样本预处理方式对罗氏沼虾碳和氮稳定同位素比值检测的影响

为研究样本预处理方式对罗氏沼虾碳和氮稳定同位素比值检测的影响,分别选用3种保存温度(常温23℃/15 d、冷藏2℃/90 d、冷冻-18℃/360 d)、2种取样方式(虾仁取样、整虾取样),以新鲜沼虾样本为对照组,对比不同样本预处理方式对罗氏沼虾碳稳定同位素比值(δ¹³C)、氮稳定同位素比值(δ¹⁵N)、碳氮比(C/N)的影响。结果表明,不同保存温度和不同取样方式对罗氏沼虾δ¹³C、δ¹⁵N、C/N的影响明显。与对照组相比,常温保存条件下的δ¹⁵N偏移量最大(1.31‰~13.16‰,平均值为6.02‰),冷冻保存条件下的δ¹³C偏移量最大(2.34‰~2.84‰,平均值为2.57‰),室温保存条件下的C/N显著增加(P<0.05),冷藏和冷冻保存条件下的C/N显著减少(P<0.05)。不同取样方式对罗氏沼虾δ¹⁵N、δ¹³C的影响还取决于保存温度,在冷冻保存条件下,整虾取样的δ¹⁵N、δ¹³C显著高于虾仁取样,而在常温保存条件下,整虾取样的δ¹⁵N偏移量显著低于虾仁取样。因此,常温(23℃)和冷藏(2℃)条件不适合保存罗氏沼虾、冷冻(-18℃)保存罗氏沼虾的时间不宜超过60 d,建议新鲜沼虾采集后应立即干燥并开展碳和氮稳定同位素检测。本研究结果为水产品碳和氮稳定同位素比值检测的样本预处理方式提供了参考。

Effects of Sample Pretreatment Methods on the Detection of Carbon and Nitrogen Stable Isotope Ratios in Macrobrachium rosenbergii

To investigate the effects of sample pretreatment methods on the detection of carbon and nitrogen stable isotope ratios in Macrobrachium rosenbergii, using fresh macrobrachium rosenbergii samples as the control group, three preservation temperatures (room temperature 23℃/15 d、refrigerated 2℃/90 d、frozen -18℃/360 d) and two sampling methods (shrimp muscle sampling、whole shrimp sampling) were used to compare the effects of different sample pretreatment methods on the δ¹³C, δ¹⁵N and C/N in Macrobrachium rosenbergii. The results showed that the effects of different preservation temperatures and different sampling methods on carbon stable isotope ratio(δ¹³C)、nitrogen stable isotope ratio(δ¹⁵N)、 carbon nitrogen ratio(C/N)in Macrobrachium rosenbergii were significant. Among them, the largest δ¹⁵N offset was observed for room temperature storage conditions (1.31‰~13.16‰, mean 6.02‰), the largest δ¹³C offset was observed for frozen storage conditions (2.34‰~2.84‰, mean 2.57‰), C/N increased significantly (P<0.05) for room temperature storage conditions, and C/N decreased significantly (P<0.05) for refrigerated and frozen storage conditions. The effect of different sampling methods on the δ¹⁵N and δ¹³C in Macrobrachium rosenbergii also depends on the preservation temperature. Under frozen conditions, the δ¹⁵N and δ¹³C of whole shrimp sampling were significantly higher than those of shrimp muscle sampling, while under room temperature conditions, the δ¹⁵N offset of whole shrimp sampling was significantly lower than that of shrimp muscle sampling. Therefore, room temperature (23℃) and refrigerated (2℃) conditions are not suitable for the preservation of Macrobrachium rosenbergii, and frozen (-18℃) preservation of Macrobrachium rosenbergii should not exceed 60 days, and it is recommended that fresh Macrobrachium rosenbergii should be dried immediately after collection for carbon and nitrogen stable isotope assays. This study provides a reference for sample pretreatment on the stable isotope detection of aquatic products