AASHTO TP 106-20 pdf free download
AASHTO TP 106-20 pdf free download.Determination of Heavy Metal Content of Glass Beads Using X-Ray Fluorescence (XRF).
7.2. Sample Preparation of Loose Glass Beads in Sample Cup—If the sample is to be tested as a loose sample, the glass beads are tested in a sample cup. Use the following steps to prepare the sample:
7.2.1. Place thin film on top of an XRF sample cup. The film goes on the end of the cup with the indented ring.
7.2.2. Secure the film with the collar. The flange inside the collar faces down and snaps into the indented ring of the cup. Inspect the installed film window for continuity and smooth, taut appearance.
7.2.3. Place the sample cup on a flat surface with the film window-side down. Fill the cup with at least
5 g of glass beads. Place the beads in an even layer and lightly tamp into place.
7.2.4. Place a tilter paper disk on the sample after tamping, then till the cup with polyester tiber stuffing. Put the cap on the cup.
7.3. Sample Preparation of Pressed Pellet—If the sample is to be tested using a laboratory model XRF with a vacuum chamber, the glass beads are tested as a pressed pellet. Use the following steps to prepare the sample:
7.3.1. Combine 6.000 g of glass beads and 1.000 g of binding agent.
7.3.2. Using a mixer or ring and puck mill, pulverize and blend the glass beads and binding agent into a homogeneous sample for pressing.
Note 2—For large beads, mill for 7—10 mm. For small beads, mill for 5—7 mm, depending on the type of mixer mill used.
7.3.3. Place an aluminum cup with tapered walls into the bottom of the press die chamber.
7.3.4. Add the homogeneous sample to the press. Follow the manufacturer procedures for the operation of the press.
7.3.5. Apply 25 tons of pressure for 4 mm and use a 1-mm release.
8. CALIBRATION
8.1. XRF Spectrometer—Calibrate the XRF spectrometer according to the manufacturer’s recommendations. A standardless or manufacturer-built program may be sufficient, but should be checked versus a known standard.
9. PROCEDURE
9.1. Hand/ieldXRF—Place the sample cup on a stable surface. Direct the handheld XRF at the sample cup and run according to the manufacturer’s recommendation for determining heavy metal concentration. Record the concentration of lead, antimony, and arsenic.
9.2. XRF wit/i Helium Flush—Place the sample cup in the XRF. Run according to the manufacturer’s recommendations under helium gas conditions using a standard-less software program. Record the concentration of lead, antimony, and arsenic.
9.3. Laboratory Model XRF with Vacuum—Place the pressed pellet in the XRF. Run according to the manufacturer’s recommendations under vacuum conditions. Record the concentration of lead, antimony, and arsenic.
10. INTERPRETATION OF RESULTS
10.1. The XRF reports the elements detected in the sample and elements that are below the detection limit. For an element to be detected by your analyzer in a given sample, the measured concentration of the sample must be at least three times the standard deviation of the measurement. This detection limit will depend on the composition of the sample. The measurement precision for each element displayed should be reported by the instrument. The precision of each measurement is two times the standard deviation (a). An element is classified as “detected” if the measured concentration (in ppm) is at least 1.5 times the precision. Detected elements are displayed in ppm, followed by the measurement precision. Nondetected elements are shown as < the detection limit (LOD) for that sample. The detection limit for a given element varies depending on the other elements in the matrix and the sample preparation used (i.e. loose beads, helium flush, etc.).AASHTO TP 106-20 pdf download.
