Simplified Colorimetric Determination of Thiocyanate in Biological Fluids, and Its Application to Investigation of the Toxic Amblyopias

Abstract

A colorimetric procedure for determination of small amounts of cyanide and thiocyanate, involving the synthesis of a pyridine dyestuff by the reaction of pyridine and an aromatic amine, has been simplified for the estimation of thiocyanate alone in biological fluids. Replacement of benzidine with p-phenylenediamine in the colorimetric reaction has both improved the precision of the analytical procedure and avoided a carcinogenic hazard. This method has been used to follow the decrease in plasma thiocyanate associated with abstinence from cigarette smoking, and its subsequent increase upon resumption. It has also been used to measure the plasma and urinary thiocyanate concentrations of patients suffering from the particular toxic amblyopias—tobacco amblyopia and Leber’s hereditary optic atrophy— believed to be associated with cyanide toxicity, and to follow the increased thiocyanate concentrations that accompany significant improvements in the patients’ vision brought about by various treatments.

Effect of smoking on theophylline disposition

“…Much higher levels of serum thiocyanate, a biotransformation product of cyanide that is inhaled during smoking (and ingested from other sources), was found III smokers (15.7 ± 2.4 mg/L) than in nonsmokers values cited elsewhere for smokers and nonsmokers. 20 The apparent volume of distribution of theophylline averaged 0.50 ± 0.12 Llkg in smokers and 0.38 ± 0.04 Llkg in nonsmokers ( Fig. 4).…”

“…10 Thiocyanate concentrations in serum were measured by the colorimetric method of Pettigrew and Fell. 20 Using nonlinear least-square regression analysis,15 the data were fitted to appropriate pharmacokinetic equations for a one-compartment model. Parameters that were calculated include the half-life, apparent volume of distribution, and body clearances 14 of theophylline.…”

A Comparative Study of the Amount of Smoke Absorbed From Low Yield (‘Less Hazardous’) Cigarettes.

“…lg) attained by the treatment group for the same periods. Although the increased ratio for the standardized saliva thiocyanate could partially be due to a cumulative efiect resulting from the relatively long half life of thiocyanate (14 days [34]) it is unreasonable to assume that this could also be true for breath carbon monoxide which has a half life of about five hours [35j.…”

A Comparative Study of the Amount of Smoke Absorbed From Low Yield (‘Less Hazardous’) Cigarettes Part 2: Invasive Measures

“…A careful inspection of Figure lc reveals that average plasma thiocyanate levels for the treatment group do not decrease significantly over periods 1-3 while Figure If illustrates that values for 'standardized' plasma thiocyanate increases considerably (==500%) during period three. Although some of this increase could result from the cumulative effect of the higher HCN deliveries of cigarettes smoked during periods one and two due to the relatively long half life of thiocyanate [27], this is unlikely. Since there is no evidence in Figure 1 f to suggest a decrease toward the end of period three the increased average 'standardized' level of plasma thiocyanate observed in period three must, like the average 'standardized' carboxyhemoglobin, reflect increased smoking intensity probably as a result of increases in depth of inhalation.…”