How To Specify a Spectrometer

Know the application

The specification of design qualification (DQ) is highly important and often underestimated. Through the DQ, a customer can ensure that the instrument has the necessary functions and performance criteria for the application. A proper design qualification also helps to separate the important from the less important features and allows the customer to survive the “battle of features” that is often waged by instrument vendors.

In determining design requirements, it helps, if customers can specify for what application they intend to use the spectrometer. One should ask: What is the primary function or the primary problem I want solved? Do I need to test fuels for a particular material specification? Do I want to optimise my blending process or comply with government or transport regulations? Specifications should follow from those answers and reflect the user’s requirements.

The design qualification also should include the answers to some very basic application-related questions. For example, will a fuel truck driver be able to measure fuel quality with the instrument? Or, will the analyzer be used by a trained spectroscopist? The requirements for various user groups will be fairly different.

Get to the core purpose

A first step in developing a specification is to get to the core purpose. Spectrometers can be used to measure many liquids, but a qualified spectrometer is already set up for a specific purpose. For example, a fuel analyzer may already be set up to measure gasoline, diesel and jet fuel, and not set up to measure waste water or solvents.

Still, an instrument may be able to measure 100+ fuel parameters right from the get go by using proven and robust fuel data from sources all around the world for analysis. But, not all of those parameters will be relevant for a particular application. Typically a limited set of parameters needs to be analyzed. So, it is important to find out if the relevant parameters are covered in the standard setup, or if a method for analyzing a new parameter needs to be added to the analyzer. Additionally, it is important to define which type of fuels the user wants to analyze. An instrument may be able to measure finished gasolines but also test nonregular fuels like naphtha or a base gasoline without oxygenates.

Possibly, some modifications may be required to the basic analyzer setup. The instrument supplier should be able to help with setting up a dedicated naphhta database to improve results.