“…In the second technique, the sample is pressed to prepare a pellet with a chemical binder (e.g., Heuzen and Morsink, 1991;Jarvis and Williams, 1993;Perkins et al, 1993;Craig et al, 2000;Tibi and Heumann, 2003;Williams and Jarvis, 1993), which causes a change in concentration (e.g., Gray, 1985), or without any binder (e.g., Becker et al, 2000;Lee et al, 2003;Holá et al, 2006;Ito et al, 2009). Standard addition and/or isotope dilution methods also are used for the pressed powder pellet to convert signal intensity to chemical concentration, causing the similar limitation as is found in fused samples (e.g., Becker et al, 2000;Lee et al, 2003;Holá et al, 2006). Use of an external standard is a good strategy (e.g., Craig et al, 2000); however, appropriate choice of the standard material is important.…”