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Breath testing instrument have been used extensively for the determination of ethanol in
medicolegal investigations due to the simplicity in their operation, the relative portability of the
instruments and the immediately available results. Unfortunately, breath alcohol instruments
universally are prone to false positives (i.e. instrument reports ethanol is present when in fact it is
responding to a different chemical) and falsely elevated breath values when ethanol is present
(due to a variety of factors). The Intoxilyzer 5000 breath alcohol instrument is no exception and
numerous studies have documented some of the sources of the errors with this instrument. The
major types of variables discussed in this chapter include physiological (biological) variables and
analytical (instrumental) variables with overlap between the two. The uncertainty in evidential
breath-analyzer readings for a random subjects in the post-absorptive state has been determined
to be as much as ±27% with over 90% of this uncertainty due to biological variables of the
subject and at least 23% of subjects having their actual blood-alcohol concentration
overestimated (Simpson 1987).
2100:1 Blood:Breath Partition Ratio
Many literature articles and breath test training manuals describe the partitioning of
ethanol from the blood to the breath as being governed by Henry's Law. This law states that
when a volatile chemical (alcohol) is dissolved in a liquid (blood) and is brought into contact
with a closed air space (alveolar breath) an equilibrium is rapidly formed and there exists a fixed
ratio between the concentration of the volatile compound in air and its concentration in the liquid
at a given temperature. In order to understand the application of this Law, one needs to imagine a
capped bottle containing water and a little ethanol. The bottle will contain the water and ethanol
in two forms; liquid, and gas above the liquid. This law states that at equilibrium, one can
measure the concentration of the ethanol in the gas phase, and from that measurement predict the
concentration in the simultaneous liquid phase. The comparison being made is that the lungs are
like the bottle, the blood in the lungs are like the liquid in the bottle, and the breath is like the gas
phase above the liquid. Unfortunately, Henry's Law does not apply in the lungs. In order for
Henry's Law to apply, three conditions must be met. One, the solution must be in a closed
system, like a sealed bottle. The lungs are open, not closed. Two, the solution must be kept at a
known, constant temperature. The lung temperature is never known, and the temperature is
always changing. And three, the pressure must be kept constant. The lungs are always changing
pressure, decreasing pressure to inhale and increasing pressure to exhale. Without all three
conditions present, it is not possible for equilibrium to occur, and Henry's Law does not apply.
At best, Henry's law can only be used as an approximation and a recent detailed
derivation of the partition ratio using the simplest water-air-ethanol system present in "simulator
solutions" concluded that if a fixed ratio is used it ought to be 1880:1 (Thomson, 1997).
Previously, Dubowski has suggested an even lower fixed value of 1720:1 (Dubowski, 1985).
Currently, the value of 2100:1 is routinely incorrectly used by manufacturers, law enforcement
agencies and legislatures as a fixed partition able to accurately predict blood alcohol levels, when
numerous studies throughout the years have shown that this is not the case and significant errors
can occur when using a fixed 2100:1 ratio (Alobaid 1976, Jones 1983, Thompson 1997). The
concept that ethanol easily evaporates from the pulmonary circulation and diffuses into the
alveolar airspace to be exhaled with each breath is the basis for believing the so-called bloodbreath
partitioning of ethanol at a fixed ratio. Recent research has demonstrated that ethanol does
not diffuse from the pulmonary circulation to the alveolar air space as has been previously
thought (Hlastala 1998). In fact the diffusion occurs from the pulmonary circulation to the
conducting airways of the lungs, bypassing the alveoli. The significance of this work is that no
stable partition ratio can exist for any given individual and certainly no partition ration can be
predicted for any given person. As a result, the 2100:1 ratio will be incorrect most of the time.
Another problem with using the 2100:1 ratio is that law enforcement assumes the subject
is in the elimination phase, that is, post-absorbed. However that information is usually lacking.
The significance is that during the absorption phase (when ethanol is being absorbed into the
bloodstream from the small intestine) the partition ratio is going to be lower compared to when
absorption is complete. Therefore in every individual their partition ratio will change as the
ethanol is absorbed, then eliminated. Generally it is not known whether a person is absorbing or
eliminating ethanol at the time of their breath test. Additionally, the hematocrit and fraction of
water in an individual's blood is variable and changes the partition ratio resulting in additional
uncertainty (Thompson 1997). Also Martin et. al. (1984) reported that during absorption, arterial
BAC tended to be higher than venous BAC, peaking at a higher level (tmax) and with a shorter
time to peak(tmax) until an arterao-venous concentration equilibrium was reached, whereafter
VBAC remained above ABAC. Although there was a close relationship between BrAC, ABAC
and VBAC during elimination, BrAC closely followed the pattern of ABAC during absorption
and tended to deviate from VBAC. BrAC, therefore, is much better predictor of ABAC during
absorption than VBAC. Simultaneous measurements of breath alcohol concentrations (BrAC)
and venous blood alcohol concentration (VBAC) has shown that actual VBAC can be
overestimated by more than 100% for a significant amount of time after drinking stops (Simpson
1987).
Absorption/Metabolism of Ethanol and Retrograde Extrapolation
Difficulties with retrograde extrapolation are highlighted by considering the "Hip Flask"
defense, whereby a motorist consumes a significant amount of alcohol beverage from their
personal flask or elsewhere following a crash. There is no way of knowing what the real ethanol
concentration was at the time of the crash if the usual one or two hours pass from the crash until
the blood or breath test. This argument is logically extended to if a person has enough alcohol in
his or her stomach at the time of a stop or crash, they will continue to absorb the ethanol for that
time interval until the blood or breath test is given. The importance of this argument is that a
person can absorb a lot of ethanol in a short time, up to 0.0025 gm/dl per minute, or 0.15 gm/dl
per hour. So even if a person has a 0.20 gm/dl breath or blood test an hour after a crash, they
could have been an 0.05gm/dl at the time of the crash. Sometimes this extrapolation argument is
used by law enforcement in the opposite way to extrapolate an even higher estimate of BrAC
based on the assumption than the person is in the fully postabsorptive state and eliminating
ethanol at a constant rate. Obviously it is impossible to know what state of absorption an
individual is and the high degree of variability in elimination rates makes any type of retrograde
extrapolation mostly guesswork unsuitable for scientific evidence in court. Studies have reported
that evidentiary BrAC analyses performed within 2h of driving can provide reasonable estimates
of the BrAC existing at the time of driving but than extrapolation is unwarranted (Gullberg and
McElroy 1992 and Gullberg 1991). Simpson (1987) has reported that reanalysis of BrAC data
indicate 68% of the population had their actual BAC underestimated, 16% were acceptably close
to the actual BAC, and 16% were overestimated in the fully postabsorptive state. Therefore,
breath test results may tend to overestimate actual BAC for significant amounts of time even
after the peak BAC has been reached.
Watkins and Adler (1993) reported that the average time required to reach maximum
BrAC was 41 min for both empty (after 6hr fasting) and full stomach conditions. The average
elimination rate of ethanol was found to be significantly lower after meal (0.017 BrAC/h
compared to 0.02 BrAC/h) but the time required to reach zero BrAC was not significantly
different (5.01 h full stomach, 5.05 h empty stomach). Rogers et. al. (1987) have reported that
carbohydrate caused a significant increase in rate of metabolism of ethanol and fat or protein
caused small but non-significant decreases. Winek and Esposito (1985) also reported that the
absorption of alcohol is influenced by gastrointestinal contents, motility, and the composition
and quantity of the alcoholic beverage. The vascularity of tissues influences the distribution of
alcohol and their water content will determine the amount of alcohol present after equilibrium.
Winek and Murphy (1984) reported that ethanol elimination is a zero order process. The mean
ethanol elimination rate for non-drinkers of 12+/- 4mg/h and for social drinkers l5+/-4mg%/h,
and for alcoholics rate of 30+/-9Yng%/h. A report by Cole-Harding and Wilson (1987) showed
that women metabolized ethanol faster than men, there was a small gender difference in peak
BAL and no gender difference in time to peak BAL. Dubowski (1985) reported that since
alcohol pharmacokinetics parameters are subject to wide intersubject variability such as time to
peak after end of drinking, rate of elimination, sex, and age, these variables make the blood
alcohol information widely distributed and inappropriate as a guide for the drinking behavior of
individuals.
Breathing (volume, hyperventilation, breath holding)
The rate of breathing affects the concentration of ethanol in the breath. Hyperventilation
causes a lower breath result (up to 55%) while hypoventilation (breath holding) increases the
breath result (up to 14% higher than actual BAC) (Ohlsson et. al. 1990). Both breathing disorders
can be caused by disease, trauma, and drugs and should be considered as a source of potential
error in breath testing. Others have reported that on a breath alcohol profile the area under the
profile curve for samples preceded by breath holding is significantly larger than when breathing
is normal prior to sample provision (Gullberg 1989). It has also been reported that exhaled air at
the end of maximal expiration does not always provide the best, or a close, indication of the
plasma(or blood) ethanol concentration particularly when conditions exist such as chronic
obstructive pulmonary disease (Russell and Jones 1983).
Body/Breath Temperature
Since heat is a driving force which causes the ethanol to diffuse from the blood to the
breath, the higher the temperature the greater the amount of ethanol which will diffuse into the
breath (keeping the blood concentration constant). A temperature of 34°C as been reported as an
average temperature for end-expired breath in healthy men (Jones 1982 and Dubowski 1975).
However, not all investigators agree (Hlastala 1998). An 8.62% increase for each degree C
increase in core body temperature and 6.8% decrease per degree C in core body temperature has
been reported (Fox and Hayward 1989, Fox and Hayward 1987). The apparent breath alcohol
concentration using the simulator increases linearly with temperature with a 6.25% per degree C
increase as seen in Figure 1 (Memari 1999). This could explain why the Intoxilyzer 5000
manufacturer requires higher concentrations for ethanol reference solutions to give proper
readings at 34°C. For example, the manufacturer specified target value for a calibrator solution is
0.0968 to produce a 0.080 on the instrument presumed to be operating at 34 °C as apposed to
normal body temperature of 37°C. Thus a four-degree rise in temperature will give a substantial
25% increase in apparent breath alcohol reading result. An individual's normal body temperature
can vary several degrees centigrade in a given 24-hour period, with the lowest temperature in the
early morning rising to its peak in the evening. The inter-individual body temperature can also
vary a few degrees centigrade. Finally, body temperature can vary four or five degrees centigrade
when a person is sick.
Interfering Volatile Organic Compounds
The Intoxilyzer 5000 is based on the transmittance of infrared energy at 3.80, 3.48 and
3.39 gm. Substances which also absorb infrared energy at similar wavelengths as ethanol will
cause interferences. Human expired air consists of a mixture of gases including mainly oxygen,
nitrogen, carbon dioxide, water vapor, and, in small amounts, a multitude of volatile organic
compounds (VOCs). The VOC's expelled in breath are produced endogenously during normal
metabolic activity or can be imbibed with food, drinks, inhaled from the ambient air in which
they exist as atmospheric pollutants or result from occupational exposure. A summary of
potentially interfering compounds at levels reported antimortem in human breath recently tested
on the Intoxilyzer 5000 is given in Table 2 (Memari 1999). Compounds which were not found to
significantly interfere were acetone, acetonitrile, isoprene, methyl ethyl ketone, trichloroethane
and trichloroethylene. Compounds which produced an interference alert on the instrument were
acetone and methylene chloride. At low levels isopropanol gave small false readings but at
elevated amounts the instrument indicated interferrent present and stopped the test. Therefore,
these compounds are unlikely to cause false positives with the Intoxilizer 5000 by themselves.
Acetaldehyde yielded an apparent breath alcohol reading of 0.009 on calibration mode and 0.01
g/210L on sampling mode and does not activate the interference indicator meaning that the
instrument cannot distinguish between ethanol and acetaldehyde. The two compounds tested
which yielded the highest false ethanol responses were toluene and methanol producing apparent
ethanol concentrations of 0.028 and 0.36 respectively. Methanol finds widespread commercial
use as a solvent, especially in paints and varnishes. It is also a constituent of some antifreeze
solutions, is used to denature ethanol, and is being considered as an alternative energy source.
Methanol, in sufficient quantity, will produce a positive apparent alcohol concentration on the
Intoxilyzer 5000, but will not illuminate an interference light.
Toluene is an aromatic petroleum hydrocarbon that has many important commercial and
industrial applications as a solvent and starting material for organic syntheses. It is present in
numerous paints, paint thinners, glues, and other products likely to be found in the household. It
can be and has been, abused by individuals who inhale its vapor. Garriott considers the
concentration "commonly found in abuse" for toluene to be about 1 to 30 mg/L (mean, 10 mg/L)
in blood (Cowan et. al. 1990). Toluene alone can account for between 0.028 and 0.033 g/2101, of
the ostensible ethanol reading without causing the interference mechanism to trigger (Table 2).
However, if the signal resulting from toluene is augmented by the presence of ethanol, the
readout could exceed legal limits without activating the interference light. Additionally,
combinations of organic compounds can yield additive effects with four such compounds
yielding apparent ethanol levels of 0.071-0.083 g/210L with no interference alert and no ethanol
present as seen in Table 2. It is possible for such combinations to be present in individuals
including due to environmental exposure or due to occupational exposure such as in the case of
painters, chemists, etc. The reason this instrument also responds to these chemicals is that they
absorb infrared radiation in the same region as ethanol as seen on Figure 2 showing the infrared
spectrum for ethanol compared to a combination of methanol and toluene with the wavelengths
were the Intoxilyzer is reported to take measurement marked with vertical lines.
The Intoxilyzer 5000 instrument has a "Custom Breath Test Mode Sequence With
Sample Capture" which allows for the breath sample to be preserved on a tube containing a
sorbent enabling one to reanalyze the sample at a later date (CMI 1989). Goldberger et. al.
(1987) have reported statistical analyses revealing good accuracy and precision and correlation
between direct and delayed vapor ethanol analyses for instruments including the Intoxilyzer 5000
(range = 0.000 to 0.250g/210L, N=42/instrument, r greater than 0.99). Goldberger et. al. (1986)
have also reported that collected breath samples on silica gel after retaining 1.25 to 2.75 years
revealed good overall correlation between direct and delayed ethanol determination (r=0.900).
Employing this quality control ensurance allows for the confirmation of breath alcohol readings
as well as checking for any potential interfering organic compounds. Unfortunately this quality
control measure is not universally employed and without such a sample it is impossible to know
whether an Intoxilyzer reading was due to ethanol alone or due to combinations of the many
other compounds which produce false breath alcohol readings.
Analytical Errors
All measurements are subject to three types of experimental errors which need to be
evaluated. The first errors are systematic errors which result from instrumental, method or
personal errors and result in a bias of values positive or negative relative to the true value.
Detection of this type of error is by the analysis of standard samples such as a calibration
standard at the legal limit for the jurisdiction (i.e. 0.08g/210L) and correcting for any bias. The
Intoxilyzer 5000 instrument has a "Control Breath Test Mode Sequence" which allows for just
such a test (CMI 1989) but this quality control ensurance is not universally employed. The
second errors are gross errors which may be rejected based on the widely used Q test for outliers.
If a calculated Qexp is greater than Qf t taken from a reference table for a given number of
measurements and confidence then a questionable result can be rejected. QeXp is difference
between the questionable result and its nearest neighbor divided by the spread of the entire data
set. The third errors are random errors which cannot be eliminated but are accounted for by
determining confidence intervals. The magnitude of random errors are determined by the
precision or repeatability and reproducibility. The exact value of the population mean, or the true
value, g, from an analytical method can never be determined exactly because this would require
an infinite number of measurements. Instead, a sample mean, ~, and a confidence interval is
calculated using the statistical parameter t to produce confidence limits (Skoog et. al. 1994).
Confidence limits define an interval around the sample mean, 4, which probably contains the
population mean at a given confidence limit (ASTM E177-90a 1999). The true value, p = ~ ±
ts/(N)ln. Where t is the t value from a reference table, s is the standard deviation of the data and
N is the number of measurements. Confidence intervals are required for any analytical
measurements including breath alcohol measurements.
For example, the statistically significant confidence interval for widely varying hypothetical
triplicate breath alcohol readings of 0.039, 0.060, 0.080 would be calculated as follows. First we
must determine if any value can or should be rejected. Qe,p = = (0.060-0.039)/0.080-0.039) =
0.512. Q~rit for this data set is 0.994 for this data set at 95% confidence therefore, based on
statistics we must retain the outlier. The true value, ~t = 4 t ts/(N)'2
= (4.30)(0.0205)/[(3)"z] = 0.0597 ± 0.0508 at 95% confidence. In other words, the error in the
measurement is nearly as great as the average value. In most cases, replicates are much closer than this
extreme example and therefore the confidence interval would be smaller. In an attempt to account for some
of the experimental inaccuracies of the Intoxilyzer 5000, duplicate measurements are required to be
within ± 0.02% and highest value of the non-excluded data is generally used. This unfortunately
is a completely scientifically unsound practice and is apparently used for convenience and to
report the highest possible breath alcohol reading rather than the statistically valid number.
Calculation of the average breath alcohol reading and the statistically sound confidence interval
for such measurements is straightforward and could be easily incorporated into the breath
alcohol instrument software or calculated in a few minutes with available data. The proper
statistical processing and reporting of data is required in all areas of chemistry and most areas of
forensic science excluding breath alcohol measurements. Proper scientific practice would include
the reporting of the average measured value with confident intervals and preferably be reduced
by a number to account for the high degree of uncertainty common in this type of measurement.
Leading scientists including Dubowski and Jones have suggested that a correction factor ranging
from 0.015 to 0.030 be subtracted from the mean of breath alcohol measurements (Labianca and
Simpson, 1995) to correct for error from this source. In the absence of statistical analysis such a
correction factor is the minimum that should be applied. Perhaps ironically, the most widely used
introductory analytical chemistry textbook in the U.S. uses a triplicate blood alcohol
determination as an example (Example 5-5) of statistical analysis with the values of 0.084, 0.089
and 0.079 yielding a true value, p = 0.084 ± 0.012% for 95% confidence (Skoog et al. 1994).
And yet, this type of calculation is not routinely performed as it should be for breath alcohol
measurements.
Accuracy and Precision of the Intozilzer 5000 Using Calibrator Solutions
A recent study showed that with pure calibrator solutions under static conditions, the
Intoxilyzer 5000 shows excellent calibration curve linearity and satisfactory precision as seen in
Table 3 (Memari 1999). Relative standard deviations for ten measurements at the five calibrator
solution concentrations was generally within 5%. This precision measure is a measure of the
repeatability of the instrument with pure calibrator solutions under static conditions and separate
from the error analysis discussed above required for actual breath sample analysis. Table 4 gives
the manufacturer recommended reference solutions to yield breath readings of 0.05, 0.08, and
0.20 g /2101, by the Intoxilyzer 5000 and the reference solution allowed range by the Florida
Department of Law Enforcement (FDLE). In order to measure the calibration error, solutions out
of the allowed alcohol concentration range were prepared and analyzed on the Intoxilyzer 5000.
Each ethanol solution was analyzed 15 times on calibration mode using the Intoxilyzer 5000. In
this study, the Intoxilyzer 5000 calibrated with solutions outside the allowed range up to +/- 10%
outside the allowed range 25% of the time (Memari 1999).
While the Intoxilyzer 5000 demonstrates good analytical precision for standard solutions it
suffers from numerous sources of error including calibration solution errors, temperature
variations and interfering endogenous volatile organic compounds. These measured analytical
instrument variations combined with the substantial biological variability (including
absorption/distribution/elimination rate variations, blood/breath partition variations, etc.) warrant
an extremely cautious approach to the reporting and use of breath alcohol readings using this
instrument. These potential errors can and should be accounted for when using this instrument
for evidentiary purposes and ultimately it should be used as a presumptive test with positive
blood alcohol confirmation by dual column GC/FID or GC/MS analysis. Analytical reliability
ensurances should always include body temperature (or instrument cell temperature)
measurements (and include a correction factor), employment of the custom breath test mode
sequence with sample capture for subsequent organic analysis of possible interferents and
employment the control breath test mode sequence to ensure proper functioning of the
instrument. Biological variables affecting reliability are more problematic and difficult to assess
or correct for.
References
Alobaid, TA. Hill DW. Payne JP. "Significance of variations in blood: breath partition
coefficient or alcohol." British Medical Journal. 2(6050), 1976 Dec 18: 1479-81.
ASTM E 177-90a, "1999 Annual Book of ASTM Standards: Section 14 General Methods and
Instrumentation", Standard Practice for the Use of the Terms Precision and Bias in
ASTM Test Methods, ASTM, West Conshohocken, PA, 1999, pp.39-50.
Reference Target Vapor Mean
Solution Concentration Intoxilizer SD RSD
g/ l 00ml g/210L Response g/210L
0.025 0.020 0.020 0.001 6.2%
0.139 0.110 0.117 0.004 3.3%
0.254 0.210 0.212 0.005 2.4%
0.369 0.305 0.303 0.008 2.6%
0.486 0.400 0.397 0.019 4.7%
Breath
Alcohol Cone.
210L)
0.050
Reference Solution
Target Value
fig/100mQ
0.0605
Reference Solution
Allowed range
(g/ l 00mL)
0.0586 to 0.0623
0.080 0.0968 0.0938 to 0.0997
0.200 0.2420 0.2347 to 0.2492
Conclusions
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Interfering Substances," Journal of Forensic Sciences, Vol. 42, No. 6, 1997: 1080-1087.
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Owensboro, KY 1989.
Cole-Harding S. Wilson JR. "Ethanol metabolism in men and women." Journal of Studies on
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Cowan JM Jr. McCutcheon Jr. Weathermon A. Institution Crime Laboratory Division, Texas
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Dubowski KM.
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93-117
Dubowski, KM. "Absorption, distribution and elimination of alcohol: highway safety aspects."
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collection employing silica gel." Journal ofAnalytical Toxicology. 10(5), 1986 Sep. Oct.:
194-7.
Goldberger, BA. Caplan YH. "In vitro accuracy and precision studies comparing direct and
delayed analysis of the ethanol content of vapor." Journal of Forensic Sciences. 32(1),
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Gullberg RG. "Differences between roadside and subsequent evidential breath alcohol results
and the forensic significance." Journal of Studies on Alcohol. 52(4), 1991 Jul.: 311-7.
Gullberg RG. McElroy AJ. "Comparing roadside with subsequent breath alcohol analyses and
their relevance to the issue of retrograde extrapolation." 57(2), 1992 Dec.: 193-201.
Gullberg RG.; "Applying a data acquisition system to the analysis of breath alcohol profiles."
Journal - Forensic Science Society. 29(6), 1989 Nov-Dec.: 397-405.
Hlastala MP. " The alcohol breath test .... a review" JApp Physiol. V84 n2 Feb 1998: 401-8.
Jones, A.W. "Quantitative measurements of the alcohol concentration and the temperature of
breath during a prolonged exhalation" Acta Physiologica Scandinavica. 114, 1982: 407-
12
Jones, AW. "Determination of liquid/air partition coefficients for dilute solutions of ethanol in
water, whole blood, and plasma" Journal of Analytical Toxicology. 7(4), 1983 jul-
Aug.:193-7.
Jones, AW. Beylich KM, Bjorneboe A. Ingum J. Morland J. "Measuring ethanol in blood and
breath for legal purposes: variability between laboratories and between breath-test
instruments." Clinical Chemistry. 38(5), 1992 May: 743-7.
Labianca D.A. and Simpson G., Medicolegal Alcohol Determination: Variability of the Blood- to
Breath-Alcohol Ratio and Its Effect on Reported Breath-Alcohol Concentrations, Eur. J.
Clin. Chem. Clin. Biochem., Vol. 33, 1995: 919-925.
Logan B.K., Gullberg R.G and Elenbaas J.K, "Isopropanol interference with breath alcohol
analysis: a case report." Journal of Forensic Sciences. 39(4), 1994 Jul.: 1107-11,
Martin, E. Moll W. Schmid P. Dettli L. "The pharmacokinetics of alcohol in human breath,
venous and arterial blood after oral ingestion." European Journal of Clinical
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M.S. in Chemistry Thesis, Florida International University, 1999.
Moore R., Journal of Analytical Toxicology, Vol. 15, 1991:346-347.
Ohlsson J. Ralph DD. Mandelkon MA. Babb AL. Mastala MP. "Institution Department of
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1990 Jan.; 6-13.
Rogers J. Smith J. Sraemer GA, Whitfield JB. Department of Dietetics, Royal Prince alfred
Hospital, Camperdown, NSW, Australia. "Differing effects of carbohydrate, fat and
protein on the rate of ethanol metabolism." Alcohol & Alcoholism. 22(4), 1987.: 345-53.
Russell JC. Jones RL. "Breath ethyl alcohol concentration and analysis in the presence of chronic
obstructive pulmonary disease." Clinical Biochemistry. 16(3), 1983 Jun.; 182-7.
Simpson, G., "Accuracy and Precision of Breath Alcohol Measurments for Subjects in the
Absorptive State," Clin. Chem.,33l6, 1987: 753-756 and Simpson G. "Accuracy and
precision of breath-alcohol measurements for a random subject in the postabsorptive
state" Clinical Chemistry, Vol. 33(2), 1987: 261-68
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Evaluation of Analytical Data, Saunders College Publishing, Philadelphia, 1994, pp.78-
95.
Thompson, RQ., "The Thermodynamics of Drunk Driving" J. Chem. Educ., 74,1997:532-536.
Watkins, RL. Adler EV. "Institution Phoenix Crime Detection Laboratory, AZ. The effect of
food on alcohol absorption and elimination patterns." Journal of Forensic Sciences.
38(2), 1993 Mar:285-91.
Winek, CL. Esposito FM. "Blood Alcohol concentrations: factors affecting predictions." Legal
Medicine. 1985: 34-61.
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| Variables Affecting the Accuracy and Precision of Breath Alcohol Instruments Including the Intozilyzer 5000 Stefan Rose, M.D. and Kenneth G. Furton, Ph.D.s 'University Medical and Forensic Consultants, Inc., 10130 Northlake Boulevard, Suite 214 # 300, West Palm Beach, Florida 33412 (561) 795-4452, Fax (561) 795-4768 and 2Department of Chemistry and International Forensic Research Institute, Florida International University, University Park, Miami, Florida 33199, Phone (305) 348-6211, Fax (305) 348-3772. |
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