1海產品中碳-14的測定管式燃燒法本標準規(guī)定了管式燃燒法分析和測定海產品中碳-14含量的GB14883.1食品中放射性物質檢驗(5.1碳-14標準溶液：活度濃度建），），5.123-甲氧基丙胺(C4H11NO，CAS號），），），2），均勻且無明顯固體顆粒。也可選用具有同等效果的商用6.10一般實驗室常用儀器和設備，如冰箱、燒杯若樣品不能及時處理，應于0℃~4℃保鮮。別置于兩個堿液吸收瓶內并稱重。取一個硅膠干燥劑管8.1.5設定氧化燃燒程序（典型海產品樣品氧化燃燒程序設定可參考附錄B啟動升溫，燃燒中仔3），8.3.1.2取5g烘干的碳酸鈣沉淀置于三口燒瓶中，加入150mL去離子水和一個），4），8.3.1.5擦干液閃計數(shù)瓶外壁后稱重，計算吸收的二氧化碳的重量。），向三口燒瓶中加入5.3g無水碳酸鈉（見5.7），按照8.3.1釋放和吸收二氧化碳，加入閃爍液（見碳-14標準溶液（見5.1），用氯化銨（見5.4）調節(jié)pH值至10-11，然后用飽和氯化鈣溶液（見5.5）滴定，直至無白色沉淀產生為止。靜置30min后，進行抽濾，并分別用去離子水和無水乙醇放入液體閃爍計數(shù)器中暗化24h后測量。建議樣品測量時間準確稱取5g無水葡萄糖（見5.8）按照8.1操作，通過稱量裝有氫氧化鈉堿性溶液的吸收瓶和硅膠9數(shù)據(jù)處理9.1儀器探測效率的計算E=Nb·········································································(1)5Nb──本底樣品的計數(shù)率，countAC1──待測樣品中碳-14的放射性比活度，Bq/(kgC)；Nb──本底樣品的計數(shù)率，countAC=Nx-Nb·····································································E懸W69.3鮮樣品的含碳率K=100%··································································(4)Y AC2──鮮樣中碳-14的放射性比活度，Bq/(kg·鮮)。9.5探測下限的計算LLDn=4.65······························································6將上述公式代替樣品凈計數(shù)率代入碳-14的放射性比活度計算公式求得樣品的7A.1合成標準不確定度uC=······························UA──測量不確定度A類評定；UB,i──i種影響因素引入的測量不確定度B類評定。A.2擴展不確定度UU=kuC=k·················································k──包含因子，一般取2，相應置信水平約為95%。 N NNtxtbuA=x+b/(Nx-Nb)·······················································(A.3)UA──碳-14放射性比活度計數(shù)率的不確定度；Nb──本底樣品的計數(shù)率，countuB,i=ai/····················