<prompt> Translate the following text to EnglishKwa ajili ya kutayarisha 20 L ya kiwango, synthetic, reconstituted maji ya bahari modified GP2 kwa kutumia reagent daraja kemikali tazama 3, na salinity ya 31, kufuata maelekezo hapa chini.  <response>: 3.1 To prepare 20 L of a standard, synthetic, reconstituted seawater modified GP2, using reagent grade chemicals Table 3, with a salinity of 31 , follow the instructions below. 