**3.3 Influence artifact formation on determining of methylmercury (Me-Hg) in biological (hair) and environmental samples**

To estimate the influence of the artifact on the methyl mercury (MeHg) and ethylmercury (Et-Hg) analysis, the artifact during extraction and derivation was investigated by comparing of un-spiked chlor alkali hair sample (CA hair, with a high level of In-Hg) with different concentration of normal abundance In-Hg (20, 40, 60, 100 mg/kg In-Hg as Hg2+). The un-spiked chlor alkali hair sample (0.02 g) was digested in 5 ml TMAH using microwave device under temperature programme of 55°C for 20 min and 60°C for 20 min. The extract for CA hair and five normal abundance In-Hg standard solutions were then derivatized with NaBPr4, extracted, and analyzed with the same procedure as described in Section 2.3. From the results as shown in **Table 5** and **Figure 12**, it can be seen that there is no substantial enhancement of artifact of Me-Hg and Et-Hg observed as compared to the amounts of artifact MeHg and EtHg shown in **Tables 3** and **4** and **Figures 10** and **11**. This result indicates that the percentage of artifact formation of methylmercury (MeHg) and ethylmercury (EtHg) from all different concentrations of normal abundance In-Hg standard solution was constant at the rates of 0.012 and 0.80%, respectively, during derivatization using NaBPr4. However, as shown in **Table 5** and **Figure 12**, the most of MeHg found in the un-spiked CA hair extract more likely originated from the CA hair sample. Taking 0.012% as average constant formation rate for artifact MeHg, the CA hair sample showed that artifact MeHg might result in less than 6% of the measured MeHg value. Moreover, **Table 5** and **Figure 12** indicate that all EtHg found in unspiked CA and five different concentrations of normal abundance In-Hg standard solutions are artifacts at the same artifacts formation percentage (0.80%) from the high level of In-Hg in the samples during derivatization using NaBPr4. Despite of this, this method is useful to measure the actual amount of MeHg in hair samples by subtracting of percentage MeHg artifact formation constant ratio (0.012%) from that found in **c**hlor alkali hair samples or any samples contains high levels of inorganic mercury (In-Hg).


### **Table 5.**

*Comparison of MeHg and EtHg % artifact formation in un-spiked CA hair with different amounts of normal abundance InHg during derivatization using NaBPr4.*

**Figure 12.**

*Comparison of MeHg and EtHg % artifact formation in un-spiked CA hair versus different concentrations of normal abundance InHg during derivatization using NaBPr4.*
