Environmental Express HotBlock CURRENT - Manual (Page 25)

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HotBlock™: Operation and Instruction Manual Adaptation of EPA Method 365.2
1.0 Scope and Application
1.1 The following procedures have been written as an aid to EPA Method
3651 for use with the Environmental Express HotBlock™. EPA Method
365.1 is for the determination of phosphorous in drinking water, surface
water and saline water and in domestic and industrial wastes. Use EPA
Method 365.1 for reference while following the sample preparation steps
outlined below. Range is 0.01 to 0.5 mg/L.
2.0 Apparatus and Materials
2.1 HotBlock™ for metals digestions — Model Numbers SC100, SC150*, or
SC154
2.2 Polypropylene Digestion Vessels — Catalog # SC475 (or SC490 for use
with HotBlock™ SC150)
2.3 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 For each digestion procedure, transfer 50mL of sample (or appropriate
volume for your lab) into the SC475 polypropylene vessel.
3.2 Add 1mL of H
2
SO
4
solution and swirl. (11 N H
2
SO
4
— Slowly add 310mL
concentrated H
2
SO
4
to 600mL distilled water. When cooled dilute to 1
liter.)
3.3 Add 0.4g of ammonium persulfate.
3.4 Heat the sample in the HotBlock™ at approximately 100°C for 40
minutes. The sample should slightly boil.
Note: Adjust the HotBlock™ temperature so that the sample obtains a temperature
of 100°C. Please refer to page 7 of the HotBlock™ Operation Manual for temperature
adjustment and principles of operation.
3.5 Using the polycarbonate transfer racks, remove samples from the
HotBlock™ and allow them to cool.
3.6 After cooling, dilute to 50mL with DI Water.
3.7 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.
Adaptation of EPA Method 365.1, Determination of
Phosphorous by Semi-Automated Colorimetry, for use with
the Environmental Express HotBlock™ Digestion System
Revised 05.05
All QC samples, concentration limitations, elemental lists and reagent specifications
are addressed in depth in EPA Method 365.1. Safety concerns are also part of the
full method. Follow the instructions listed in EPA Method 365.1. These steps should
only be used as a guide to help improve the performance of your HotBlock™.