• What's New
• Exhibitions, Clinics & Workshops
• XRF Sample Cups
  • RoHS Compliant Sample Cups
  • Technical Data
  • How to Select a Sample Cup
  • Quick Reference Chart
• Grinding Equipment
• Briquetting Presses
• Briquetting Dies
• Briquetting Cups
• Grinding/Briquetting Additives
• Fusion Machines and Accessories
• Petrochemical Oil Standards
• PE and PVC Polymer Compliance Standards
• Thin-Film Sample Supports
• Microporous Film
• Sample Cup Accessories
• RoHS European Council Directive 2002/95/EC
• Technical Reprints

How to Select a Sample Cup

Selection of the most applicable XRF Sample Cup is based on satisfying the following conditions:

• Matching the dimensions of the sample cup to a sample cup holding device.
• Type of sample substances; e.g. solid, liquid or powder.
• Analyte-line consideration dictating the analysis in air, inert gas or vacuum.
• Maintaining equalization of pressure within the sample cup and sample chamber to avert distension or convolution of the sample plane.

Dimensions

In consideration of the many types of x-ray analytical instrumentation available and sample cup holding devices incorporated or provided with the equipment, the method of sample cup selection has remained virtually unchanged. It is related to the inside diameter of the sample cup holding device together with the inside diameter of the aperture. There should also be adequate height clearance for safely accepting XRF Sample Cups without interference. Once these measurements are ascertained, sample cup selection is narrowed to a specific size and further selection is based on additional attributes that may be required such as sample substance type and the need for specific analyte-line investigations to be conducted in an air, inert gas or vacuum.

Measure Inside Diameter (A)

Measure Inside Aperture Diameter (C)

Measure Inside Height (B)

Aperature

The geometry of x-ray systems directs the energy from an excitation source to impinge upon the surface of a sample substance. The point of impingement is referred to as the focal spot. In most cases, the focal spot is ovate attributed to the angle of energy incidence. Some instruments incorporate a sample rotation provision that tends to average non-circularity differences. The principal concern is to limit and confine the focal spot to within the sample surface area to avoid irradiating the sample cup holding device and XRF Sample Cup and unknowingly introduce spectral lines affecting the analysis especially if they are similar to those of investigative interest. It is important to consider an XRF Sample Cup with an aperture larger in diameter to the aperture of the sample cup holding device.

Environmental Conditions and Pressure Equalization

The analyte lines of interest together with elemental concentration levels invariably dictate the environmental condition. The more energetic short wavelength spectral lines are acceptably investigated in air and do not necessarily require sample cups with venting provision and sample cup selection is considerably broad.

Spectral analyte-lines characterized by less energetic long wavelengths and particularly low elemental concentrations command analysis in an inert gas, such as helium, or evacuation of the sample chamber. Special attention in establishing and maintaining a taut flat thin-film surface that defines the sample plane is important. Any inaccuracies associated with variations in the distance between the sample plane and excitation source can potentially affect the analytical data. A sample plane that is outwardly distended, attributed to evacuation of the sample chamber and a consequential positive pressure build-up within a sealed sample cup, tends to shorten the x-ray travel distance and generates greater intensity values. This translates into higher elemental concentrations than actuality. Sample cup venting is therefore an important consideration.

A positive pressure build-up in the sample chamber by introducing an inert gas, results in concaved sample planes on un-vented sample cups. The x-ray path of travel is lengthened resulting in a decrease in intensity values that imply lower analyte concentrations. It is therefore important to establish an equalization of pressure within the sample cup and sample chamber in order to maintain a flat thin-film sample plane; again narrowing sample cup selection to venting provisions.

Innovative Sample Preparation Technology

There are other features incorporated into XRF Sample Cups that represent ease-of-assembly, "Snap-On Ring" Thin-Film Assemblies, Trimless Thin-Film Assemblies, pressure equalization through Microporous Film and thermoplastic Vent Hole provisions, ventable Snap-On Caps, External and Internal Overflow Reservoirs, "thin-layered" powdered sample sandwiching, micro-sample mounting and most recently the first to incorporate Integrated Thin-Film Trimming that completely eliminates the troublesome experiences in performing and handling extraneous thin-film trimming. This suffices to serve in further exploring our products and service potential with XRF Sample Cups in satisfying the needs of today's x-ray spectroscopist in virtually all scientific disciplines.