• Analytical Science and Technology
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• v.13 no.1
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• pp.81-88
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• 2000

A rapid preconcentration method was developed for the speciation of the trace mercury compounds in water sample. The mercury compounds were extracted and preconcentrated simply as their dithizone complexes by passing through the dithizone impregnated ultra-high molecular weight polyethylene (UHMWPE) membrane solvent inlet filter following sanification in methanol solvent. The concentrated dithizonates were separated by liquid chromatography on a $C_{18}$ column. Complete resolution was obtained between methyl-, ethyl-, phenyl-, and inorganic mercury with a mobile phase of 0.05 M acetate buffer (pH=4)/THF/methanol(3:5:2). The separnted mercury chelates were detected by spectrophotometrically at 475 nm. The proposed method was successfully applied to the speciation of mercury compounds in waste water with detection limit at the subnanogram/mL level.

• Journal of Food Hygiene and Safety
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• v.21 no.2
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• pp.82-91
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• 2006

Standard and lead limit test in general test method of Korea, Japan, Joint FAO/WHO Expert Committee of Food Additives (JECFA), USA, and EU on synthetic and natural food additives were compared. There were found that the general test methods in 'Korea Food Additives Code' were different from standards of various institutes on lead limit test. For the lead limit test of food additives, Korea used dithizone method, Japan used atomic absorption spectrophotometry, and USA used dithizone method, flame atomic absorption spectrophotometric method, atomic absorption spectrophotometric graphite furnace method, and APDC extraction method. In addition, JECFA and EU used dithizone method and atomic absorption spectrophotometric method. The dithizone methods of Korea, USA, and JECFA were nearly identical. In the case of USA, JECFA, and EU, the analytical methods for lead limit test were shown in individual monograph. Lead limit test against 13 synthetic, such as magnesium stearate and L-cystine, and 12 natural, such as gua gum and diatomaceous earth, food additives distributed in Korea were performed by the analytical method of each institute. Although all institutes use various methods for analysis of lead, contents of lead in food additives tested fell into the standard of each institute.

• Journal of Preventive Medicine and Public Health
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• v.17 no.1
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• pp.269-279
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• 1984

The optimum conditions for measuring cadmium content of less than 0.2ppm by flame atomic absorption spectrophotometry were investigated. The cadmium in urine was extracted by APDC-MIBK for the analysis by atomic absorption spectrophotometry after ashing them by a wet method. 1. Optimum conditions by APDC-MIBK and DDTC-MIBK extractions. The acidic aqueous solution was prepared with appropriate amount of 0.IN nitric acid, 5ml of 25% (W/V) sodium potasstum tartarate, 10ml of saturated ammonium sulfate, and 2ml of 2% APDC(or 1 ml of 5% DDTC) chelating agent. The total volume of solution was adjusted to 55 ml and pH to $2{\sim}10$ (or$7{\sim}10$). The aqueous solution was extracted with 10ml MIBK. Concentration of Triton X-100 did not effect the absorbance for APDC-MIBK extraction of cadmium, but absorbance decreased as the concentration increased for DDTC-MIBK extraction. The sensitivity and detection limits for the cadmium determination from APDC-MIBK extraction were 0.0038ppm and 0.0102, 0.0022ppm and 0.0116 for DDTC-MIBK, and 0.0132ppm and 0.0034 for 0.1N nitric acid. APDC-MIBK and DDTC-MIBK extractions were 3 times higher than 0.1N nitric acid for the sensitivity. 2. Excretion of cadmium in 24-hour urine by APDC-MIBK extraction. Determination of cadmium in urine by atomic absorption spectrophotometry of A.A. (Cd=2 mA) mode and B.C. (Cd=4 mA) mode and B.C. (Cd=4mA, $D_2=20mA$) mode showed some difference (p<0.05). The difference of cadmium determination and recovery according to method of standard additions and standard calibration curve method in urine was not significant (p>0.05, $93.48{\pm}11.78%,\;94.83{\pm}22.00%$). Excretion of cadmium in 24-hour urine collection from normal person and variance analysis within measurement variation was not significant (p>0.05), but between interindividual was significant (0.05). Determination of cadmium content by two different methods of flame atomic absorption spectrophotometry and dithizone colorimetry showed that the results from the two methods can be described by a regression line with a good correlation (y=1.0153x-0.2927, x=Cd by D.C., y=Cd by A.A.S., $r=0.8651^*$, p<0.01).