Taiki Aoyama

Changes of Free Formaldehyde Quantity in Non-iron Shirts by Washing and Storage

Many non-iron shirts are finished with formaldehyde (HCHO) resin or HCHO vapor. Free HCHO in the non-iron shirt mostly decreases by washing. However, free HCHO sometimes increases once again with time by decomposition of resin. We have measured the quantity of free HCHO in 27 non-iron shirts and 3 regular shirts as control samples, before and after washing and drying, 1 week, 2 weeks, 1 month and 6 months after washing. Consequently, before washing, the quantity of free HCHO in 8 non-iron shirts was found to exceed 75ppm, max up to 202ppm. Seventy-five ppm is the standard value detected in underwears for adults according to the Law for the Control of Household Products Containing Harmful Substances. Even after washing, the quantity of free HCHO in 2 non-iron shirts did not fall below 75ppm. And after the storage for 6 months, the quantity of free HCHO in 7 non-iron shirts exceeded 75ppm. Six months after triple washing, the quantity of free HCHO in 5 non-iron shirts exceeded 75ppm. Our study revealed that the patterns of change in the quantity of free HCHO were dependent on the types of finishing.

A micro diffusion analysis of MeOH in house hold aerosol commodities.

A simpler procedure for the routine measurement of methanol (MeOH) in house hold aerosol commodities was studied by the microdiffusion analysis. MeOH in the aerosols was converted to formaldehyde (HCHO) by potassium permanganate in an outer ring of Conway microdiffusion cells. The HCHO is absorbed in 0.1% methylbenzothiazolinonehydrazone (MBTH) solution of a center portion by means of diffusion in the cells standing for 4 h. at 40°C. To the solution of the center portion is added 1 ml of 5% ferric ammonium sulfate solution for color development. This procedure is available in screening of many samples examined for MeOH comparing the colors between the tested and standard solution. The samples positive toward MeOH are further examined by gas chromatography. A minimum amount of MeOH detectable by this method was 0.1 mg/g (sample).