(a) This method describes a procedure for determining the odor (that is, the property that affects the sense of smell) of industrial water and industrial waste water. A suggested system for classifying odors is given as an appendix to the method. The method is applicable to the determination of odor intensity in terms of threshold odor number or odor intensity index (Note 1). Note 1.-—Odor intensity index is the number of times the concentration of the original samples is halved by addition of odor-free water to obtain the least definitely perceptible odor. (b) Industrial effluents may carry a myriad of compounds that contribute to odor difficulties and yet can be measured individually only with difficulty. Combinations of compounds can provide odor intensity or characteristics that cannot be anticipated from individual analyses. (c) Because of the variation in human sensitivity, high precision in determining odor intensity is not possible. There will not always be agreement on odor characteristics by various testers. Odor analysis provides the tool to measure variation in odor intensity at a given sampling point. The degree of variation may indicate the magnitude or importance of an odor problem. Determining the cause of the variation or the source of the objectionable characteristic may define the odor problem better than analysis for individual compounds.

<h4>Rationale</h4>Geosmin and 2-methylisoborneol (2-MIB) are odor-active compounds responsible for earthy off-flavors in fish, creating significant quality concerns in recirculating aquaculture systems (RAS). Their extremely low odor thresholds make rapid and highly sensitive detection essential for maintaining product quality and consumer acceptance in aquaculture production.<h4>Methods</h4>A novel analytical method was developed using static headspace sampling combined with proton transfer reaction-mass spectrometry (PTR-MS) for the detection of geosmin and 2-MIB in aquaculture water. Sample preparation was optimized by sodium chloride addition to enhance salting out, incubation at 90 °C, and maximization of headspace injection speed into the PTR-MS system to improve analyte sensitivity.<h4>Results</h4>The optimized method achieved detection limits of 19 ng·L⁻¹ for geosmin and 4 ng·L⁻¹ for 2-MIB with a total sample screening time of less than 10 minutes. Detection limits were within the same low ng·L⁻¹ range as the odor thresholds of these compounds, enabling quantification at sensorily relevant concentrations associated with off-flavor perception.<h4>Conclusions</h4>This PTR-MS-based approach provides a rapid and sensitive method for objective detection of geosmin and 2-MIB in aquaculture water at concentrations relevant to sensory off-odor impairment. The method shows strong potential for routine monitoring in RAS and may be extended to other volatile compounds and aqueous analytical applications.

through the posterior nares. Thus an odor tasted is often stronger than an odor smelled. Chemically pure water … recorded, while a microscopical examination of the water has seldom revealed the presence of the suspected … have been collected on the sand. When all the water has passed through and before the sand has become

Do powszechnie występujących zanieczyszczeń, szczególnie wód powierzchniowych należą substancje humusowe (SH), w tym rozpuszczalne kwasy fulwowe (KF). SH dotychczas uważane były za substancje zupełnie nieszkodliwe dla człowieka, a usuwane były z wody głównie ze względu na mętność, barwę oraz jako źródło przykrego zapachu. W procesach utleniania oraz dezynfekcji SH są prekursorami substancji kancerogennych oraz mutagennych. Ze względu na ten fakt przeprowadzono analizę studialną ich budowy oraz właściwości, a także stosowanych metod ich unieszkodliwiania.