Preparation of gold nanoparticles using low-temperature heating of the dry residue of a droplet of an HAuCl4 solution in air.

In the present study, by heating a quartz glass substrate having the dry residue of a 10 µL droplet of a solution of HAuCl4 and a counter substrate facing to the dry residue from room temperature to one hundred and several tens of degrees Celsius in 20 min in air, highly dense gold nanoparticles were produced on the counter substrate. A gold nanoparticle substrate produced by this simple method was utilized as a substrate for surface-enhanced Raman scattering analysis.

Analysis of Single Synthetic Fibers Using a Portable Total Reflection X-ray Fluorescence Spectrometer.

In this study, single synthetic fibers obtained from several textile products were analyzed by a portable total reflection X-ray fluorescence spectrometer. Characteristic elements, which would originate from such materials as catalysts, delustering agents, and dyes used for manufacturing synthetic fibers, were detected from single synthetic fiber samples, and the difference in the types of characteristic elements among the single synthetic fiber samples was observed.

Gold Nanoparticles Produced by Low-temperature Heating of the Dry Residue of a Droplet of an HCl Acidic Solution of HAuCl4·4H2O in a Low Vacuum.

An easy method is presented for producing gold nanoparticles. We show that by performing simultaneous low-temperature heating of a quartz glass substrate on which the dry residue of a 10 µL droplet of an HCl acidic solution of HAuCl4·4H2O is deposited and a counter substrate using Peltier devices in a low vacuum produced by a rotary pump, gold nanoparticles with sizes ranging from about twenty to one hundred and several tens of nanometers are produced on the counter substrate. In this study, an application of a gold nanoparticle substrate produced by this method to the sample holder for surface-enhanced Raman scattering analysis is also shown.

Surface-enhanced Raman Scattering and X-ray Fluorescence Analyses of a Single Hair Colored with a Hair Dye Product.

This paper describes a method for obtaining information that can contribute to individual identification from a single hair colored with a hair dye product using a combination of surface-enhanced Raman scattering (SERS) and X-ray fluorescence (XRF) analyses. SERS and XRF spectra of single hog hairs colored with several commercially available hair dye products were measured. SERS spectral patterns tended to be different depending on the hair dye products used for hair coloring. However, SERS spectral patterns of single hog hairs colored with different hair dye products that would produce similar types of dyes were similar. By performing XRF analysis, characteristic metallic elements originating from some hair dye products were detected. Therefore, XRF can contribute to identifying the difference among colored hairs that cannot be identified only by SERS. SERS and XRF analyses of a single shed hair can contribute to individual identification used in forensic science.

Effects of Mechanical Vibration during Drying of Solution Sample in Enhancing the Sensitivity of Total Reflection X-ray Fluorescence Analysis.

This study describes a sample preparation method for trace element analysis using total reflection X-ray fluorescence analysis. The procedure of this method is as follows: 1) a hydrophobic-coated sample holder whose hydrophobic film at around the center of the surface is partially dissolved by acetone is prepared; 2) a droplet of a sample solution is dropped on the sample holder; and 3) the sample droplet is heated and dried while vibrating it. This sample preparation method is effective for reducing the size of the dry residue of the sample solution and suppressing the coffee-ring formation. Furthermore, this method leads to an enhancement in the intensity of an X-ray fluorescence line from an analyte element in the sample residue. In this study, this sample preparation method led to an improvement in the detection limit for vanadium in commercially available bottled drinking water.

Trace Determination of Cyanocobalamin (Vitamin B12) by Analyzing Cobalt Using a Portable Total-Reflection X-ray Fluorescence Spectrometer.

A method is presented for the detection of a trace amount of cyanocobalamin (vitamin B12) using a combination of solid-phase extraction and the measurement of cobalt in vitamin B12 by a portable total-reflection X-ray fluorescence spectrometer. Using this combination, a detection limit of 1 ng/mL was achieved for vitamin B12.

Trace Elemental Determination Using a Portable Total Reflection X-Ray Fluorescence Spectrometer with a Collodion Film Sample Holder.

Using a portable total-reflection X-ray fluorescence (TXRF) spectrometer with a collodion film sample holder, a spectrum of an analyte containing 50 ng of aluminum was measured. The Al Kα line (1.49 keV) that partially overlaps with the Si Kα line (1.74 keV) from a quartz glass substrate usually used as a sample holder for TXRF analysis, was clearly detected when using the collodion film sample holder. To investigate the quantitative performance of the portable spectrometer with a collodion film sample holder, the concentrations of Cr, Mn, and Fe in a certified reference material of river water (JSAC 0302-3b), whose certified values are 10.0, 5.1, and 59.6 µg/L, respectively, were determined by the internal-standard method. We showed that approximate concentrations of these elements were determined.

Note: Portable total reflection X-ray fluorescence spectrometer with small vacuum chamber.

To improve the detection limits of a portable total reflection X-ray fluorescence (TXRF) spectrometer using white X-rays (i.e., both characteristic X-rays and continuum X-rays) from a 5 W X-ray tube, the measurement was performed in vacuum. The TXRF spectrum measured in vacuum was compared with that measured in air. The spectral background was significantly reduced when the scattering of the incident X-rays from air was reduced using a vacuum pump, leading to improvement in the detection limit. A detection limit of 8 pg was achieved for Cr when measuring in vacuum.

A portable total reflection X-ray fluorescence spectrometer with a diamond-like carbon coated X-ray reflector.

A diamond-like carbon (DLC) coated quartz glass sample holder is used in a portable total reflection X-ray fluorescence (TXRF) spectrometer. A spot area of a water sample on the DLC sample holder becomes smaller than that on a quartz glass sample holder usually used in TXRF analysis because DLC is more hydrophobic. Therefore, the use of the DLC sample holder enhances fluorescent X-rays reaching a detector compared with the use of a quartz glass sample holder, leading to improvement in detection sensitivity. A detection limit of 28 pg is achieved for Cr in a river water sample when using the DLC sample holder.

Polychromatic excitation improves detection limits in total reflection X-ray fluorescence analysis compared with monochromatic excitation.

Detection limits obtained by a portable total reflection X-ray fluorescence (TXRF) spectrometer with or without a monochromator are compared. A 1 W X-ray tube (tube voltage: 20 kV) is used in this spectrometer. Polychromatic excitation improves the detection limits in TXRF analysis with the low power X-ray tube compared with monochromatic excitation. A detection limit of 26 pg is achieved for Co when using the weak polychromatic X-rays.

Spatially resolved X-ray fluorescence analysis with a pyroelectric X-ray emitter.

A portable instrument for two-dimensional X-ray fluorescence imaging was assembled with an X-ray source using a pyroelectric crystal, which was driven by a 9-V dry battery, a Si-PIN detector, a slit, and pulse motors. Line scanning for a mug and a knife-edge-scan of an iron sheet were carried out using this spectrometer. The sensitivity of the spectrometer was sufficient for elemental analysis of a mug using a 1 mm(2) slit, and several elements, such as Co, Ni, Zn, Pb and Zr, were detected. The estimated spatial resolution using a 0.8-mm pinhole was 3.5 mm.

Trace elemental analysis of commercial bottled drinking water by a portable total reflection X-ray fluorescence spectrometer.

A portable total reflection X-ray fluorescence spectrometer was applied to commercial bottled drinking water containing 62 ppb (microg/L) V, 7.5 ppm (mg/L) Ca, and 1 ppm K. A dry residue, prepared by repeated pipetting and drying a 20 microL portion of drinking water on a sample holder six times, and another dry residue, prepared by pipetting and drying a 120 microL portion of the drinking water, were measured. The size of the dry residue of the drinking water was reduced by repeating the pipetting and drying. Calcium and potassium were easily detected in these two dry residues. Vanadium was detected in the dry residue prepared by repeated pipetting and drying. Vanadium, calcium, and potassium were quantified by using an internal standard, and the average quantified concentrations of V, Ca, and K were 91 ppb, 8.2 ppm, and 1.5 ppm, respectively. Although these quantified concentrations deviated from the certified concentrations (62 ppb of V, 7.5 ppm of Ca, and 1 ppm of K), it was possible for this portable spectrometer to estimate approximate concentrations.

Portable total reflection X-ray fluorescence spectrometer for nanogram Cr detection limit.

A portable total reflection X-ray fluorescence spectrometer is presented. The present spectrometer mainly consists of a 1.5-W X-ray tube, a waveguide type slit, a detector, and a sample carrier (a quartz optical flat), and these components are contained in an attache case-type box. Continuum X-rays emitted from the low-power X-ray tube are used for the excitation of the X-ray fluorescence, and the minimum detection limit for Cr is a few nanograms or the level of 1013 atoms/cm2.