Environmental Express HotBlock Pro - Manual (Page 26)

800.745.8218 / 843.576.1147 / www.environmentalexpress.com Environmental Express • 24
HotBlock™: Operation and Instruction Manual EPA Method 3050B
5. Using the polycarbonate transfer racks, remove samples from the HotBlock™ and allow them to cool.
6. After cooling, dilute to 30mL with DI Water and adjust the pH of the sample to 7.0 ± 0.2 with 1 N NaOH using a pH meter. If the
sample is not clear at this point, add 2-3 drops of acid. Bring the sample to the 50mL mark.
7. 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. All QC samples, concentration limitations, elemental lists and reagent
specifications are addressed in depth in EPA Method 365.2. Safety concerns are also part of the full method. Follow the instructions
listed in EPA Method 365.2. These steps should only be used as a guide to help improve the performance of your HotBlock™.
Adaptation of EPA Method 3050B
for use with the Environmental Express HotBlock™ Digestion System
Revised 05.05
Scope and Application:
The following procedures have been written as an aid to EPA Method 3050B for use with the Environmental Express HotBlock™. EPA
Method 3050B is for the preparation of sediment, sludge, and soil samples for analysis. Use EPA Method 3050B for reference while following
the sample preparation steps outlined below. A complete list of elements appropriate for analysis is included in EPA Method 3050B. Analysis
can be performed by flame atomic absorption, GF/AA, ICP and ICP-MS.
Apparatus and Materials:
1. HotBlock™ for Metals Digestions — Model Numbers SC100, SC150*, or SC154
2. Polypropylene Digestion Vessels — Part Number SC475 (or SC490 for use with HotBlock™ SC150)
3. 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 )
4. FilterMateTM — Part Number SC0401 (or appropriate FilterMate™) for sample filtration if necessary
* Note: When using the SC150 block with the SC490 digestion vials with a 100mL sample, double the volume of all reagents and
acids added.
Procedure, Aqueous Sample Preparation:
1. Mix sample thoroughly to achieve homogeneity and sieve if appropriate. For each digestion procedure, weigh to the nearest 0.01
gram and transfer a 0.5-1-gram aliquot (or appropriate amount for your lab) to the SC475 polypropylene digestion vessel. For best
results, weigh the sample directly in the vessel on a tared balance.
2. Add 5mL (1:1) HNO3 + DI Water and swirl. Cover with a ribbed watch glass or reflux cap and heat the sample in the HotBlock™ at
95°C for 15 minutes without boiling.
Note: If using the watch glass, adjust the HotBlock™ temperature so that a 50mL, 5% acid solution is heated to 85°C. Laboratory
tests have proven that the addition of the ribbed watch glass will add approximately 10°C to the sample temperature. Refer to
page 6 of the operations manual for instructions on HotBlock™ temperature adjustment.
3. Allow the sample to cool, then add 5mL concentrated HNO3 and reflux at 95°C for 30 minutes. Repeat this step until NO brown
fumes are given off by the sample.
4. Heat sample with the ribbed watch glass for an additional 1.5 hours. Do not allow the sample to boil or go dry. Neither of these
aspects should occur if the temperature of the HotBlock™ is adjusted correctly.