Blood Alcohol Stability In Postmortem Blood Samples
Ethyl alcohol is a 2-carbon alcohol with a molecular formula of CH3CH2OH (Smith, 2014). Ethyl alcohol is an inebriating substance commonly found in alcoholic beverages. This substance acts as a central nervous system depressant and is commonly referred to as a “psychoactive drug,” which is capable of altering brain function. This substance can be lethal if consumed in high doses. The amount of ethyl alcohol that is consumed can be quantified by blood alcohol content (BAC). BAC is measured as weight per unit of volume and it is commonly written and described as a percentage. The percentage of blood alcohol content will indicate an individual’s level of intoxication. An individual can risk the possibility of death when their blood alcohol content ranges from 0.400% to 0.500%, or exceeds 0.500%. Qualitative and quantitative analysis of ethyl alcohol in postmortem specimens are commonly explored with the use of gas chromatography. Gas chromatography can assist in determining the amount of ethyl alcohol present at the time of death. This information could reveal whether a high level of ethyl alcohol contributed to the cause of death.
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The article “Blood alcohol stability in postmortem blood samples,” examined the effects of long-term storage on blood alcohol stability in postmortem blood samples.
The authors created a comprehensive experimental design to examine the changes in blood alcohol content due to the loss of ethyl alcohol concentration caused by oxidation, or the increase of ethyl alcohol concentration due to degradation caused by the influence of microorganisms. The authors evaluated the stability of ethyl alcohol in postmortem blood samples that were stored in a refrigerator at a temperature of -20◦C, within a 6 month period. The blood alcohol concentration was measured twice. The first measurement was taken 1 to 4 days after being taken from the Laboratory of Forensic Toxicology and then measured again after some period of time within
storage.
The samples examined within this experiment were measured by a Shimadzu 2010 gas chromatography instrument and flame ionization detector. The carrier gas used within the gas chromatography instrument was Ultrapure-grade helium. The flow rate of the carrier gas was 11.70 mL/min. The injection port temperature and flame ionization detector temperature was set to 200◦C. The chromatographic column used within this experiment was the RTX-BAC2.
The method validation, a process that is needed in order to confirm that the analytical procedure used was appropriate for its intended use and also depicts the quality, reliability, and precision of results, was accomplished with the use of a linear calibration curve of ethanol concentration. This was done by using five standard solutions ranging from 0.5 to 2.50 g/kg. The data collected was expressed as average, median, and standard deviation. The differences between measurements one and two were plotted and a significance level of 95% was used. A Bland-Altman plot was used to calculate bias and imprecision within the data collected.
Sultovic, et al. (2014) adequately addressed the issue at hand with the use of gas chromatography. Gas chromatography is commonly used for qualitative and quantitative analysis of an analyte of interest. The major components of a gas chromatography instrument are the carrier gas, flow controller, injector port, gas chromatography syringe, column, column oven, detector, and recorder. According to Skoog, et al. (2006), the sample is first injected into the injector port where it is then vaporized and enters the head of the gas chromatography column. The analyte will then travel through the column by the flow of the carrier gas. The compounds of the mixture can then be separated by their different traveling speeds. These various compounds will have different affinities to the column’s stationary phase, which will result in different traveling speeds (commonly referred as retention time). The column typically contains a liquid stationary phase which is adsorbed onto the surface of an inert solid (inner wall) of the column.
According to Sultovic, et al. (2014), the detector used within the experiment was the flame ionization detector. As stated by Skoog, et al. (2006), the effluent is directed into a flame within the detector, which consists of H2 and air, and is then pyrolyzed. Once the effluent is pyrolyzed, the compound will produce ions. These ions will be attracted to a collector plate. These ions will then hit the plate, which will then induce a current. The current is then measured with a high impedance picoammeter and fed into an integrator. The flame ionization detector is mass-sensitive and will therefore respond to the number of carbons atoms entering the detector (the carbon atoms are reduced within the flame). The components of the vaporized sample are separated because they are partitioned between a mobile gaseous phase and a liquid stationary phase held in the column. Elution is brought about by the flow of an inert gaseous mobile phase. The mobile phase will not interact with molecules of the analyte (it will only transport the analyte through the column).
The author is capable of not only detecting if ethyl alcohol is present by its retention time but also the concentration of the ethyl alcohol within the sample. The author is able to integrate the signal associated with ethyl alcohol. Once the signal is integrated, the area of the peak produced can be determined. The area will determine the relative amount of ethyl alcohol within that sample. The results obtained within this experiment concluded that many of the samples showed significant loss of ethyl alcohol concentration. Although, many of the samples showed a decrease in concentration, some of the samples showed an increase in concentration. I strongly with the author that such large deviations between both measurements is not acceptable when dealing with forensic samples. Such discrepancy will cause issues in a court proceeding and will lead to a possible false accusations or unreliable evidence. The decrease in ethyl alcohol concentration may have been due improper sample storage. The polypropylene tubes used to store the samples, were not filled to the top and because of the headspace within the tubes, ethyl alcohol oxidation may have occurred within the sample. The experimenters should have ensured that every tube was filled properly or a tube of a suitable volume should have been used. Samples which increased in ethyl alcohol concentration may have been due to the production of endogenous ethyl alcohol from microorganisms via fermentation of carbohydrates. The experimenters should have added more of the 2% sodium fluoride preservative in order to ensure that the blood samples would have not increased in concentration, which can once again lead to discrepancy within the courtroom.
According to regulations, blood samples should have been stored for at least 6 months from the first time they are analyzed. The storage time within this experiment superseded the storage minimum. The experimenters should have followed the regulations because this may have added to the discrepancy of the variations between concentration values. Also, some of the samples taken from post-mortem showed signs of drug use. Within this experiment, I believe they should have solely worked with blood samples containing only ethyl alcohol. As a reader, I would not know if the presence of a drug can contribute to an increase or decrease in ethyl alcohol concentration. Their research not only improved forensic science and courtroom discrepancies, but can now also lead to other possible research projects. One possible research project that could stem from their research is the possibility of finding a preservative that can be added to blood samples in order to ensure that the ethyl alcohol concentrations does not change within long periods of time.
The article “Blood alcohol stability in postmortem blood samples,” examined the effects of long-term storage on blood alcohol stability in postmortem blood samples.
The authors created a comprehensive experimental design to examine the changes in blood alcohol content due to the loss of ethyl alcohol concentration caused by oxidation, or the increase of ethyl alcohol concentration due to degradation caused by the influence of microorganisms. The authors evaluated the stability of ethyl alcohol in postmortem blood samples that were stored in a refrigerator at a temperature of -20◦C, within a 6 month period. The blood alcohol concentration was measured twice. The first measurement was taken 1 to 4 days after being taken from the Laboratory of Forensic Toxicology and then measured again after some period of time within
storage.
The samples examined within this experiment were measured by a Shimadzu 2010 gas chromatography instrument and flame ionization detector. The carrier gas used within the gas chromatography instrument was Ultrapure-grade helium. The flow rate of the carrier gas was 11.70 mL/min. The injection port temperature and flame ionization detector temperature was set to 200◦C. The chromatographic column used within this experiment was the RTX-BAC2.
The method validation, a process that is needed in order to confirm that the analytical procedure used was appropriate for its intended use and also depicts the quality, reliability, and precision of results, was accomplished with the use of a linear calibration curve of ethanol concentration. This was done by using five standard solutions ranging from 0.5 to 2.50 g/kg. The data collected was expressed as average, median, and standard deviation. The differences between measurements one and two were plotted and a significance level of 95% was used. A Bland-Altman plot was used to calculate bias and imprecision within the data collected.
Sultovic, et al. (2014) adequately addressed the issue at hand with the use of gas chromatography. Gas chromatography is commonly used for qualitative and quantitative analysis of an analyte of interest. The major components of a gas chromatography instrument are the carrier gas, flow controller, injector port, gas chromatography syringe, column, column oven, detector, and recorder. According to Skoog, et al. (2006), the sample is first injected into the injector port where it is then vaporized and enters the head of the gas chromatography column. The analyte will then travel through the column by the flow of the carrier gas. The compounds of the mixture can then be separated by their different traveling speeds. These various compounds will have different affinities to the column’s stationary phase, which will result in different traveling speeds (commonly referred as retention time). The column typically contains a liquid stationary phase which is adsorbed onto the surface of an inert solid (inner wall) of the column.
According to Sultovic, et al. (2014), the detector used within the experiment was the flame ionization detector. As stated by Skoog, et al. (2006), the effluent is directed into a flame within the detector, which consists of H2 and air, and is then pyrolyzed. Once the effluent is pyrolyzed, the compound will produce ions. These ions will be attracted to a collector plate. These ions will then hit the plate, which will then induce a current. The current is then measured with a high impedance picoammeter and fed into an integrator. The flame ionization detector is mass-sensitive and will therefore respond to the number of carbons atoms entering the detector (the carbon atoms are reduced within the flame). The components of the vaporized sample are separated because they are partitioned between a mobile gaseous phase and a liquid stationary phase held in the column. Elution is brought about by the flow of an inert gaseous mobile phase. The mobile phase will not interact with molecules of the analyte (it will only transport the analyte through the column).
The author is capable of not only detecting if ethyl alcohol is present by its retention time but also the concentration of the ethyl alcohol within the sample. The author is able to integrate the signal associated with ethyl alcohol. Once the signal is integrated, the area of the peak produced can be determined. The area will determine the relative amount of ethyl alcohol within that sample. The results obtained within this experiment concluded that many of the samples showed significant loss of ethyl alcohol concentration. Although, many of the samples showed a decrease in concentration, some of the samples showed an increase in concentration. I strongly with the author that such large deviations between both measurements is not acceptable when dealing with forensic samples. Such discrepancy will cause issues in a court proceeding and will lead to a possible false accusations or unreliable evidence. The decrease in ethyl alcohol concentration may have been due improper sample storage. The polypropylene tubes used to store the samples, were not filled to the top and because of the headspace within the tubes, ethyl alcohol oxidation may have occurred within the sample. The experimenters should have ensured that every tube was filled properly or a tube of a suitable volume should have been used. Samples which increased in ethyl alcohol concentration may have been due to the production of endogenous ethyl alcohol from microorganisms via fermentation of carbohydrates. The experimenters should have added more of the 2% sodium fluoride preservative in order to ensure that the blood samples would have not increased in concentration, which can once again lead to discrepancy within the courtroom.
According to regulations, blood samples should have been stored for at least 6 months from the first time they are analyzed. The storage time within this experiment superseded the storage minimum. The experimenters should have followed the regulations because this may have added to the discrepancy of the variations between concentration values. Also, some of the samples taken from post-mortem showed signs of drug use. Within this experiment, I believe they should have solely worked with blood samples containing only ethyl alcohol. As a reader, I would not know if the presence of a drug can contribute to an increase or decrease in ethyl alcohol concentration. Their research not only improved forensic science and courtroom discrepancies, but can now also lead to other possible research projects. One possible research project that could stem from their research is the possibility of finding a preservative that can be added to blood samples in order to ensure that the ethyl alcohol concentrations does not change within long periods of time.