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| Question
Categories: |
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| What the
advantages the Velp DK block has over other blocks in
the market? |
| What are
the main applications for heating block digesters? |
| What is
a Kjeldahl digestion for nitrogen determination? |
| What is
the heating block temperature range? |
| How
long does it take to do a digestion? |
| What
is a Kjeldahl digestion for phosphorus determination? |
| What
catalyst is best for digesting samples: copper or mercury? |
| What
is the recommended procedure for storing samples that
will be digested? |
| Do
I need to place the block in a hood? |
| What
are the specifications for the block? |
| What
is the typical maintenance that the block requires? |
| What
digestion procedure should be used for total phosphorus
determination: Kjeldahl or persulfate? |
| How
can I test the block to ensure it is working properly
at any given time? |
| What
kind of warranty does the block have? |
| How
many programs can be stored in the block? |
| Can
the block be connected to printer or computer? |
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1. Maximize accuracy
and precision
The DK block have accuracy of :
- Stability of heating block temperature : ±0.5°C
- Homogeneity of temperature in the block : ±0.5°C
- Precision of temperature: ±0.5°C
2.Reduce overflow of samples with surfactants
Many discharge water samples contain varying levels
of surfactants, which will cause foaming of the sample
during digestion. The foam may then overflow from
the tube onto the heated block. The special design
of the DK blocks prevent spillage from reaching the
electronic parts of the system
3.A full system scrubber and pump
Together with a suction cup, the connectivity to our
efficient scrubber will aliment 95% of the fume from
being released in to the air.
4. Increased reliability of controller
The integral DK blocks programmable controller is
separated in the block by divider , which keeps it
dry and away from spillage. |
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| The block digester is designed
for Kjeldahl digestions of total nitrogen and total
phosphorus. |
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| Samples are digested in
a solution of sulfuric acid, potassium sulfate and a
catalyst (mercuric oxide or cupric sulfate). Organic
nitrogen compounds are converted into ammonium. Kjeldahl
nitrogen is the sum of organic nitrogen and ammonia
nitrogen. Nitrogen can be determined by using an FIA
system, where the sample pH is raised to a basic pH.
The in-line neutralization of the sample converts the
ammonium to ammonia, which reacts with a series of reagents
to produce a reaction product, the absorption of which
is directly proportional to TKN concentration. |
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| The block temperature
range is Ambient to 450°C |
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| The typical
Kjeldahl digestion takes about two hours. |
|
| This digestion is used when
the same samples are being analyzed for Kjeldahl nitrogen
as well. Samples are digested in a solution of sulfuric
acid, potassium sulfate and a catalyst (mercuric oxide).
Polyphosphates and organic phosphorus are converted
into orthophosphate. We typically refer to the resulting
analyte as Total Kjeldahl Phosphorus (TKP) in order
to specify the procedure used for digesting the samples.
The resulting orthophosphate can be determined by using
an FIA system, where the orthophosphate ion reacts with
reagents in order to form a colored complex. The absorption
of which is directly proportional to the TKP concentration. |
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| Mercury (mercuric
oxide) has been found to be the most effective catalyst
for digesting nitrogen, but it is also an element of
considerable environmental concern. Copper (copper sulfate)
is suitable for a wide variety of samples and it has
become the catalyst of choice in recent years. To test
completeness of digestion, it is recommended to determine
nitrogen recovery from samples that have been fortified
(spiked) with nicotinic acid. Ammonium chloride is usually
used as a fortifying (spiking) solution to test for
loss of nitrogen during the digestion. |
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| Samples should be analyzed
as soon as possible after collection. If storage is
required, preserve samples by acidifying to pH 1.5 to
2.0 with concentrated sulfuric acid (H2SO4)
and store at 4°C. |
|
| The use of the Velp complete
system (DK block – SMS Scrubber – JP PUMP)
will aluminates 95-98% of fume released to the air during
operation. However, for safety reasons, it is recommended
that any digester block should always be placed in a
hood. |
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- Our DK6 block requires a 110V outlet!
- All other block sizes require an outlet for 200V-240V
, 50/60 Hz.
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- Cleaning the racks if any spills occurs.
- Cleaning up any spills onto the block.
- Cleaning the glassware.
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| If the samples are going
to be analyzed for Kjeldahl nitrogen as well, the same
digestion would take of the total phosphorus. The persulfate
digestion (autoclave) is usually preferred if the only
analyte of interest is phosphorus. |
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| The block has an insert
in which a mercury thermometer can be inserted in order
to certify the block temperature, which should match
the reading on the controller display. |
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| The blocks have a one-year
limited warranty. Neutec group has a loaner and extended
warranty programs that can be purchased separately.
All servicing is performed at Neutec group service lab. |
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| The block can store up to
20 programs with 4
ramps in each one. |
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| Yes, the DK blocks have RS232
interface that can be connected to printer or computer
in order to download all stored data. |
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The
digester block by VELP Scientifica works to specs, and even
though similar equipment can be bought from other companies,
I am not sure the service would be there.
Fully
Automatic Distillation unit with
colorimetric
Titrator.