Institute of Legal Medicine, Johannes Gutenberg-University of Mainz, Mainz, Germany.
Forensic Sci Int. 2012 Jan 10;214(1-3):113-7. doi: 10.1016/j.forsciint.2011.07.030. Epub 2011 Aug 30.
The in vitro production of GHB was observed in freshly collected, untreated whole blood samples using glass BD-Vacutainers and polypropylene S-monovettes. GHB concentrations were determined daily over a period of one week and after 3, 6 and 9 weeks again. Furthermore, the GHB concentration in 40 untreated random whole blood samples stored at 4°C for a longer period of time (10 samples 12 month, 10 samples 24 month and 20 samples 36 month) was also determined. For comparison, the in vitro production of GHB in freshly collected and prepared serum samples was observed. GHB serum concentrations were determined three times over a period of one week and once again after six weeks. Sample preparation was performed by means of methanolic extraction following the precipitation of whole blood and serum samples. A methanolic standard calibration was done in a low range of 0.005-0.1 μg/mL (LOD: 0.004, LLOQ: 0.013). For quantification a spiked blood bank serum with a determined GHB concentration of 0.09 μg/mL was used. Corrected calibrations in the range of 0.09-5.09 μg/mL were used (LOD: 0.08 μg/mL, LLOQ: 0.30 μg/mL), recovery: 91.3% (high level: 4.09 μg/mL) 50.5% (low level: 0.19 μg/mL).
Relevant elevation of GHB was observed in all whole blood samples stored in liquid form (4°C or room temperature). In two of the 40 whole blood samples stored over a longer period of time at 4°C, GHB concentrations in the range of 13 μg/mL were even determined. These findings constitute grounds for caution. Even a GHB cut-off level of 5 μg/mL cannot be considered as "absolutely positive" proof of a case of exogenous administration, at least in untreated liquid blood samples in long time storage. However, no significant elevations of GHB were otherwise observed in any of the serum samples independently of storage temperature nor in the whole blood samples that were frozen for storage.
The results suggest that the cut-off for exogenous GHB of 5 μg/mL could be lowered significantly, with the consequence of winning valuable time for the potential victim, but only if serum is collected for GHB determination or if the whole blood sample is frozen immediately after collection and the procedure well documented.
使用玻璃 BD-Vacutainers 和聚丙烯 S-单采管从新鲜采集的未经处理的全血样本中观察到 GHB 的体外产生。在一周的时间内每天测定 GHB 浓度，并在 3、6 和 9 周后再次测定。此外，还测定了 40 份未经处理的随机全血样本在 4°C 下长时间（12 个月 10 份样本，24 个月 10 份样本和 36 个月 20 份样本）储存的 GHB 浓度。为了比较，观察了新鲜采集和制备的血清样本中 GHB 的体外产生。在一周的时间内测定 GHB 血清浓度三次，六周后再次测定。通过全血和血清样本沉淀后甲醇提取进行样品制备。在低浓度 0.005-0.1 μg/mL（LOD：0.004，LLOQ：0.013）范围内进行甲醇标准校准。定量使用已知 GHB 浓度为 0.09 μg/mL 的掺加血库血清进行。使用 0.09-5.09 μg/mL 的校正校准（LOD：0.08 μg/mL，LLOQ：0.30 μg/mL），回收率：91.3%（高水平：4.09 μg/mL）50.5%（低水平：0.19 μg/mL）。
所有以液体形式（4°C 或室温）储存的全血样本均观察到 GHB 浓度升高。在 40 份在 4°C 下储存时间较长的全血样本中，有两份样本的 GHB 浓度甚至达到了 13 μg/mL。这些发现构成了谨慎的理由。即使是 5 μg/mL 的 GHB 截止值也不能被认为是对外源性给药的“绝对阳性”证据，至少在长时间储存的未经处理的液体血液样本中是这样。然而，在任何血清样本中，无论储存温度如何，以及在冷冻储存的全血样本中，都没有观察到 GHB 的显著升高。
结果表明，5 μg/mL 的外源性 GHB 截止值可以显著降低，从而为潜在受害者赢得宝贵的时间，但前提是收集血清进行 GHB 测定，或者在采集后立即冷冻全血样本，并妥善记录程序。
