Determination of copper and arsenic in refined beet sugar by stripping voltammetry without sample pretreatment

Abstract

Copper and arsenic have been analysed in refined beet sugar at the microgram kg-1 level by anodic stripping voltammetry (copper) and cathodic stripping voltammetry (arsenic) in the differential-pulse mode (DPASV and DPCSV) at a hanging mercury drop electrode (HMDE). DPCSV measurements of arsenic are based on its accumulation onto the HMDE as an intermetallic Cu-As compound followed by the reduction of As0 to arsine in hydrochloric acid medium. Measurements were directly carried out on untreated sugar solutions. The performance of the procedures was compared with electrothermal atomic absorption spectrometry and stripping voltammetry applied to digested sugar samples, and showed in general better accuracy. The procedures were applied to the determination of these toxic elements in commercial beet sugar samples of concentrations below 50 micrograms kg-1 copper and 15 micrograms kg-1 arsenic were found, which are much lower that those allowed by the current regulations.

Trace metal contents in chewing gums and candies marketed in Turkey

“…The highest amount was found in cocoa based candy sample and the lowest in fruit based one (Table 4). In the literature copper levels in selected sweets of different shops of Karachi city have been reported in the range of 0.07-4.0 ppm (Naqvi et al 2004), in sugar samples produced by Spanish sugar beet refineries have been reported in the range of 16-47 μg/kg (Sancho et al 1998), in chewing gum samples have been reported in the range of 1.60-5.38 μg/g (Kilic et al 2002).…”

Analysis and Speciation of Traces of Arsenic in Environmental, Food and Industrial Samples by Voltammetry: a Review

“…The digestion of organic material is not always a must: for example, the same results were obtained for the determination of total arsenic and copper (detection limit of 2 ppb) in refined beet sugar with or without pretreatment [98].…”

“…MDEs are much less common (e.g., in [98]) because of the already mentioned low solubility of arsenic in this metal. Probably for the same reason, there is only one example of Hg-modified graphite electrodes and another of graphite electrodes with adsorbed HgI 2À 4 [99,100].…”

“…Dissolution with HCl/H 2 SO 4 ; distillation of AsCl 3 under vacuum; As( V ) 3 As( III ) with N 2 H 4 ¥ H 2 SO 4 for total As determination as As( III ) [86] ed as SO 2À 3 [12,14,50,73,102,133,138], HSO À 3 [49] or SO 2(g) [34,36,52,66]), S 2 O 2À 3 [70], hydrazine (added as sulfate or hydrochloride) on its own or in the presence of HBr [24,34,35,67,74,86,87,98], KI (sometimes in the presence of ascorbic acid) [65, 103, 110 ± 112, 114, 122, 123, 131] and hydroxylamine [135]. Dubey and Puri [64] claim that As(V) is reduced to As(III) during the solid-phase extraction of its morpholine-4-carbothioate complex onto naphthalene.…”

Optimization of the Voltammetric Determination of Arsenic in Foodstuffs

“…Meanwhile, because of the compactness, simplicity, and low price of its equipment, stripping voltammetry is promising for field analysis and analysis in mobile laboratories and can become widespread in food laboratories, especially in underdeveloped countries. Stripping voltammetry is used to analyze wine and drinks [3]; milk and dairy produce [4]; standard reference samples of meat, liver, and fish [4,5]; seafood [6,7]; vegetables and spinach [7,8]; beet sugar [9]; etc. [10].…”