Environmental Express HotBlock Pro - Manual (Page 28)

800.745.8218 / 843.576.1147 / www.environmentalexpress.com Environmental Express • 26
HotBlock™: Operation and Instruction Manual Ghost Wipe
Sample Preparation for Lead Analysis with the Ghost Wipe
Revised 05.05
Methodology Note:
The following procedure has been written as an aid for use with the Environmental Express HotBlockTM and strictly follows HUD
(Housing and Urban Development) guidelines for Lead in Dust Wipes Appendix A-5.0 which references NIOSH 7082.
Scope and Application:
This application deals with the preparation of samples using lead wipes, specifically the Ghost Wipe from Environmental Express. The
sample is heated in the presence of Nitric and Hydrochloric acids to dissolve the wipe and all lead compounds into solution. Analysis can be
performed by flame atomic absorption (FLAA) or inductively coupled plasma technique (ICP).
Apparatus and Materials:
1. HotBlock™ for Metals Digestions — Model Numbers SC100, SC150*, or SC154
2. Ghost Wipe — Part Number SC4210 or SC4250
3. Polypropylene Digestion Vessels — Part Number SC475 (SC490 for HotBlock™ SC150)
4. Ribbed Watch Glasses, Part Number SC505 or Reflux Caps, Part Number SC506
(for use with SC490 vials for HotBlock™ SC150, use Ribbed Watch Glasses, Part Number SC610 )
5. FilterMateTM — 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.
Reagents:
1. Concentrated Reagent-grade HNO3 (5mL repipet dispenser recommended)
2. Concentrated Reagent-grade HCl (5mL repipet dispenser recommended)
Procedure:
1. ransfer 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.
2. Add 10mL DI Water, 2mL HNO3 and 2mL HCl. Cover with a ribbed watch glass.
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 6 of the operations
manual for instructions on HotBlock™ temperature adjustment.
4. Using the polycarbonate transfer racks, remove samples from the HotBlock™ and allow them to cool for approximately 10 min
utes. Bring the sample to 50mL volume. If excess amounts of undigested material remain, filter the sample using a 2.0μm PTFE
FilterMate™.
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 Lead per wipe.