A Comparison between Ion chromatography and Inductively Coupled Plasma for the Determination of Bromate in Certain Samples of Foodstuffs

Ion chromatography (IC) and inductively coupled plasma (ICP-MS) both were applied for the determination of bromate in some food samples. Attempts were made to establish calibration curves, however in case of IC, an additional abnormal peak was found to overlap with the bromate peak. This renders IC to be unsuccessful in the determination of bromate compared to ICP-MS technique. ICPMS was found to give accurate results; therefore, it was applied for the determination of bromate in different samples of food stuffs.


INTRODUCTION
Bromate ion (BrO 3 -) is formed as a byproduct during the ozonation of drinking waters containing bromide.Bromate was classified as a "Group 2B" which was considered as a possible human carcinogen by the International Agency of Research on Cancer (IARC, 1999).
Bromate concentration was regulated in drinking water and the maximum contaminant level (MCL) was set at a level of 10 µg/L by the United States Environmental Protection Agency (as recorded by USEPA 2001 at the EPA/635/R-01/002 acts) and the WHO (World Health Organization (2006).However, the USEPA has considered a concentration of 0.05 µg/l of bromate to be responsible for a ratio of 1 in 1,000,000 cancer risk.In 2008, California Office of Environmental Health Hazard Assessmenthasset a level of 0.1 µg/ Lbromate to be responsible for cancer risk.In Europe, an amount of 10 µg/Lof bromate was proposed (WHO 2006) as MCL.The US Environmental Protection Agency (USEPA 2014)andthe WHOhave set a provisional guidelinevalue of 25µg/L(WHO 1996) and recommends an amount of 0.01 mg/l as a provisional guideline value of bromate in drinking water (European Union, 1980).
Potassium bromate is considered as a nephrotoxic and carcinogenic substance.As a result, the US Food and Drug Agency (FDA) has defined the value of 0.02µg/g (0.02mg/kg) to be the maximum concentration of potassium bromate allowed in bread.Bromate hasalso been classifiedby the International Agency for Research on Cancer (IARC) as a possible human carcinogen.This was attributed to themutagenic in experimental animals (IARC 1986).The main symptoms of the acute phase of bromate poisoning are vomiting, diarrhea and abdominal pain.Features of chronic toxicity of KBrO 3 , include hypertension, depression of the central nervous system and thrombocytopenia (Kurokawaet al., 1986).
Bromate in the form of KBrO 3 or NaBrO 3 is a colorless, odorless and tasteless white crystals that are commonly used in food industry.For instance, bromate salts are added by bakeries as an improver to increase the volume and the texture of the bread (Joint FAO/WHO 1992).While, it acts as a maturing agent and dough conditioner by oxidizing the sulfhydryl groups of the gluten protein in flour into disulphidebridges making it less extensible and more elastic; this makes the dough viscoelastic as a result of retaining the CO 2 produced by the yeast.The overall effect is to make bread rise in the oven, increase loaf volume and texture (Nakamura et al., 2006).According to USEPA, bromate could be determined by various methods likeion chromatography using the conductivity detector.However, in presence of chloride, this method suffers from serious limitations because the chloride peak will overlap with the bromate peak.A Dionex AG 10 column has been used to preconcentrate the bromate, however,it has been noted that in presence of sulphateanion affinity problem has occurred (Joyce and Dhillon, 1994).Gordon and Bubins(1995)  This work was primarily initiated to make a comparison between IC and ICP-MS techniques in determining the concentration of bromate in certain samples of foodstuffs taken from the local market in Saudi Arabia.

EXPERIMENTAL
Chemicals used in this work were of analytical reagent grade and were used as received.Potassium bromate salt was obtained from Sigma-Aldrich Company.All of the stock solutions were prepared in doubly distilled deionized water and were immediately used.Standard solutions of different concentrations of bromate were prepared from the stock solution by dilution using the doubly distilled deionized water.The stock solutions were kept in dark area.

Food Samples
Specified food samples which are listed in An exactweight of each samplewastaken, dissolved in water, filtered and collected in a volumetric flask in order to determinethe concentration of bromate in each of those samples that are listed in Table (1).

Instrumentation
For ICP-MS measurment, a blank and the following standard solutions of 10 ppb, 50 ppb, 100 ppb, 200 ppb and 500 ppb of bromate were prepared from the stock solution.
In case of IC method a blank and six standard solutions of 20 ppb,50 ppb, 200 ppb, 500 ppb, 1000 ppb and 5000 ppb of bromate were prepared.To each of these, an aliquot volume of sodium chloride (50 ppb), potassium iodide (50ppb) and sodium fluoride (50ppb)solutions was added.Each of these solutions was diluted up to the mark with doubly distilled deionized water.Analysis of bromate was performed according to Heitkemperet al., (1994) and the specification condition were as follows: ICP-MS ( XSERIES 2ICP-MS) was applied to determine bromate using the following operation conditions.
The RF Generator type was Solid state, 2.0 MHz and the frequency was 27.12 MHz.The RF generator power was 1550W, the reduced extraction was-115 V, the auxiliary gas flowratewas0.7 L/min, the nebulizer gas flowratewas0.9L/min, the cool gas flowratewas12L/ min, the hexapole bias was-09V, thequadruple biaswas -11 V, the sample uptake rate was0.4mL/ min, helium of 99.999 % purity was used as a carrier gas at a flow rate of 5.5 ml/min.Ion chromatograph, ICmodel Dionex ICS-1100 was applied using the following operating conditions: the eluent was 35mM KOH, the flow rate was0.25mL/min, the detector was suppressed conductivity, the suppressor was dionex anion selfregenerating suppressor (Dionex ASRS TM 2mm) auto suppression recycle mode, the applied current was 13 mAand the injection volume was 25µL.
For sample preparation for bromate determination by ICP-MS and IC instruments, the following procedure was followed: An amount of 5.0 g of each of the testedsample was grinded, transferred into a 50 ml volumetric flask.A volume of 50 mL of deionized water was added slowly and the mixture was shaken up to 30 min.The mixture was left for 1 hour, decantedand filtered with whatman filter paper (40).The filtrate was taken into a 50 mL volumetric flask and the deionized water was added up to the mark.For ICP-MS analysisthe tested sample was diluted up to 20times with 2% HNO 3 Solution (0.5ml was madeup to 10ml) before startup the ICP-MS analysis.
In case of IC analysisthe tested sample was diluted five time (1ml wasmade up to 5ml by deionized water).All the prepared samples were filtered through 0.2µm filter just before the startup of the IC analysis.

RESULTS AND DISCUSSION
The levels of bromate in foodstuffsthat are generally consumed in KSA need to be investigated.It is important to shed more light on such levelsin order to examine their safety for human consumption.ICP-MS and IC techniques are generally used for the determination of bromate in drinking water as well as in foodstuffs.At the beginning of this work, calibration curves for bromate were established using both ICP-MS and IC methods.The concentrations of bromate in each of the prepared standard solutions was determined by ICP-MS and IC.To examine the effectiveness of these instruments, the concentration of bromate in each standard was checked by ICP-MS as well as by IC techniques.Table (2) shows the concentrations of bromate in each of those standard solutions examined.Figures 1 and 2 show the calibration curves obtained for the IC and ICP-MS methods, respectively.
It is obvious that in case of ICP-MS,there is a minor variation between the concentrations of the prepared standard solutions and their respective values when they were determined.However, in case of IC technique there is significant variations between the concentrations of the prepared standard solutions and their respective determined values.This variation is quite obvious in solutions of lower bromate concentrations, 20 and 50 ppb.The correlation coefficient (R 2 ) seemed to be equal in the twomethods, whereas the intercept  In order to determine the bromate concentration in the foodstuffs depicted in Table (1), ICP-MS was adopted because of its sensitivity compared to that of IC method.Table (4) shows the concentrations of bromate in the foodstuff samples chosen.
The data presented in Table (4) shows that the bromate levels in some of the studied foodstuffs have the range of 150 ppb to 457 ppb.The highest amount of bromate was detected in milk biscuit, bread mix, snacks and white burger bunsamples which have 457 ppb, 449ppb, 442ppb and 410 ppb, respectively.On contrary, the lowest amounts were found in the corn thins, chocolate petals, rice flicks and cereal balls which have 150ppb, 178 ppb, 181ppb and 187 ppb, respectively.This table also shows that most of the bread samples, either locally manufactured or imported, have the high bromates level, particularly in, milk biscuit, bread mix, snacks and white burger bun samples.
By considering the allowable bromate amounts in the foodstuffs, the FDA and China both permit the use ofpotassium bromate up to a maximum level in bread of50 mg/kg of flour mass.However, Japan permits its inclusion onlyup to 10 mg/kg of flour (Kurokawaet al., 1990).In California a warning labelis required when bromated flour is used and currently, itis recognized that it is inappropriate to use potassium bromate in any product or production method which cannotbe formulated without residues below the level of 20 ppb(i.e.0.020 mg/kg or 0.020g/g) in the finished product.Joint FAO/WHO (1992) committee's initial recommendation of acceptable level of 0-60 mg KBrO3/kg flour waswithdrawn because of long term toxicity and carcinogenicitystudies in vitro and in vivo revealed renal cell tumors inhamsters.

CONCLUSION
This study reveals that many wellknownprovisionally foodstuffsthat have tolerable weekly intake of bromate amounts can be considered out of the recommended regulations.Consequently, there is a need to place a close surveillance on producersor importers of bread or other bakery products in order to ensure better compliance with the bromate health regulations.The utilization of ICP-MS instrument in determining bromate amounts is more accurate than the utilization of IC technique.
have developed a flow injection analysis method for the determination of bromate.Heitkemperet al.(1994) have combined IC with ICP-MS for the determination of bromate in bread.Several analytical methods have been applied for the determination of bromate (Delcomynet al., 2001, Pisarenkoet al., 2010, Garcia-Villanovaet al., 2010, Himata et al., 1997 and Akiyama2002).

Table ( 1
)were selected from the most popular producers or distributers in the local market of Saudi Arabia.The exported food samples were of the trade mark of international companies.