Kaksoisläpäisykoe

Kaksoisläpäisykoe is a Finnish term that translates to "double-pass test" or "double-dilution test" in English. It refers to a method used in analytical chemistry and environmental monitoring to determine the concentration of a substance in a liquid sample. This technique is particularly useful when dealing with complex matrices or when the substance of interest is present at very low concentrations, making direct measurement difficult or prone to interference.

The core principle of the kaksoisläpäisykoe involves passing the sample through two separate analytical separation or concentration steps. The first pass aims to isolate or pre-concentrate the target analyte from the bulk of the sample matrix. This might involve techniques like solid-phase extraction, liquid-liquid extraction, or chromatography. The eluent or concentrated fraction from the first pass is then subjected to a second, often more sensitive, analytical measurement. This second pass could be another separation step to further purify the analyte or directly a highly sensitive detection method such as mass spectrometry or highly selective chromatography.

The advantage of the double-pass method lies in its ability to significantly reduce background noise and matrix effects that could otherwise interfere with accurate quantification. By effectively removing interfering substances in the first step, the sensitivity and reliability of the final measurement are greatly enhanced. This makes it a valuable tool for analyzing trace pollutants in water, complex biological fluids, or environmental samples where sample preparation is critical for obtaining meaningful results.