Labor free, eco-friendly concentration Comply with US EPA regulations

Labor free, eco-friendly concentration
Comply with US EPA regulations
Automated solvent concentration at Con-Test® Analytical Laboratories.
Abstract
Figure 1: Syncore Analyst in the R-12 format with the
Vacuum Pump V-700 and the Vacuum Controller V-855
on top of it. The post-pump secondary condenser is
on the rear of the pump. The recirculating chiller is not
shown.
The BUCHI parallel evaporator, Syncore®
Analyst, is an efficient tool to concentrate
organic extraction from wastewater (EPA
608), air (EPA TO-13A), and soils (EPA 3500
series). It reduces the manual handling typically involved in Kuderna-Danish procedures
due to its convenient way of concentrating
large volumes (180 mL) simultaneously to
pre-defined residual volumes (1 mL). Solvent
emission is significantly reduced due to its
unprecedented high recoveries (> 95%).
Introduction
Environmental waste, water, and air samples
are usually concentrated before analysis.
During the concentration step, traditionally
performed by Kuderna-Danish (KD) or nitrogen blowdown devices, organic solvent
fumes could escape into the environment.
Thus, the condensation of solvent vapors is
inefficient, if possible at all. These solvent vapors are harmful to exposed operators and
persist in the atmosphere where they may
accelerate global warming.
Obviously, environmental laboratories play a
pioneering role in benign use and recycling
of organic solvents. Therefore, environmental laboratories are strictly controlled by
governmental bodies. Special attention is
paid to chlorinated solvent emission monitoring. Methylene chloride, for example, has a
high global warming potential and is considered a probable human carcinogen [1]. High
solvent emissions and non-compliance with
US EPA regulations, could lead to severe
monetary fines.
We present the Syncore® technology applied in automatized parallel concentration of samples and recuperation of organic
solvents. Selected US EPA applications are
listed where the Syncore Analyst has been
proven to be a “work horse” for the environmental chemist.
The Syncore® technology
The Syncore Analyst is a vacuum vortex
evaporator for concentrating multiple samples to a predefined volume of 3, 1, or 0.3
mL. A schematic representation of a Syncore
is shown in Figure 2.
An aluminum rack with up to 12 positions is
placed onto the Syncore platform and sealed
by a vacuum cover. Both the platform and the
cover are heatable. Evaporation at low temperature is achieved by applying a vacuum.
Figure 2: Schematic set-up of a Syncore Analyst, equipped with a vacuum pump and vacuum controller, a Flushback module and a recirculating
chiller. Blue lines represent the cooling water loop, black lines the vapor pathway.
Evaporation retardation is avoided by applying a horizontal orbital movement creating a vortex in the sample
vessel. A predefined final volume is retained by means of
a temperature gradient between the upper sample vessel
and the cooled appendix. Solvent vapor is condensated
at the primary condenser and collected to be reused or
disposed. A secondary condenser is placed at the pump
outlet to ensure that solvent vapors do not escape into
the lab and eventually the atmosphere.
Condenser, secondary condenser, appendix, and Flushback module are chilled and connected to a cooling
media loop. Using a recirculating chiller and a closed
cooling loop may save up to 50,000 L of tap water a
year. Importantly, an optimized Syncore Analyst method
can run safely, automatically, and without supervision
by employing the V-855 Vacuum Controller. The V-855
allows for gentle pressure decrease with the pre-programmed multi-step gradient function. It also stops the
process and aerates the system after a defined period of
time (Figure 4).
Figure 3: Schematic representation of the Flushback effect.
High analyte recoveries are obtained using a chilled
Flushback module 6 . The Flushback module partially
condenses the solvent vapor at the top of the sample
vessel generating a continuous rinsing along the glass
wall 5 . Thus, adsorption of analytes at the glass wall is
avoided 3 .
Figure 4: Pressure gradient for the concentration of 60 mL of methylene chloride to 1 mL at 55 °C including a ramp in the beginning and
automatic aeration when the process is finished.
Selected US EPA applications
Due to the Syncore Analyst, Con-Test® Analytical Laboratories automated the sample concentration for organochlorine pesticide and PCB analysis in wastewater
(US EPA 608) as well as the determination of polycyclic
aromatic hydrocarbons in air (US EPA TO-13A). Additionally, sample preparation according to the US EPA
3500 series, where it is allowed to use other concentration devices in place of Kuderna-Danish, significantly
facilitated and increased their sample throughput. To reduce sample handling during the evaporation process,
e.g. for the US EPA 608, enlarged vessels with a working
volume of 180 mL were developed.
Example – methylene chloride evaporation
Sample concentration of 12 times 60 mL methylene
chloride to 1 mL final volume using a Syncore Analyst in
combination with a V-700 pump and a V-855 controller is
completed in less than 45 minutes. Applied parameters
are presented in Table 1.
Parameter
Setting
Platform temperature
55 ºC
Cover temperature
50 ºC
Cooling temperature
10 ºC
Orbital movement
300 rpm
Vacuum gradient
Table 1. Parameter settings for automated methylene
chloride evaporation employing the Syncore Analyst, a
V-700 pump, V-855 controller and an F-114 chiller, for
details see [2].
Step
Pressure (mbar)
Time (min)
1
ambient-600
1
2
600-525
10
3
525-450
20
4
450-450
10
5
450-ambient
1
Conclusion
Acknowledgement
Automated sample concentration and effective solvent
recovery are reported for selected and validated US
EPA methods for environmental waste, water, and air
samples. The presented Syncore technology reduces
manual labor and increases analyte recovieries due the
Flushback effect. It also is the ideal tool to reduce solvent
emissions yielding recoveries of >95%.
Tod Kopyscinski of Con-Test® Analytical Laboratory in
Longmeadow (MA) is kindly acknowledged for fruitful
discussions.
Reference
[1] www.epa.gov/ttnatw01/hlthef/methylen.html
[2] Syncore® Application Guide, BUCHI Labortechnik 2012. For further information see : www.buchi.com/applications
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0310 WP Syncore EPA
Labor free, eco-friendly concentration
Comply with US EPA regulations