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Hydrogen fluoride in a standard or sample gas stream at 200 ml min−1permeates through a teflon membrane (0.8 μm pore size, 0.08 mm thick) into an absorption solution (citrate/acetate buffer at pH 5.4) flowing at 30 ml min−1. The fluoride produced is measured with the fluoride-selective electrode. The response time is about 12 min. The absorption efficiency of hydrogen fluoride is about 70% between 6.5 and 0.25 ppm by volume (5.2 and 0.2 mg m−3). In this range, the Nernst equation is valid with a relative standard deviation of less than 1.8%. The lower determination limit for hydrogen fluoride is 0.1 ppm (0.08 mg m−3).

A new chemiluminescence system, brilliant sulfoflavine-hydrogen peroxide-sodium hydroxide-acetonitrile, is described for continuous flow analysis for Fe(II) and Cr(III). This permits highly selective determination with detection limits of 1×10−9M for Fe(II) and 3×10−8M for Cr(III).

Luminous oxidation of 7,7,8,8-tetracyanoquinodimethane(TCNQ) by dissolved O2is utilized for sensitive determination of Mn(II), The weak chemiluminescence of TCNQ is effectively sensitized by eosin Y in didodecyldimethylammonium bromide bilayor vesicles. The limit of determination is 0.01 ng(20-μl sample injection).

An ion flotation-atomic absorption spectrometry method is described for the determination of six heavy metal ions: Fe(lll), Ni(ll), Co(ll), Cu(ll), Cd(ll) and Zn(ll), in water. Heavy metal ions in 1000 ml samples were chelated with 1,10-phenanthroline at pH 4.0 and were floated with the aid of sodium lauryl sulfate and nitrogen bubbles. Each metal ion concentration was determined by a conventional flame atomic absorption spectrometry after diluting to 10 ml. The linear calibration curve of each ion was obtained in the concentration range of 4×10-8M-8×10-7M. The proposed method was successfully applied to the determination of these ions in hot spring waters.

The waste water sample is pumped at the flow rate of 4 cm3min-1to the mixing joint, where a reaction solution (5×10-3M bismuth nitrate-containing sodium acetate buffer at pH 5.0) is mixed at the rate of 1 cm3min-1. Then the mixture containing hydrogen cyanide is fed into a gas-liquid separator. The hydrogen cyanide permeates through a Teflon membrane (0.80 μm pore size, 0.08 mm thick) into an absorption solution (0.02% sodium hydroxide) flowing at 24 cm3h-1. The cyanide ion produced is measured with the cyanide selective electrode. The response time is about 1.3 min at a concentration of 1 ×10-4M cyanide. The Nernst equation is valid with a relative standard deviation of less than 2.8% in the range between 1 ×10-3and 1 ×10-6M. The lower detection limit is 1 ×10-7M (2.6 CN-ppb). This method can detect free cyanide ion and indirectly metal cyano complexes whose stability constants are below 1017.

Flow injection analysis, with chemiluminescence detection, is used to determine traces of copper(II) by means of the flavin mononucleotide–hydrogen peroxide–phosphate buffer system. This permits the determination of copper(II) more selectively than any other chemiluminescence system with a detection limit of 0.03 ng(20-μl sample injection) or 0.06 ng ml−1(continuous sample flow). The linear range is 3 orders of magnitude, the sampling rate is 120 h−1, and the relative standard deviation is 3.1% for 1 ng Cu(II)(n=10). Iron(II) and chromium(III and VI), the strongest enhancer after copper(II), provide signals 2–3% of that for copper(II). Effect of surfactant micelles on the signal for copper is also discussed. The method is successfully applied to real samples.

Ultrasonic irradiation of alkaline luminol solution produces intense light emission (sonic chemiluminescence) as a result of the reaction of luminol with reactive species which are generated ultrasonically from water molecule. For the analytical application of ultrasound-induced luminescence, the sonic chemiluminescence of luminol is first utilized for the determination of ultratraces of cobalt(II) by flow injection and continuous flow methods. This novel method is based on the measurement of sonic chemiluminescence enhanced by the presence of cobalt(II); it provides analytical characteristics comparable to those for the conventional luminol chemiluminescence method using hydrogen peroxide as an oxidizing agent. The limit of detection is 0.06 pg(10-μl sample injection) or 0.06 pg ml−1(continuous sample flow), the linear dynamic range is 3 orders of magnitude (10-μl sample injection), the sampling rate is 120 h−1, and the relative standard deviation is 3.9% for 6 pg Co(II) (n=10). The method is successfully applied to real samples. Possible explanation of sonic chemiluminescence is also presented; the mechanism involving superoxide anion radical is proposed for the cobalt(II)-catalyzed sonic chemiluminescence.

The determination of arsenic(III) by anodic stripping using co-deposition with copper was worked out. A 0.24 M hydrochloric acid containing arsenic(III) and copper(II) was electrolyzed with a rotating platinum electrode (rpm=800) at a constant current. The deposit on the electrode was stripped by linear potential sweep method in 4 M hydrochloric acid. The stripping voltammogram was recorded in the span voltage -0.2–+1.2 volt vs.SCE. The stripping voltammogram showed two peaks, at zero volt and 0.5 volt vs.SCE. The area of the second peak was proportional to the concentration of arsenic. Linear dynamic range was 1–20 microgram per milliliter. The method was rapid and simple, the time required for analysis being about 35 minutes (electrolysis temperature, 25°C). X-ray and electron diffractions indicate that the second peak in the stripping voltammogram results from the dissolution of Cu3As.

Quantitative treatment of alkali metals in a small hydrogen flame in the presence or absence of halogens was studied. The proportionality of the ion current to the concentration of alkali metals was found to depend on the applied potential of the electrodes. On adding halogens, the concentration of free neutral alkali atoms decreased. Addition of bromine and iodine increased the ionization of alkali metals, while fluorine decreased it slightly. Addition of chlorine increased or decreased the ionization. The thermionic detection mechanism of halogen-containing compounds in TID of gas chromatograph was discussed.

Behavior of alkali metals in the small hydrogen flame for ultra-micro analysis of alkali and alkaline earth metals were investigated. Distribution of free neutral atoms and formation of alkali hydroxides were studied by the photometric method, distribution of charged particles was determined by the Langmuir probe method, and confirmation of whether negative-charged particles are mostly electrons or negative ions by the sheath method. It was found that only lithium formed hydroxide in the flame, ionization chiefly occurred in the part 0–5 mm above the jet, and that most of negative-charged particles are not electrons but negative ions.