[Latar belakang Pemakaian heroin masih cukup tinggi di Indonesia. Tesis inimembahas tentang pengaruh penambahan natrium florida pada penyimpanansampel darah yang mengandung heroin ( 6 monoacetylmorphine dan morfin ) dikulkas suhu 5 0 C – 150Metode Penelitian ini merupakan penelitian analitik eksperimental dalamlingkungan yang terkontrol. Terhadap 8 subjek penelitian diambil darahnyasebanyak 9 ml yaitu yang menggunakan heroin 30 menit hingga 3 jam sebelumpengambilan darah. Kemudian 9 ml darah dibagi menjadi 3 tabung, masingmasingtabung 3 ml. Tabung pertama langsung diperiksa kadar 6monoacetylmorphine dan morfin menggunakan Gas Choromatography MassSpectrometry. Tabung kedua yaitu darah dengan natrium florida dan tabung ketigadarah tanpa natrium florida disimpan dikulkas suhu 5C selama 3 hari.0 C – 150Hasil Pada pemeriksaan sampel hari pertama terhadap zat6 monoacetylmorphine tidak ditemukan adanya zat tersebut. Karena padakedelapan sampel , 6 monoacetylmorphinenya telah berubah menjadi morfin.Tetapi 6 monoacetylmorphine ini tetap ada hingga hari ketiga pada 50% sampelyang disimpan dengan natrium florida. Rata-rata kadar morfin hari pertama adalah860,2 ± 669,5 ng/ml menurun pada hari ketiga menjadi 656,6 ± 425,8 ng/ml( sampel dengan penambahan natrium florida) , 448,2 ± 270,7 ng/ml ( sampeltanpa penambahan natrium florida). Rata-rata perbedaan antara sebelum dansesudah penyimpanan pada sampel yang ditambahkan natrium florida adalah203,6 ± 252,4 ng/ml dengan signifikansi (p) = 0,057. Rata-rata perbedaan antarasebelum dan sesudah penyimpanan pada sampel tanpa penambahan natriumflorida adalah 411,9 ± 475,2 ng/ml dengan signifikansi (p) = 0,044.C ( kulkas bagianForensik Rumah Sakit Cipto Mangunkusumo) selama 3 hari. Pada hari ketigasampel darah pada tabung kedua dan ketiga akan diperiksa kadar 6monoacetylmorphine dan morfin menggunakan Gas Choromatography MassSpectrometry.Kesimpulan Dengan penambahan natrium florida dapat mencegah perubahan 6monoacetylmorphine menjadi morfin pada 50% sampel penelitian. Pada sampelyang disimpan dengan natrium florida, tidak ada perbedaan bermakna antarakadar morfin sebelum dan sesudah penyimpanan selama 3 hari dikulkas suhu50 C – 150 C. Pada sampel yang disimpan tanpa natrium florida , terdapatperbedaan yang bermakna antara kadar morfin sebelum dan sesudah penyimpananselama 3 hari dikulkas suhu 50 C – 150, Background Heroin consumption is still quite high in Indonesia. This study is todiscuss the effect of adding sodium fluoride to the storage of blood samplescontaining heroin (6 monoacetylmorphine and morphine) in a refrigerator with atemperature of 50C to 150Methods This study is an experimental analysis in a controlled environment. Tothe 8 subject of study, 9 ml of blood was drawn who was using heroin 30 minutesto 3 hours before blood sampling. This 9 ml of blood were then saved into 3 tubesof 3 ml each. The first tube was directly examined for the levels of 6monoacetylmorphine and morphine using Gas Choromatography-MassSpectrometry. The second tube of blood with sodium fluoride and the third tube ofblood without sodium fluoride were stored in refrigerator of 5C for 3 days.0C to 150Results On the first day examinations, 6 monoacetylmorphine were not found,because all of the samples, 6 monoacetylmorphine has changed to morphine. Butthis 6 monoacetylmorphine remains until the third day in 50% of samples storedwith sodium fluoride. Average concentration of morphine in the first day was860.2 ± 669.5 ng/ml and decreased to 656.6 ± 425.8 ng/ml on the third day(samples with the addition of sodium fluoride), and to 448.2 ± 270.7 ng / ml(sample without the addition of sodium fluoride). The average difference betweenbefore and after storage in the samples added with sodium fluoride is 203.6 ±252.4 ng/ml with significance of (p) = 0.057. The average difference betweenbefore and after storage in the samples without the addition of sodium fluoridewas 411.9 ± 475.2 ng/ml with significance (p) = 0.044.Ctemperature (refrigerator in Department of Forensic Medicine, CiptoMangunkusumo Hospital) for 3 days. On the third day, The second blood sampleand the third were examined for the levels of 6 monoacetylmorphine andmorphine also using GC-MSConclusion The additions of sodium fluoride prevent changes of 6monoacetylmorphine into morphine in 50% of the study sample. In samples storedwith sodium fluoride, there is no significant difference between the levels ofmorphine before and after storage for 3 days in refrigerator with temperature of5OC to 15OC. In the samples stored without sodium fluoride, while there is asignificant difference between the levels of morphine before and after storage for3 days in refrigerator temperature of 5OC to 15OC]