Environmental Express HotBlock CURRENT - Manual (Page 17)

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HotBlock™: Operation and Instruction Manual EPA Method 200.2, Revision 2.8
1.0 Scope and Application
1.1 The following procedures have been written as an aid to EPA digestion
procedure 200.2 for use with the Environmental Express HotBlock™.
EPA Method 200.2 is for the determination of total recoverable analytes
in groundwater, surface water, drinking water, wastewater and (with
the exception of silica) in solid samples such as sediment, sludge
and soil. Use EPA Method 200.2 for reference while following the
sample preparation steps outlined below. A complete list of elements
appropriate for analysis is included in EPA Method 200.2. Analysis can be
performed by flame atomic absorption, GF/AA, ICP and ICP-MS.
2.0 Apparatus and Materials
2.1 HotBlock™ for Metals Digestions — Model Number SC100, SC150* or
SC154
2.2 Polypropylene Digestion Vessels — Catalog # SC475 (or SC490 for use
with HotBlock™ SC150)
2.3 Ribbed Watch Glasses, Catalog # SC505 or Reflux Caps, Catalog # SC506
(for use with SC490 vials for HotBlock™ SC150, use Ribbed Watch Glasses,
Catalog # SC610 )
2.4 FilterMate™ — Catalog # SC0401 (or appropriate FilterMate) for sample
filtration if necessary
*Note: For all procedures, when using the SC150 block with the SC490 digestion vials with
a 100mL sample, double the volume of all reagents and acids added.
3.0 Procedure, Aqueous Sample Preparation
3.1 Mix sample thoroughly to achieve homogeneity. For each digestion
procedure, transfer a 50mL sample (or appropriate volume for your lab)
into the SC475 polypropylene vessel. For best results, weigh the sample
directly in the vessel on a tared balance.
3.2 Add 1mL (1:1) HNO
3
and 0.5mL (1:1) HCl, then swirl. Heat the sample
in the HotBlock™ at 95°C for 2.5 hours without boiling. Place a ribbed
watch glass (SC505) on top of the digestion vessel.
Note: When using a watch glass, adjust the control point temperature of the HotBlock™
so that a 50mL, 5% acid solution is heated to 85°C BEFORE placing the watch glass over
the sample. Laboratory tests have proven that the addition of the ribbed watch glass will
add approximately 10°C to the sample temperature, bringing the sample temperature
up to 95°C. Refer to page 7 of the operations manual for instructions on HotBlock™
temperature adjustment.
3.3 Using the polycarbonate transfer racks, remove samples from the
HotBlock™ and allow them to cool.
3.4 After cooling, dilute samples to 50mL with DI Water.
3.5 If necessary, filter with SC0401 (or appropriate FilterMate) to remove
insoluble material.
Note: The filtration step should be performed slowly with little pressure placed on the
plunger. If excessive back pressure occurs, stop filtration and allow sediments to “settle
out”. Applying pressure to the plunger may cause sample “blow through” allowing
sediment to pass through the filter into the digestate.
Adaptation for EPA Method 200.2, Revision 2.8 for use with the
Environmental Express HotBlock™ Digestion System
Revised 05.05