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A method is described for the modification and use of a gas chromatograph heated inlet for the preparation of trace vapor reference standards. A conventional GC-MS is used to validate the prepared vapor standards and an evaluation is provided on the reproducibility of replicate measurements made from a single sample as well as individual measurements made between replicate samples. The described method is applied to the preparation of single component trace organic vapors, complex vapor mixtures (containing greater than 10 components over a concentration range spanning four orders of magnitude), and low vapor pressure analytes, which are solids under ambient conditions (e.g., ferrocene). Results demonstrate delivery of picomole quantities of single component organic vapors with a reproducibility of ca. 1% RSD., The original document contains color images.

A liquid delivery system for nebulizers typically used in inductively coupled plasma spectrometry is implemented with active, closed-loop feedback to generate a constant, stable flow rate over extended periods of time. An electronic pressure control unit is coupled with a pressure vessel and flow meter in three separate configurations. The first configuration uses a computer to monitor the flow rate and adjust the pressure based on a PID algorithm. The second configuration uses an embedded microcontroller in a separate control box, and the third configuration places all the components in a single box. Flow rates with less than 0.5% relative standard deviation are possible, and results are compared with a syringe pump and capillary-high pressure liquid chromatography pump., Supporting documents are attached to the report as separate files (PDF)., The original document contains color images.