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Products > Human-Field > Human African Trypanosomiasis > FAQ
Human African Trypanosomiasis - FAQ
Is the buffer the same for all Coris BioConcept kits? If I need some more for my tests, may I use the one from another kit?
According to the "Instructions For Use", it is not allowed to exchange buffer between kits. If you have some volume problems, please contact your distributor who is able to provide additional vials. Nevertheless, the buffer is the same within one product of different lot numbers (e.g. HAT Sero K-SeT buffer exchange between different lots will not give rise to any problem on the tests taking into account the validity (expiration date) of the buffer used). At present, 9 different buffers are used in Coris’products.
|
Buffer |
Coris BioConcept's kits |
|
Extraction Buffer |
RSV Respi-Strip, RSV Respi K-SeT |
|
Saline Buffer |
Influ-A&B Respi-Strip |
|
RE-A Buffer |
Influ A+B K-SeT |
|
HC Dilution Buffer |
Adeno Respi K-SeT, Adeno Respi-Strip |
|
Hydro-K Buffer |
Adeno Respi K-SeT, Adeno Respi-Strip |
|
P-Buffer |
Legionella K-SeT |
|
BL-A Buffer |
HATSeroK-SeT |
|
ST-A Buffer |
C. diff-Strip, Clostridium K-SeT |
|
Sample Dilution |
all others products |
Detection kits based on PCR method (T.cruzi OligoC-Test and Leishmania OligoC-Test) have their own running buffer.
When dipping the stick in diluted sample, the level of sample passes beyond the limit indicated by the arrows at the bottom of the stick. Is there any consequence on the test reactivity?
The red arrow indicates the limit that could not be exceeded beyond during any incubation.
It could happen that the in some cases operator exceeds the indicated limit line by using different but routinely used tubes in laboratories. However, it is still possible to security a validate test as long as the incubation level is still below1cm (i.e. the green line indicated on the figure) while the gold conjugate is placed at 2cm from the bottom of the stick.
What happens when the clinical specimen is a strongly positive specimen? What about the control line?
There are two different kinds of conjugates in the strip: a specific reagent for test line and a specific reagent for the control line. A strong positive specimen has NO effect on the intensity of the control line onto the nitrocellulose of the strip. As long as the control line appears with whatever intensity level, the test should be regarded as valid.
Why does the control line sometimes appear very weak while the test line is positive?
Control line is aimed to ensure that chromatography has been performed up to the top of the strip. It is not related with the result of the diagnostic itself.Sometime, the control line might be "slightly weak" without any precise reason. It could be only an effect of the sample migration and/or responsiveness at the control line. To sum up, the control line is aimed to validate the test conditions using diverse specimen.
Why is stability relatively short after opening of individual pouches containing cassette?
The red arrow indicates the limit that could not be exceeded beyond during any incubation.
It could happen that the in some cases operator exceeds the indicated limit line by using different but routinely used tubes in laboratories. However, it is still possible to security a validate test as long as the incubation level is still below1cm (i.e. the green line indicated on the figure) while the gold conjugate is placed at 2cm from the bottom of the stick.
How to use correctly Coris BioConcept's kits?
- Always store the reagents at the indicated storage temperature : between 4 and 30°C for all kits except for Oligochromatographic kits which contain Ampli-Reagents that requires to store at –20°C
- Always use gloves manipulate kit components and samples
- Always use the provided buffer (Extraction, Dilution, …) even for the sample already diluted (e.g. in a transport medium)
- Always ensure that the solution sample – buffer is homogenous before testing
- Always ensure the sample-buffer immerse below the limit line marked by red arrow on the strip in order to avoid colloidal gold conjugate dilution in the buffer
- Always read the results when the stick is wet after 15 minutes of run.
- After opening of the tube which contains the strip format of kit HAT Sero K-SeT, quality is guaranteed during 3 weeks
- After opening of the pouche which contains the cassette format of kit HAT Sero K-SeT, run the test immediately Always close the tube after every use to avoid that strips become wet. Always leave the desiccant inside the tube. If storing the strips' tube at 4°C, always ensure to warm up to room temperature before proceeding the test
How shall we use positive controls with our kits?
The positive control should be used and diluted with the provided buffer of the respective kit. The mixture should be well homogenized before testing. Follow the “Instruction for Use” of each positive control.
How many tests can be performed with a positive control?
It could be various between positive controls forms, e.g. freeze-dried or liquid. The dilution level of positive control will determine the number of possible tests. Please refer to the “Instruction for Use” of each positive control.
The bottom of the nitrocellulose (visible in reading window of the K-SeT tests) shows a pinkish aspect. Is it normal?
No. Maybe the sticker covering the bottom of the nitrocellulose is peeled off. In this case, the test is invalidated. Please perform the test with another test.
The liquid does not go up the strip inside the K-SeT test.
Invalid migration may be due to a lack of buffer deposited to start the test or to excessive evaporation during the test. Lack of buffer is adjusted to the next test by depositing an exact volume of buffer (85μl) as recommended in the "Instruction for Use" of the kit. To avoid excessive evaporation, the cassette must be left in the pouch for the15 minutes of reaction.
Is it a problem if the test has "run" more than the recommended time?
Yes. It might cause the appearance of false positive signal on test.
The signal of the test line is very weak in comparison with the control line. Do I have to consider that the result is positive?
The control line is aimed to ensure the user that the chromatography is performed up to the top of the strip. It does not give any indication on the diagnostic result. Whenever a signal is observed on the test line (weak or strong), it means that the sample is positive for the test of interest.
Is it important to dispense the sample (blood/serum/plasma) and buffer at different locations in the sample well ?
Yes. Whole blood (25μl) or serum/plasma (15μl) should be dispensed into the inner side of the device sample well as illustrated below and the BL-A buffer (85μl) into the outer side of the sample well.
This is a good way to proceed in order to avoid a decrease in signal intensity on the test line of a test with HAT positive specimens.
Should we completely slide the device within the pouch during the test reaction
(15 minutes) ?
Yes. The device must be put back into the pouch to prevent excessive evaporation of buffer which could cause invalid results (no line control) or false-positive signal.
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