A method is presented for the determination of trace elements in plant materials. The samples were composed of organic material, which was eliminated by wet ashing, large amounts of group I and II elements, and many trace elements of interest in the concentration range 0.1–100 ppm. An attempt to achieve preconcentration of the trace elements by absorption on cation-exchange membrane (which could have been used directly for analysis) was unsuccessful because of preferential absorption and saturation of the membrane by group I and II cations. Formation of complex-metal anions in acid solution and absorption on anion-exchange resin was more successful, but, because of a lack of precision and incomplete absorption, the technique was inadequate. In the most successful preconcentration scheme, an organo-metallic precipitation was used in a matrix suitable for X-ray analysis. In this precipitate the elements Fe, Mn, Cu, Zn, Co, Mo, Cr, Ni, Ti, V, Ca, Sn, Sc, Ba, and Pb could be quantitatively determined. In many cases the lower limit of detection was 0.01 ppm. The accuracy and precision of the technique were proved by comparison to chemically analyzed samples, recovery experiments, and replicate analyses. The method is generally applicable for the analysis of many organic materials.

Various sample-mounting devices are described for use with a commercial flat-crystal X-ray fluorescence spectrometer having conventional (i.e., not inverted) geometry: (1) a sample drawer with two sample “spinners,” one for rotation of flat samples in their own plane, the other for rotation of cylindrical or filamentary samples about an axis normal to the plane defined by the directions of the primary and secondary X-ray beams; (2) rotatable mounting stages for filter paper disks and various very small samples; (3) a sample drawer for selected area operation with pinhole or slit apertures in the primary beam or pinhole apertures in the secondary beam; (4) a liquid cell with 0.00025-in. Mylar window (the cell is inexpensive, easily filled and rinsed, and usable 20-50 times before the window must be replaced); (5) three types of cell for powder samples (one has a 0.00025-in, Mylar window and is filled through a port in the top; the other types are open on both sides and are filled by placing them on glass plates and introducing the powder from the back; one of these back-loading cells permits rotation of the powder sample); (6) rotatable stages for briquetted powder samples; (7) mounting devices for wire samples on small spools (one of these devices permits rotation of the spool).

These devices were designed and made at the X-ray laboratory of the RCA plant at Harrison, N. J., and have been used there successfully with a wide variety of samples for several years.

Container glass, which is derived from the fusion of sand, sodium carbonate, limestone or dolomite, and feldspar, along with small amounts of colorants, reducing agents, and other modifiers, offers quite a challenge to the analyst, whether it be by conventional wet-chemical methods or by modern instrumentation. An analysis for 12 elements, which would take many days by standard wet methods, can now be done in 3–4 hr for a single sample, or 2 hr when analyzed in groups of three or more samples.

X-ray procedures have been developed and calibration curves obtained for SiO2, CaO, MgO, K2O, Al2O3, Cr2O3, Mn2O3, Fe2O3, CoO, BaO,TiO2, SrO, ZrO2, As2O5, and SO3 In glass. With a gravimetric determination of Na2O added to the elements determined by Xray, the total should approach 100%. An analysis Is considered satisfactory if the combined determinations total within ±0.3% of 100%. Various X-ray procedures and matrix effects shall be discussed.

This paper describes equipment and performance characteristics of an X-ray emission analyzer designed specifically for continuous, 24-hr on-line process chemical analysis and control. Analysis of elements from Mg (12) upward in the periodic chart are generally feasible.

The basic instrument is a multichannel spectrometer with provision for the simultaneous analysis of up to six elements. Either curved or flat crystals may be used as dictated by the particular application for which it is intended. X-ray detection is accomplished with flow proportional, sealed proportional, and scintillation detectors with both counter tube gas and electronic discrimination against undesired X-rays. The instrument is designed for excellent stability with provision for either automatic or simple manual standardization for long-term drift. A helium atmosphere is used for light elements, and through great care in spectrometer head design consumption is limited to 1 ft3/hr. A number of sample-presenting apparatus have been designed as companions to the basic equipment, including a continuous automatic powder, slurry, and liquid presenter. The powder presenter is particularly adaptable Co continuous analysis of materials which are finely ground (e.g., -200 mesh), whereas the slurry presenter is adaptable to continuous monitoring of solutions or finely ground particles in a slurry state. Readout is available as a d-c signal suitable for strip-chart recorders, voltmeters, data loggers, computers, and control. Digital readout and print out are also available. Performance tests in both the laboratory and field indicate an instrument suitable for on-line process use in a wide variety of industries, including cement, steel, mining, petroleum, and chemicals.

With the introduction in 1960 of the first commercial multichannel vacuum X-ray spectrometers, ARL opened the way for greater economy of operation for light-element analysis over conventional helium-path instrumentation. The design concepts and features of these instruments are discussed, including the adaptability to “on-stream” or continuous analyzer programs. The successful application of vacuum X-ray equipment for the analysis of ores, concentrates, and slags will be presented. Factors relating to sample preparation, precision, and accuracy are given and analytical sensitivity and speed are covered.

The application of X-ray fluorescence-analysis methods to process control is discussed. Various methods of sample preparation are reviewed and compared. The use of the direct sampling technique is discussed and consideration is given to the effects of particle size on precision and accuracy of analytical results. The mechanism of these effects if presented, and some general principles concerning the relationship of fluorescent intensities and particle sizes of pure materials and mixtures are derived. Examples of particle-size effects in cement and mining applications are illustrated.

Quantitative de terminations of thickness and composition are presented for 100- to 10,000-A iron-nickel films. Calibration of X-ray intensities with interferometric and calorimetric values give linear plots for films deposited on Mylar or glass substrates. Application of a film-casting technique shows promise of alleviating two of the problems encountered in X-ray spectroscopy, i.e., matrix-effect-caused deviations from proportionality and the lack of standards for calibration of many types of material.

Frequently it is desirable to perform an X-ray spectrographic analysis on an area of a specimen which is considerably smaller than that normally irradiated in bulk-production spectrographs. Ideally, one would turn to an electron-beam microanalyzer for this type of analysis. Unfortunately, there are few of us who can justify the expenditure necessary to equip our laboratories with this instrument. Therefore, a compromise measure has been arrived at which permits the analyst to examine an area many magnitudes smaller than that obtainable from production spectrographs and many magnitudes less expensive than that encountered in electron-probe microanalyzer instrumentation.

An attachment to a commercial flat-crystal X-ray fluorescent goniometer permits analysis of small areas. The selection of the sample area is achieved by collimating the secondary beam. The geometry of the probe, its stage, and counting statistics applied to the probe are discussed. Experimental data are shown referring to determination of spot size, counting rates obtained, and both qualitative and quantitative applications.

The Bureau of Mines purchased the electron optics, vacuum system, and sample stage assembly for the electron-probe X-ray spectrograph and designed and built the two reflection and two transmission scanning curved-crystal spectrometers. The reflection spectrometers were placed in a vacuum chamber for measurements of long-wavelength X-radiation. Operational characteristics of this spectrograph were determined. A low-alloy stainless-steel sample containing 5 wt. % depleted uranium and a stainless-steel sample containing 20 wt. % gadolinium were analyzed.

A versatile beam-scanning system has been developed for use with the Electron Microprobe X-ray Analyzer manufactured by Applied Research Laboratories, Inc. It provides for the display of X-ray intensities from any of three spectrometers, three nondispersive detectors (either counters or scintiallation counters), as well as the current collected by the target or the current backscattered by the target. The electrostatic deflection system does not interfere with the use of the optical-viewing system and provides a maximum scanning area of only slightly less than field of view of the optical-viewing system.

A stepping motor, controlled from the readout console, has also been developed which permits automatic point-by-point analysis of a specimen with minimum operator attention. In the use of this attachement, measurements may be made for fixed time, fixed charge, or fixed counts (integrated intensity) at each point. As a result, the step-scanning motor facilitates accurate measurement of one-dimensional concentration fluctuations and is particularly useful for phase identification and studies of diffusion and segregation.