Evaluating the Interference of Residual 'Teepol' Detergent on Serum Electrolytes, Protein, and Cholesterol: An In-Vitro Study

Abstract

INTRODUCTION: In low-resource settings, reusing blood collection tubes cleaned with detergents such as 'Teepol' is common due to economic constraints. However, residual detergent may interfere with biochemical assays. This study evaluated the effect of residual 'Teepol' on serum electrolyte, total protein, and cholesterol, with emphasis on direct ion-selective electrode (ISE) methods. METHOD: A controlled interference experiment was conducted using pooled human serum spiked with increasing concentrations of 'Teepol' (0%, 0.2%, 0.5%, and 1.0% v/v of original detergent). Serum sodium and potassium were measured using direct ISE (Ortho_Vitros® 4600), while total protein and cholesterol were measured via colorimetric methods (BS 800M). All analytes were tested in a single run to avoid inter-run variability. Statistical significance was assessed via Pearson correlation and comparison against 95% confidence intervals derived from quality control data. RESULTS: Serum sodium and potassium showed a concentration-dependent decline with increasing 'Teepol'. At 1.0%, sodium decreased by ~12% and potassium by ~43% compared to control, with values falling outside the 95% confidence intervals, confirming significant interference. Total protein and cholesterol measurements remained within expected analytical variation. Strong negative correlations were observed for sodium (R=-0.966) and potassium (R=-0.989) with 'Teepol' concentration (p< 0.05). CONCLUSION: Residual 'Teepol' ≥0.5% v/v significantly interferes with serum sodium and potassium measurements using direct ISE. These findings highlight the importance of strict tube-washing protocols or the use of disposable tubes for critical assays. Inconsistent cleaning practices in low-resource laboratories may allow such interference, posing a risk to result accuracy and clinical decision-making.