EXPERIMENTAL
The types of products included in the scope of this work can be categorized as follows. These
category types were predicated on whether their physical nature after the addition of water would
result in product consistency such that all particulate matter was either suspended or not
suspended.
Type I Products: Semi-solid or soft candy (e.g., chocolate-based, fruit-based, including
tamarind, tejocote, apple, etc.) with or without chili or other visible particulate ingredients (i.e.,
Chaca-Chaca, Pelon-Pelon Rico)
Type II Products: Hard candy (including suckers) with or without visible particulate ingredients
(chili) either in the candy or on the surface of the candy (i.e., Vero brand Rabaniditas suckers)
Type IIA Products: Hard candy (including suckers) with supplemental but separate salt and chili
(i.e., Vero brand Super Rabaniditas)
Type III Products: Powdered sugar or flavored salt products with or without other particulate
ingredients, e.g., chili (i.e., Brinquintos - flavored, acidified, sugars; Pica Limon - flavored,
acidified salt).
The general analytical procedure used to obtain reproducible measurements of lead in high salt
candy products is similar to the approach used for canned foods described by Jones and Boyer
[8]. Further details on this procedure are described in a draft method [9] which will be
incorporated into future versions of the EAM. The general steps in this procedure are as follows.
1. Blending/mixing of this composite sample with water and/or nitric acid
2. For those samples that would suspend, pre-digestion of a rather large (40 g) sample portion
3. Microwave digestion of an aliquot equivalent to approximately 0.5 g of the product
4. GFAAS and ICP-MS analysis
Blending of Composite Sample
A 1 kg composite sample and an equivalent mass of deionized water (for Type I products) or
10% nitric acid (Type II products) were placed in a large sized Nalgene polymethylpentene
mixing vessel. The mixture was covered and left overnight to facilitate softening/dissolution of
the product. In some cases, heating was required to assist in this process. The resulting mixture
was blended in a 6 L stainless steel bowl of a Robot Coupe RSI 6Y food chopper until a visually
homogeneous mixture was obtained. In the case of chocolate-based products, smaller amounts
of water were required to avoid formation of water-insoluble fat layer. In the case of Type II,
IIA, and III products, the mixture was subjected to an additional blending step using a high-shear
type Brinkmann Polytron mixer to facilitate homogenization of remaining particulate materials
in the mixture. It should be noted that although some candy additives such as silicon dioxide and
titanium dioxide may not be completely dissolved after this treatment process, this process
provides a mixture that is homogeneous with respect to lead content and stable enough to allow
selection of a subsample for subsequent digestion and analysis.