Environmental Express HotBlock CURRENT - Manual (Page 29)

800.745.8218 / 843.576.1147 / www.environmentalexpress.com Environmental Express • 27
HotBlock™: Operation and Instruction Manual Using the GhostWipe
2.2 Ghost Wipe — Catalog # SC4210 or SC4250
2.3 Polypropylene Digestion Vessels — Catalog # SC475 (SC490 for HotBlock™
SC150)
2.4 Ribbed Watch Glasses, Catalog # SC505 or Reflux Caps, Catalog # SC506
(for use with SC490 vials for HotBlock™ SC150, use Ribbed Watch Glasses,
Catalog # SC610)
2.5 FilterMate™ — optional if sample does not completely dissolve
* 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 Reagents
3.1 Concentrated Reagent-grade HNO
3
(5mL repipet dispenser recommended)
3.2 Concentrated Reagent-grade HCl (5mL repipet dispenser recommended)
4.0 Procedure
4.1 Transfer the wipe to the SC475 digestion cup. It is recommended that
the wipe is sent to the sampling area with a cup and wipe so no transfer
steps are required. The wipe must be transported in a rigid-walled
container according to the sampling procedure ASTM E1728.
4.2 Add 10mL DI Water, 2mL HNO
3
and 2mL HCl. Cover with a ribbed watch
glass.
4.3 Heat the sample for 45 minutes at 95°C.
Note: When using a watch glass, adjust the set point temperature of the HotBlock™ so
that a 50mL 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.
4.4 Using the polycarbonate transfer racks, remove samples from the
HotBlock™ and allow them to cool for approximately 10 minutes. Bring
the sample to 50mL volume. If excess amounts of undigested material
remain, filter the sample using a 2.0µm Teflon® FilterMate.
4.5 Cap and mix well.
According to AIHA Policies 2001- Revision Nov. 2000, one LCS, one matrix spike
and one duplicate must be run every 20 samples. “The LCS shall be a solid matrix
material with an established concentration obtained from a source independent
of the instrument calibration and traceable to NIST or other similar reference
material. Liquid spikes may not be used for preparing LCSs”. Environmental Express
does offer NIST traceable spiked Ghost Wipes. The catalog number is SC4252. The
range is 175-200µg of Lead per wipe.