XRF (Total Reflection X-ray Fluorescence) is a fast and cost-effective method of trace element analysis, suitable for a range of applications including water testing.
The technique has several benefits over alternative methods, such as AAS (Atomic Absorption Spectrometry) ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry):
- Fast and easy sample preparation
- No external calibration
- Multi-element analysis – including halogenides
- Low running costs
- Portable – analyse on-site in the field
Example Applications
TXRF is extremely versatile and is suitable for a variety of water testing applications. With capacity for a range of sample types, you can test liquids, sludge, suspensions and filter water with fine particles.
- Industrial wastewater – all industries, including cement and petrochemicals
- Sewage
- Freshwater
- Tap water
- Toxic elements
- Environmental monitoring
- Water monitoring with bioindicators and biofilms
Example: Trace Element Analysis of Fresh Water Samples
In this example, TXRF was used to analyse trace elements in fresh water samples, using two certified water standards (NIST 1640 and NIST 1643d).
Instrumentation
These measurements were performed using the S2 PICOFOX. The new S4 TStar is also available for more powerful ultra trace element analysis, with <10ppb sensitivity.
Sample Preparation
Sample preparation is fast and much simpler than alternative techniques:
- 1 ml of the certified standard was mixed with 20 μl of a standard solution (Ga; 10 mg/l) for internal calibration.
- 10 μl of the mixture was placed on a quartz glass carrier and dried on a heating plate.
- This was repeated, for a total of 30 μl on the carrier.
For statistical evaluation, 10 samples were prepared for each of the two reference standards. The measurement time was 1000 seconds.
Results
The results demonstrate how TXRF can be used to analyse trace elements in fresh water samples, even when present in the low μg/l range:
Light elements such as Li, Be and B were not detectable or were present in concentrations below the detection limit (Al). Ag, Cd and Sb were not detected because of the Mo-excitation. These elements can be analysed by the weak L-lines, which are overlapped by strong Ca and K signals. The use of a Mo tube also prevents the analysis of Mo.
Na and Mg were detected with a good recovery, as well as K, Ca, V, Mn, Ni, Cu, As, Se, Rb, Sr, Ba, Pb and Cr (with restrictions). The elements P, S, Cl, Ti, Br and Y were also detected in both samples.
Detection limits were in the medium to low μg/l range for most of the detectable elements:
The deviation of the detection limits originates in part from the different measurement times. The general differences between both samples are caused by the distinctly higher matrix concentration (mainly Ca and Fe) of sample NIST 1643d.
Further Examples
- Analysing heavy metals in sewage – Read a lab report
- Detecting mercury in tap water – Read a lab report
- Anakysing industrial wastewater and sewage – Webinar slides
More Information
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Contact us on +44 (0)1223 422 269 or info@blue-scientific.com
