Labconco Two and Six-Place (Macro) Kjeldahl Distillation Systems 2125603 - Manual (Page 7)

Chapter 1: Introduction
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Performance
The Two and Six-Place Kjeldahl Digestion Systems have been designed for
use in the determination of nitrogen (or ammonia) concentrations. By
calculation, nitrogen can be converted to protein values for products such as
plant tissues, meats and other food substances. Nitrogen determinations with
the (Macro) Digestion Systems can accommodate sample sizes up to 5
grams, due to the size of the digestion flasks. However, high levels of
organic content within a specific sample type will require smaller sample
sizes due to the vigorous digestion reaction. Detailed procedures developed
by professional laboratory organizations such as American Association of
Analytical Chemists (AOAC) and American Association of Cereal Chemists
(AACC) should always be consulted for step by step analytical procedures
when operating this equipment. For methodology precision and accuracy
please consult the specific published method for the type of sample or
substance that will be analyzed.
Component Identification
1. Electric Heaters. 600-watt heaters are used in the digestion rack of the
units. Infinite control switches regulate each of the heaters. The curved
heater elements are provided and allow for the round base of the Kjeldahl
flasks, providing faster and more evenly distributed heat. The heating
element assembly on the digestion rack can be moved closer to or away
from the acid fume removal manifold to accommodate different size
Kjeldahl flasks. The six-place systems have heaters and temperature
controllers which are wired to a common subpanel electrical box. The
two-place systems come pre-wired with a three wire cord and plug, for
easy connection to a facility electrical circuit.
2. Fume Removal Manifold. Located in back of the digestion heaters, this
manifold is manufactured from chemical resistant chlorinated polyvinyl
chloride and features heat resistant PTFE nipples designed to prevent
leakage of the hot sulfuric acid fumes created during the digestion
process. The nipple design, extends in to the flask opening, and
efficiently removes excess acids fumes during the digestion process. The
flasks are oriented at a 45 degree angle to the fume removal manifold to
promote the condensation and refluxing of the acid fumes back down into
the digestion flask. The refluxing process prevents the samples from
boiling dry during the 45+ minute digestion process.