## 3 The Nature of Malodorous Gases in Relation to Their Detection
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Measurement** & **Measurement Range** & **Typical Issues and Sources of Errors** & **Ref.** \\ \hline \multicolumn{5}{c}{**Methods based on classical chemical analysis**} \\ \hline \multicolumn{5}{c}{Knowledge of gas composition is required for proper selection of chromatographic column, solvent and operating parameters. Averaging necessary to obtain a representative sample and appropriate sample quantity (signal noise and disturbances). Stable sample dosing required (broad, irregular chromatographic peaks). \\ \hline \multicolumn{5}{c}{Temperature and humidity affect sensor sensitivity and stability. Exceeding the measurement range causes erroneous readings. Long-term exposure to high concentrations leads to sensor degradation. Cross-sensitivity to other gases causes signal disturbances and misinterpretation. Reaction and recovery time may extend measurement duration. Sensor ageing and wear cause sensitivity decline. Regular calibration required. Membrane damage or contamination may block gas access to the electrode, resulting in false results. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of methods for measuring odour nuisance in the air. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measurement** & **Measurement Type** & **Detector Type** & **Disadvantages** & **Advantages** \\ \hline \multicolumn{5}{c}{**Methods Based on Classical Chemical Analysis**} \\ \hline \multicolumn{5}{c}{**Methods Based on Classical Chemical Analysis**} \\ \hline \multicolumn{5}{c}{Chromatographic Analysis} & Emission/Immunision & \begin{tabular}{c} Chemical/Electro- \\ chemical/Optical, etc. \\ \end{tabular} & Difficulties in interpretation for odorant mixtures (synergy, masking, neutralisation & Facilitates the selection of an phenomena) appropriate \\ \hline \multicolumn{5}{c}{**Methods Based on Classical Chemical Analysis**} \\ \hline \multicolumn{5}{c}{Chromatographic Analysis} & Emission/Immunision & \begin{tabular}{c} Chemical/Electro- \\ chemical/Optical, etc. \\ \end{tabular} & Difficulties in interpretation for odorant mixtures (synergy, masking, neutralisation & Facilitates the selection of an phenomena) appropriate \\ \hline \multicolumn{5}{c}{**Methods Based on the Human Nose as a Detector**} \\ \hline \multicolumn{5}{c}{**Methods based on the Human Nose as a Detector**} \\ \hline \multicolumn{5}{c}{Dynamic Olfactory} & Emission & Sensory & \begin{tabular}{c} Lack of chemical composition \\ knowledge—Difficulty in \\ selecting a deodorisation \\ method \\ \end{tabular} & Enables the analysis of gas mixtures \\ \hline \multicolumn{5}{c}{**Inspector Team**} & Immission & Sensory & \
\begin{tabular}{c} Subjectivity in \\ perception—requires strict \\ adherence to procedures \\ The number of personnel \\ required for measurements \\ \end{tabular} &
\begin{tabular}{c} Enables the analysis \\ of gas mixtures \\ Methods most \\ closely resembling \\ human sensory \\ experiences \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Typical measurement ranges and potential sources of errors in the obtained results. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measurement Method** & **Measurement Range** & **Typical Issues and Sources of Errors** & **Ref. ** \\ \hline  & & Cross-sensitivity to other gases causing signal disturbances and misinterpretation. Temperature, humidity, and pressure affect sensitivity and stability. & \\ Optical sensors & 1 ppm–10 ppm & Limited selectivity—response to groups of compounds. Regular calibration required. Low resolution and sensitivity for certain gases. Optical contamination, dust or moisture deposition on sensor surfaces. & \\ \hline  & & Possibility of ionic interference and signal overlap. & \\ Mass sensors & \multirow{2}{*}{ppt–ppm} & \multirow{2}{*}{Effects—interference from other components causing signal disturbances and misinterpretation. Low resolution may cause difficulties in distinguishing compounds with very similar masses.}