00:00:00 This film is dedicated to Dr. G. Machata and his team at Perkin-Elmer.

00:00:30 Blood alcohol analysis with gas chromatography seems to be the most modern procedure.

00:00:49 Besides the determination of ethanol, other volatile compounds can be easily detected.

00:00:54 Automation of this procedure was necessary to increase the speed as well as the precision of the analysis.

00:01:01 The best way was to apply headspace analysis in combination with a fully automated sample injection system.

00:01:08 The first equipment of this type was developed by Perkin-Elmer, Germany, in cooperation with the author of this film.

00:01:15 It has been under continuous operation since April 1968 at the Institute of Forensic Medicine of the University of Vienna.

00:01:24 The so-called Multifract F-40 consists of a temperature-controlled sample changer designed as a turntable,

00:01:31 the usual gas chromatograph with a special dosing system, the programmer for controlling the automatic cycle,

00:01:37 the pressure regulating unit, and the recorder.

00:01:41 To increase the accuracy of the method, an internal standard is added to the sample,

00:01:45 and the quotient of the individual peak heights is determined.

00:01:49 The absolute alcohol content may be read on a calibration curve.

00:01:53 The difference of the vapor pressures in serum or blood is accounted for by calculation.

00:02:04 Tertiary butanol is used as an internal standard.

00:02:08 The vapor pressure curve of this substance runs parallel with that of ethanol over a wide range of temperatures.

00:02:29 This scheme shows the construction of the new electro-pneumatic dosing system.

00:02:33 The carrier gas first flows through a reducing valve and then through a solenoid valve into the column.

00:02:39 A small part of the carrier gas is used for continuous cleaning of the dosing capillary.

00:02:44 Afterwards, it passes through the movable sealing cylinder and then through the cleaning line and a valve to the exterior.

00:02:52 A silicone rubber membrane closes the sealing cylinder,

00:02:56 and a solenoid valve in the cleaning line regulates the pressure in the sealing cylinder.

00:03:09 After pushing the start button, the turntable goes to the next position and is lifted to the upper position.

00:03:19 The dosing capillary pierces the seals of the cylinder and of the sample bottles.

00:03:23 The carrier gas flows into the bottle until a corresponding pressure is built up.

00:03:33 By closing the solenoid valve of the carrier gas,

00:03:36 a small amount of the sample is transferred into the gas chromatographic column.

00:03:41 The flow of sample vapor into the column is interrupted by opening the solenoid valve again.

00:03:53 The turntable remains in the upper position for a short time at the beginning of the gas chromatographic separation.

00:04:00 This avoids disturbing the carrier gas flow.

00:04:12 The turntable then returns to the lower position and is now in state.

00:04:23 At the end of the analysis, the turntable takes up the middle position.

00:04:27 The end of the dosing capillary is now between the seals of the dosing cylinder and the sample bottle.

00:04:33 A strong flow of carrier gas frees the capillary from the remaining sample vapors.

00:04:42 The turntable again moves to the lower position and goes on to the next sample.

00:04:54 The samples and the internal standard are placed in special sample bottles by normal or automatic pipettes.

00:05:24 The bottles are closed with rubber septums and secured with aluminum caps.

00:05:55 The bottles containing the samples are inserted into the thermostating turntable, heated to 60 degrees centigrade.

00:06:12 The different steps of analysis will be selected on the programmer.

00:06:17 After conditioning the gas chromatograph, the analysis is started.

00:06:24 The automatic sequence is marking the sample on the diagram,

00:06:31 pressure increasing in the sample bottle, sample withdrawal,

00:06:42 analysis,

00:07:08 cleaning of the dosing capillary,

00:07:15 changing to the next sample,

00:07:22 marking the sample.

00:07:27 The parameters of analysis can be varied extensively,

00:07:30 and manual injection is possible through a separate injection port.

00:07:34 A zero adjustment device automatically corrects the baseline.

00:07:41 The accuracy of the analysis is very high.

00:07:44 Evaluation by electronic integrator and further by computer is possible.

00:07:52 The most frequently used stationary phase is Carbowax 1500.

00:07:56 For special separations, Halkomid or Poropak columns are used.

00:08:01 The multifract F40 is used in our laboratory for the routine determination of blood alcohol,

00:08:07 as well as for the clinical estimation of acetone, ether, and fluotan in blood during narcosis.

00:08:13 Two hours instrument time are required for 30 samples of blood,

00:08:17 and one more hour for the preparation of the samples and for the calculation of the results.

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