Thiocyanate In Samples Research Articles

Thiocyanate ion selective electrode based on bis(N-3-methylphenyl salicylidenaminato)copper(II) ionophore

Abstract In this work a PVC membrane electrode based on bis(N-3-methyl phenyl salicylidenaminato)copper(II) as ionophore was prepared. The electrode was tested by inorganic anions and showed good selectivity for thiocyanate ion. This sensor showed Nerstian behavior with a slope of a −59.3 mV per decade at 25 °C. The proposed electrode exhibited a wide linear range from 1.0 × 10−6 mol/L to 1.0 × 10−1 mol/L with a detection limit of 5.0 × 10–7 mol/L . The electrode response was independent of pH in the range of 4.0–10.0. The response time is about 9–21 s, and the electrode can be used for over 60 days without considerable deterioration. The prepared sensor was applied as an indicator electrode in potentiometric titration of SCN− with Ag+ ion and to determine the thiocyanate in samples of urine and saliva.

Spectrophotometric determination of thiocyanate by sequential injection analysis

A sequential injection analysis (SIA) system was developed for the spectrophotometric determination of thiocyanate as Fe(SCN) 2+. The physical parameters (flow rate, sample and reagent volumes, holding coil and reaction coil internal diameter and length) which influence dispersion in a SIA system were optimized. The effect of the reagent concentration and nitric acid concentration (in the reagent solution and carrier stream, respectively), were also studied. Reagent consumption was effectively reduced by introducing the reagent as a zone into the nitric acid carrier stream, compared to flow injection analysis where the reagent itself is the carrier stream. The system is fully computerized and able to monitor thiocyanate in samples at 24 samples per hour with a relative standard deviation of <1.20% for samples and standards with thiocyanate concentrations above 10.0 mg l −1. The calibration graph is linear from 2.0 to 150.0 mg l −1 with a 3 σ detection limit of 1.1 mg l −1. The system has been applied to the determination of thiocyanate in process solutions and waste waters.

Estimating the hazards of “less hazardous” cigarettes. III. A study of the effect of various smoking conditions on yields of hydrogen cyanide and cigarette tar

A brand of cigarette with nominal tar and nicotine yields of 4.0 mg and 0.4 mg, respectively, was examined under various machine-smoked conditions that reflect the wide range of human smoking behavior. Three levels of each of five smoking parameters--butt length, puff duration, puff interval, puff volume, and ventilation occlusion--were examined, and the effects on puff number and total particulate matter (TPM) as well as gas phase, particulate phase, and total HCN yields were estimated. Yields of hydrogen cyanide (a ciliatoxic agent) and TPM varied significantly under different smoking conditions. Ventilation occlusion had the most pronounced effect, accounting for 34% of the response variation of TPM yields and 42% of the response variation for total hydrogen cyanide yields. In the survey of available brands, total hydrogen cyanide yields varied from 2 to 233 micrograms/cigarette for the 115 brands tested, a range less than that observed for a single brand smoked under various nonstandard conditions, providing a possible explanation for the previously noted lack of correspondence between HCN yields under standard conditions and levels of thiocyanate in samples of smokers' plasma and saliva. In addition, hydrogen cyanide yields and efficiency of filters in removing HCN were examined under standard smoking conditions. Acetate filters, the most common variety, were found to remove an average of about 14% of the hydrogen cyanide from the mainstream smoke.