Table Salt Samples Research Articles

On the control of interferences in the potentiometric fluoride analysis of table salt samples

The causes for the apparent diminishment of the fluoride content as a function of storage time in table salt samples were studied. Originally, the survey was focused on the evaluation of the ion-selective potentiometric method based in the official Mexican Norm NOM-040-SSA-1993. The analysis of fluoride in 20 table salt samples using this procedure showed lower values of analyte content than those expected according to the manufacturers’ specifications and revealed that the amount of fluoride measured varied significantly in many cases. These results prompted analysis and further optimization of the EUSalt Standard Method to free all the fluoride present in the salts. For the optimization, several pretreatment approaches were analyzed, and the most frequently strong complex-forming metal ions present in the salt samples (calcium, magnesium, iron, silicon and aluminum) were determined via inductively coupled plasma optical emission spectrometry (ICP-OES) to simulate the matrix compositions. The results confirmed that the capability of the potentiometric technique is highly influenced by the matrix components (mainly introduced in the form of additives) and indicated that, depending on the nature and concentration of certain additives present and storage time, a thermal ion-release pretreatment may be necessary to obtain reliable results.

Electrothermal atomic absorption spectrometry in direct determination of tin in brines, sodium chloride and table salt samples.

Electrothermal atomic absorption spectrometry in direct determination of tin in brines, sodium chloride and table salt samples.

Iodine-deficiency disorders in the Aseer region, south-western Saudi Arabia: 20 years after the national survey and universal salt iodization.

To study (i) the current prevalence of iodine-deficiency disorders among schoolchildren in south-western Saudi Arabia after universal salt iodization and (ii) the iodine content of table salts and water. Cross-sectional study on a stratified proportional allocation sample of children. Thyroid gland enlargement was assessed clinically and by ultrasound scanning. Urine, table salt and water samples were taken to measure iodine content. Settings The Aseer region, south-western Saudi Arabia. Schoolchildren aged 8-10 years. The study included 3046 schoolchildren. The total goitre rate amounted to 24·0 %. Prevalence of enlarged thyroid by ultrasound was 22·7 %. The median urinary iodine concentration of the study sample amounted to 17·0 µg/l. The iodine content of table salt ranged from 0 to 112 mg/kg; 22·5 % of the table salt samples were below the recommended iodine content (15 mg/kg) set by WHO. The total goitre rate increased significantly from 19·8 % among children using table salt with iodine content ≥15 mg/kg to reach 48·5 % among children using table salt with 0 mg iodine/kg. Analysis of water samples taken from schools showed that the majority of water samples (78·8 %) had an iodine content of 0 µg/l. The study documented that 18 years after the national study, and after more than a decade of universal salt iodization in Saudi Arabia, the problem of iodine-deficiency disorders is still endemic in the Aseer region. Efforts should focus on fostering advocacy and communication and ensuring the availability of adequately iodized salt.

Method development for the determination of mercury(II) by sequential injection/anodic stripping voltammetry using an in situ gold-film screen-printed carbon electrode

A computer-controlled system, included a sequential injection system and an electrochemical detector, was developed for the determination of mercury(II) ion (Hg2+) concentrations. The screen-printed carbon electrode (SPCE), a well-known low-cost electrode, was modified by overlaying in situ with a gold film (Au-SPCE). Square wave anodic stripping voltammetry (SWASV) using the Au-SPCE was performed with a two-step deposition potential of an initial −0.5V vs Ag/AgCl for the preparation of the gold film and then a deposition potential of +0.2V vs Ag/AgCl for the preconcentration of mercury. An on-line medium exchange method was included in the injection step to reduce the effect of chloride ions, whilst a solid phase extraction cartridge was used to remove interference for copper(II) ions. The flow pattern of the sequentially injected solutions with the synchronized two-step deposition potentials did not significantly affect the detection of Hg2+. Square wave parameters of a 4mV step potential, 150Hz frequency and 30mV amplitude gave an optimal Hg2+ detection sensitivity with a limit of detection of 0.22μgL−1 (sample volume of 0.9mL) without any significant interference effect. This method was successfully applied to determine Hg2+ concentrations in real water samples, including in the chloride-rich samples of sea water and table salt, with very good accuracy (recovery in the range of 96.0–101%).

Determination of trace amount of IO 3 − with KIO3-KBr-(DBS-arsenazo) system by spectrophotometry

In the medium of 0.45 M nitric acid IO3− oxidizes KBr to produce Br2, which oxidizes DBS-arsenazo (DBS-ASA) to decolour. Based on this principle, a new method for the determination of iodate has been developed. The KIO3-KBr-(DBS-ASA) system presents a maximum absorption at 530 nm. At that wavelength, Beer’s law is obeyed over the range of 0.050–0.60 μg/mL of IO3− presenting a linear relationship. The apparent molar absorptivity is 1.75 × 105 L/mol cm and the detection limit is 0.048 μg/mL. This method has been successfully applied to the determination of IO3− content in the iodized table salt sample with good results.

Novel attapulgite/polyaniline/phosphomolybdic acid-based modified electrode for the electrochemical determination of iodate

A novel attapulgite/polyaniline/phosphomolybdic acid-based amperometric sensing platform was constructed for the determination of iodate. Nanostructured attapulgite was utilized for reducing agglomeration of polyaniline particles, and the as prepared attapulgite/polyaniline composite was used to immobilize phosphomolybdic acid. Excellent electrocatalytic performance was obtained due to the synergistic effect of nanostructured attapulgite, polyaniline and phosphomolybdic acid. The electrochemical responses of as prepared modified electrode were investigated by cyclic voltammetry and chronoamperometry. The modified electrode exhibited linear amperometric response for iodate in the concentration range of 2.0×10−6M–5.2×10−4M (R=0.999). The detection limit was calculated as 5.3×10−7M. Good reproducibility, high stability, fast amperometric response, and possibility of rapid preparation were also great advantages of this modified electrode. Based on this work, the attapulgite/polyaniline/phosphomolybdic acid modified electrode was successfully applied to determine iodate in a commercial table salt sample.

A rapid assessment method for determination of iodate in table salt samples

In the present work, a simple and rapid method for determination of iodate is described. Iodometric reaction between iodate, excess iodide, and acid has been used, and the iodine liberated is allowed to react with variamine blue (VB) dye in the presence of sodium acetate to yield a violet-colored species. A calibration curve was obtained in the concentration range of 2 to 30 μg of iodate in a final equilibration volume of 10 mL. The effect of different interfering anions on determination of iodate was also studied. The developed method was applied to iodate determination in various iodized salt samples obtained from local markets in and around Pune city, India. The amount of iodate in various table salt samples was in the range of 10 to 25 ppm.

Iodine nutrition in elementary state schools of Queretaro, Mexico: correlations between urinary iodine concentration with global nutrition status and social gap index

To estimate median urinary iodine concentration (UIC), and to correlate it with global nutrition indicators and social gap index (SGI) in 50 elementary state schools from 10 municipalities in the State of Queretaro, Mexico. 1,544 students were enrolled and an above of requirements of iodine intake was found (median UIC of 297 µg/L). Iodine status was found as deficient, adequate, more than adequate and excessive in 2, 4, 19 and 25 schools, respectively. Seventy seven percent of table salt samples showed adequate iodine content (20-40 ppm), while 9.6% of the samples had low iodine content (< 15 ppm). Medians of UIC per school were positively correlated with medians of body mass index (BMI) by using the standard deviation score (SDS) (r = 0.47; p < 0.005), height SDS (r = 0.41; p < 0.05), and overweight and obesity prevalence (r = 0.41; p < 0.05). Medians of UIC per school were negatively correlated with stunting prevalence (r = -0.39; p = 005) and social gap index (r = -0.36; p < 0.05). Best multiple regression models showed that BMI SDS and height were significantly related with UIC (p < 0.05). There is coexistence between the two extremes of iodine intake (insufficient and excessive). To our knowledge, the observed positive correlation between UIC and overweight and obesity has not been described before, and could be explained by the availability and consumption of snack food rich in energy and iodized salt.

A highly sensitive non-aggregation colorimetric sensor for the determination of I− based on its catalytic effect on Fe3+ etching gold nanorods

I− could accelerate the selective etching along longitudinal direction of gold nanorods (AuNRs) induced by Fe3+ in HCl medium, which decreased the aspect ratio (length/width) of AuNRs, and thus the longitudinal surface plasmon resonance (LSPR) absorption peaks of AuNRs blue shifted (Δλ=λ0−λ), the corresponding absorbance decreased (ΔA=A0−A), and the color of the solution obviously changed. Therefore, a non-aggregation AuNRs colorimetric sensor for the detection of I− was developed. The proposed colorimetric sensor is responsive, simple, selective and sensitive with the limit of quantization (LOQ) of 8.8×10−8M. The highly accurate sensor has been used to determine the content of I− in table salt samples with the results consistent with those obtained by inductively coupled plasma-mass spectroscopy (ICP-MS). Moreover, the morphological changes of AuNRs during the etching procedure were characterized by high resolution transmission electron microscopy (HRTEM) and the sensing mechanism for I− detection was also discussed.

A Preconcentration Procedure for Determination of Ultra-Trace Mercury (II) in Environmental Samples Employing Continuous-Flow Cold Vapor Atomic Absorption Spectrometry

New functionalized magnetic nanoparticles as solid-phase sorbent were prepared and investigated for extraction of ultra-trace amounts of mercury from environmental samples. The Fe3O4 magnetic nanoparticles functionalized with dithizone were characterized by Fourier transform infrared spectrometer. X-ray diffraction and scanning electron microscopy confirmed the size of nanoparticles. Effects of several factors on the extraction procedure were investigated. The optimized conditions were established to be 80 mg of polymer, 8.5 for solution pH, 5 min for adsorption time, 5 min for desorption time, 2 mL for HCl (0.1 mol L−1)/ thiourea 0.05 % as the eluent, 500 mL for breakthrough volume, and without addition of salt. Under the optimal conditions, the limit of detection, maximum capacity, and preconcentration factor were 0.05 ng mL−1, 0.557 mmol g−1, and 250, respectively. Limit of quantification was in the range of 0.2–2 ng mL−1 for various matrices. Accuracy and precision of the method were about ±2.0 and below 11.1 %, respectively. Finally, the present method has been successfully applied to mercury determination in table salt, green tea, vegetables, toothpaste, and water samples. The mercury content found in the real samples was from 0.6 to 15.74 ng mL−1 without addition of mercury.

Nutritional Iodine Status in Gestation and its Relation to Geographic Features in Urmia County of Northwest Iran

Iodine is an important component for the proper function of the thyroid and fetal development. To evaluate the influence of geographic variation on nutritional iodine status during pregnancy. Four hundred eighty-nine women in the first trimester of pregnancy were enrolled. Of these, 419 (85.5%) were from the plain districts and 70 (14.5%) from mountainous regions. Data were obtained on demographic characteristics and accessibility of iodized salt, and samples of table salt were collected. In the third trimester, 322 women remained in the study: 281 (87.2%) from the plains and 41 (12.8%) from the mountainous regions. Salt and urine samples were analyzed for iodine content. All participants stated that they used iodized table salt. The proportion of salt samples with optimal iodine content (30 ppm) from the plains and mountain regions were 68.7% and 88%, respectively. The median urinary iodine content (UIC) in the plains area in the first and third trimesters was 82 and 119 microg/L, respectively. The corresponding values in the mountain region were 34.5 microg/L and 76 microg/L. The prevalence of subjects with an inadequate iodine intake (UIC < 150 microg/L) in first and third trimester in the plains and mountain regions were 84.5% and 66.9% vs 98.6% and 90.2%, respectively. The prevalence of pregnant women exhibiting UIC < 150 microg/L in the mountain region was substantially higher than those in the plain district. Our findings also show that the current strategy for eradication of iodine deficiency in school-aged children would not fulfill iodine requirements in pregnancy and that additional source(s) of iodine are required to prevent the adverse effects of iodine deficiency in pregnancy. Further studies are needed to address the cause(s) for the rapid depletion of iodine stores in pregnancy.

Benefits and risks from the national strategy for improvement of iodine nutrition: A community-based epidemiologic survey in Chinese schoolchildren

ObjectiveMild to severe iodine deficiency has been documented in China since 1960. To eliminate this persisting iodine deficiency, legislation on universal salt iodization was introduced in 1995 as a long-term public health intervention strategy. We examined the urinary iodine excretion and the iodine content of drinking water and salt samples to assess the benefits and risks of this national strategy. MethodsWe examined the urinary iodine excretion of 1594 schoolchildren 8 to 10 y old from the 16 counties of China. The iodine content of 1097 drinking water and 4501 table salt samples also was assessed in these counties. The study was conducted from April 2009 through October 2010. Urinary iodine excretion and iodine levels in drinking water and table salt samples were measured based on the Sandell–Kolthoff reaction. Data were interpreted according to World Health Organization criteria. ResultsThe median urinary iodine levels of the schoolchildren were 198.2, 277.2, 336.2, and 494.8 μg/L in areas with iodine levels lower than 10, 10 to 150, 150 to 300, and higher than 300 μg/L in the drinking water, respectively. The mean iodine level in the table salt specimens was 30.4 mg/kg, the coverage rate was 98.6%, and the qualified rate was 96.7%. The goiter prevalence was 8.0% in the areas with an iodine level higher than 150 μg/L in the drinking water. ConclusionIn each area, the median urinary iodine of schoolchildren was nearly or above 200 μg/L, which confirmed the effectiveness of the iodization strategy. However, in areas with an iodine content higher than 150 μg/L in the drinking water, the schoolchildren had more than adequate or excessive iodine intake, which was associated with the prevalence of goiter. Therefore, it is important to adjust the strategy of universal salt iodization control in China.

Determination of Trace Amount of Cadmium by Atomic Absorption Spectrometry in Table Salt after Solid Phase Preconcentration Using Octadecyl Silica Membrane Disk Modified by a New Derivative of Pyridine

Silica‐C18 bonded disk modified by a four‐dentate Schiff base has been used for preconcentration of cadmium in table salt samples followed by flame atomic absorption spectrometry. The method is based on the adsorption of Cd on 1,2‐bis(pyridin‐2‐ylmethylene) hydrazine as Schiff base ligand on silica‐C18 disk. The effects of several factors such as type and concentration of the eluent, pH of sample solution, amount of ligand, and breakthrough volume have been optimized based on one variable at a time. In optimum conditions (type of eluent, HNO3 1.0 mol/L; volume of eluent, 5.0 mL; solution pH, 9.0; breakthrough volume, 1000.0 mL), preconcentration factor of the present method is about 200. The resultant limit of detection is 5.0 μg/L. Finally, the performance of the method has been evaluated for extraction and determination of Cd (II) in salt samples at milligram per liter concentration, and satisfactory results have been obtained (RSD ≤ 2.0%).

Potentiometric sensing of iodide using polymeric membranes of microwave stabilized β-AgI

A polymer based heterogeneous ion selective electrode (ISE) membrane was fabricated for the potentiometric sensing of iodide. The sensing element used for the preparation of the ISE membrane was microwave stabilized β-AgI. Because microwave energy was found to be beneficial for causing hysteresis at the phase transition temperature of AgI, an attempt has been made to prepare stable and conductive β-AgI crystals by post microwave irradiation under high pressure. A conventionally precipitated AgI based ISE was also fabricated for comparative studies. The β-AgI based ISE could respond to a wide range of iodide concentrations (1×10−8 to 1M) within 60s with a detection limit of 10nM. The ISE gave stable response to iodide ions in a pH range of 2.0–8.0 and was highly selective in the presence of various interfering ions. The performance of the proposed iodide ISE in the analysis of natural and seawater samples was encouraging, and the determination of iodide in table salt and human urine samples was explained using the developed sensor.

Elimination of suction effect in interfacing microchip electrophoresis with inductively coupled plasma mass spectrometry using porous monolithic plugs

A suction-free interfacing method was developed for microchip electrophoresis hyphenated with inductively coupled plasma mass spectrometry (MCE-ICP-MS). The hyphenated system was composed of a microchip, a demountable capillary microflow nebulizer (d-CMN) combined with a heated single pass spray chamber, a negative pressure sampling device, a high voltage power supply, a syringe pump and an ICP-MS. To eliminate the nebulizer suction generated by the pneumatic nebulizer and to ensure that the makeup solution flowed into the nebulizer, two porous polymer plugs were fabricated in the microchip. As a result, reasonably true electropherograms were obtained when compared to the CE separation performed in the traditional MCE-ICP-MS mode without porous polymer plugs. Electrophoretic separation of I(-) and IO(3)(-) was achieved within 25 s in a microchip with an effective separation length of only 15 mm at an electric field of 857 V cm(-1) using 10 mmol L(-1) borate (pH 9.2) as the running buffer. A resolution of 1.3 was obtained and the absolute detection limits for I(-) and IO(3)(-) were 0.12 and 0.13 fg, respectively. The precisions (RSD, n = 10) of the migration time and peak height for I(-) and IO(3)(-) were in the range of 1.1-1.6% and 2.5-2.8%, respectively. Two table salt samples were analyzed by an external calibration method. The iodate contents were in accordance with their labeled values. The recoveries of I(-) and IO(3)(-) in the table salt samples were in the range of 92-105%.

Structural Characterization of Some Table Salt Samples by XRD, ICP, FTIR and XRF Techniques

In this study, we have investigated structure and impurities of six different salts which have a great importance in our everyday life, namely source salt, Himalayan salt, rock salt, sea salt, lake salt and reduced sodium salt (minsalt) by means of different analytical methods, namely X-ray powder diffraction, scanning electron microscope–energy dispersive X-ray spectroscopy, inductive coupling plasma optic emission spectroscopy, X-ray fluorescence spectrometer and the Fourier transform infrared spectroscopy. With the light of obtained results, suitability and performance of the different analytical methods were discussed in some details.

Determination of Copper, Cobalt, Lead, and Iron in Table Salt by FAAS After Separation Using Violuric Acid and Multiwalled Carbon Nanotubes

A separation–enrichment technique for the determination of trace amounts of copper(II), cobalt(II), lead(II), and iron(III) as violuric acid chelates on multiwalled carbon nanotubes at pH 6.0 was established. Analytes were determined by flame atomic absorption spectrometry. The effects of some analytical parameters like pH, amounts of violuric acid, flow rates, eluent type, and sample volume were investigated. The influences of the matrix ions were also investigated. The relative standard deviations for analyte elements were below 10%. The quantification limits of the analyte ions were found as 0.36 μg g−1 for copper, 0.43 μg g−1 for lead, 0.15 μg g−1 for cobalt, and 0.38 μg g−1 for iron. The accuracy of presented method was checked by the analysis of TMDA 54.4 fortified lake water, NIST SRM 1515 apple leave, and HR-1 Humber river sediment certified reference materials. The method was applied to analyte contents of table salt samples from different origin. The levels of iron in the analyzed table salt samples were found in the range of 1.6–6.4 μg g−1, while lead was found in only one sample as 5.0 μg g−1. In all other samples, cobalt, lead, and copper were found below the quantification limits of the analytes.

Arsenic and antimony determination in refined and unrefined table salts by means of hydride generation atomic absorption spectrometry--comparison of sample decomposition and determination methods

An evaluation was made of different digestion methods for the determination of arsenic and antimony in table salt samples prior to hydride generation atomic absorption spectrometric analysis. Microwave acid digestion, classical wet digestion, dry ashing, and fusion were applied to the decomposition of salt samples and optimum conditions were investigated. Samples were decomposed by changing heating time, digestion techniques, and the amount and composition of acid, and then the concentrations of arsenic and antimony in an unrefined salt sample were measured. It is concluded that microwave acid digestion decomposes salt samples with a very short heating time and with small amounts of reagents compared with the classical wet digestion methods, which require several hours for the heating step and several milliliters of reagents. The accuracy of the procedure was checked using pond sediment certified reference material. The proposed procedure was applied for the determination of arsenic and antimony in several table salt samples collected in ›zmir, Turkey, and the arsenic contents in the samples were found to be below the maximum permissible limits. Microwave digestion in combination with hydride generation atomic absorption spectrometry could be used routinely to monitor these metals in table salt samples.

A novel method for iodate determination using cadmium sulfide quantum dots as fluorescence probes

We have developed a novel method for the determination of iodate based on the carboxymethyl cellulose-capped CdS quantum dots (QDs). Factors affecting the iodate detection were investigated, and the optimum conditions were determined. Under the optimum conditions, the relative fluorescence intensity of CdS quantum dots was linearly proportional to IO 3 − over a concentration range from 1.0 × 10 −8 to 1.0 × 10 −5 mol L −1 with a correlation coefficient of 0.9987 and a detection limit of 6.0 nmol L −1. Iodide, being oxidized by bromine to form iodate, was detected indirectly. The method was successfully applied to the determination of iodate and total amount of iodine in table salt samples. The related mechanism was also discussed.

Salt-assisted liquid–liquid microextraction for the determination of iodine in table salt by high-performance liquid chromatography-diode array detection

2-Iodosobenzoate and N,N-dimethylaniline have been used at pH 6.4 for selective conversion of iodide to 4-iodo- N,N-dimethylaniline which was extracted with ethanol, when the phase separation occurred by addition of ammonium sulphate, a process called salt-assisted liquid–liquid microextraction (SALLME), and analysed by high-performance liquid chromatography-diode array detection. Iodate was reduced to iodide before derivatisation. The method has been optimised for extracting solvent, salt for phase separation, and reaction time. A linear calibration was obtained for 10 μg-10 mg L −1 of iodide with correlation coefficient of 0.9989 and limit of detection of 3.7 μg L −1. The SALLME produced 280-fold enrichment of the derivative. The commercial iodised table salt samples have been found highly inhomogeneous; the RSD in analysis of different aliquots of the same sample ranged 18.0-78.1%. The average recovery of spiked iodide to real samples was 98.4% with an average RSD of 7.9% (range 5.2-12.4%).