血液保存中碳氧血红蛋白稳定性研究进展

通过分析近年来有关血液样品中碳氧血红蛋白稳定性方面的研究资料,发现血液中碳氧血红蛋白的稳定性受到盛放容器、保存温度、容器顶部空气体积、初始HbCO饱和度及防腐剂的添加与否的影响,其中保存温度、容器顶部空气体积及初始HbCO饱和度则是其主要影响因素。     

探究尸体血样中乙醇、乙基葡萄糖醛酸苷和硫酸乙酯的产生

目的探索尸体血样保存过程中乙醇的产生情况及乙基葡萄糖醛酸苷(EtG)和硫酸乙酯(EtS)的产生可能。方法对照组为7例阳性静脉血,而实验组则为7例阴性尸体血。每例血样分成3份并保存在室温(18~22℃),4℃及-20℃等3种不同的条件下,在保存天数为0、2、3、5、7、9、11、13、15、17、19、21等时间点取样。使用顶空气相色谱法(HS-GC)检测乙醇,采用固相萃取提取EtG和EtS,使用高效液相色谱-三重四级杆质谱(LCMS/MS)法检测EtG和EtS。结果保存期间,对照组各血样中的乙醇、EtG和EtS浓度均呈下降趋势;实验组中1、2、4、5、6、7号血样的室温及4℃的样本在保存第2~3天时检出乙醇,而7号-20℃的样本在第6天检出乙醇。其中,6号室温血样的乙醇峰值浓度为64.27mg/100mL。各血样中均未检出EtG,EtS。结论室温及4℃保存的尸体血可产生乙醇且产生速度较快,反复冻融可导致-20℃保存的尸体血产生乙醇,乙醇峰值浓度可超过法定酒驾标准,但实验组血样中均无EtG和EtS产生。因此,尸体血中的EtG,EtS可以作为乙醇生前入体的特异性标志物,区分乙醇生前入体和腐败产生乙醇的依据。实际工作中,乙醇原体检测的酒精认定应注意血样保存和运输条件造成的影响。为了避免假阳性结果,涉及死亡的案件进行酒精认定时有必要辅以EtG和EtS的检测。     

死后血浆和溶血样本中IgE的稳定性

目的探究死后血浆和溶血样本中免疫球蛋白E(immunoglobulin E,IgE)经过不同保存条件及冻融处理后的稳定性。方法选取39例死后48h内非冷冻尸体的心血样本,其中20例取血浆样本,19例取全血制成溶血样本。将样本置于-20℃、4℃、25℃条件下保存28d及-80℃条件下保存1年以探究IgE在不同保存条件下的稳定性。利用5次反复冻融处理样本探究死后血浆及溶血样本IgE的冻融稳定性。应用电化学发光法检测处理前后血浆和溶血样本中IgE的浓度。结果血浆样本中IgE在-20℃、4℃、25℃3种保存条件下的降解率接近,28d后降解率均值在15%左右,相同条件下溶血样本中IgE降解速度快于血浆(P<0.05),并且在25℃条件下降解率高于另外两种(P<0.05)。血浆样本于-80℃冷冻保存1年后的浓度与冷冻前相比差异无统计学意义(P>0.05),而溶血样本在-80℃冷冻保存1年后浓度有所降低(P<0.05)。死后血浆和溶血样本在反复冻融5次后检测结果与冻融前相比差异无统计学意义(P>0.05)。结论死后血浆及溶血样本中IgE具有良好的冻融稳定性。IgE在死后血浆样本中的稳定性优于溶血样本,因此在实际案例中建议及早分离血浆保存待测。     

不同保存条件下呋喃丹及其代谢物在血液中的稳定性研究

目的研究呋喃丹及其代谢物呋喃酚在不同条件保存血液中的稳定性,为呋喃丹中毒案件的法医学鉴定提供实验依据。方法犬经口灌胃4LD50(13.5mg/kg)呋喃丹致死后,取血液分为五等份,分别为添加1%氟化钠(1%NaF)、添加2.5mg/m L枸橼酸钠(NC)、20℃、4℃和-20℃保存实验组。于保存当时(0d)、5d、7d、15d、40d、83d和150d取上述样品,多反应离子检测(MRM),气相色谱-质谱联用(GC-MS/MS)法检测其中呋喃丹及呋喃酚含量。结果血液中呋喃丹的含量随保存时间均呈下降趋势,7d显著下降(P0.05),之后下降缓慢。不同条件保存血液中呋喃酚的含量均呈先升高后下降趋势。枸橼酸钠和氟化钠可加快血液中呋喃丹的分解。结论呋喃丹及其代谢物呋喃酚在保存检材中均可发生分解,20℃保存分解较快,4℃和-20℃保存分解速度较慢,不适宜用枸橼酸钠或氟化钠作抗凝剂或防腐剂。在呋喃丹的相关案件的法医学鉴定中,生物检材应注意冷藏、冷冻保存,并尽快送检。     

血液和尿液样品中海洛因代谢物稳定性研究

目的对尿液和血液中海洛因代谢物3-β-D-葡萄糖醛酸吗啡（M3G）,吗啡,O6-单乙酰吗啡（O6）在180d内的稳定性进行研究。方法准备空白添加血液、尿液、染毒动物（大白兔）血液、尿液和吸食海洛因者血液、尿液样本,分别置于20℃、4℃、-20℃下,分别于0、1、2、4、7、14、28、56、112、156、180d时间点测定样品中M3G、吗啡,O6相对含量。结果在3种不同温度下,随保存时间的延长,血液、尿液中的O6含量均逐渐下降至零;血液中吗啡含量升高（空白血液添加组）或下降（染毒动物组）,在尿液则均升高;血液样中M3G含量均升高,尿样中则略有下降。下降和升高的幅度均随保存温度的下降而缩小。结论海洛因代谢物在-20℃时保存稳定性最佳。     

UPLC-MS/MS法监测污水中甲卡西酮稳定性试验研究

目的通过正交试验比较甲卡西酮在不同溶剂pH值、浓缩温度、保存时间和保存温度提取条件下的稳定性,建立适合污水中甲卡西酮稳定测定的提取制备方法用于超高压液相色谱质谱联用仪的检测。方法在甲卡西酮检测过程中设置4个因素(提取溶剂pH值、浓缩温度、保存时间、保存温度)进行考察,每个因素选择3个水平,然后采用L9(3~4)进行正交试验,提取液使用液相色谱三重四极杆串联质谱仪(Exion LC/QTRAP 6500)检测,以甲卡西酮m/z=105.1的子离子峰面积作为定量指标,采用SPSS 16.0统计软件进行数据分析找出最佳条件。结果正交试验结果分析表明,提取溶剂pH=2.0,保存时间0d,保存温度-20℃,浓缩温度60℃为最佳提取条件,并根据该条件进行了方法学考察,结果表明甲卡西酮在1ng/L～500ng/L浓度范围内线性良好,提取回收率90%,RSD5.33%,基质效应6.52%,RSD0.31%,均符合相关标准要求。结论本研究通过正交试验筛选到的甲卡西酮制备方法有利于其稳定检测,适用于质谱的定性定量分析,可用于对污水中甲卡西酮成分的监测工作。     

腐败血液中乙醇的顶空气相色谱分析

目的分析血液腐败后产生的乙醇及其他物质并探讨腐败血液中乙醇的检测及计算方法。方法以正常人空白血液制作腐败血样,采用1,4-二氧六环为内标物,通过顶空气相色谱进行定性及定量分析。结果血中乙醇在0.0625～1mg/mL范围内线性关系良好（r^2=0.9996）,各质量浓度组的变异系数（CV%）〈2%,血中乙醇的最低检出限为1μg/mL（S/N≥3）。腐败血样所产生乙醇与正丙醇的比例大致为25：1。结论检验方法简便、准确。为法医毒化检验相关工作提供了依据。     

血和肝脏检材保存条件对氰化物浓度的影响

研究了大白鼠血液和肝脏检材保存时间及保存温度对氰化物浓度的影响。研究表明，保存168h，保存温度4℃，血液和肝脏检材中的氰化物含量变化很小；保存温度25℃，血液和肝脏险材中的氰化物浓度随时间延长而上升，肝脏检材中氰化物浓度在168h为4h的1．17倍。4h染毒组大白鼠氰化物浓度血中比肝脏中高2．3倍，证实了氰化物在体内分布的差异性。     

血中碳氧血红蛋白饱和度测定影响因素的研究

目的 考察血中碳氧血红蛋白饱和度(HbCO％)测定的影响因素,为其结果评定和所需样品保存条件提供实验依据。方法 利用三种分光光度法,测定30d内不同条件下保存的CO阳性血的HbCO％的变化。结果 还原双波长法、双波长法测定结果比较稳定,单波长法抗干扰能力较差;尸检所取血样的保存条件包括温度、保存时间及与空气接触程度对HbCO％的测定均有影响,其中温度影响较为显著。结论 利用还原双波长法与双波长法,并结合光谱扫描观察峰形变化可得到比较可靠的结果。30d内4℃条件下,密闭容器中血样接触少量空气不影响其HbCO％的测定。     

保存温度对血液酒精含量检测的影响

目的为筛选最佳的保存温度,准确检测酒驾血液酒精含量,为交管部门客观判断酒驾行为提供技术支撑。方法本研究选取EDTA-2真空抗凝采血管,采取酒后人体静脉鲜血后,分别在-20℃、4℃~8℃、25℃常温、35℃~42℃高温等4个温度条件下保存,GC法按0、3d、7d、14d、21d及28d后检测血液酒精含量,并对测试结果进行比较统计分析。结果在35℃~42℃和25℃温度下存储的血液酒精含量在0~3d内基本稳定,3d后显著下降(P0.05);4℃~8℃温度下存储的血液酒精含量在0~14 d内基本稳定,14d后显著下降(P0.05);-20℃温度保存条件下血液酒精含量测试28d统计结果间无显著差异。结论建议血样采集后低温保存,-20℃温度为血样的最佳保存温度。     

Kinetics of ethanol degradation in forensic blood samples

To determine ethanol in human post-mortem blood samples is problematic, largely due to the inappropriate and variable methods of preserving and storing, which can cause decomposition and loss of alcohol concentration. In this study, four crucial parameters of sample conservation were studied: temperature (T), percentage of air chamber in container (%CA), ethanol concentration in blood and post-mortem time. Blood samples from post-mortem cases were stored under different conditions (ethanol levels were known in all cases); factorial design variables: (%CA) 0, 5, 20, 35, 65%; storage temperature: 25, 4 and -10 degrees C; in a total of 15 experiments. No preserving agent was used in samples. Quantification of ethanol in blood was carried out by gas chromatography with head-space FID detector. Initial ethanol concentration ranged from 0.50 to 4.30 g/L. The kinetics of degradation observed was pseudo-first-order. The parameter that characterised the kinetics of ethanol degradation (k(0)) ranged from (4 x 10(-4) and 5.0 x 10(-1) day(-1)), depending on storage conditions. A strong dependence between ethanol degradation and the content of the air chamber was observed and this dependence was found to be stronger than that between degradation and temperature; there was an experimental relation between (k(0)) and (%CA). Activation energy for different conditions, i.e. 0, 5, 20, 35 and 65 (%CA), were calculated and contour plots were made. A mathematical equation relating air chamber, temperature and ethanol concentration at a certain time was determined. This equation allowed estimation of initial concentrations of ethanol with minimal error. A good correlation between experimental data and data calculated with the equation was obtained (r(2) = 0.9998). The best storage conditions were: 0% CA and storage at -10 degrees C, obtaining an ethanol degradation of 0.01% after 15 days. However, 33% of ethanol degradation was obtained with 35% CA at 25 degrees C after 15 days. This equation is useful in forensic cases in which original concentration of ethanol has to be estimated under different sample storage conditions.     

Improper sealing caused by the Styrofoam integrity seals in leakproof plastic bottles lead to significant loss of ethanol in frozen evidentiary urine samples

Evidentiary urine samples (n = 345) stored frozen at -20 degrees C in their original containers (leakproof 100 mL plastic bottles) upon retesting for ethanol resulted in concentrations that were significantly lower (average loss = approximately 30%) than those prior to their storage at -20 degrees C (p < or = 0.0001). The observed loss of ethanol was independent of the method of thawing or the concentration of ethanol in the samples, but was dependent on the sample volume in the container, i.e., the larger the volume of sample the larger the magnitude of ethanol loss. The loss of ethanol was determined to be due to improper sealing by a Styrofoam integrity seal attached to the mouth of the container. Accordingly, adopting leakproof plastic containers that do not contain Styrofoam integrity seals, but rather an outside and across the cap tape integrity seal for evidence collection and long-term storage, will prevent loss of ethanol due to evaporation.     

Headspace gas chromatographic determination of ethanol: the use of factorial design to study effects of blood storage and headspace conditions on ethanol stability and acetaldehyde formation in whole blood and plasma

Our headspace gas chromatographic flame ionization detection (HS-GC-FID) method for ethanol determination showed slightly, but consistently, low ethanol concentrations in whole blood (blood) in proficiency testing programs (QC-samples). Ethanol and acetaldehyde were determined using HS-GC-FID with capillary columns, headspace equilibration temperature (HS-T degrees ) of 70 degrees C and 20 min equilibration time (HS-EqT). Full factorial designs were used to study the variables HS-T degrees (50 degrees -70 degrees C), HS-EqT (15-25 min), ethanol concentration (0.20-1.20 g/kg) and storage at room temperature (0-6 days) with three sample-sets; plasma, hemolyzed blood and non-hemolyzed blood. A decrease in the ethanol concentration in blood was seen as a nearly equivalent increase in the acetaldehyde concentration. This effect was not observed in plasma, indicating chemical oxidation of ethanol to acetaldehyde in the presence of red blood cells. The variables showed different magnitude of effects in hemolyzed and non-hemolyzed blood. A decrease in ethanol concentration was seen even after a few days of storage and also when changing the HS-T degrees from 50 to 70 degrees C. The formation of acetaldehyde was dependent on all the variables and combinations of these (interactions) and HS-T degrees was involved in all the significant interaction effects. Favorable instrumental conditions were found to be HS-T degrees of 50 degrees C and HS-EqT of 15-25 min. The ethanol concentrations obtained for the range 0.04-2.5 g/kg after analyzing authentic forensic blood samples with a HS-T degrees of 50 degrees C were statistically significantly higher than at 70 degrees C (+0.0154 g/kg, p < 0.0001, n = 180). In conclusion, chemical oxidation of ethanol to acetaldehyde in the presence of red blood cells has been shown to contribute to lowered ethanol concentrations in blood samples. Storage conditions before analysis and the headspace equilibration temperature during analysis were important for the determination of blood ethanol concentrations.     

Postmortem production of ethanol in different tissues under controlled experimental conditions

The aim of this study was to follow the postmortem ethanol production phenomenon under controlled experimental conditions (temperature, time interval) in different tissues. Specimens of blood, liver, skeletal muscle and kidney were taken from 30 corpses and no chemical preservatives were used in the specimens collected. Ethanol concentrations were detected by gas chromatography. All specimens stored at -20 degrees C and 4 degrees C did not show any change in ethanol concentration in an eight-day time interval. At 20 degrees C and 30 degrees C, all tissues, except blood, showed statistically significant ethanol production over the time interval tested. However, blood sample kept at 30 degrees C, showed statistically significant increase in ethanol production on the 2nd and 4th day comparing to the controls. Thus, we can state that postmortem ethanol production occurs in different tissues, and is increased at higher temperatures and, in general, it is in accordance with the course of time.     

Blood, bone marrow and eye fluid ethanol concentrations in putrefied rabbits

The effect of putrefaction on postmortem blood, bone marrow and eye fluid ethanol levels was evaluated in rabbits. Control and dosed animals were sacrificed and stored at either room temperature (approx. 19 degrees C) or cold temperature (approx. 3.5 degrees C) for as long as 28 days. Control animals stored at room temperature showed ethanol levels in the bone marrow that peaked at 7 days after sacrifice, followed by decreases to a nondetectable level at 21 days. Overall decreases were demonstrated in bone marrow of dosed rabbits stored at room temperature for all postmortem intervals. The control animals stored at low temperature showed no ethanol in the bone marrow and blood until 21 days after sacrifice. Dosed rabbits stored at low temperature showed no significant changes in blood and marrow ethanol until 21 days after sacrifice.     

Stability of Morphine,Codeine, and 6‐Acetylmorphine in Blood at Different Sampling and Storage Conditions

The stability of drugs in biological specimens is a major concern during the evaluation of the toxicological results. The stability of morphine, codeine, and 6‐acetyl‐morphine in blood was studied after different sampling conditions: (i) in glass, polypropylene or polystyrene tubes, (ii) with addition of dipotassium ethylene diamine tetraacetic acid (K₂EDTA) or sodium oxalate (Na₂C₂O₄), and (iii) with or without the addition of sodium fluoride (NaF). Spiked blood samples were stored at two different temperatures (4 and ?20^°C), analyzed after different storage times and after three freeze–thaw cycles. Opiate concentrations were decreased in all conditions, but the most unstable was 6‐acetyl‐morphine. The addition of NaF as preservative improved the stability of opiates at all conditions studied, whereas the type of anticoagulant did not affect the stability of opiates. It was concluded that blood samples should be stored at ?20^°C in glass tubes containing oxalate and NaF for maximum stability.     

Gamma-hydroxybutyric acid stability and formation in blood and urine

Gamma-hydroxybutyric acid (GHB) can cause problems in interpretation of toxicological findings due to its endogenous nature, significant production in tissues after death and potential formation in stored samples. Our study was designed to determine the influence of storage conditions on GHB levels and its possible in vitro formation in blood and urine in cases where no exogenous use of GHB or its precursors was suspected. The samples were prepared by validated method based on liquid-liquid reextraction with adipic acid internal standard and MSTFA derivatization and assayed on a GC-MS operating in EI SIM mode. The first part of the study was performed with pooled blood and urine samples obtained from living and deceased subjects stored with and without NaF (1% w/v) at 4 and -20 degrees C over 8 months. In ante-mortem samples (both blood and urine) no significant GHB production was found. After 4 months of storage, the substantial GHB rise up to 100 mg/Lwas observed in post-mortem blood stored at 4 degrees C without NaF with subsequent gradual decrease in following months. The inhibition of GHB production was apparent during storage in NaF treated frozen blood samples. In post-mortem urine only slight temporary GHB levels were ascertained (up to 8 mg/L). The second part of our study was aimed to analyse 20 individual post-mortem blood samples stored at 4 degrees C for 16-27 days between autopsy and analysis without preservation followed by storage at 4 degrees C with NaF for 4 months. The temporary GHB production with maximum of 28 mg/Lwas detected in some samples.     

Ethanol formation in unadulterated postmortem tissues

During the investigation of aviation accidents, postmortem samples obtained from fatal accident victims are submitted to the FAA's Civil Aerospace Medical Institute (CAMI) for toxicological analysis. During toxicological evaluations, ethanol analysis is performed on all cases. Many species of bacteria, yeast, and fungi have the ability to produce ethanol and other volatile organic compounds in postmortem specimens. The potential for postmortem ethanol formation complicates the interpretation of ethanol-positive results from accident victims. Therefore, the prevention of ethanol formation at all steps following specimen collection is a priority. Sodium fluoride is the most commonly used preservative for postmortem specimens. Several studies have been published detailing the effectiveness of sodium fluoride for the prevention of ethanol formation in blood and urine specimens; however, our laboratory receives blood or urine in approximately 70% of cases. Thus, we frequently rely on tissue specimens for ethanol analysis. The postmortem tissue specimens received by our laboratory have generally been subjected to severe trauma and may have been exposed to numerous microbial species capable of ethanol production. With this in mind, we designed an experiment utilizing unadulterated tissue specimens obtained from aviation accident victims to determine the effectiveness of sodium fluoride at various storage temperatures for the prevention of microbial ethanol formation. We found that without preservative, specimens stored at 4 degrees C for 96 h showed an increase in ethanol concentration ranging from 22 to 75 mg/hg (average 42 +/- 15 mg/hg). At 25 degrees C, these same specimens showed an increase ranging from 19 to 84 mg/hg (average 45 +/- 22 mg/hg). With the addition of 1.00% sodium fluoride, there was no significant increase in ethanol concentration at either temperature.     

Mitochondrial DNA and STR analyses of maggot crop contents: effect of specimen preservation technique

DNA analysis of maggot crop contents can be used to identify a missing body or aid entomologists with interpreting evidence used for PMI estimations. Entomological evidence is often collected and preserved to keep identifiable external features intact. The preservation methods currently in use may not be suitable for preserving DNA in the maggot crop for later analysis. In this study, carrion maggots raised on human tissue were preserved under the following 8 preservation conditions: no fluid at -70 degrees C, no fluid at 4 degrees C, no fluid at 24 degrees C, 70% ethanol at 4 degrees C, 70% ethanol at 24 degrees C, 95% ethanol at 24 degrees C, Kahle's solution at 24 degrees C and formaldehyde at 24 degrees C. Maggots were dissected following 2 weeks, 8 weeks and 6 months of preservation. The maggot crops were extracted, human DNA was quantitated, and an attempt was made at amplifying mitochondrial DNA (mtDNA) and short tandem repeat (STR) loci. Both mtDNA and STRs were successfully amplified from maggots stored in ethanol or without any preservation fluid. Formalin-containing preservation solutions reduced the recovery of DNA. The best results were observed from maggots stored without any preservation fluid at -70 degrees C.     

The effect of temperature on the formation of ethanol by Candida albicans in blood

The effect of temperature on microbial fermentation in blood was studied. Specimens of human blood from a blood bank were inoculated with Candida albicans, an organism capable of causing fermentation. A preservative was added to a portion of the inoculated specimens. These inoculated specimens, as well as uninoculated blood, were stored under various temperature conditions. Production of ethyl alcohol was monitored over a period of six months. Fermentation was found to be highly temperature dependent, with refrigeration proving to be most effective at inhibiting ethanol formation.