This analytical chemistry paper describes a colorimetric optical sensor (optode) for germanium(IV) and applies it to ten foods bought in Benha City, Egypt, and to water and soil samples. Unspiked food results ranged from 11.2 ng/g in rice to 71.3 ng/g in beans, with values close to an ICP-AES comparison. The paper does not say how many samples of each food were bought, and each result is the mean of six determinations, so the figures describe method performance on those samples rather than germanium levels in the food supply.
Key numbers
- Linear range 6.00 to 174 ng/mL germanium(IV); detection and quantification limits 1.75 and 5.75 ng/mL (abstract, p. 2801; p. 2807).
- Unspiked foods, optode mean ± SD (n = 6 replicate determinations): beans 71.3 ± 0.16, egg 53.5 ± 0.09, sunflower oil 43.3 ± 0.25, chicken 25.6 ± 0.13, butter 21.7 ± 0.11, peach 21.6 ± 0.42, cornmeal 16.0 ± 0.24, tea 14.1 ± 0.26, apple 13.2 ± 0.39 and rice 11.2 ± 0.31 ng/g (Table 4, p. 2811). Because 1 ng/g equals 1 µg/kg, these are the same numbers in µg/kg. The basis (fresh or dry) is not stated.
- ICP-AES comparison values for the same foods were within 0.4 ng/g of the optode values, for example rice 11.0 and beans 70.9 ng/g (Table 4, p. 2811).
- Spike recoveries for foods were 98.8 to 102.1 percent for the optode (Table 4, p. 2811).
- Seawater from Alexandria 12.1 and water after oil pumping 30.7, and soils from Shoubra 26.5 and Quesna 12.3, printed under a ng/mL column header (Table 3, p. 2810); the text says germanium was concentrated 200-fold during treatment, so these are not interpretable as original-sample concentrations without clarification.
Methods (brief)
The optode immobilizes a triazole-thiol Schiff-base reagent and the ion exchanger Aliquat-336 in a plasticized cellulose triacetate film, read by absorbance at 545 nm after equilibration at pH 7.50. Foods were digested under reflux with nitric and sulfuric acid followed by hydrogen peroxide, starting from 5.00 g of sample (p. 2805). Soils were digested in hydrochloric and nitric acid. Accuracy was checked by spiking and by comparison with ICP-AES using t and F tests.
Evidence fitness
The paper supports claims about the sensor’s analytical performance and gives germanium values for ten purchased foods measured by two methods. It does not support statements about typical germanium levels in these foods, regional or national occurrence, dietary intake, or health risk. Sampling dates, brands, sample numbers per food, and moisture basis are not reported.
Limitations
The number of samples per food is not reported. The text names AAS as the reference method while the tables label the comparison ICP-AES. One spiked tea row (65.0 ng/g added, ICP-AES 67.9 ng/g found) is inconsistent with its printed recovery of 98.4 percent. Water and soil units are ambiguous. The introduction’s statements about germanium dioxide toxicity and soil germanium levels are background drawn from other work.
Related evidence
- Germanium
- Legumes
- Rice
- Eggs
- Corn
- Apple
- Chicken
- Sunflower Oil
- Peach
- Tea
- Butter and ghee
- ICP-OES — optical emission spectrometry
Update history
No substantive edit history is available in this build. The full commit record is available in git.