Determination of titanium dioxide in foods using inductively coupled plasma optical emission spectrometry

Abstract

Titanium dioxide is a common food additive of increasing interest in dietary intake studies and dietary exclusion studies. Food labelling for titanium dioxide is imprecise so a method was developed for its rapid determination in foods using acid digestion and inductively coupled plasma optical emission spectrometry (ICPOES). Twenty-five foods thought to contain titanium dioxide were obtained. Based on preliminary digestion studies, samples (500 mg) were digested in 18 mol l-1 H2SO4 at 250 degrees C for 1 h and then diluted to 5.9 mol l-1 H2SO4 before determination of titanium by ICPOES at 336.121 nm. Emission intensity was suppressed by H2SO4 so standards were matched for acid concentration. Titanium dioxide embedded in gelatine was used to assess accuracy. A standard reference material of known titanium concentration and six foods of known titanium dioxide content were used as external reference materials. Limits of detection were 2-7.5 ppb, depending on spectral integration times, and the signal was linear up to 5 ppm. Results for all control samples were in good agreement with the expected values. Twelve of the foods contained detectable titanium, ranging from 0.001 to 0.782% by weight, but only eight indicated this on their labels, four being exempt under food labelling regulations. Based on food portion sizes, an individual's daily intake of titanium dioxide could exceed 200 mg from just one of these products. This method may facilitate future studies on titanium dioxide intake, given the present limitations of food labelling.

Fine and ultrafine particles of the diet: influence on the mucosal immune response and association with Crohn’s disease

“…For example, labelling is not required when additives perform no additive function in the final product and are used in compound ingredients that make up less than 25 % of the finished product (Lomer et al 2000). In addition, of course, many foods purchased as ready-to-eat do not carry food labels.…”

“…Indeed, an individual's dietary choices or preferences will dictate their intestinal exposure to TiO 2 . In extreme cases just one portion of a salad dressing (225 mg TiO 2 ; Lomer et al 2000) could exceed the average daily intake of 5·4 mg (Ministry of Agriculture, Fisheries and Food, 1993) by > 40-fold.…”

Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population

“…It is the brightest known white pigment and, in foods, it provides a basic white background colour that acts as an opacifier, and reflects light across most of the visible spectrum. It may also act as a barrier by physically separating other colours (Lomer et al, 2000). TiO 2 is authorised as a food colour in the European Union (EU) as E 171 (EU, 2011a) and is commonly used as a food additive (Peters et al, 2014).…”

Binding of Human Serum Proteins to Titanium Dioxide Particles In Vitro

“…Hence, the International Agency for Research on Cancer has concluded that while there is inadequate evidence of the carcinogenicity of TiO 2 in humans, there is sufficient evidence from studies in experimental animals, and has thus classified titanium dioxide as a Group 2B compound (possibly carcinogenic to humans) 1) . In general, however, TiO 2 has been regarded as inert and is added to cosmetics, toothpaste, drugs and foods 8) . It has often been used as a negative control in experiments on the effects of particles or fibers in cells and animals 9,10) .…”