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Environmental Express
• 22
AutoBlock® Fill:
Operation and Instruction Manual
Adaptation of EPA Method 365.1
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 — Item # C6002, SC100, SC150*, SC151*,
SC154, SC2015, SC2050, or SC2100*
2.2 Polypropylene Digestion Vessels — 50mL or 100mL
2.3 FilterMate — Item # SC0401 (or appropriate FilterMate® or FlipMate®) for
sample filtration if necessary
* Note: For all procedures, when using the 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 polypropylene digestion 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.
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® or FlipMate®)
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 12.13
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.
