Some window materials may not be suitable for analyzing sulfur in diesel fuel, gasoline and other petroleum products containing aromatic hydrocarbons. ASTM D-6445-99 (Reapproved 2004) e1: "Samples of high aromatic content may dissolve polyester and polycarbonate films. In these cases, other materials besides these films may be used for X-ray windows, provided that they do not contain any elemental impurities. An optional window material is polyimide film. While polyimide film absorbs sulfur x-rays more than other films, it may be a preferred window material as it is much more resistant to chemical attack by aromatics and exhibits higher mechanical strength.” ASTM D 4294-08a: “Any film that resists attack by the sample, is free of sulfur, and is sufficiently X-ray transparent can be used. Film types can include polyester, polypropylene, polycarbonate, and polyimide. However, samples of high aromatic content can dissolve polypropylene, polycarbonate and polyester."
CAUTION: All thin-film window materials affixed to sample cups present the risk of stretching or rupturing in the sample chamber and/or causing sample cup leakage through the ring and cell juncture or disassembly with potential contamination and damage to the system. These conditions are especially amplified when the sample chamber is subjected to a change in pressure attributed to evacuation, introduction of an inert gas flush or from pressure build-up within the sample cup from a sample substance out gassing or from volatility. Additionally, the possibility of pinholes, pores and depressions existing in any thin-film sample support substance regardless of form, configuration and packaging can present leakage of a sample with subsequent contamination and damage to the analytical instrumentation and its components. It is strongly recommended that the products used be subject to judicious testing, use and applications and user evaluation prior to actual use by a method that does not risk contamination or damage to the x-ray analytical spectrometer. The responsibility of product acceptance and performance resides totally with the user. Chemplex® Industries, Inc. assumes no liability or guarantees whatsoever that the products will perform in accordance with their usage, advertisements or methodologies written, orally expressed, implied or insinuated.