Cadmium uptake by onions, lettuce and spinach in New Zealand: Implications for management to meet regulatory limits.

Paired soil and plant samples collected from the main commercial growing areas for onions (Allium cepa), lettuce (Lactuca sativa) and spinach (Spinacia olearacea) in New Zealand were used to assess the influence of plant and soil factors on cadmium (Cd) uptake in these crops. Differences in Cd concentration between eight lettuce sub-types were not consistent across sites, nor were differences in Cd concentrations in three crisphead cultivars assessed at two sites. Similarly, differences in Cd concentrations between four onion cultivars were inconsistent across sites. Mean lettuce Cd concentrations in eight lettuce varieties (range 0.005-0.034 mg∙kg-1 (fresh weight, FW) were markedly lower than those in baby leaf and bunching spinach, (range 0.005-0.19 mg∙kg-1 FW). Significant regional variation was observed in Cd concentrations in one onion cultivar (mean range 0.007-0.05 mg∙kg-1 FW). Soil Cd concentration, pH and region were statistically significant predictors of onion Cd concentration, explaining low (38% for soil Cd and pH) to moderate (50% for all three parameters) percentage of the variation. Soil Cd concentration and exchangeable magnesium or total carbon were statistically significant predictors of Cd concentration in baby leaf and bunching spinach, respectively, explaining a moderate percentage (49% and 42%) of the variation in Cd concentration. Increasing pH and soil carbon may assist in minimising Cd uptake in onion and bunching spinach, respectively. The low to moderate proportion of explained variation is partly attributable to the narrow range in some measured soil properties and indicates factors other than those assessed are influencing plant uptake. This highlights a challenge in using these relationships to develop risk-based soil guideline values to support compliance with food standards. Similarly, the inconsistency in Cd concentrations in different cultivars across sites highlights the need for multi-site assessments to confirm the low Cd accumulation status of different cultivars.

The heavy metals cadmium, lead and mercury in raw materials of animal origin: evaluation of data from practice.

Raw materials from animal origin are widely used in homoeopathy. Due to the lack of dedicated limits, the quality requirements for herbal drugs of the European Pharmacopoeia (Ph. Eur.) and/or the German Homoeopathic Pharmacopoeia (Homöopathisches Arzneibuch, HAB), including limits for heavy metals such as cadmium, lead and mercury, have been applied. A recent database evaluation shows that for some raw materials of animal origin the Ph. Eur. limits for herbal drugs cannot be met in practice. For this reason proposals for new limits for cadmium, lead and mercury are made based on recent experiences from the companies' daily practice. These specific limits are suggested to be included in the individual monographs of the Ph. Eur. or at least the German HAB, respectively, for Ambra grisea, Euspongia officinalis, Formica rufa and Sepia officinalis.

Recognizing and overcoming analytical error in the use of ICP-MS for the determination of cadmium in breakfast cereal and dietary supplements.

The potential effect of spectral interference on the accurate measurement of the cadmium (Cd) mass fraction in fortified breakfast cereal and a variety of dietary supplement materials using inductively coupled plasma quadrupole mass spectrometry was studied. The materials were two new standard reference materials (SRMs)--SRM 3233 Fortified Breakfast Cereal and SRM 3532 Calcium Dietary Supplement--as well as several existing materials--SRM 3258 Bitter Orange Fruit, SRM 3259 Bitter Orange Extract, SRM 3260 Bitter Orange-containing Solid Oral Dosage Form, and SRM 3280 Multivitamin/Multielement Tablets. Samples were prepared for analysis using the method of isotope dilution and measured using various operating and sample introduction configurations including standard mode, collision cell with kinetic energy discrimination mode, and standard mode with sample introduction via a desolvating nebulizer system. Three isotope pairs, (112)Cd/(111)Cd, (113)Cd/(111)Cd, and (114)Cd/(111)Cd, were measured. Cadmium mass fraction results for the unseparated samples of each material, measured using the three instrument configurations and isotope pairs, were compared to the results obtained after the matrix was removed via chemical separation using anion exchange chromatography. In four of the six materials studied, measurements using the standard mode with sample introduction via the desolvating nebulizer gave results for the unseparated samples quantified with the (112)Cd/(111)Cd isotope pair that showed a positive bias relative to the matrix-separated samples, which indicated a persistent inference at m/z112 with this configuration. Use of the standard mode, without the desolvating nebulizer, also gave results that showed a positive bias for the unseparated samples quantified with the (112)Cd/(111)Cd isotope pair in three of the materials studied. Collision cell/kinetic energy discrimination mode, however, was very effective for reducing spectral interference for Cd in all of the materials and isotope pairs studied, except in the multivitamin/multielement matrix (SRM 3280) where the large corrections for known isobaric interferences or unidentified interferences compromised the accuracy. For SRM 3280, matrix separation provided the best method to achieve accurate measurement of Cd.

On the certification of cadmium at trace and ultratrace levels in standard reference materials using ID ICP-MS.

Analytical methods used for the isotope dilution inductively coupled plasma mass spectrometric (ID-ICP-MS) measurement of Cd at microg kg(-1) and sub-microg kg(-1) levels are described and applied to the certification of new dietary supplement, blood, and serum Standard Reference Materials (SRMs). The materials are: SRM 3240 Ephedra sinica Stapf Aerial Parts, SRM 3241 Ephedra sinica Stapf Native Extract, SRM 3243 Ephedra-Containing Solid Oral Dosage Form, SRM 3244 Ephedra-Containing Protein Powder, SRM 966 Toxic Metals in Bovine Blood, Level 1 (L1) and Level 2 (L2), and SRM 1598a Animal Serum. The concentration of Cd in the materials ranges from 120 microg kg(-1) down to 0.03 microg kg(-1). At these levels, the factors that most influence the accuracy of the ICP-MS data are the procedure blank and spectral and nonspectral interferences. Nonspectral interference, caused by the high concentration of dissolved solids in the matrices investigated, resulted in signal suppression. Matrix separation was used to enhance signal intensity and to reduce spectral interference for the accurate determination of Cd in SRM 1598a and SRM 3244. Chromatographic separation procedures using Chelex for SRM 1598a and anion exchange for SRM 3244 were optimized to achieve the desired separation characteristics without substantially increasing the procedure blank. Sensitivity for the determination of Cd in serum was additionally enhanced through the use of desolvation nebulization. We determined that separations were not required for the accurate ICP-MS determination of Cd in SRM 3240, SRM 3241, SRM 3243, and SRM 966 L2 under optimized analysis conditions. These samples were diluted to a minimum volume and introduced to the ICP-MS via low flow (40-100 microL/min) microconcentric nebulizers. SRM 966 L1 was also analyzed directly, but results were highly variable. The ID-ICP-MS sample preparation and ratio measurement protocols described here resulted in total expanded uncertainties of less than 1% for the determination of 90.85 microg kg(-1) Cd in SRM 3240, and less than 10% total expanded uncertainty for the determination of 0.0468 microg kg(-1) Cd in SRM 1598a.