# Field Experience for Determination of Formaldehyde in Stack Emissionss
## 3 Results and Discussion
### Analysis  
In Figure 4, three chromatograms obtained by HPLC are shown:  
* The first (a) represents a reference standard used (the concentration values are guaranteed by the sample supplier). The peaks of the chromatograms are described in Table 8;
* The second (b) represents a blank sample, which shows the substantial suitability of the solutions used (the blank samples are real analytical samples not exposed to the fumes but which have been treated exactly like the others);
* The third (c) represents one of the analyzed samples: the sample contains only formaldehydeHyde (H\(-\)CHO and acetaldehyde (CH\({}_{3}\)CHO), compatible with the analyzed analytes. The chromatogram results with a good baseline and very well identified \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Sampling**} & **Humidity** & **H\(-\)CHO** \\  & **(\%)** & **(mg/m3)** \\ \hline
1 & 2.4 & 11.7 \\
2 & 1.7 & 11.4 \\
3 & 1.8 & 9.3 \\
4 & 1.7 & 11.4 \\
5 & 1.9 & 11.0 \\
6 & 1.6 & 10.8 \\
7 & 1.5 & 10.2 \\
8 & 1.6 & 11.4 \\
9 & 1.6 & 11.0 \\
10 & 1.6 & 11.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Humidity and H\(-\)CHO obtained by Lab. RSE. during Second Campaign. Figure 3: Relation between measured humidity and H\(-\)CHO concentrations obtained by Lab. RSE during Second Campaign. peaks, which guarantees good accuracy of results, demonstrating the validity of the method. Figure 4: (**a**) Chromatogram of a reference standard used; (**b**) Chromatogram of a blank sample; (**c**) Chromatogram of a blank sample of one of the analyzed samples. The values of samples obtained by Lab. APPA Trento are shown in Table 11.  
Lab. APPA Trento also analyzed the samples obtained from Lab. RSE to verify the reproducibility of the 2 laboratories. In Table 12, the comparison is shown. Lab. RSE conducted 10 samplings simultaneously with those at Lab. APPA Trento. The results are reported in Table 13, where the main values obtained are reported. The samples are those immediately complexed and analyzed 5 days after collection. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sampling**} & \multicolumn{2}{c}{**Volume of Sampled**} & \multicolumn{2}{c}{**Relative Humidity**} & \multicolumn{2}{c}{**H\(-\)CHO**} \\  & **(L)** & **(\%)** & **(mg/L)** \\ \hline
1 & 34.449 & 11.712 & 2.954 \\
2 & 29.228 & 11.366 & 1.802 \\
3 & 32.199 & 9.327 & 2.162 \\
4 & 32.271 & 11.356 & 2.072 \\
5 & 34.519 & 11.011 & 2.316 \\
6 & 32.229 & 10.788 & 1.870 \\
7 & 71.547 & 10.247 & 3.272 \\
8 & 30.724 & 11.417 & 2.006 \\
9 & 30.877 & 11.017 & 1.888 \\
10 & 30.725 & 11.129 & 1.902 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Values of the sampling conducted by the Lab. RSE with acid solution and analysis by HPLC; the solutions were complexed the same evening as the sampling of the Second Campaign. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sampling**} & \multicolumn{2}{c}{**Hy Volume of Sampled**} & \multicolumn{2}{c}{**Hy Volume of**} & \multicolumn{2}{c}{**H\(-\)CHO (VDI 3862-2)**} & \multicolumn{2}{c}{**H\(-\)CHO**} \\  & **(L)** & **(L)** & **mg/L** & **(EPA 323 VDI 3862-6)** \\ \hline
1 & 32.20 & 31.10 & 0.647 & 0.435 \\
2 & 30.50 & 29.30 & 0.566 & 0.423 \\
3 & 31.00 & 29.70 & 0.735 & 0.561 \\
4 & 31.00 & 29.70 & 0.694 & 0.578 \\
5 & 31.00 & 29.50 & 0.716 & 0.598 \\
6 & 30.50 & 28.90 & 0.799 & 0.717 \\
7 & 67.40 & 63.90 & 1.674 & 1.523 \\
8 & 31.00 & 29.30 & 0.846 & 0.777 \\
9 & 31.00 & 29.20 & 0.819 & 0.739 \\
10 & 31.50 & 29.60 & 0.926 & 0.897 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: The results obtained by Lab. APPA Trento (sampling #1 and #2) from sampling in acid solution, washing, and analysis with HPLC are reported. The addition of DNPH was made directly at the end of the sampling. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Sampling**} & \multicolumn{2}{c}{**H\(-\)CHO (Lab. APPA Trento)**} & \multicolumn{2}{c}{**H\(-\)CHO (Lab.