Abstract: Disclosed is a convenient sample preparation method for a medium suspected of containing contaminants, the method comprising a) passing a known volume of said medium through a filter from an influent side to an effluent side thereby concentrating the contaminants on the influent side of the filter, b) contacting the influent side of the filter with a liquid vehicle containing at least one substrate that through interaction with the contaminants each produces a detectable moiety, c) and allowing the substrate to interact with the contaminants on the influent side of the filter for a period of time, which is sufficient to allow the detectable moiety to be detected in the liquid vehicle. The method may further comprise a detection step, where the amount of detectable is determined in the liquid vehicle, preferably after the liquid vehicle has been separated from the contaminant, e.g. by passing the liquid vehicle through the filter and performing a measurement on the contaminant free liquid vehicle.

Abstract: Disclosed is a convenent sample preparation method for a medium suspected of containing contaminants, the method comprising a) passing a known volume of said medium through a filter from an influent side to an effluent side thereby concentrating the contaminants on the influent side of the filter, b) contacting the influent side of the filter with a liquid vehicle containing at least one substrate that through interaction with the contaminants each produces a detectable moiety, c) and allowing the substrate to interact with the contaminants on the influent side of the filter for a period of time, which is sufficient to allow the detectable moiety to be detected in the liquid vehicle. The method may further comprise a detection step, where the amount of detectable is determined in the liquid vehicle, preferably after the liquid vehicle has been separated from the contaminant, e.g. by passing the liquid vehicle through the filter and performing a measurement on the contaminant free liquid vehicle.

Abstract: Disclosed is a convenent sample preparation method for a medium suspected of containing contaminants, the method comprising a) passing a known volume of said medium through a filter from an influent side to an effluent side thereby concentrating the contaminants on the influent side of the filter, b) contacting the influent side of the filter with a liquid vehicle containing at least one substrate that through interaction with the contaminants each produces a detectable moiety, c) and allowing the substrate to interact with the contaminants on the influent side of the filter for a period of time, which is sufficient to allow the detectable moiety to be detected in the liquid vehicle. The method may further comprise a detection step, where the amount of detectable is determined in the liquid vehicle, preferably after the liquid vehicle has been separated from the contaminant, e.g. by passing the liquid vehicle through the filter and performing a measurement on the contaminant free liquid vehicle.

Abstract: The invention facilitates a determination of the rate at which soil organic nitrogen is converted to inorganic nitrogen or mineral nitrogen. This conversion is known as N-mineralization. The total release of plant available nitrogen in a soil, i.e., the gross N-mineralization rate quantifies the conversion in the soil of organic nitrogen to inorganic nitrogen. The present invention provides a quick and reliable method for measuring the gross N-mineralization rate of a soil sample. The method exploits that a microbial enzyme activity of a functional ornithine acid cycle present in said sample is correlatale with the rate or gross N-mineralization of that same sample. The method of the invention can be used e.g. in a determination of the amount of a nitrogen-containing fertilizer to be applied to a soil such as e.g. a field of agricultural crops.

Abstract: A method for selectively determining a fungal biomass by detection of a fungal enzymatic activity that is present in substantially all fungal species, such as enzymes involved in chitin metabolism (chitinase, chitin synthase, chitosanase, N-acetyl-glucosaminidase and &bgr;-N-acetylhexosamidase). The invention can be used for detecting a fungal biomass in environmental samples, food products, plant material, building materials, industrial fungal cultures or sample from a human being or animal including blood samples. In particular, 4-methylumbelliferyl-N-acetyl-&bgr;-D-glucosaminide is used as substrate for &bgr;-N-acetylhexosamidase (EC 3.2.1.52). This enzyme activity correlates with the amount of fungal biomass present in a sample.