Sensitivity assessment of the modified ABAcard® HemaTrace® and p30 immunochromatographic test cards

Operational forensic laboratories routinely perform immunological assays for detecting various body fluids. The ABAcard® p30 and HemaTrace® immunochromatographic tests from Abacus Diagnostics are used for detecting the p30 enzyme in human semen and human haemoglobin present in blood respectively. In early 2023, manufacturer modifications to the ABAcard® p30 and HemaTrace® tests resulted in a reduction in card size and volume of sample extract used in the recommended protocol. This change in card design and/or the reduced volume of sample extract may alter the sensitivity of the test. This study established and compared the limit of detection (LOD) for the old and newly modified ABAcard® p30 and HemaTrace® test cards. The LOD values showed that the new test cards were approximately 2.4-fold (HemaTrace® test) and 3.4-fold (p30 test) more sensitive than the old cards. Additionally, it was found that the new HemaTrace® test cards were more susceptible to the high dose hook effect. In response to the increased sensitivity, existing data pertaining to the reactivity of these test cards to non-target body fluid and substances warrants re-investigation to ensure positive results are interpreted correctly.