Determination Of Iodine In Milk Research Articles

Determination of iodine content in milk and food supplements by inductively coupled plasma mass spectrometry (ICP-MS)

The determination of iodine in milk and food supplements by inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Several parameters of the equipment were optimized automatically such as power of radio frequency, nebulizer gas, and voltage of ion lens. Iodine was extracted from samples by using 2% HNO3 with ultrasonic at 80ºC. Sample solutions were adjusted to the pH of 9÷10 by using ammonium hydroxide, and then filtered by using a 0.45 µm membrane before being analyzed by means of ICP-MS. The method has good repeatability and high recovery efficiency that are suitable for the determination of iodine in milk and food supplements.

Head-space single drop microextraction combined with gas chromatography with an electron capture detector for determination of iodine in infant formulas

Headspace single-drop microextraction (HS-SDME) coupled with gas chromatography with electron capture detection (GC-ECD) was used for quantification of total iodine in milk based samples of infant formula. In this procedure 3 μL of a mixture containing 1-octanol and 3-pentanone was exposed to the headspace of a 5 mL acidic (H2SO4, 2 mol L−1) aqueous solution containing 1.5 mol L−1 ZnSO4 for 30 minutes followed by addition of 1 mL of 1 mol L−1 H2O2 for in situ generation of iodine. Optimization of the microextraction system was carried out using the Taguchi experimental design method. The limit of detection was determined to be 250 ng L−1 with an enrichment factor of 150. The repeatability, expressed as a relative standard deviation, was 1.9% (n = 6). The linear calibration working range was between 0.75 and 2000 μg L−1 (r2 = 0.998). The method was successfully applied for determination of iodine in milk based samples of infant formula.

Flow Injection Spectrophotometr ic Catalytic Determination of Iodine in Milk.

A flow injection method based on the catalytic action of iodide on the color-fading reaction of the FeSCN2+ complex was proposed and applied to the determination of iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbancy of Fe3+-SCN (0.10 and 0.0020 mol l-1) in the presence of NO2- (0.3 mol l-1) is proportional to the concentration of iodide, with linear response up to 100.0 μg I- l-1. The detection limit was determined as 0.99 μg I- l-1 (3σ blank/slope); and the system handles 48 samples h-1. Organic matter was destroyed by a dry procedure carried out under alkaline conditions. Alternatively, the use of a Schoninger combustion after the milk dehydration was evaluated. The residue was taken up in 0.12 mol l-1 KOH solubilization. For typical samples, recoveries varied from 94.5 to 105%, based on the amounts of both organic matter destroyed. The accuracy of the method was established by using a certified reference material (IAEA A-11, milk powder) and a manual method. The proposed flow injection method is now applied as an indicator of milk quality in a Brazilian milk production system.

Determination of iodine in milk and oyster tissue samples using combustion and peroxydisulfate oxidation.

Two methods are described for the preparation of samples for total iodine measurement in biological matrices. In the first method, the samples were combusted in a stream of oxygen to release iodine that, subsequently, was trapped in a solution as iodide. The second method is a new approach in which the samples were oxidized in a basic solution of peroxydisulfate. In this case, the iodine was retained in solution as iodate. Total iodine was measured by gas chromatographic analysis of the 2-iodopentan-3-one derivative. The methods were tested using Standard Reference Materials (SRMs) 1549 Non-Fat Milk Powder, and 1566a and 1566 Oyster Tissue. Also, KI and KIO3 were used for testing the procedures. The results obtained for the SRMs, given as average +/- standard deviation in micrograms g-1, were: 3.39 +/- 0.14 and 3.40 +/- 0.23 for SRM 1549; 4.60 +/- 0.42 and 4.51 +/- 0.45 for SRM 1566a; and 2.84 +/- 0.16 and 2.76 +/- 0.06 for SRM 1566; values corresponding to combustion and wet oxidation, respectively. Overall, the absolute recoveries varied between 91 and 103%. These methods can also be used in the preparation of targets for the measurement of 129I using accelerator mass spectrometry.

Liquid Chromatographic Method for Determination of Iodine in Milk: Collaborative Study

Abstract Nine laboratories participated in an AOAC International/ International Dairy Federation collaborative study on a liquid chromatographic (LC) method for determination of iodine in milk. Liquid milk is passed through a 25 000 MW membrane filter to remove protein and insoluble material. Iodine (in the form of iodide) in the clear filtrate is separated by reversed-phase ion-pair LC and is detected electrochemically. Participants analyzed 2 commercial pasteurized whole milks and 5 nonfat dry milk powders in blind duplicate. Each sample was tested in duplicate on 2 days. Repeatability and reproducibility standard deviations (sr and SR, respectively) and repeatability and reproducibility relative standard deviations (RSDr and RSDR, respectively) for determinations of iodine in whole milk (mean recovery, 86.7%) were as follows: sr, 22 μg/L; SR, 22 μg/L; RSDr, 8.2%; and RSDR, 8.3%. For powdered milk (mean recovery, 91 %), the values were as follows: sr, 0.14 μg/g; SR, 0.22 μg/g; RSDr, 9.0%; and RSDR, 12.7%. The method was adopted first action by AOAC International.

Rapid and sensitive determination of iodine in fresh milk and milk powder by inductively coupled plasma ? mass spectrometry (ICP-MS)

A rapid and sensitive method for the determination of iodine in fresh milk and milk powders by inductively coupled plasma — mass spectrometry is described. The method is applied to the analysis of the two standard reference materials BCS-CRM Nos. 63 and 150. The iodine concentrations found in these materials are 0.28±0.01 μg/g and 1.21±0.01 μg/g, respectively. In fresh milk, iodine concentrations between 50 and 2300 ng/ml were determined. The ICP-MS results for these milk samples are compared to the results which were obtained by a chemical method and by X-ray fluorescence analysis. Because of the simple sample preparation and the good sensitivity and selectivity ICP-MS is the only method which allows the determination of iodine in milk samples down to the lower ng/ml range together with a high sample throughput.

Iodine Concentrations in Milk from Iodophor Teat Dips

Forty Holstein and Jersey cattle were assigned to four groups by milk production of Dairy Herd Improvement Association records. Cattle were on pasture and free-choice roughage supplemented with a concentrate and mineral mixture that was mixed without iodine supplementation. Teats of cows in each group were dipped for 27 days with chlorhexidine (controls) or iodophor teat dips with 1, .25, or .1% concentrations of iodine. Individual milk samples were taken on days 0, 20, and 27 for determination of iodine in milk. Mean iodine remained fairly constant, although there was a transitory increase for 1 and .25% dips at day 20. Mean iodine in milk (μg/liter) for days 0, 20, and 27 were control: 31.3, 19.8, 14.7; 1.0%: 21.8, 51.5, 23.7; .25%: 34.5, 46.9, 36.7; .1%: 13.6, 14.5, 14,9. Iodophor teat dips did not add appreciable amounts of iodine to the bulk milk.

The Determination of Iodine in Milk and Milk Chocolate by Anion HPLC

Abstract An HPLC method is described for the extraction and analysis of iodine as iodide in milk, cocoa beans and milk chocolate. Prior to analysis samples are finely ground if necessary and combusted in a modified Shoeninger flask. The liberated halide is absorbed in a basic reducing medium which is concentrated and brought to volume with distilled water prior. HPLC analysis used an 8 mm 5μ C18 cartridge in a RCM-100 with detection of the iodide ion at 226 nm. The mobile phase consisted of an ion-pairing agent, buffer and acetonitrile. The method is accurate and precise showing reasonable agreement with a National Bureau of Standards spray dried milk sample.

Differential Pulse Polarographic Determination of Total Iodine in Milk

A differential pulse polarographic method for total iodine in milk is presented. Samples are ashed, sodium hypochlorite is added to oxidize iodide to iodate, and the product is mixed with sodium sulfite solution and measured by differential pulse polarography at -90 V against SCE. The standard deviation for 53 duplicate samples was 0.011. Average recovery for 10 or more samples at different levels was 98.6% with a standard deviation of 2.9%.

Simple and rapid determination of iodine in milk by radioactivation analysis.

Iodine has been determined in milk samples by radioactivation analysis by using a Van de Graaff accelerator. The iodine is separated from the irradiated sample with an iodine-loaded resin. The limits of detection of iodine by gamma-ray spectrometry and beta-counting are 10 and 5 µg, respectively. The precision of the proposed method is ±5% when the iodine content exceeds 0.01 p.p.m.

Gas-Liquid Chromatographic Determination of Total Inorganic Iodine in Milk

Total inorganic iodine in milk is determined by conversion to iodobutanone, which is quantitated by gas-liquid chromatography and electron capture detection. As little as 10 microgram/L can be determined. The thyroid-active iodine content of milk can be determined rapidly with a relative standard deviation of 1.9%. Average recoveries for added iodide and iodine were 95.5 and 94.6%, respectively.

Rapid Neutron Activation Method for Determination of Iodine in Milk

A simple method for determination of total iodine in milk, based on neutron activation analysis is described. After the irradiation, iodine is separated from the milk samples by a radiochemical procedure based on solvent extraction and precipitation, and 128I activity is subsequently measured with a gamma-ray spectrometer. Precision of the method at iodine concentrations of the order of 0.1ppm is about 5%.

Determination of iodine in milk

A method of iodine determination in milk is described. Dry ashing and extraction of the ash with water is followed by photometric determination of the catalytic influence on the Ce-As reaction. Distillation proves to be unnecessary. Determination with this method can be performed in any laboratory, though not specially equipped for trace analyses.