1、API PUBL*4592 94 I 0732270 0517413 084 Odor Threshold Studies Performed with Gasoline and Gasoline Combined with MTBE, ETBE and TAME HEALTH AND ENVIRONMENTAL SCIENCES API PUBLICATION NUMBER 4592 JANUARY 1994 American Petroleum Institute 1220 L Street. Northwest 11 Washington, D.C. 20005 API PUBLr459
2、2 94 0732290 0517414 TIO Odor Thresholds Studies Performed with Gasoline and Gasoline Combined with MTBE, ETBE and TAME Health and Environmental Sciences Department API PUBLICATION NUMBER 4592 PREPARED UNDER CONTRACT BY: TRC ENVIRONMENTAL CORPORATION 5 WATERSIDE CROSSING WINDSOR, CONNECTICUT DECEMBE
3、R 1993 American Petroleum Institute API PUBL*4592 94 m 0732290 05117435 957 m FOREWORD API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERAL NATURE. WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, STATE, AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED. AFI IS NOT UNDERTAKING TO MEET THE DU
4、TIES OFEMFLOYERS, MANWAC- TLJRERS, OR SUPPLIERS To WARN AND PROPERLY TRAIN AND EQUIP THEIR EMPLOYEES, AND OTHERS EXPOSED, CONCERNING HEALTH AND SAFETY RISKS AND PRECAUTIONS, NOR UNDERTAKING THEIR OBLIGATIONS WER LOCAL, STATE, OR FEDERAL LAWS. NOTHING CONTAINED IN ANY API PUBLICATION IS TO BE CONSTRU
5、ED AS GRANTING ANY RIGHT, BY IMPLICATION OR OTHERWISE, FOR THE MANU- FACTURE, SALE, OR USE OF ANY METHOD, APPARAWS, OR PRODUCT COV- ERED BY LETTERS PATENT. NEITHER SHOULD ANYTHING CONTAINED IN ITY FOR INFRINGEMENT OF LETTERS PATENT. THE PUBLICATION BE CONSTRUED AS INSURING ANYONE AGAINST LIABIL- Cop
6、yright Q 1994 American Petroleum Institute ii API PUBL+4592 74 = 0732290 05l174Lb 893 = ACKNOWLEDGMENTS THE FOLLOWING PEOPLE ARE RECOGNIZED FOR THEIR CONTRIBUTIONS OF TIME AND EXPERTISE DURING THIS STUDY AND IN THE PREPARATION OF THIS REPORT MI STAFF CONTACT Robert Barter Ph.D., Health and Environme
7、ntal Sciences Department AD HOC WO RKGROW O F THE TOXICOLOGY TASK FORCE Charles R. Clark B.D., Unocai Corporation Wayne Daughtrey Ph.D., Exxon Biomedicai Sciences Mark D. Saperstein ARCO iii API PUBLJ4592 4 = 0732290 05L7417 72T TABLE OF CONTENTS SECTION EXECUTIVE SUMMARY 1. INTRODUCTION 2. EXPERIME
8、NTAL PROCEDURES TASTE EVALUATION PROCEDURES ODOR EVALUATION PROCEDURES Threshold Determinations in Air Samples Threshold Determinations in Aqueous Samples CALCULATION OF ODOR AND TASTE THRESHOLD VALUES PANEL 3. RESULTS AND CONCLUSIONS TASTE EVALUATION RESULTS ODOR EVALUATION RESULTS Results From the
9、 Evaluation of MTBE Results From the Evaluation of Gasoline Results From the Evaluation of the Gasoline and Oxygenate Mixtures CONCLUSIONS REFERENCES APPENDIX A MTBE Data Sheets APPENDIX B Gasoline Headspace Vapor Data Sheets PAGE e5-1 1-1 2-1 2-1 2-2 2-2 2-8 2-8 . 2-12 3-1 3-1 3-1 3-1 3-3 3-5 3-9 R
10、- 1 APPENDIX C Gasoline-Oxygenate Headspace Vapor Data Sheets API PUBL*4592 94 m 0732290 0537438 bbb m TABLE 2- 1 2-2 2-3 3- 1 3-2 3-3 3-4 3-5 3-6 3-7 FIGURE 2- 1 2-2 LIST OF TABLES TFIC SOLVENT BAG STANDARD PREPARATION DATA FORM 2-3 E), EVALUATION FORM FOR THE DYNAMIC TFIIANGLE OLFACTOMETER 2-9 TAB
11、LE FOR CONVERSION OF RANK DATA TO X-AXIS PL.OT VALUES 2-1 o TASTE THRESHOLD VALUES FOR MTBE IN WATER 3- 1 ODOR DETECTION AND RECOGNITION THRESHOLD VALUES FOR MTBE IN AIR AND WATER ODOR INTENSITY VALUES FOR MTBE IN AIR AND WATER 3-1 3-2 OUOR DETECTION AND RECOGNITION THRESHOLD VALUES FOR GASOLINE HEA
12、DSPACE VAPOR SAMPLES ODOR INTENSITY VALUES FOR GASOLINE HEADSPACE VAPOR SAM PLES 3-4 ODOR DETECTION AND RECOGNITION THRESHOLD VALUES GASOLINE-OXYGENATE HEADSPACE VAPOR SAMPLES 3-5 ODOR INTENSITY VALUES FOR GASOLINE-OXYGENATE HEADSPACE VAPOR SAMPLES 3-7 3-3 LIST OF FIGURES DW C DIL ITION FORCED-CHOIC
13、E TRIANG OL-FACTOM ETER B LITANOL OLFACTOMETER E 2r6 2-7 API PUBL*4592 94 0732290 0517419 5T2 EXECUTIVE SUMMARY The Clean Air Act Amendments of 1990 require that gasoline sold in areas of non- attainment for carbon monoxide or ozone contain specified amounts of fuel oxygenates. Fuel oxygenates inclu
14、de, methyl-tertiary-butyl ether (MTBE), ethyl- tertiary-butyl ether (ETBE), and tertiary-amyl-methyl ether (TAME). These oxygenated compounds increase the oxygen content of fuels, producing a more complete combustion, resulting in a reduction in carbon monoxide emissions. Oxygenated compounds such a
15、s MTBE have been previously added to gasoline to enhance octane ratings. More recently, larger amounts of oxygenates, MTBE, in particular, have been added to fuels to meet Clean Air Act Amendment requirements. This study examines the effect of oxygenate addition on the odor of gasoline blends. Three
16、 blends of gasoline (summer, winter and a “composite“) were evaluated for their odor detection and recognition thresholds in air. These gasolines were also combined with the gasoline oxygenates MTBE, ETBE or TAME to evaluate the effect of the oxygenates on the gasolines odor detection and recognitio
17、n thresholds. Additionally, commercialgrade MTBE (97% pure, obtained from ARCO Chemical Co.) was evaluated for its odor detection and recognition thresholds in air and water as well as its taste threshold in water. The detection threshold is defined as the minimum concentration at which 50 percent o
18、f a given population can differentiate between a sample containing the odorant and a sample of odor free air. The recognition threshold value is defined as the minimum concentration at which 50 percent of a given population can recognize or identify the odorant. These evaluations were conducted at T
19、RC Environmental Corporations (TRCs) Odor Laboratory in Windsor, Connecticut. The average detection and recognition threshold values for commercial grade MTBE were determined to be 0.053 and 0.1 25 parts-per-million (ppm), respectively. The average detection and recognition threshold values for this
20、 MTBE in water were ES-1 API PUBL*4572 74 H 0732290 0537420 234 W determined to be 0.045 and 0.055 ppm, respectively. In general, compounds with odor thresholds below.1 ppm are considered highly odorous. The panelists descriptions of MTBEs odor included alcohol, chemical, ether and butane. Finally,
21、the average taste detection threshold value for this oxygenate was determined to be 0.039 ppm. The panelists found the taste of MTBE to be highly objectionable. The average detection and recognition threshold values for the headspace vapor of the three gasoline blends are as follows: summer blend -
22、0.576 and 0.802 ppm, respectively; winter blend - 0.479 and 1.121 ppm, respectively; and “composite“ blend - 0.474 and 0.765 ppm, respectively. In general, the panelists described all three blends as smelling like gasoline. The average detection and recognition threshold values for the headspace vap
23、or of the gasoline-oxygenate mixtures are as follows: summer blend + 3% MTBE (97% purity) - 0.5 and 0.696 ppm, respectively; summer blend + 11 % MTBE (97% purity) - 0.275 and 0.710 ppm, respectively; summer blend + 15% MTBE (97% purity) - 0.264 and 0.686 ppm, respectively; summer blend + 15% MTBE (9
24、9% punty) - 0.1 13 and 0.358 ppm, respectively. The odors associated with these mixtures included organic volatile, gasoline, ether, car exhaust, sweet gasoline and gasoline with ether. The summer blend of gasoline was also mixed with 15% ETBE (99% purity) and also with 15% TAME (94% purity). The av
25、erage detection and recognition threshold values for these mixtures aire 0.064 and 0.139 ppm (summer blend + ETBE) and 0.1 14 and 0.207 ppm (summer blend + TAME). The odors the panelists associated with these mixtures includeld ether, gasoline, chemical with gasoline, cleaning fluid and natural gas.
26、 The winter and composite gasolines were each mixed with 15% MTBE (97% purity), respectively. The average detection and recognition threshold values for these mixtures were 0.219 and 0.398 ppm (winter blend + MTBE) and 0.085 and 0.1 85 ppm (composite blend + MTBE), respectively. The odor of the wint
27、er gasoline - MTBE ES-2 API PUBL*4592 94 0732290 05L7421 150 M mixture was associated with gasoline, chemical and ether by the panelists. The odor of the “composite“ gasoline - MTBE mixture was associated with gasoline, gasoline with ether, and permanent marker by the panelists. ES-3 API PUBLX4572 7
28、4 m 0732270 0517422 O97 m Section 1 INTRODUCTION The Clean Air Act Amendments of 1990 require that gasoline sold in areas of non- attainment for carbon monoxide or ozone contain specified amounts of fuel oxygenates. Fuel oxygenates include, methyl-tertiary-butyl ether (MTBE), ethyl- tertiary-butyl e
29、ther (ETBE), and tertiary-amyl-methyl ether (TAME). These oxygenated compounds increase the oxygen content of fuels, producing a more complete com bustion, resulting in a reduction in carbon monoxide emissions. Oxygenated compounds such as MTBE have been previously added to gasoline to enhance octan
30、e ratings. More recently, larger amounts of oxygenates, MTBE, in particular, have been added to fuels to meet Clean Air Act Amendment requirements. This study examines the effect of oxygenate addition on the odor of gasoline blends. A commercial blend of MTBE (97% purity, obtained from ARCO Chemical
31、 Co.) was also evaluated for its odor detection and recognition thresholds in air and water as well as its taste threshold in water. MTBE (99% purity) and ETBE (99% purity) were also supplied by ARCO Chemical Company. TAME (94% purity) was obtained by API from Aldrich Chemical Company and supplied t
32、o TRC through APls chemical repository, Experimental Pathology Laboratories, Inc. (Herndon, VA). The gasoline blends were furnished through Experimental Pathology Laboratories, Inc., Herndon, VA (summer blend - API Reference Fuel 91-01), and Sun Co., Inc., Marcus Hook, PA (winter blend and “composit
33、e“ sample). The Reid Vapor Pressure (RVP) for the gasoline blends (in psi) are 8.5, for the summer blend; 12.3 for the winter blend; and 7.9 for the “composite sample“. 1-1 API PUBL*4592 94 O732290 0537423 T23 Section 2 EXPERIMENTAL PROCEDURES TASTE EVALUATION PROCEDURES The taste threshold determin
34、ations met the criteria specified in Review of Publis,ec Odor and Taste Threshold Values of Soluble Gasoline Components (TRC, 1985). These criteria are summarized as follows: 1. Panel selection of at least six per group; 2. Panel selection based on taste sensitivity; 3. Panel calibration; 4. A “sip“
35、 and “spit“ presentation method; 5. Room temperature solutions; 6. Purified water as a diluent; 7. Rinse between stimuli; 8. Consideration of threshold type; 9. Staircase presentation series; 1 O. Forced-choice procedure; 11. Repeated trials; 12. Concentration step increasing by a factor of two or t
36、hree. TRC performed the taste threshold testing following the procedure in Standard Method 2160B for the Examination of Water and Wastewater (APHA et al., 1992). The taste threshold value of MTBE was determined by comparing this oxygenate with water. Aliquots of the MTBE solutions used for the aqueo
37、us odor testing were also used for the taste tests. The samples were presented to the panelists in a series of increasing concentrations, and each sample was paired with a water reference. Each panelist was required to sip the sample via straw, hold it inside the mouth for a few seconds and discharg
38、e it without swallowing. The panelist then compared the sample of oxygenate with the reference sample and indicated whether or not a flavor or aftertaste could be detected. 2- 1 API PUBL*4592 94 0732290 0517424 9bT ODOR EVALUATION PROCEDURES These studies were conducted in TRCs Odor Laboratory in Wi
39、ndsor, Connecticut. The odor threshold determinations met the criteria specified in Review of Published Odor and Taste Threshold Values of Soluble Gasoline Components (TRC, 1985). These criteria are summarized as follows: 1. Panel selection of at least six per group; 2. Panel selection based on odor
40、 sensitivity; 3. Panel calibration; 4. Consideration of vapor modality (air and water); 5. Diluent in accord with compound; 6. Presentation mode that reduces ambient air intake; 7. Analytical measurement of odorant concentration; 8. Calibration of flow rate and face velocity (for olfactometers); 9.
41、Consideration of threshold type (detection or recognition); 1 O. Ascending presentation series; 1 1. Repeated trials; 12. Forced-choice procedure; 13. Concentration step increasing by factor of two or three. Threshold Determinations in Air Samples Air samples of neat MTBE were produced by vaporizing
42、 a known volume of MTBE (0.6 pl) in a known volume of hydrocarbon-free air (0.400 fi3) which was contained in a TedlarB bag. The concentration in each sample bag was calculated according to the equation presented in Table 2-1 and expressed in parts-per-million (ppm). The average starting concentrati
43、on of MTBE in the Tedlaa bag was calculated to be 11.16 PPm. In contrast to the wholly vaporized MTBE samples, the headspace vapor samples from the summer, winter and “composite“ gasolines as well as from the gasoline- oxygenate mixtures were generated by a mini-impinger system. Ten milliliters of g
44、asoline or gasoline-oxygenate mixture were placed into a glass impinger. Carbon- filtered air was passed through an inlet tube over the headspace and the vapor was collected through an outlet tube into a Tedla? bag. The resultant headspace vapor was diluted approximately 2000-fold prior to presentat
45、ion to the odor panel. The 2-2 API PUBL*4592 94 = 0732290 0517Y25 8Tb Table 2-1. TRC Solvent Bag Standard Preparation Data Form TRC Projecc Dace Loca t ion Technician- Solvenc Species Holecular Ueighc Dens icy Di lut ion Ambient Barornectic Gas Temper a cur e Pressure Dry Gar Heter Calibration Facto
46、r (Y) Volune of In jeered Volume of Solveoc Soivenc Tm fm PDCX Pm DiLuCion Gar Concencracion .Bag No. (uL) - (OF) (OK) (in. YaO) (in. Hg) (fc) ( ppm) NOE: Pa - prcisure measured AC the dry gas mecer (PCCH) + barometric precaurc. Standard conditions are 68F, 29.92 inches Hg. 2-3 API PUBL*4592 94 m 07
47、32290 0537426 732 m concentration (in ppm) of total hydrocarbons in the Tedla? bags containing the diluted gasoline headspace vapor was approximated by using an Organic Vapor Analyzer (OVA) (Foxboro 128). The OVA was calibrated against a gaseous mixture of 45% butane, 45% pentane and 10% hexane. The
48、 Tedlap bag containing the diluted gasoline headspace vapor was then connected to the sampling port of the OVA and a reading obtained. The readings for each sample were recorded on the appropriate ED, evaluation forms (Appendices B and C). An API study of consumer gasoline vapor exposure during refu
49、eling demonstrated that approximately 80% of gasoline vapors are comprised of saturated C,-C, compounds (Clayton Environmental Consultants, 1993). The dilution-to-threshold (DR) values used to calculate the threshold concentration levels were measured with a dynamic dilution triangle olfactometer (IITRI System, 1979 Model). The D/T value represents the ratio of the volume of odor-free air that must be added to the odorous sample to reach threshold. For example, a D/T of 100 means that 100 volumes of odor-free air must be added to one volume of odorous air to dilute it to
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