Collection of absorbance peaks

Introduction

This section contains an example of how to collect absorbance peaks through outlets F3 and F4.

Example instruction

This is an example instruction as it would be presented in the Text window:

0.00 Block ELUTION

(Elution)

0.00 Base SameAsMain

0.00 Gradient 100.0 {%}, 20.00 {base}

0.00 Watch_UV1 Greater_Than, 100 {mAU}, Peak_1

(Peak_1)

0.00 Base SameAsMain

0.00 OutletValve F3

0.00 Watch_UV1 Less_Than_Or_Valley, 100 {mAU}, Waste

(Waste)

0.00 Base SameAsMain

0.00 OutletValve WasteF1

0.00 Watch_UV1 Greater_Than, 100 {mAU}, Peak_2

(Peak_2)

0.00 Base SameAsMain

0.00 OutletValve F4

0.00 Watch_UV1 Less_Than, 100 {mAU}, End_collect

(End_collect)

0.00 Base SameAsMain

0.00 OutletValve WasteF1

0.00 End_Block

0.00 End_Block

0.00 End_block

0.00 End_Block

20.00 End_Block
Illustration

The illustration below shows peaks collected by the method in the example above.

This is what happens

In this example, one or two absorbance peaks are collected through outlets F3 and F4 respectively with waste fractions collected through outlet valve F1 (waste). Each called block (except End_collect) resets the Watch condition so that the method reacts correctly to subsequent changes in the UV absorbance.

Invalid Watch instructions

The design of a method of this kind (with several Watch instructions for the same monitor) is important. The construction in the following three lines appears simpler but is incorrect:

0.00 Watch_UV Greater_than, 100 {mAU}, Peak_2

0.00 Watch_UV Less_than, 100 {mAU}, End_collect

0.00 End_block

Here, the second Watch instruction will annul the first, since a signal can only be watched for one condition at a time.

2005-06-15