A simple spectrophotometric method for the determination of carboxyhemoglobin in blood

The spectrophotometric method for the determination of carboxyhemoglobin (HbCO) in blood reported by Fretwurst and Meinecke was modified so as to give the same values of percentage HbCO (HbCO%) as those determined by the oxygen electrode method. Values of HbCO% of nine practical samples determined by both the oxygen electrode method and the present method were nearly identical regardless of the presence of methemoglobin (Met-Hb) in blood. The present method is suitable for forensic practice.     

Rapid determination of carboxyhemoglobin in blood by Oximeter

Different methods to determine carboxyhemoglobin (COHb) in blood are described in the literature. In our laboratory three methods to analyze COHb in post-mortem blood samples were compared: the spectrophotometric method of Maehly, a gas chromatographic method with a thermal conductivity detector (GC-TCD) and the Oximeter. Several COHb containing blood samples of deceased persons were analyzed. Results of all three methods were comparable for low concentrations (ca. 10% COHb) as well as for high concentrations (ca. 80% COHb) regardless of the viscosity of the blood samples. The advantages of the Oximeter when compared to Maehly's method and GC-TCD are extreme short time of analysis (<1min), very small blood volume required (<0.1ml) and easy handling. In our opinion application of the Oximeter is not limited to analyses of blood samples from living persons (e.g. in clinical toxicology); it can as well be used for the determination of COHb in post-mortem blood samples. Hence it is a useful and time saving tool in forensic toxicology.     

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。     

Failure to detect elevated levels of carboxyhemoglobin in infants dying from SIDS

Carboxyhemoglobin (COHb) levels were determined in stored blood samples from 91 infants diagnosed to have died from the sudden infant death syndrome (SIDS) (0.59+/-0.41%, excluding one outlying value of 10.83%); 48 age-matched controls (0.53+/-0.38%); and three individuals who died from fire related causes (41+/-20%). No statistical differences in COHb levels were detected between blood from SIDS and control infants (p = 0.43).     

A comparison of carboxyhemoglobin saturation values in postmortem heart blood and peripheral blood specimens

The following is a study conducted to determine whether there was any significant difference in carboxyhemoglobin (COHb) saturation levels between the heart blood and blood collected from a peripheral site. The average heart blood to peripheral blood COHb saturation level ratio in the 42 cases studied was 1.09. Sixty-two percent (26 of 42) of the cases had a heart blood to peripheral blood ratio between 0.9 and 1.1; 74% (31 of 42) had a ratio between 0.8 and 1.2. Eighty-three percent (35 of 42) had a ratio between 0.7 and 1.3. There were four cases where the heart blood to peripheral blood ratio was either below 0.6 or greater than 1.4. The differences between the two sites were not statistically significant.     

A practical method for the accurate determination of methemoglobin in blood containing carboxyhemoglobin

Kinetics of the oxidation of carboxyhemoglobin (HbCO) by potassium ferricyanide was studied photometrically in a weakly acid solution. An increase in the absorbance at 630 nm reached a maximum within 10 min when over a 100-fold excess of ferricyanide to hemoglobin iron was used. A slight decrease in the absorbance was observed after completion of the reaction when over a 500-fold excess of the reagent was used. In the presence of 0.4% Sterox SE, the absorbance began to decrease without complete oxidation. From these findings, a simple, rapid and accurate method for the determination of methemoglobin (Met-Hb) in blood was devised. The method was compared with two other methods, using 11 blood samples containing various amounts of HbCO, and proved to be suitable for blood containing elevated HbCO as well as for ordinary blood.     

Decision theory and standards of proof

Conclusion What is important about Kaplan's thesis is not whether his model succeeds in particular applications and in its present form, but that it indicates a method for analyzing the legal system which could improve it. This is not inconsistent with the lesson to be learned from Tribe.What is important in Tribe's position is the realization that the possible consequences of changing long-established and deeply entrenched social institutions should not be taken lightly. At the same time, avoiding problems by formulating principles vaguely enough that conflicts are simply not apparent is in no sense a solution. The lesson to be learned is not halt, but proceed with caution.     

Determination of total hemoglobin in forensic blood samples with special reference to carboxyhemoglobin analysis

For the determination of total hemoglobin (Hb) in blood containing elevated carboxyhemoglobin (COHb), a newly developed reagent containing a 100-fold concentration of ferricyanide (20 g/l) and a 2-fold concentration of Sterox SE was compared with a standard reagent (0.2 g/l ferricyanide), the reagent of van Kampen and Zijlstra, using forensic blood samples and experimentally heated blood samples. There were no significant differences between the spectra of hemiglobincyanide (HiCN) solution produced with our reagent and the van Kampen and Zijlstra reagent using experimentally heated blood samples. Although the spectra of HiCN changed gradually with increased heating time and with the passage of time after mixing, the absorbance at 540 nm (A540) did not change until at least 120 min for both the reagents. When forensic blood samples containing elevated COHb were mixed with the van Kampen and Zijlstra reagent, total-Hb concentrations determined 5 min after mixing were 10-20% higher than those determined after 180 min. The overestimates of total Hb determined after 5 min resulted in comparable underestimates of percentage saturation of COHb (COHb%) when COHb% was obtained from the ratio of COHb content, determined by gas chromatogrpahy, to total-Hb concentration in blood. However, there was an extremely good correlation between the values of total Hb in forensic blood samples determined with the van Kampen and Zijlstra reagent after 180 min and those determined with our reagent after 5 min. From the results obtained, our reagent proved to be suitable for the determination of total Hb in forensic science practice.     

Never say never. Negligible carboxyhemoglobin in the victim of a smoldering mattress fire

For many years, a high blood carboxyhemoglobin concentration has been used as a criterion for determining that a victim of conflagration was alive in the fire. We report a case in which a man died from the combined effects of burns and hypertensive cardiovascular disease. He had a negligible blood carboxyhemoglobin concentration, but the environmental evidence and autopsy findings are indicative of life in the fire, which arose in a smoldering mattress. We conclude that uncritical, rigid adherence to the requirement that fire victims have high carboxyhemoglobin concentrations can be misleading.     

A study on house fire victims: age, carboxyhemoglobin, hydrogen cyanide and hemolysis.

Correlation among age, concentrations of carboxyhemoglobin and hydrogen cyanide, oxygen density and hemolysis were studied in 120 house fire victims. Victims aged over 60 years comprised approximately 50% of the pooled subjects. Blood samples were mainly collected from the left ventricle, but sometimes from both the right and left ventricles. The concentration of carboxyhemoglobin ranged from 1-95%, of which 71 persons (59.7%) died with carboxyhemoglobin concentrations below 60%. Carboxyhemoglobin concentrations below 10% were found in 9 persons (7.5%). Most of these cases involved the elderly persons. In this paper, we report on the death of elderly victims as a result of low carboxyhemoglobin concentrations. A significant correlation of blood carboxyhemoglobin concentrations existed between the right and left ventricles. The concentration of carboxyhemoglobin in the left ventricle was significantly higher than that in the right. Two out of 31 victims whose hydrogen cyanide concentrations were determined, succumbed to hydrogen cyanide poisoning, having a high concentration of hydrogen cyanide and a low concentration of carboxyhemoglobin. On analysis, oxygen density was found to be low in 13 persons. A negative correlation was shown between carboxyhemoglobin concentration and hemolysis. Inasmuch as hemolysis may indicate the extent of heat dissociation, hemolysis should provide an index of carbon monoxide dissociation from carboxyhemoglobin. In the present study of victims, possible causes of death i.e., carbon monoxide gas poisoning, hydrogen cyanide poisoning, oxygen deprivation, burning, shock due to burns and others were estimated. The survival time for elderly victims was considered to be short.     

Simple determination of carboxyhemoglobin by double wavelength spectrophotometry of absorbance difference and the comparison with gas chromatographic method

This paper describes the spectrophotometric determination of carboxyhemoglobin (CO-Hb) in blood on the basis of double wavelength spectrophotometry of absorbance difference. Absorbance measurements are made in the 500–600 nm region at a blood dilution of 100–200-fold. Blood is diluted with a solution containing Na₂S₂O₄ to provide two components of CO-Hb and deoxyhemoglobin (deoxy-Hb). Absorbance difference at the two wavelengths at which deoxy-Hb has the same absorbance reflects only the CO-Hb component because the opposite component is nulled out of the mixture. After measurement of the absorbance difference, the measuring solution is saturated with CO gas to make all Hb derivative CO-Hb and remeasured at the same wavelengths. The percent of CO-Hb is considered the absorbance difference ratio. Results obtained by the present method was in satisfactory agreement with gas chromatographic data in blood not containing methemoglobin (Met-Hb). Comparative experiments using the gas chromatographic method and the present method were performed with samples containing Met-Hb. However, while there is a deficiency in the gas chromatographic method when the samples contain Met-Hb, the results of the present method were in close agreement with theoretical values when samples are mixed with CO-Hb, O₂-Hb and Met-Hb. Advantages of this method are that it is simple and accurate, standard curve or equation for calculation and accurate dilution are not necessary.     

Analysis of carboxyhemoglobin and cyanide in blood from victims of the Dupont Plaza Hotel fire in Puerto Rico

Ninety-seven people died from a fire that occurred in the Dupont Plaza Hotel in Puerto Rico on 31 Dec. 1986. All, except four who died later in the hospital, were found dead at the scene. All of the fatalities at the hotel (except for eight) were burned beyond recognition. Blood from seventy-eight of the victims was screened for carboxyhemoglobin at the Institute for Forensic Sciences in Puerto Rico and was then sent to the National Institute of Standards and Technology, Gaithersburg, Maryland, for analysis of carboxyhemoglobin and cyanide concentrations. The blood data indicated that carbon monoxide and hydrogen cyanide, singly or combined, were probably not responsible for the majority of the deaths that occurred in the badly burned victims. On the other hand, the significantly higher carboxyhemoglobin in the nonburned victims indicated that carbon monoxide alone or combined with hydrogen cyanide probably played a major role in the cause of their deaths.     

Changes in the concentration of carboxyhemoglobin in the blood under the action of high temperatures

Changes in carboxyhemoglobin concentrations are studied in 18 specimens of cadaveric blood 1-2 h and 3 days after heating to 50, 65, 70, 75, 80, and 90 degrees C for 5, 10, and 20 min. The concentration of carboxyhemoglobin decreased to 15% after heating at 70-75 degrees C for 10 and 20 min. Heating to 80-90 degrees makes the measurements impossible. Five-min heating at 50-65 degrees C did not change the concentration of carboxyhemoglobin in the blood.     

Automated determination of carboxyhemoglobin contents in autopsy materials using head-space gas chromatography/mass spectrometry

To establish a method for the routine analysis of carboxyhemoglobin (COHb) in autopsy materials including those which have undergone postmortem changes, e.g. thermo-coagulation, putrifaction and contamination, an automated head-space gas chromatography/mass spectrometry (GC/MS) analysis was utilized. The procedure consisted of preparation of the sample in a vial and a carbon monoxide (CO) saturated sample, for estimation of hemoglobin content, in another vial, the addition of n-octanol, potassium ferricyanide and an internal standard (t-butanol), GC separation and determination of CO using a GC/MS system equipped with an automated head-space gas sampler. The method was practical not only with the blood and bone marrow aspirates to confirm the findings on the CO-oximeter system, but also with the thermo-coagulated and putrified blood.     

Run-specific limits of detection and quantitation for STR-based DNA testing

STR-based DNA profiling is an exceptionally sensitive analytical technique that is often used to obtain results at the very limits of its sensitivity. The challenge of reliably distinguishing between signal and noise in such situations is one that has been rigorously addressed in numerous other analytical disciplines. However, an inability to determine accurately the height of electropherogram baselines has caused forensic DNA profiling laboratories to utilize alternative approaches. Minimum thresholds established during laboratory validation studies have become the de facto standard for distinguishing between reliable signal and noise/technical artifacts. These minimum peak height thresholds generally fail to consider variability in the sensitivity of instruments, reagents, and the skill of human analysts involved in the DNA profiling process over the course of time. Software (BatchExtract) made publicly available by the National Center for Biotechnology Information now provides an alternative means of establishing limits of detection and quantitation that is more consistent with those used in other analytical disciplines. We have used that software to determine the height of each data collection point for each dye along a control sample's electropherogram trace. These values were then used to determine a limit of detection (the average amount of background noise plus three standard deviations) and a limit of quantitation (the average amount of background noise plus 10 standard deviations) for each control sample. Analyses of the electropherogram data associated with the positive, negative, and reagent blank controls included in 50 different capillary electrophoresis runs validate that this approach could be used to determine run-specific thresholds objectively for use in forensic DNA casework.     

血液样品中防腐剂对碳氧血红蛋白稳定性的影响

目的研究临床上常用8种试剂对血液样品中碳氧血红蛋白(HbCO)稳定性的影响。方法将血液样品分为高、低两个HbCO浓度组,选用临床常用的甲醛、氟化钠、乙二胺四乙酸二钠、亚硝酸钠、草酸钾、肝素钠、柠檬酸钾及氟化钠与草酸钾混合物(1:3)8种试剂,按常用浓度分别添加到血样品中,并于添加后0h、2h、8h、24h、3d、7d用紫外可见光分光光度法检测其中HbCO饱和度,用统计学方法进行结果分析。结果本实验选用的8种试剂只有甲醛和亚硝酸钠对HbCO的稳定性影响较为显著,而其余6种对HbCO稳定性的影响无统计学意义。结论在检验疑似CO中毒并经甲醛或亚硝酸钠防腐的检材时应慎重,以免导致错误的鉴定结论。     

Robots,standards and the law: Rivalries between private standards and public policymaking for robot governance

This article explains the complex intertwinement between public and private regulators in the case of robot technology. Public policymaking ensures broad multi-stakeholder protected scope, but its abstractness often fails in intelligibility and applicability. Private standards, on the contrary, are more concrete and applicable, but most of the times they are voluntary and reflect industry interests. The ‘better regulation’ approach of the EU may increase the use of evidence to inform policy and lawmaking, and the involvement of different stakeholders. Current hard-lawmaking instruments do not appear to take advantage of the knowledge produced by standard-based regulations, virtually wasting their potential benefits. This fact affects the legal certainty with regards to a fast-paced changing environment like robotics. In this paper, we investigate the challenges of overlapping public/private regulatory initiatives that govern robot technologies in general, and in the concrete of healthcare robot technologies. We wonder until what extent robotics should be governed only by standards. We also reflect on how public policymaking could increase their technical understanding of robot technology to devise an applicable and comprehensive framework for this technology. In this respect, we propose different ways to integrate the technical know-how into policymaking (e.g., collecting the data/knowledge generated from the impact assessments in shared data repositories, and using it for evidence-based policies) and to strengthen the legitimacy of standards.     

The evolution of insanity standards

Health care professionals are often called upon as expert witnesses in insanity determinations. Most are familiar with the “insanity standard” applicable in the court in which they are called to testify. It might be helpful to understand that not all jurisdictions apply the same standard and how the different standards are related. This article is intended to address the problems associated with each insanity “test” presently in use and how “determining” insanity is an evolutionary process.     

法医学鉴定标准的现状与问题

司法鉴定标准化是一个世界性的司法话题,伴随我国司法改革的实施和政府对标准化工作的重视,我国将迎来建立法医学鉴定标准体系的黄金时代。然而当前我国法医学鉴定标准却存在标准少、质量参差不齐、更新缓慢、标准制定的科学性不足等问题,导致司法鉴定工作与实践脱轨,很多鉴定项目缺乏鉴定标准。为此,作者建议,正确认识法医学鉴定标准的法律地位和存在的错误,致力于法医学鉴定标准化。     

试论行政规范的合理性

满足合理性要求的行政规范有助于建立有效的利益调节机制。因为这样的行政规范能够在价值合理性的基础上实现工具合理性,即以相对较低成本谋求多数人利益需求。因此,必须预设行政规范目的是从“众意”中寻找“公意,”而且规范的内容是对经济和社会的适度干预,设计满足简单而公正的要求的具体程序制度,并建立对已经生效的行政规范的审查、监控机制,从而最大程度地使制定出来的行政规范具有合理性。