{"id":163,"date":"2022-05-16T23:12:16","date_gmt":"2022-05-16T23:12:16","guid":{"rendered":"https:\/\/openbooks.library.unt.edu\/forensicchemistrylabmanual\/?post_type=chapter&p=163"},"modified":"2022-05-17T17:35:12","modified_gmt":"2022-05-17T17:35:12","slug":"blood-alcohol-concentration","status":"publish","type":"chapter","link":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/chapter\/blood-alcohol-concentration\/","title":{"raw":"Blood Alcohol Concentration","rendered":"Blood Alcohol Concentration"},"content":{"raw":"

Introduction<\/h1>\r\n\r\n
\r\n\r\n

Purpose<\/h2>\r\nQuantify the amount of ethanol in an unknown 'blood' sample using headspace GC with a flame ionization detector.\r\n

BAC Samples<\/h2>\r\nBlood alcohol measurement is one of the most common toxicology analyses performed in the U.S. In addition to breath alcohol testing with preliminary breath testing instruments and\/or IR, GC-FID (flame ionization detector) of blood samples is the typical way we do this. Urine can be tested for ethanol metabolites, but it is generally less reliable.\r\n\r\nHeadspace sampling<\/strong> is the typical method used for GC sample introduction in BAC analyses, as shown in Figure 1 below.\u00a0 It is performed by placing a blood sample in a headspace vial. Headspace vials are sealed but have a septum that may be pierced by a syringe. By gently heating the vials, we can take advantage of the partial pressure of the gas phase ethanol being proportional to the concentration of ethanol in the blood sample. A gas-tight syringe can then be used to extract a headspace sample containing gas phase ethanol and inject the sample onto the GC column.\r\n\r\n[caption id=\"attachment_170\" align=\"aligncenter\" width=\"1024\"]\"\" Figure 1. Headspace sampling for BAC is performed by piercing the septum of the sample vial with a gas-tight syringe, drawing gas phase sample into the syringe, and injecting the sample directly on the GC column.[\/caption]\r\n

Materials and Methods<\/h1>\r\n\r\n
\r\n\r\n

Supplies<\/h2>\r\n
    \r\n \t
  1. Ethanol<\/li>\r\n \t
  2. Internal standard<\/li>\r\n \t
  3. Volumetric flask(s)<\/li>\r\n \t
  4. Pipette<\/li>\r\n \t
  5. Unknown samples<\/li>\r\n \t
  6. Headspace vials<\/li>\r\n \t
  7. Headspace-GC-FID<\/li>\r\n<\/ol>\r\n

    Procedure<\/h2>\r\n

    Prepare Calibration Solutions<\/h3>\r\n
      \r\n \t
    1. Determine the ethanol concentrations you want to use for external calibration and have them approved by the TA\r\n
        \r\n \t
      • Be sure to take a 1:1 dilution with the internal standard solution into account<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
      • Make your calibration solutions<\/li>\r\n \t
      • Transfer 1 mL aliquots to a headspace vial and label it with the concentration<\/li>\r\n \t
      • Add 1 mL of internal standard solution to the vial<\/li>\r\n<\/ol>\r\n

        Prepare Unknown Sample<\/h3>\r\n
          \r\n \t
        1. Transfer 1 mL of your sample to a headspace vial and label it<\/li>\r\n \t
        2. Add 1.0 mL of internal standard solution to the unknown in the vial<\/li>\r\n<\/ol>\r\n

          GC-FID<\/h3>\r\n
            \r\n \t
          1. First, run a blank<\/li>\r\n \t
          2. Run calibration solutions in triplicate<\/li>\r\n \t
          3. Check that all RTs, ethanol and internal standard, are acceptable<\/li>\r\n \t
          4. With your TA, ensure the data is acceptably linear using the provided software\r\n
              \r\n \t
            • R-squared = 0.95-0.985 is typically the minimum desired linearity\r\n
                \r\n \t
              • You may move forward with unknowns if you obtain a value of 0.80 or higher if all but 1 data point seem reasonably linear<\/li>\r\n \t
              • If your R-squared value is between 0.80-0.95, perform a Grubb's Test when writing your report and before calculating your unknown concentration<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
              • Each group should then run their unknown sample in triplicate<\/li>\r\n \t
              • Ensure your internal standard is present and RTs are acceptable<\/li>\r\n \t
              • Each group should use the software to obtain peak areas of the calibration and unknown samples<\/li>\r\n \t
              • Obtain data for one calibration chromatogram and the unknown chromatogram to plot<\/li>\r\n<\/ol>\r\n
                \r\n

                Lab Report<\/h1>\r\n<\/header>\r\n
                \r\n
                  \r\n \t
                • Data table with concentrations and areas<\/li>\r\n \t
                • Calibration curve and linear regression equation<\/li>\r\n \t
                • Grubb's Test calculations and if your R-squared value is less than 0.95<\/li>\r\n \t
                • Original and revised calibration curve, regression equation, and R-squared if you remove an outlier based on Grubb's Test results\r\n
                    \r\n \t
                  • How did removing the point affect your data?<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
                  • Calculate concentration of unknown with original and revised calibration curves\r\n
                      \r\n \t
                    • How did removing the point affect your final results?<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n ","rendered":"

                      Introduction<\/h1>\n
                      \n

                      Purpose<\/h2>\n

                      Quantify the amount of ethanol in an unknown 'blood' sample using headspace GC with a flame ionization detector.<\/p>\n

                      BAC Samples<\/h2>\n

                      Blood alcohol measurement is one of the most common toxicology analyses performed in the U.S. In addition to breath alcohol testing with preliminary breath testing instruments and\/or IR, GC-FID (flame ionization detector) of blood samples is the typical way we do this. Urine can be tested for ethanol metabolites, but it is generally less reliable.<\/p>\n

                      Headspace sampling<\/strong> is the typical method used for GC sample introduction in BAC analyses, as shown in Figure 1 below.\u00a0 It is performed by placing a blood sample in a headspace vial. Headspace vials are sealed but have a septum that may be pierced by a syringe. By gently heating the vials, we can take advantage of the partial pressure of the gas phase ethanol being proportional to the concentration of ethanol in the blood sample. A gas-tight syringe can then be used to extract a headspace sample containing gas phase ethanol and inject the sample onto the GC column.<\/p>\n

                      \"\"
                      Figure 1. Headspace sampling for BAC is performed by piercing the septum of the sample vial with a gas-tight syringe, drawing gas phase sample into the syringe, and injecting the sample directly on the GC column.<\/figcaption><\/figure>\n

                      Materials and Methods<\/h1>\n
                      \n

                      Supplies<\/h2>\n
                        \n
                      1. Ethanol<\/li>\n
                      2. Internal standard<\/li>\n
                      3. Volumetric flask(s)<\/li>\n
                      4. Pipette<\/li>\n
                      5. Unknown samples<\/li>\n
                      6. Headspace vials<\/li>\n
                      7. Headspace-GC-FID<\/li>\n<\/ol>\n

                        Procedure<\/h2>\n

                        Prepare Calibration Solutions<\/h3>\n
                          \n
                        1. Determine the ethanol concentrations you want to use for external calibration and have them approved by the TA\n
                            \n
                          • Be sure to take a 1:1 dilution with the internal standard solution into account<\/li>\n<\/ul>\n<\/li>\n
                          • Make your calibration solutions<\/li>\n
                          • Transfer 1 mL aliquots to a headspace vial and label it with the concentration<\/li>\n
                          • Add 1 mL of internal standard solution to the vial<\/li>\n<\/ol>\n

                            Prepare Unknown Sample<\/h3>\n
                              \n
                            1. Transfer 1 mL of your sample to a headspace vial and label it<\/li>\n
                            2. Add 1.0 mL of internal standard solution to the unknown in the vial<\/li>\n<\/ol>\n

                              GC-FID<\/h3>\n
                                \n
                              1. First, run a blank<\/li>\n
                              2. Run calibration solutions in triplicate<\/li>\n
                              3. Check that all RTs, ethanol and internal standard, are acceptable<\/li>\n
                              4. With your TA, ensure the data is acceptably linear using the provided software\n
                                  \n
                                • R-squared = 0.95-0.985 is typically the minimum desired linearity\n
                                    \n
                                  • You may move forward with unknowns if you obtain a value of 0.80 or higher if all but 1 data point seem reasonably linear<\/li>\n
                                  • If your R-squared value is between 0.80-0.95, perform a Grubb's Test when writing your report and before calculating your unknown concentration<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
                                  • Each group should then run their unknown sample in triplicate<\/li>\n
                                  • Ensure your internal standard is present and RTs are acceptable<\/li>\n
                                  • Each group should use the software to obtain peak areas of the calibration and unknown samples<\/li>\n
                                  • Obtain data for one calibration chromatogram and the unknown chromatogram to plot<\/li>\n<\/ol>\n
                                    \n
                                    \n

                                    Lab Report<\/h1>\n<\/header>\n
                                    \n
                                      \n
                                    • Data table with concentrations and areas<\/li>\n
                                    • Calibration curve and linear regression equation<\/li>\n
                                    • Grubb's Test calculations and if your R-squared value is less than 0.95<\/li>\n
                                    • Original and revised calibration curve, regression equation, and R-squared if you remove an outlier based on Grubb's Test results\n
                                        \n
                                      • How did removing the point affect your data?<\/li>\n<\/ul>\n<\/li>\n
                                      • Calculate concentration of unknown with original and revised calibration curves\n
                                          \n
                                        • How did removing the point affect your final results?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<\/div>\n

                                           <\/p>\n

                                          Media Attributions<\/h2>
                                          • BAC Headspace Sampling © Charlie Williams <\/li><\/ul><\/div>","protected":false},"author":20,"menu_order":5,"template":"","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-163","chapter","type-chapter","status-publish","hentry"],"part":90,"_links":{"self":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapters\/163","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/wp\/v2\/users\/20"}],"version-history":[{"count":5,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapters\/163\/revisions"}],"predecessor-version":[{"id":173,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapters\/163\/revisions\/173"}],"part":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/parts\/90"}],"metadata":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapters\/163\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/wp\/v2\/media?parent=163"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/pressbooks\/v2\/chapter-type?post=163"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/wp\/v2\/contributor?post=163"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/openbooks.library.unt.edu\/forensicchemlabmanual\/wp-json\/wp\/v2\/license?post=163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}