SG Diagnostics

SG Diagnostics COVID-19 Saliva Antigen Rapid Test Kit

The SG Diagnostics COVID-19 Saliva Antigen Rapid Test Kit (Colloidal Gold- Based) is a single-use test kit intended to detect the novel coronavirus SARSCoV- 2 that causes COVID-19 from self-collected saliva samples in individuals with known or suspected COVID-19 infection. This test utilizes a lateral flow immunoassay technology for the qualitative detection of spike and nucleocapsid protein antigens of SARS-CoV-2.


The novel coronavirus SARS-COV-2 is the causative pathogen for the global pandemic of COVID-19 that has spread to 219 countries. Most infected people will experience mild to severe respiratory illness and recover without special treatment. The most common symptoms are fever, cough and fatigue. Older people and those with underlying medical problems (e.g. cardiovascular disease, diabetes, chronic respiratory disease and cancer) are more likely to develop serious illness and serious symptoms include difficulty breathing or shortness of breath, chest pain and loss of speech or movement. It typically takes 5 – 6 days for someone that is infected with the virus for symptoms to appear but it can take up to 14 days in some individuals.


Source: economist.com

The SG Diagnostics COVID-19 Saliva Antigen Rapid Test Kit is an immunochromatographic membrane assay that uses highly sensitive antibodies to detect SARS-CoV-2 spike and nucleocapsid protein antigens from saliva samples via the double antibody sandwich method. 

After loading, the sample will diffuse upwards from the charging end by capillary action, and then the SARS-CoV-2 spike and nucleocapsid protein antigens in the sample will combine with the antibody in the marker pad to form colloidal gold antibody-antigen complex; the complex continues to diffuse upwards to the nitrocellulose membrane with the sample, and then blocked by Test (T) Line packed with antibody to form colloidal gold labeled antibody-antigen-immune complex. The rest unblocked colloidal gold complex continues to move upwards and combine with Control (C) line (quality control line), indicating that the reaction is completed.

  • The assay time is shorter (within 10 minutes as compared to around 24 hours for enzyme-linked immunosorbent assay (ELISA))
  • The cost is cheaper than ELISA
  • The test can be carried out at the point-of-care
  • It is a one-step assay that requires no special skills or instrumentation to achieve the result(s)
  • It has a long shelf life and assay reagents do not require refrigeration or freezer storage
  • The samples do not need to be pre-treated before applying to the assay

Step 1: Collect Saliva Sample

  1. 30 minutes before collecting the saliva sample rinse the mouth with clear water. Do not eat or drink or smoke etc. for the next 30 minutes. Place the tip of the tongue against the root of the upper or lower front teeth to enrich the saliva.
  2. Collect saliva sample – Remove the white cap from the elution tube, hold the funnel upright over the elution tube and gently spit saliva into the funnel. The salivation amount should reach between scale line 1 and scale line 3 of the elution tube
  3. Remove the funnel and close the white lid.

Step 2: Extract Sample
Note: For best performance, sample should be extracted and tested as soon as possible afterwards, no later than 1 hour after collection.

  1. Mix the saliva sample with the elution buffer by turning the elution tube upside down 5 times.
  2. Remove the white lid and cover the elution tube tightly with the nozzle connected to the tube.

Step 3: Run Test
Note: The test cassette must be at room temperature before use, and the test must be operated at room temperature.

  1. Open the test cassette package and lay it flat.
  2. Add 4 drops of the test sample into the oval sample well (marked !).
  3. Start and timer and read the results after 10 minutes. The result is invalid after 15 minutes.
  4. Place the used Funnel, Sample Eluent Vial and Test Cassette in a plastic disposal bag and dispose of the filled bag in your trash bin.


Note: In a valid, tested device, a red line appears at the Control Line position, confirming that the sample has flowed through the test strip and the reagents are working.

The test results are analyzed as follows:

A negative specimen will give a single red colored Control Line in the top half of the window, indicating a negative result. This Control Line means that the detection part of the test was done correctly, but no COVID-19 antigen was detected.

Note: Negative result implies that you do not have SARS-CoV-2 at the time of testing.

A positive specimen will give two red colored lines. This means that COVID- 19 antigen was detected. Specimens with low levels of antigen may give a faint Sample Line. Any visible red colored Sample Line is positive.

Note: Positive result implies that you are infected with SARS-CoV-2. Follow the advisory of your local health department. Please quarantine yourself at home and do everything in order to avoid infecting others.

If no lines are seen, if just the red Test Line is seen, or if the red Control Line is not seen, the assay is invalid. Invalid tests should be repeated.

Note: When you are tested positive or negative, please follow the national guidelines for COVID-19 in the country you are based.

Coming soon

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Test Kit Specifications Materials Provided

Test Cassettes (10/2)
A test cassette consists of a test strip, packed individually in a sealed desiccant foil pouch.
Disposable Funnel (10/2)
Single-use funnel for saliva collection
Sample Eluent (10/2):
0.5mL of phosphate buffer with surfactant
Product Insert (1)

Test Kit Characteristics

Assay format
Lateral flow test / immunochromatographic
Testing Time
10 – 15 mins
Type of analyte
Spike protein antigen and Nucleocapsid protein antigen
Sample material

External Clinical Evaluation
Coming soon

For more information, you can download the file below.