Collection Schemes - Teledyne Foxy R1 Instruction Manual

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Foxy R1 and Foxy R2 Fraction Collectors
Section 1 Introduction

1.1 Collection Schemes

1-2
The fraction collector supports several types of collection
schemes. Basic collection schemes collect uniform volumes (frac-
tionation). These uniform modes for tube advances include:
Drop Counting – The fraction collector counts the drops from
the drop former. When the count reaches a user-specified
number of drops, the fraction collector advances to the next
tube. The fraction collector can count up to 999 drops per
fraction. Drop counting is not available on the Foxy R2
High Flow fraction collector.
Time Intervals – The fraction collector can advance to the next
tube at fixed time intervals. Tube changes can occur as
r a p i d l y a s e v e r y s e c o n d , o r w a i t u p t o 9 9 : 5 9 : 5 9
(HH:MM:SS).
Volume Intervals – The fraction collector can switch tubes at
fixed volume intervals. This collection mode requires an
input signal from a pump that correlates its delivery vol-
ume. This signal can represent actual volumetric units, or
more typically, a pump revolution counter. The fraction col-
lector can count up to 999 units.
The fraction collector can perform additional tube advances
based on a variable input signal. The fraction collector reads this
input signal from an external device to isolate peak fluids from
non-peak fluids. Typically the input signal represents UV light
absorbing compounds in chromatographic eluate. Signals may
also represent other measurable liquid properties such as visible
light absorbance, fluorescence, pH, or any parameter with an
analog output signal. Tube advances at the leading and lagging
edges of the peak isolate peak fluids from non-peak fluids, com-
monly called "peak cutting."
These peak collection modes are:
Threshold Peak Detection – The fraction collector can per-
form a tube advance whenever the monitored signal passes
a user-specified threshold. The threshold, set as a percent-
age of the input signal, typically is set high enough to elim-
inate false peaks due to a noisy signal baseline.
Peak Width Detection – The fraction collector can perform a
tube advance when the rising or falling slope of the input
signal indicates the leading or lagging edge of a peak. The
user-selected peak width setting is part of a peak detection
algorithm which differentiates true peaks from false indi-
cations such as noise and shifting baselines. With the cor-
rect peak width setting, this collection mode can cut closely
eluting and even overlapping peaks.
Threshold and peak width detection may be combined together.
Additionally, whether one or both peak detections modes are
used, the fraction collector always combines peak detection with
a uniform mode so that it does not exceed the tube capacity while
a peak is active.
The fraction collector can also limit the fraction collection to
certain time durations during a collection routine. The Time
Windows collection scheme is described below.