of enzyme conjugate and 50 µL of the
antibody working solution into each well, seal the microplate with
the cover membrane, mix gently by shaking the plate manually, and incubate at 25 ℃ for 30 min.
- Pour liquid out of microwell, flap to dry on absorbent paper; add
250 µL/well of washing buffer, wash for 15-30 seconds, then take
out and flap to dry with absorbent paper, repeat 4-5 times. (if
there are the bubbles after flapping, cut them with the clean tips)
6 Coloration: add 50 µL of the substrate A solution, 50 µL of the B
solution into each well. Mix gently by shaking the plate manually,
and incubate at 25 ℃ for 15 min at dark for coloration.
7 Determination: add 50 µL of the stop solution into each well. Mix
gently by shaking the plate manually. Set the wavelength of the
microplate reader at 450 nm to determine the OD value of every
well. (Recommend to read the OD value at the dual-wavelength
450/630 nm within 5 min).
7. Result judgment
There are two methods to judge the results; the first one is the
rough judgment, while the second is the quantitative determination.
Note that the OD value of the sample has a negative correlation
with the Ractopamine in the sample.
7.1 Qualitative determination
The concentration range (ng/mL) can be obtained form comparing the
average OD value of the sample with that of the standard solution.
Assuming that the OD value of the sampleⅠ is 0.3, and that of the
sampleⅡ is 1.0, the OD value of standard solutions is: 2.243 for
0ppb, 1.816 for 0.05ppb, 1.415 for 0.15ppb, 0.74 for 0.45ppb, 0.313
for 1.35ppb, 0.155 for 4.05ppb, accordingly the concentration range
of the sampleⅠ is 1.35 to 4.05ppb, and that of the sampleⅡ is
0.15ppb to 0.45ppb.
7.2 Quantitative determination
The mean values of the absorbance values obtained for the average
OD value (B) of the sample and the standard solution divided by the
OD value (B0) of the first standard solution (0 standard) and subsequently
multiplied by 100%, that is
|Percentage of absorbance value =||B||×100%|
B—the average OD value of the sample or the standard solution
B0—the average OD value of the 0 ng/mL standard solution
Draw the standard curve with the absorption percentages of the
standard solutions and the semilogarithm values of the Ractopamine
standard solutions (ng/mL) as Y- and X-axis, respectively. Read the
corresponding concentration of the sample from the standard curve
by incorporating its absorption percentage into the standard curve.
The resulting value is subsequently multiplied by the corresponding
dilution fold, finally obtaining the actual concentration of
Ractopamine in the sample.
Using the professional analyzing software of this kit will be more
convenient for the accurate and rapid analysis of a large amount of
samples. (Please contact us for this software)
- The room temperature below 25 ℃ or the temperature of the reagents
and the samples being not returned to the room temperature (20-25
℃) will lead to a lower standard OD value.
- Dryness of the microplate in the washing process will be
accompanied by the situations including the non-linear standard
curves and the undesirable reproducibility; So continue to next
step immediately after washing.
- Mix evenly, wash plate completely, the reproducibility of the ELISA
analysis, to a large degree, depends on the consistency of plate
- The stop solution is the 2 M sulfuric acid solution, avoid
contacting with skin.
- Do not use the kit exceeding its expiry date. The use of diluted or
adulterated reagents from the kits will lead to the changes in the
sensitivity and the detecting OD values. Do not exchange the
reagents from the kits of different lot numbers to use.
- Put the unused microplate into an auto-sealing bag to re-seal it.
The standard substance and the colourless color former is light
sensitive, and thus they cannot be directly exposed to the light.
- Discard the colouration solution with any color that indicates the
degeneration of this solution. The detecting value of the 0
standard solutin of less than 0.5 (A450 nm< 0.5 ) indicates its
- The optimum reaction temperature is 25 ℃, and too high or low
temperatures will result in the changes in the detecting
sensitivity and OD values.
9. Storage and expiry date
Storage: store at 2-8 ℃, not frozen.
Expiry date: 12 months; date of production is on box.
Note: If the Vacuum package of microplate has leakage, it is still
valid to use, do not affect the test result, be relax to use.