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SPECIMEN STABILITY Flipbook PDF
SPECIMEN STABILITY
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XOILL GROUP LIMITED
SPECIMEN STABILITY ANTIGEN TEST KIT NASAL
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold)
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Specimen Stability 1.
Objective
To study the stability of nasal swab specimens under the conditions of 2-8℃, 25℃ and -20℃, so as to determine the storage conditions and valid date of specimen. 2.
Equipment
Thermostat
Thermometer
Refrigerator
3.
Materials
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold): Lot No.2006003, 2006004, 2006005.
Negative specimens:
Negative nasal specimens: 3 specimens (collected from healthy individuals, purchased from Hangzhou KingMed Diagnostics Laboratory Co.,Ltd.)
Positive specimens:
Positive nasal specimens: 3 specimens (prepared by adding inactivated SARS-COV-2 virus to negative NP specimens with titers of 2.7×103 TCID50/mL, namely 20×LoD) 4.
Methods
4.1. Stability study of the specimens stored in 2-8 ℃ condition. Stored 6 (3 positive and 3 negative) of nasal swab specimens and 3 of nasal swab specimens which are near the cut-off value respectively at 2-8 ℃. Tested these specimens by the selected three batches of Lyher kits respectively at first day and repeated the operation every 3 days thereafter until the test result were unqualified. Table 4.1-1 Results of stability study of Specimens Stored At 2-8℃ Condition. (Tested at 2020.06.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 1
2006004 Negative Negative Negative Positive
2006005 Negative Negative Negative Positive
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
Positive Positive Positive Positive Positive
Positive Positive Positive Positive Positive
Positive Positive Positive Positive Positive
Table 4.1-2 Results of stability study of Specimens Stored At 2-8℃ Condition. (Tested at 2020.06.29) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Negative Negative Positive
It can be seen from the above detection results, at 2-8℃, the test results of the nasal swab specimens being stored at 2-8℃ for three days may be false-negative, so the specimens should not be stored for more than 24 hours. 4.2. Specimen stability study at 25 ℃ condition Stored 6 (3 positive and 3 negative) of nasal swab specimens and 3 of nasal swab specimens which are near the cut-off value respectively at 25 ℃. Tested these specimens by the selected three batches of Lyher kits respectively at first day and repeated the operation every 1 hours thereafter until the test result were unqualified. Table 4.2-1 Results of stability study of Specimens Stored At 25 ℃ Condition. (Tested at 2020.06.26, 13:15) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2-2 Results of stability study of Specimens Stored At 25 ℃ Condition. 2
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) (Tested at 2020.06.26, 14:15) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2-3 Results of stability study of Specimens Stored At 25 ℃ Condition. (Tested at 2020.06.26, 15:15) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2-4 Results of stability study of Specimens Stored At 25 ℃ Condition. (Tested at 2020.06.26, 16:15) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2-5 Results of stability study of Specimens Stored At 25 ℃ Condition. (Tested at 2020.06.26, 17:15) Test results of Lyher kits
Specimen
2006003 3
2006004
2006005
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Negative nasal swab1 Negative nasal swab2 Negative nasal swab3
Negative Negative Negative
Negative Negative Negative
Negative Negative Negative
Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
Positive Positive Positive Positive Positive Positive
Positive Positive Positive Positive Positive Positive
Positive Positive Positive Negative Positive Positive
It can be seen from the above test results, at 25 ℃, the test results of the nasal swab specimens being stored in 25 ℃ for five hours may be obtained false-negative, so the specimens should not be stored for more than 4 hours. 4.3. Stability study of the samples stored at -20℃ condition Stored 6 (3 positive and 3 negative) of nasal swab specimens and 3 of nasal swab specimens which are near the cut-off value respectively in a refrigerator set at -20 ℃. Tested these specimens by the selected three batches of Lyher kits respectively at first day and repeated the operation every 30 days thereafter until the test result were unqualified. Table 4.3-1 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.06.26) Test results of Lyher kits Specimen Negative nasal swab1 Negative nasal swab2
2006003 Negative Negative
2006004 Negative Negative
2006005 Negative Negative
Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
Negative Positive Positive Positive Positive Positive Positive
Negative Positive Positive Positive Positive Positive Positive
Negative Positive Positive Positive Positive Positive Positive
Table 4.3-2 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.07.27) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 4
2006004 Negative Negative Negative Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Cut-off nasal swab3
Positive
Positive
Positive
Table 4.3-3 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.08.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.3-4 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.09.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.3-5 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.10.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.3-6 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.11.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 5
2006004 Negative Negative Negative
2006005 Negative Negative Negative
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
Positive Positive Positive Positive Positive Positive
Positive Positive Positive Positive Positive Positive
Positive Positive Positive Positive Positive Positive
Table 4.3-7 Results of stability study of Specimens Stored At -20℃ Condition. (Tested at 2020.12.26) Test results of Lyher kits
Specimen
2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
This study was only tested for 6 months. 4.4. Stability study of specimens stored at -20℃ that repeated freezing and thawing Stored 6 (3 positive and 3 negative) of nasal swab specimens and 3 of nasal swab specimens which are near the cut-off value respectively in a refrigerator set at -20 ℃.Tested these specimens by three batches of Lyher kits respectively.The specimens shall be balanced to room temperature for 1 hour before testing, then restore the specimens in refrigerator at -20℃ at least for 4 hours. And repeated the above operation until the test result were unqualified. Table 4.2.3.-1 Results of stability study of specimens stored at -20℃ that repeated freezing and thawing (Tested at 2020.06.26, 9:02) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2.3.-2 Results of stability study of specimens stored at -20℃ that repeated freezing and thawing (Tested at 2020.06.26, 14:06) 6
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2.3.-3 Results of stability study of specimens stored at -20℃ that repeated freezing and thawing (Tested at 2020.06.26, 20:01) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2.3.-4 Results of stability study of specimens stored at -20℃ that repeated freezing and thawing (Tested at 2020.06.27, 8:35) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
2006004 Negative Negative Negative Positive Positive Positive Positive Positive Positive
2006005 Negative Negative Negative Positive Positive Positive Positive Positive Positive
Table 4.2.3.-4 Results of stability study of specimens stored at -20℃ that repeated freezing and thawing (Tested at 2020.06.27, 14:13) Test results of Lyher kits Specimen 2006003 Negative Negative Negative Positive
Negative nasal swab1 Negative nasal swab2 Negative nasal swab3 Positive nasal swab1 7
2006004 Negative Negative Negative Positive
2006005 Negative Negative Negative Positive
Novel Coronavirus (COVID-19) Antigen Test Kit (Colloidal Gold) Positive nasal swab2 Positive nasal swab3 Cut-off nasal swab1 Cut-off nasal swab2 Cut-off nasal swab3
Positive Positive Positive Positive Positive
Positive Positive Positive Negative Positive
Positive Positive Positive Negative Positive
From the above test results, the treated nasal swab specimens can be frozen and thawed up to 4 times at -20℃. To ensure sample validity, repeated freezing-thawing should not exceed 3 times.
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