This datasheet investigates the capabilities of the Epsilon 1, a benchtop energy dispersive X-ray fluorescence spectrometer as a tool for screening lead in wheat noodles. The simple sample preparation along with quick measurements of elements, make the XRF technique an interesting analytical method for the food industry. It allows analysis close to production lines.
The Codex Alimentarius requires a maximum level of lead to be less than 0.2 mg/kg in cereal grains (Codex Standard 193-1995). Five in-house wheat noodle standards were used to set up the calibrations for lead in instant noodles. Five grams of loose powder were weighed into a disposable sample cup for measurement
The Codex Alimentarius requires a maximum level of lead to be less than 0.2 mg/kg in cereal grains (Codex Standard 193-1995). This datasheet investigates the capabilities of the Epsilon 1, a benchtop energy dispersive X-ray fluorescence spectrometer as a tool for screening lead in wheat noodles. The simple sample preparation along with quick measurements of elements, make the XRF technique an interesting analytical method for the food industry. It allows analysis close to production lines.
Measurements were performed using an Epsilon 1 EDXRF spectrometer, equipped with a 50 kV silver anode X-ray tube, 6 filters and a high-resolution silicon drift detector. The data was automatically processed by the Epsilon 1 software.
Five in-house wheat noodle standards were used to set up the calibrations for lead in instant noodles. Five grams of loose powder were weighed into a disposable sample cup for measurement.
A single measurement condition was used to analyze lead in the standards (Table 1). The total measurement time was only 5 minutes per standard. Figure 1 shows part of the XRF spectrum of one of the standards containing 100 mg/kg lead
| Condition | kV | μA | Medium | Filter | Meas. time (s) |
|---|---|---|---|---|---|
| Pv | 50 | 100 | Air | Ag | 300 |
Figure 1. XRF spectrum of an instant noodle standard
Figure 2 shows the calibration graph for lead in noodles. The graph shows very good correlation between the concentrations and the measured intensities. Detailed calibration results are shown in Table 2. The RMS (root mean square) value equals 1 sigma standard deviation. The lower limit of detection (LLD) is also shown in Table 2.
| Element | Concentration range (mg/kg) | RMS* (mg/kg) | Correlation | LLD (mg/kg, 300s) |
|---|---|---|---|---|
| Pb | 0 - 100 | 0.4 | 0.99997 | 0.2 |
Figure 2. Calibration graph for lead in noodles
To test the instrument precision, one of the calibration standards containing 2 mg/kg lead was measured as an unknown sample, twenty times consecutively. This is graphically presented in Figure 3. The average concentration and RMS value are shown in Table 3. The results show excellent repeatability.
Figure 3. Repeatability results for 2 mg/kg lead in noodles
| Element | Average Conc. (mg/kg) | RMS (mg/kg) | Rel. RMS (%) |
|---|---|---|---|
| PB | 2.2 | 0.09 | 4.2 |
The results clearly demonstrate the excellent capability of Epsilon 1 for the screening of lead in wheat noodles. The high resolution and sensitivity of the silicon drift detector combined with powerful software deconvolution algorithms make it possible to rapidly screen for Pb in noodles in 5 minutes with a limit of detection of 0.2 mg/kg. Furthermore, the repeatability of the measurements demonstrates that the Epsilon 1 is a stable instrument for screening Pb in wheat noodles.
