10 Analytical Instrumentation
MATRIX EVALUATION ON THE XPLORER-V WITH VECTRA AUTOSAMPLER ACCORDING TO ASTM5453
Introduction: At the beginning of 2024, TE Instruments introduced a new autosampler designed for the introduction of liquid sample materials for the Xplorer Total Sulfur (TS), Total Nitrogen (TN), and Total Halides (TX) elemental combustion analyzer series. The innovative Vectra model incorporates advanced movement principles, off ering an expanded range of motion and paving the way for future enhancements in sample handling.
Initially, the Vectra was exclusively compatible with the Xplorer TN/TS/TX analyzers (horizontal version) and the XPREP C-IC. However, TE Instruments has extended the compatibility of the Vectra to include the Xplorer-V analyzer.
Background:
In the classic Xplorer TN/TS, the furnace is positioned horizontally, and a separate liquids injection module is used for evaporation of sample material. This module is typically maintained at a temperature of 500 °C. It is recommended that the maximum boiling temperature for liquid samples is limited to 420 °C for the Xplorer TN/TS to prevent accumulation of sample material in the introduction module.
When samples with higher boiling ranges need to be injected on the Xplorer TN/TS, a boat inlet module should be utilized instead of the liquid injection module. With this boat inlet introduction, the sample is injected into a quartz cup fi lled with quartz wool. The cup is transferred into the high-temperature furnace with a pre-defi ned boat program. This method is advantageous for high boiling samples and complex matrices, as the introduction is precisely controlled by the speed of the cup movement, allowing for the measurement of samples with relatively high boiling points.
However, a minor drawback is the increased analysis time due to the cooling step at the end of a boat introduction program. Sample analysis using a liquid introduction module typically takes approximately 3 to 6 minutes, while a boat introduction extends the analysis time to about 5 to 9 minutes. Controlled sample evaporation prior to the combustion is essential for achieving optimal results.
In the Xplorer-V confi guration, the sample is injected vertically into the pre-combustion inlet, where it fully evaporates under an inert carrier gas stream at a higher temperature compared to the liquid module of a horizontal setup. The vertical placement of the furnace allows for a broader boiling point range of liquid sample material to be injected. While a classic horizontal liquid module typically can handle samples
with a maximum boiling point of 420 °C, the Xplorer-V can accommodate samples with a boiling point up to 650 °C.
Additionally, the automatic cleaning step is performed after each analysis, where the carrier gas is switched to oxygen via an automatic valve, enabling all residual condensates to be burned off and prepare the system for the next analysis.
For example, the analysis of biodiesel mixtures and pure B100/ FAME samples is possible on the Xplorer-V with a direct liquid injection, where a conventional horizontal setup still require a boat introduction for B100/FAME samples.
Xplorer-V and the Vectra autosampler: Picture 1: Wide working area of the Xplorer-V with Vectra
Upon its introduction in 2021, the Xplorer-V featured an internally integrated liquid autosampler with a capacity for 26 sample positions. The sample injection principle was based on a “transfer tube” design which separates the needle from
Sulfur Calibration (mg/kg) N = 5 0.5 1.0 2.5 5.0 7.5 10 25 50 75
100 Overview 1: List of calibration standards and plotted calibration standards
PIN AUGUST / SEPTEMBER 2024
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