Erlenmeyer flask

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Emil Erlenmeyer

The Erlenmeyer flask (synonym shake flask ) was developed in 1860 by Emil Erlenmeyer (1825–1909) - a German chemist. It is a glass vessel with a  neck that narrows towards the top, unlike a beaker . It is used as a laboratory device . In laboratory use, there are different versions of the Erlenmeyer flask, the narrow neck (DIN 12380 / ISO 1773) and wide neck shape (DIN 12385) with beaded rim and graduation and, depending on the application, also flasks with standard ground joint (DIN EN ISO 4797), e.g. B. also for atomizers or iodine value flasks with and without a collar.

Due to the tapering neck, the risk of liquids escaping from the flask in an uncontrolled manner when adding substances, swirling, stirring or boiling, is significantly lower than with beakers.

So, in the Erlenmeyer flask, z. B. liquids are mixed or dissolution processes are accelerated by - even relatively violent - swirling or stirring. Like the round bottom flask  , it is also suitable for a magnetic stirrer , but can be put down directly because of its flat bottom. (The round bottom flask, on the other hand, needs a cork ring or a tripod for a firm stand, the latter makes swiveling by hand or frequent checking by holding into the backlight more cumbersome.)

Thin-walled Erlenmeyer flasks must not be exposed to a vacuum , as there is a risk of implosion due to the flat bottom . A thick-walled special form of the Erlenmeyer flask is the feeding bottle .

Erlenmeyer flasks are mainly made of glass (today mainly borosilicate glass ), but sometimes also from various plastics such as polycarbonate , polyethylene terephthalate copolyester (PETG), polymethylpentene , polypropylene or polytetrafluoroethylene (PTFE). Traditionally, Erlenmeyer flasks are closed with stoppers to prevent contamination, but there are also models with screw caps. The volumes range from 25 to 10,000 ml. Glass flasks are chemically resistant to solvents, strong acids or alkaline solutions and can be easily cleaned and autoclaved so that they can be used several times. Depending on the material used, plastic pistons are partially resistant to solvents and can be autoclaved to a limited extent and are usually used as single-use items.

Wide-necked Erlenmeyer flask, formerly known as mouth monkey called.

Applications

  • Mixing: liquids can be mixed in the Erlenmeyer flask by swirling or stirring, suspensions can be kept stable or dissolution processes can be accelerated. The flat bottom ensures that Erlenmeyer flasks are stable and can be used on magnetic stirrers to mix materials. The cone shape and the narrowing neck reduce the risk of splashing compared to open beakers.
  • Heating: Erlenmeyer flasks made of glass are suitable for heating liquids.
  • Cultivation of microorganisms: Mechanically shaken culture vessels are used to cultivate aerobic microorganisms; Erlenmeyer flasks are well suited for this. The Erlenmeyer flask filled with the liquid culture is moved on a shaking machine in order to keep the microorganisms evenly distributed in the liquid and to promote the gas exchange between the liquid and the gas phase. The size of the Erlenmeyer flasks used varies, depending on the application, from the milliliter to the liter scale. Baffles (inwardly directed projections) in the Erlenmeyer flask increase the turbulence in the liquid when shaken and thus promote the gas exchange between the liquid and the gas phase. This promotes the introduction of oxygen and thus accelerates the growth of the cultivated organisms. This type of cultivation is often used before more technically demanding cultivations are carried out in the laboratory fermenter .

Oxygen supply in shaking cultures

The sufficient supply of a liquid culture with oxygen and an optimum pH are basic requirements for all cellular processes. The oxygen concentration in liquid media depends on the amount of oxygen dissolved in the medium, the amount of oxygen in the gas phase above the culture medium and the amount of gas bubbles in the medium. For the efficiency of the oxygen input ( volume-related mass transfer coefficient , synonym kLa value) into the cultivation vessel, the size of the gas bubbles, which arise from mixing movements, is of decisive importance. In order to reduce foam formation, in stirred bioreactors z. T. antifoam agents added, which lead to a significant reduction in the kLa value. Traditional stoppers and the length of the flask neck also reduce the supply of oxygen to the liquid culture. In contrast to this, Erlenmeyer flasks with baffles increase both the mixing of the liquid and the surface available for the oxygen transfer at the air-liquid boundary and thus lead to a better gas supply to the cells.

The monitoring of the oxygen supply and other physicochemical environmental parameters (e.g. pH value, concentration of dissolved carbon dioxide) in shake flasks is especially important in bioprocess engineering in order to keep the living conditions in the liquid culture constant. In addition to classical chemical and electrochemical methods for determining the oxygen concentration , luminescence-based techniques are increasingly used today. The advantage of these optical measurement methods is that no oxygen is consumed in the medium, the measurement is independent of the pH value and the ionic strength and even several metabolic parameters can be determined in parallel under aseptic conditions without sampling. With this online control, critical process parameter concentrations can be detected in good time with liquid cultures and corrected by changing media or further processing of the culture.

For good aeration and mixing of the liquid culture, the rotation of the liquid "in phase" is also important. H. the synchronous movement with the shaking movement of the tray. The shaken culture can go “out of phase” under certain conditions. The liquid sloshes in an uncontrolled manner at the bottom of the piston, which results in poor mixing, reduced gas-liquid mass transfer and reduced power input. The main factor that causes a liquid culture to "get out of phase" is the viscosity of the medium. However, small shaking diameters, low filling levels and many and / or large baffles also favor the change in state.

Designs

There are several standards that deal with Erlenmeyer flasks:

  • DIN ISO 1773 narrow-necked Erlenmeyer flasks
  • EN ISO 24450 wide-necked Erlenmeyer flasks
  • DIN ISO 4797 Erlenmeyer with standard cut

The following sizes are described in the standards


Narrow neck Erlenmeyer flask
Nominal volume
ml
Largest outer diameter
mm
Outer neck
diameter mm
Total height
mm
Wall thickness (min.)
Mm
25th 42 ± 1 22 ± 1 75 ± 3 0.8
50 51 ± 1 22 ± 1 90 ± 3 0.8
100 64 ± 1.5 22 ± 1 105 ± 3 0.8
250 85 ± 2 34 ± 1.5 145 ± 3 0.9
500 105 ± 2 34 ± 1.5 180 ± 4 0.9
1000 131 ± 3 42 ± 2 220 ± 4 1.3
2000 166 ± 3 50 ± 2 280 ± 4 1.5
3000 187 ± 3 50 ± 2 310 ± 5 1.8
5000 220 ± 3 50 ± 2 365 ± 5 1.8


Wide neck Erlenmeyer flask
Nominal volume
ml
Largest outer diameter
mm
Outer neck
diameter mm
Total height
mm
Wall thickness (min. / Max.)
Mm
50 51 ± 1 34 ± 1.5 85 ± 3 0.8 / 2.5
100 64 ± 1.5 34 ± 1.5 105 ± 3 0.8 / 2.5
250 85 ± 2 50 ± 2 140 ± 3 09 / 3.3
500 105 ± 2 50 ± 2 175 ± 4 09 / 3.3
1000 131 ± 3 50 ± 2 220 ± 4 1.3 / 3.6


  • DIN 4797 describes two different series of Schlifferlenmeyer flasks
Schlifferlenmeyer flask
Nominal volume
ml
row 1 Row 2
Total height
mm
Joint size
NS
Nominal total height
mm
Joint size
NS
10 60 ± 3 14/23 --- ---
25th 70 ± 3 14/23
19/26
70 14/23
19/26
50 85 ± 3 14/23
19/26
85 14/23
19/26
24/29
29/32
100 100 ± 6 14/23
19/26
24/29
29/32
105 14/23
19/26
24/29
29/32
250 140 ± 6 19/26
24/29
29/32
135 19/26
24/29
29/32
34/35
500 175 ± 6 19/26
24/29
29/32
170 19/26
24/29
29/32
34/35
1000 220 ± 7 24/29
29/32
34/35
210 24/29
29/32
34/35
2000 270 ± 7 24/29
29/32
34/35
275 24/29
29/32
34/35
3000 --- --- 310 34/35
45/40
5000 --- --- 365 34/35
45/40

literature

  • D. Schlee, H.-P. Kleber (Ed.): Dictionaries of Biology - Biotechnology Part II. Gustav-Fischer Verlag, Jena 1991, ISBN 3-334-00311-6 , p. 923.
  • Inorganic Chemistry Textbook. Verlag Walter de Gruyter, Berlin 1985, ISBN 3-11-007511-3 , p. 7.
  • Pocket atlas of biotechnology and genetic engineering. Wiley-VCH Verlag, Weinheim 2002, ISBN 3-527-30865-2 , p. 192.

Web links

Commons : Erlenmeyer Flask  - Collection of Images, Videos, and Audio Files

Individual evidence

  1. ^ Brockhaus ABC chemistry. FA Brockhaus Verlag, Leipzig 1965, pp. 702–703.
  2. Arthur Stähler et al. (Ed.): Handbook of working methods in inorganic chemistry. Veith & Co., Leipzig 1913, p. 99.
  3. S. Schiefelbein, A. Fröhlich, GT John, F. Beutler, C. Wittmann, J. Becker: Oxygen supply in disposable shake-flasks: prediction of oxygen transfer rate, oxygen saturation and maximum cell concentration during aerobic growth. In: Biotechnology Letters. 35, No. 8, 2013. doi: 10.1007 / s10529-013-1203-9 . PMID 23592306
  4. a b V. C. Hass, R. Pförtner (Ed.): Practice of bioprocess engineering with virtual internship. Springer Spectrum, Wiesbaden 2009, ISBN 978-3-8274-1795-4 , pp. 19f.
  5. ^ S. Routledge: Beyond de-foaming: The effects of antifoams on bioprocess productivity. In: Computational and Structural Biotechnology Journal. 3, No. 4, 2012. doi: 10.5936 / csbj.201210014 . PMID 24688674 .
  6. JS Schultz: Cotton closure as an aeration barrier in shaken flask fermentation. In: Journal of Applied Microbiology. 12, No. 4, 1964. PMC 1058122 (free full text).
  7. a b A. Gupta, G. Rao: A Study Of Oxygen Transfer in Shake Flasks Using a Non-Invasive Oxygen Sensor. In: Biotechnology and Bioengineering. 84, No. 3, 2003. PMID 12968289 .
  8. Y. Amao: Probes and polymers for optical sensing of oxygen. In: Mikrochimica Acta. 143, No. 1, 2003, doi: 10.1007 / s00604-003-0037-x .
  9. T. Anderlei, W. Zang, M. Papaspyrou, J. Büchs: Online respiratory activity measurement (OTR, CTR, RQ) in shake flasks. In: Biochemical Engineering Journal. 17, No. 3, 2004, doi: 10.1016 / S1369-703X (03) 00181-5 .
  10. J. Buechs, U. Maier, C. Milbradt, B. Zoels: Power consumption in shaking flasks on rotary shaking machines: II. Non-dimensional description of specific power consumption and flow regimes in unbaffled flasks at elevated liquid viscosity. In: Biotechnology and Bioengineering. 68, No. 6, 2000. PMID 10799984 .
  11. J. Buechs, S. Lotter, C. Milbradt: Out-of-phase operation conditions, a hitherto unknown phenomenon in shaking bioreactors. In: Biochemical Engineering Journal. 7, No. 2, 2001. doi: 10.1016 / S1369-703X (00) 00113-3 .
  12. CP Peter, S. Lotter, U. Maier, J. Buechs: Impact of out-of-phase conditions on screening results in shaking flasks experiments In: Biochemical Engineering Journal. 17, 2004. doi: 10.1016 / S1369-703X (03) 00179-7 .