A continuous stream flash evaporator for the calibration of an IR cavity ring down spectrometer for isotopic analysis of water

TL;DR

This paper introduces a continuous stream flash evaporator system designed for high-resolution, real-time isotopic analysis of water vapor using IR cavity ring-down spectroscopy, enabling precise calibration and unattended operation.

Contribution

The novel continuous stream flash evaporator allows for stable, automated, and efficient isotopic water vapor analysis, improving calibration and measurement precision for IR spectrometers.

Findings

System achieves 100% vaporization efficiency at 170°C.

Provides stable and precise isotopic calibration on VSMOW scale.

Demonstrates low dead volume and suitability for unattended operation.

Abstract

A new technique for high resolution simultaneous isotopic analysis of $\delta^{18}\mathrm{O}$ and $\delta\mathrm{D}$ in liquid water is presented. A continuous stream flash evaporator has been designed that is able to vaporise a stream of liquid water in a continuous mode and deliver a stable and finely controlled water vapour sample to a commercially available Infra Red Cavity Ring Down Spectrometer. Injection of sub $\mu l$ amounts of the liquid water is achieved by pumping liquid water sample through a fused silica capillary and instantaneously vaporising it with a 100% efficiency in a home made oven at a temperature of $170 ^{o}$C. The system's simplicity, low power consumption and low dead volume together with the possibility for automated unattended operation, provides a solution for the calibration of laser instruments performing isotopic analysis of water vapour. Our work is mainly driven by the possibility to perform high resolution on line water isotopic analysis on Continuous Flow Analysis systems typically used to analyze the chemical composition of ice cores drilled in polar regions. In the following we describe the system's precision and stability, sensitivity to varying levels of sample size and we assess the observed memory effects. A test run with standard waters of different isotopic composition is presented, demonstrating the ability to calibrate the spectrometer's measurements on a VSMOW scale with a relatively simple and fast procedure.