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Quantitative Analysis of a Four-Component Sample Using a Benchtop X-ray Diffractometer

Measurement of metals, especially toxic heavy metals, in aerosols on air filters is demonstrated. Simple linear empirical calibration is discussed, and performance is shown for measurement precision and typical detection limits.

	Element analysis of aerosols and particulate matter released in smokestacks and other industrial gas discharge is vital to ensure that environmentally acceptable levels of toxic and hazardous elements are released properly into the air. Monitoring smoke or other gaseous waste is important in order to minimize air pollution and the release of toxic metals in compliance with United States Environmental Protection Agency and other world and regional or local governing regulations.

	As a tool to help ensure compliance and proper release, Rigaku offers the NEX DE EDXRF analyzer with 60 kV excitation source and high resolution and throughput Si Drift Detector, providing a fast, simple, yet powerful means for elemental analysis of air filters.

Nuclepore(r) polycarbonate Aerosol membranes

Helium (for optimum light element performance)

10-position 40 mm Automatic Sample Changer 

	Air filter material used was Nuclepore polycarbonate aerosol membrane. The filter membrane is supported by a 40 mm diameter plastic outer ring. Samples lie flat and smooth in the 10-position autosampler, covering the analysis aperture.

	A single-point linear empirical calibration was made for each element using the Standard Value loading levels.

	To determine the Lower Limit of Detection (LLD) using the empirical method, ten repeat analyses of a blank filter membrane sample were measured and the standard deviation calculated. The LLD is then defined as three times the standard deviation. This approach ensures that analyses above the determined LLD are measuring signal above background.

	To demonstrate typical measurement recovery and instrument precision, each calibration standard was measured in 10 repeat analyses using a total analysis time of 1200 s (300 s per measurement condition).

	The Rigaku NEX DE combines filtered direct excitation with a high performance SDD detector capable of 500,000+ cps throughput to deliver excellent sensitivity for the measurement of metals in aerosols on air filters. The NEX DE analyzer is capable of elemental analysis from Na–U, making the XRF technique ideal for other elements on air filters, as well. For the measurement of light elements Na-Cl, helium purge is used to remove air from the optical path and optimize analysis sensitivity. Elements from Cr and above can be easily measured in air without the need for helium purge.

	The NEX DE analyzer also gives the user a very versatile tool not only for monitory air filters, but also elemental analysis of solids, powders and liquids.

	9009 New Trails Drive, The Woodlands, TX 77381

Analysis of Metals in Aerosols on Air Filters

This report introduces an X-ray fluorescence (XRF) analysis for the detection of ppb levels of hazardous heavy elements in wastewater and river water using "Ultracarry®" high sensitivity micro-droplet filter paper and the "Ultradry™" vacuum dryer.

	There has been growing demand globally for the analysis of environmentally hazardous substances. Detection of a trace amount of wastewater and heavy elements in wastewater and river water is achieved by XRF analysis with the UltraCarry® sample preparation technique.

	A liquid sample of wastewater or river water is dropped onto an Ultracarry filter paper. An Ultradry, which dries the solution by decompression and heating, was employed to shorten the drying time. The dried Ultracarry pads were mounted on aluminum or titanium cups to avoid scattered X-rays. The cups were set in the sample holders of the XRF instrument.

	The Rigaku ZSX Primus II wavelength-dispersive X-ray fluorescence spectrometer was used for the analysis. It has a high spectral resolution that enables a high precision analysis of wastewater with a complex sample matrix. The combination of ZSX Primus II and Ultracarry enables wastewater analysis of a trace of zinc down to about 1 ppb. The time for drying the Ultracarry was about 30 min, and the time for the XRF qualitative analysis was 2 to 3 min per sample. It is typically necessary to use condensed sample solutions to meet environmental regulations for hazardous heavy elements in river water. The Ultradry can be used for this type of analysis because it is equipped with a decompression evaporating apparatus. A NIST1643c standard (reference solution of river water) was used. The material was first condensed by 50 times with an Ultradry then dropped onto an Ultracarry and dried.


	Figure 1: XRF spectrum of river water (21°–36°2q , LiF (200) analyzing crystal, Cu primary-beam filter, 50 kV and 50 mA.

	XRF peaks for As (82.1 ppb), Pb (35.3 ppb), Se (12.7 ppb), and Rb (11.4 ppb) contained in the reference solution were clearly detectable.

	The technique of using Ultracarry filter paper and an Ultradry vacuum dryer shows that the XRF method can be used effectively for a low ppb level analysis of environmental heavy hazardous elements in wastewater and river water due to its simple and rapid sample preparation. Since industrial wastewater likely contains a number of heavy elements, a prescreening analysis is useful before a conventional analysis with an atomic absorption spectrometer or inductively coupled plasma spectrometer.


	9009 New Trails Drive, The Woodlands, TX 77381
	tel. (281) 362-2300, fax (281) 364-3628
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Author | Rigaku

Articles

Quantitative Analysis of a Four-Component Sample Using a Benchtop X-ray Diffractometer

Analysis of Metals in Aerosols on Air Filters

Trace Heavy Element Analysis for Wastewater and River Water by X-ray Fluorescence Spectrometry