Principle

The RPR reagent containing modified VDRL antigen and microparticulate carbon particles, flocculate when mixed with sample containing “regain”.

A reactive specimen is indicated by macroscopically visible black clumps against white background, in contrast nonreactive specimen appear to have smooth uniform light gray colour. This test is a screening test and if positive, further testing with specific confirmatory tests are required.  

Specimen: Serum/Plasma  

Requirement

1. RPR Antigen Suspension   
2. Positive Control Serum   
3. Negative Control Serum  

Procedure

A. QUALITATIVE TEST

1. Using disposable serum dropper, place one free falling drop of serum/plasma or control on the card and spread it to fill the entire circle with the help of disposable applicator stick.  
2. Gently shake the RPR Antigen Suspension bottle to resuspend the particle. From the dropper dispense few drops of the reagent back into the reagent bottle it self to remove air trapped in to the dropper.  
3. Add one free falling drop of RPR Antigen Suspension using antigen delivery dropper. Keep the delivery dropper vertical, exactly at 90o while adding antigen suspension Do not mix.
4. Place the card on the mechanical rotator under humidifying cover and rotate the card for 8 minutes at 100±2 rpm.                   
5. After 8 minutes, immediately remove the card form the rotator; rotate and tilt the card gently by hand
6. Observe the result under a high intensity lamp or strong day light.  

Perform the quantitative test for specimens exhibiting any degree of flocculation or “Roughness”.  

B. SEMI-QUANTITATIVE TEST

1. Place 50μL of 0.9 % saline solution in 2nd, 3rd,4th and 5th circles of the card by using micropipette Do not spread saline solution.   
2. Using micropipette, add 50μL sample to saline in 1st and 2nd circle.  
3. Mix sample with saline in 2nd circle by drawing the mixture up and down for 8 times in the micropipette. Avoid bubble formation.  
4. Aspirate 50μL from 2ndcircle and transfer to 3rd circle. Repeat the same successively upto 5th circle.  
5. Aspirate 50μL from the 5th circle and discard it.  
6. Repeat step no.2-6 of qualitative test for each of diluted sample drop.  
7. Complete test as described in qualitative test procedure. Use a clean tip for each specimen tested.
8. Prepare a higher dilution if necessary in 1:50 nonreactive serum diluent. 
9. The end point is the highest dilution showing visible black clumps.   

Observation table of RPR test

Qualitative test   

Semi-quantitative test