Cadmium In Fertilizers Research Articles

Method development for the determination of cadmium in fertilizer samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and slurry sampling

The determination of cadmium (Cd) in fertilizers is of major interest, as this element can cause growth problems in plants, and also affect animals and humans. High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with charge-coupled device (CCD) array detection overcomes several of the limitations encountered with conventional line source AAS, especially the problem of accurate background measurement and correction. In this work an analytical method has been developed to determine Cd in fertilizer samples by HR-CS GF AAS using slurry sampling. Both a mixture of 10 μg Pd + 6 μg Mg in solution and 400 μg of iridium as permanent modifier have been investigated and aqueous standards were used for calibration. Pyrolysis and atomization temperatures were 600 °C and 1600 °C for the Pd-Mg modifier, and 500 °C and 1600 °C for Ir, respectively. The results obtained for Cd in the certified reference material NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer) of 16.7 ± 1.3 μg g −1 and 16.4 ± 0.75 μg g −1 for the Pd–Mg and Ir modifier, respectively, were statistically not different from the certified value of 16.9 ± 0.2 μg g −1 on a 95% confidence level; however, the results obtained with the Ir modifier were significantly lower than those for the Pd–Mg modifier for most of the samples. The characteristic mass was 1.0 pg for the Pd–Mg modifier and 1.1 pg Cd for the Ir modifier, and the correlation coefficients (R 2) of the calibration were > 0.99. The instrumental limits of detection were 7.5 and 7.9 ng g −1, and the limits of quantification were 25 and 27 ng g −1 for Pd–Mg and Ir, respectively, based on a sample mass of 5 mg. The cadmium concentration in the investigated samples was between 0.07 and 5.5 μg g −1 Cd, and hence below the maximum value of 20 μg g −1 Cd permitted by Brazilian legislation.

Health Risks Associated with Predicted Increase of Cadmium in Cultivated Soils and in the Diet

We have assessed the change of the dietary intake and the potential health risks of cadmium in Finland, assuming that a high level of cadmium in fertilizers (138 mg Cd/kg P) would prevail for the next 100 years. Soil measurements and modelling were used to derive the predicted level of cadmium in foods. In three important cultivars, wheat, potato and sugar beet, the cadmium concentration would increase by 20–35%. Consequently, the average dietary intake of cadmium in Finland would increase from 7.9 to 10.0 μg/day, corresponding with the urinary level of about 0.2 μg/l, a level that has not been associated with effects on the human health. However, in the risk group with 1) high dietary intake of cadmium, 2) elevated gastrointestinal absorption, and 3) tobacco smoking, the estimated urinary level of cadmium would be 2.0 μg/l. Recent epidemiological studies have shown that urinary level of 1–2 μg Cd/l is associated with an increased risk of bone demineralization and fractures, and 2–4 μg Cd/l with pre-clinical kidney damage. People characterized by more than one of the above-mentioned risks factors, may develop the adverse health effects at an old age, when cadmium has accumulated in the body.

Assessing long-term environmental risks of trace elements in phosphate fertilizers

The potential risks originating from arsenic and cadmium accumulations in cropland soils through the fertilizer applications have been public concern. A generalized trace element mass balance model was developed to evaluate the long-term fate and transport of arsenic and cadmium in cropland soils. Model simulation results showed that normal cropping practices do not have a significant effect on the total As content of the receiving soils, but the application of Cd-containing P fertilizers could, over time, cause Cd to accumulate in soil and therefore increases the risk of its transfer through the food chain. Regulations have been enacted in several states to set the maximum contaminant levels for arsenic and cadmium in fertilizers. The simulation outcomes indicated that some of the existing fertilizer regulations are not strict enough to prevent significant accumulation of Cd in cropland soils. Sensitivity analyses show the solid-solution partitioning coefficient, and the plant uptake factors are primary factors that affect the fate and transport of As and Cd in cropland soils. The uncertainty associated with assessing the fate of trace elements in cropland soils is due to the high variability of model parameters.

Determination of cadmium in fertilizers by flow-injection spectrophotometry

A flow-injection procedure for spectrophotometric determination of cadmium in fertilizers based on formation of the blue ternary complex between cadmium, iodide and Malachite Green (MG) is proposed. Addition order and concentrations of reagents, interaction time between iodide and MG, flow rates, pH and temperature for ternary complex formation, surfactant addition, and presence of potential interferent ions were studied. A 30-s interaction between iodide and MG, a temperature of 20 °C and use of picolinic acid for copper masking were selected. Linearity of the calibration graph was improved with cadmium addition. For selectivity enhancement, masking agents, kinetic discrimination, and ion-exchange separation were investigated and a Chelex-100 resin minicolumn (50–100 mesh) was employed for in-line interferent removal. The proposed system is very stable and handles about 60 samples per hour (10.0–100.0 μg Cd l −1) corresponding to 0.105 mg MG and 166 mg KI consumed per determination. Linearity of the calibration plot is observed up to 200 μg Cd l −1, the detection limit being 2 μg Cd l −1. Results are precise ( R. S. D. = 1.3% and 4.0% for 93.0 and 35.3 μg Cd l −1) and in agreement with tungsten coil atomic absorption spectrometry. Accurate results are also obtained for lobster and soya bean samples.

A comparison of some flame atomic absorption spectrometric methods for the determination of cadmium in fertilizers and related materials

A liquid-liquid extraction procedure for cadmium in phosphate rock and phosphate-based fertilizers is described. Extraction with tri-n-octylamine and potassium iodide into methyl isobutyl ketone is shown to be simpler and less prone to interferences than the more commonly used methods based on ammonia pyrrolidine-dithiocarbamate. Iron interest strongly in the dithiocarbamate method. Addition of ascorbic acid, and extraction at low pH allows the dithiocarbamate method to operate up to 0.15 g Fe l −1, while the amine method tolerates at least 0.2 g Fe l −1. Direct determination is suitable on samples with a sufficiently high cadmium content. The amine extraction method has been applied successfully at an apatite containing only 0.03 mg kg −1 cadmium.

Determination of cadmium in fertilizers by atomic absorption spectrophotometry

Abstract Recently, environmental disruption has been very important problem in our society. Cadmium was acknowledged also as a kind of water or nir pollutant, which wns likely to cause an endemic in the country of Japan. Therefore, microanalysis of this harmful clement is necessary for water, soil, food or vegetation, dust in air, and also fertilizers or their raw materials. Spectrophotometric determination with dithizone (diphenylthiocnrbazone) reagent (1, 2, 3) is popular as the standnrd method of analysis of cadmium, but its procedure is rather trouble some and its results do not show good reproducibi1ity.