Analytical and Bioanalytical Chemistry (v.332, #5)

Surface analytical methods such as AES, ESCA, SIMS, RBS, ISS, GDOES and others have been at the disposal of materials researchers for about two decades. In many cases, the challenge of materials research has stimulated innovations or improvements in analytical techniques, and conversely, improved analytical tools have encouraged materials scientists to tackle problems which previously had appeared forbiddingly complicated. The interplay of analytical developments and progress in the understanding and manipulation of materials behaviour is reviewed, using as examples such widely different areas of technology and science as grain boundary segregation and embrittlement; fabrication and characterization of microelectronics devices; adhesion and tribology; automotive steel plate, and progress in quantitative techniques in surface analysis.

By using thin-layer chromatography with selected mobile phases numerous substance groups of non-polar to polar character occurring in water, waste water and sludges or sediments can be prepared for infrared spectroscopy. The required substance quantity of 5 to 100 μg is usually isolated on silica gel layers through multistage chromatography. This technique is described by way of examples as is the interpretation of optimal spectra to be adopted. In addition to substance groups from the aquatic environment, metabolites from the biochemical degradation of technical products (e. g. detergents) as well as of single compounds (e. g. surfactants) are also included in the examples. The publication presents a summarized report, in consideration of systematic viewpoints, on the results obtained from 20 years of experience with the combination of thin-layer chromatography and infrared spectroscopy.

A method for the determination of extremely low levels of arsenic by hydride AAS is presented. It is based on hydride preconcentration in a quartz tube at liquid nitrogen temperatures under carefully evaluated and optimized experimental conditions, followed by rapid heating up to 100° C and measurement in a heated quartz cell. Under the given experimental conditions an absolute detection limit of 0.05 ng and a linear range up to 6 ng could be achieved, representing a 6.5-fold improvement of detection power in comparison to commercially available hydride systems.

Manganese(VII) (0–120 μg) can be determined spectrophotometrically at 548 nm after its adsorptive extraction at pH 6 as its trimethylene-bis(triphenylphosphonium) ion pair with microcrystalline naphthalene after dissolution of the solid phase in chloroform. The effects of pH, reagent conditions and diverse ions are reported. The system has been applied to the determination of manganese in a range of steels. For the determination of 60 μg of manganese the relative standard deviation was 0.61%.

The Grimm-type glow discharge lamp (GDL) working in a modulated way can be used as primary light source for atomic absorption measurements. The number of element radiations is given by the composition of the target (sample on GDL) which becomes sputtered. Its composition can be adopted to the analytical problem to be solved. It is easy to change the target.The glow discharge source generated at relatively low power (10–24 W) is burning stable for >20 min on the same spot. This is time enough to operate atomic absorption measurements of 10 samples simultaneously, for example, by using the normal flame technique or the graphite tube furnace or the atomsource sputter method to generate atoms of the sample material. The monochromator device of an AA spectrometer has to be replaced by a polychromator one.The spectral behaviour of the glow discharge source compared to that of the hollow cathode lamps of the elements studied is described here by using a double beam two channel AA spectrometer for simultaneous reading of both the signals. In most cases the glow discharge source is the better one. Home-made targets are used to measure first analytical results.

A simple, rapid, and reproducible method for the determination of urea, creatinine, and uric acid in human serum and urine by ion-pair reversed-phase high-performance liquid chromatography with UV detection (196 nm) has been developed. The method involves the pretreatment of serum samples with trichloroacetic acid and centrifugation followed by the isocratic separation of compounds on a μ-Bondapak C18 column using a mobile phase consisting of 1.25 mmol/l tetrabutylammonium phosphate. For urine samples no special pretreatment is necessary. In addition, this method allows, with some limitations, the determination of creatine in serum.

HPLC-Bestimmung von Nizatidin in Serum und UrinHPLC determination of nizatidine in serum and urine by A. Tracqui; P. Kintz; P. Kreissig; P. Mangin; A. A. Lugnier; A. J. Chaumont (468-469).

New books (470-471).

2.6 Foods (496-500).

2.7 Pesticides (500-503).