Environmental Express HotBlock CURRENT - Manual (Page 30)

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HotBlock™: Operation and Instruction Manual Adaptation of EPA Method 3060
1.0 Scope and Application
1.1 The following procedures have been written as an aid to EPA Method
3060A for use with the Environmental Express HotBlock™ and StirBase.
EPA Method 3060A is an alkaline digestion procedure for extracting
hexavalent chromium [Cr(6+)] from soluble, adsorbed, and precipitated
forms of chromium compounds in soils, sludges, sediments, and similar
waste materials. Use EPA Method 3060A for reference while following the
sample preparation steps outlined below. The quantification of Cr6+ in
Method 3060A digests should be performed using a suitable technique
with appropriate accuracy and precision.
2.0 Apparatus and Materials
2.1 HotBlock™ for sample digestion – Model Numbers SC100, SC154, SC150,
or SC151
2.2 StirBase stirring device – Catalog # SC160
2.3 Polypropylene Digestion Vessels – Catalog # SC475 (or SC490 for use with
the SC150 or SC151 HotBlocks™)
2.4 Ribbed Watch Glasses – Catalog # SC505 (or SC610 for use with the SC150
or SC151 HotBlocks™)
2.5 Reflux Caps – Catalog # SC506 (used as an alternative to the SC505 only)
2.6 Stir Bars – Catalog # SC168
2.7 FilterMate – Catalog # SC0407 (or appropriate FilterMate) for sample
filtration if necessary
2.8 FlipMate – Catalog # SC0301 (or appropriate FlipMate) for sample
filtration if necessary
3.0 Procedure, Solid Sample Preparation
3.1 Place 2.5 ±0.10 g of the field-moist sample into a clean and labeled
digestion vessel. The sample should have been mixed thoroughly before
the aliquot is removed.
3.2 For the specific sample aliquot being spiked, the spike material should
be added directly to the sample aliquot at this point.
3.3 Add 50mL±1mL of digestion solution to each sample using a graduated
cylinder, and also add approximately 400 mg of magnesium chloride
and 0.5mL of 1.0M phosphate buffer. For analytical techniques that can
correct for oxidation/reduction of Cr, the addition of Mg(2+) is optional.
Cover all samples with watch glasses or reflux caps.
3.4 Stir the samples continuously (unheated) for at least five minutes using
the StirBase.
3.5 Heat the samples to 90 - 95ºC, then maintain the samples at 90 - 95ºC for
at least 60 minutes with continuous stirring.
3.6 Gradually cool, with continued agitation, each vessel to room
temperature.
Adaptation of EPA Method 3060 for use with the HotBlock™™
and StirBase Systems
Revised 05.05