Page 55 - LC-SFC_Pharma_Brochure

C190-E152

Auto Dilution of Standard and
Technical
Report Sample Solutions Using
the SIL-30AC Autosampler

1. Introduction
Standard stock solution Sample stock solution
When conducting quantitative analysis by HPLC, dilution of standard
solutions and sample solutions is typically performed manually. Not
500
only does this operation require some degree of experience and
knowledge, the time and effort associated with these tasks are
certainly not insignificant. With recent advances in instrumentation
technology, there is considerable expectation that labor savings 250 100 50 25 10 5
through automation will enable improved throughput. Delivering on Standard solution Sample solution
this expectation by automating these dilution-related tasks should Dilution operation takes time and effort
have a very positive impact on productivity.
The Nexera SIL-30AC autosampler system incorporates such
®
pretreatment functionality as a standard feature, allowing dilution
Automation of
and reagent addition to be fully automated. Dilution Process
Here, we introduce an example of analysis of caffeine in beverages
using the pretreatment feature of the SIL-30AC.

2. Automatic Preparation of Standard stock solution Sample stock solution
Standard and Sample Solutions
Quantitation methods typically use a calibration curve, where 500
multiple standard solutions are prepared at known concentrations,
Concentrated stock solutions are simply placed
and analysis of these provides an equation that defines the correlation
in the autosampler rack
between known analyte concentrations and peak area or peak height.
Then, the peak area or peak height obtained in the subsequent
analysis of the unknown sample is used to calculate the concentration
Fig. 1 Advantage of Automated Dilution
of the analyte. The concentration range is set to obtain a linear
calibration curve, and dilution of the sample solution is sometimes
necessary to keep the analyte concentration within the linear range.
3. Templates Facilitating Use of
The SIL-30AC's pretreatment feature eliminates the manual
Pretreatment Function
operations related to preparation of standard solutions (Fig. 1). The
standard solutions are automatically prepared at the desired The pretreatment functions of the SIL-30AC are controlled by LabSo-
concentration levels, and will be injected automatically. Sample lutions chromatography software. Common pretreatment functions
solutions can also be diluted to the appropriate dilution factor and like dilution and reagent addition are easily accessed through preset
then injected, all automatically. templates. Additionally, a custom pretreatment program is available
for setting up user-defined commands to accomplish specific opera-
tions.
In this example, we present an analysis of caffeine in beverages
using the pretreatment template for dilution.

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