Analysis of Perchlorate in Foods and Beverages by Ion ... · surface water, its contamination may persist for long time. Since April 19976, perchlorate has been found in over 500

OverviewThis application note describes the

development of an IC/MS/MS

method for the determination of

perchlorate (ClO4–) in food products,

e.g., fresh fruits and vegetables, milk,

alcoholic and non-alcoholic beverages,

baby foods, and other food products

harvested or processed in many parts

of the world. Samples of food and

beverage products from around the

world were purchased in local grocery

stores in or around Toronto, Ontario,

Canada. The instrumentation consisted

of an ion chromatography system and

an API 2000™ LC/MS/MS System.

The system was optimized to monitor

two pairs of precursor and fragment

ion transitions, i.e., multiple reaction

monitoring (MRM). The minimum

detection limit (MDL) for this

method in de-ionized water is 4 ng/L

(parts-per-trillion, ppt) using MRM

99/83 and a 100 µL injection volume.

The lowest concentration minimum

reporting level (LCMRL) defined by

US EPA is 15.7 ppt. The levels of

perchlorate found in food products

ranged from 0.047 ± 0.006 µg/Kg

(ppb) to 463.5 ± 6.36 µg/Kg (1.4%).

IntroductionPerchlorate became a well publicized

environmental contaminant in the

spring of 1997, when development of

an analytical method with a quantifi-

cation level at 4 ppb became available

by US EPA.1 Perchlorate exists in the

form of ammonium, sodium, potassium,

and other metal salts in nature and

also as man-made products. Naturally

occurring perchlorate is found in

nitrate deposits in Chile. One major

source of environmental contamina-

tion is the manufacture or improper

storage or disposal of ammonium

perchlorate used as a primary compo-

nent of solid propellant for rockets,

missiles, fireworks 2,3,4, of explosives in

various military munitions and air bag

inflators.5 Perchlorate salts dissolve

readily in water, and because perchlo-

rate anion adheres poorly to mineral

surfaces, it can spread in waterways.

Because perchlorate is believed to be

relatively inert in typical ground and

surface water, its contamination may

persist for long time. Since April 19976,

perchlorate has been found in over 500

drinking water supplies in at least 20

states, serving well over 20 million

people in the USA. In 2002, the EPA

recommended a maximum containment

level (MCL) for perchlorate of 1 µg/L

(ppb) in drinking water. Some states

have set their own limits ranging

from 4 to 18 ppb and California’s

current “notification level” is 6 ppb.6

These limits are currently being

reviewed. Perchlorate data in food

products are very limited. Recently,

perchlorate has been found in various

food products, e.g., lettuce, cantaloupe,

milk, and bottled water.7,8 Valentin-

Blasini et al. at the Centers for Disease

Control and Prevention, Atlanta, GA,

recently published the detection of

perchlorate in human urine using ion

chromatography and an API 4000™

LC/MS/MS System.9

Analysis of Perchlorate in Foods andBeverages by Ion Chromatography Coupledwith the API 2000™ IC/MS/MS System

Application Note Perchlorate Analysis

www.appliedbiosystems.com

AB05082_perchlorate_AN_FLO.qxp 7/15/05 1:28 PM Page 1

High doses of perchlorate can decrease

thyroid hormone production, needed

for normal growth and development

of the central nervous system of fetuses

and infants.10,11 Chronic lowering of

thyroid hormones due to high per-

chlorate exposure may also result in

thyroid gland tumors. The National

Research Council of the National

Academies published its technical

review of the health implications

of perchlorate ingestion in January

2005. From this review, the EPA has

established an official reference dose

of 0.0007 mg/kg/day of perchlorate.

A reference dose is a scientific esti-

mate of a daily exposure level that is

not expected to cause adverse health

effects in humans.12

Ion chromatography (IC) is a form of

liquid chromatography that uses ion-

exchange resins to separate atomic or

molecular ions based on their interac-

tion with resins. US EPA established

Method 314.0 “Determination of

Perchlorate in Drinking Water Using

Ion Chromatography” Revision 1.0 in

November 1999.13 With conductivity

detection, the IC method can quan-

tify perchlorate down to 2 ppb14,15,16

using 100 µL injection. Although

the IC method with conductivity

detection has been used for the deter-

mination of trace levels of perchlorate

ion in water, chromatographic reten-

tion times are not considered to be

unique identifiers and often cannot be

used in legal proceedings without

another confirmatory testing. Tandem

mass spectrometry (MS/MS) offers a

better detection limit because of the

reduction in chemical noise, especially

in very complex matrices, when com-

pared with the conductivity detector.

In addition, MS/MS offers more

selective detection than conductivity

in that they monitor the mass-to-

charge ratio (m/z) transition of

the precursor analyte ion into a

unique fragment ion17, and an

additional check based on the

isotopic abundance ratio between

chlorine 35 and chlorine 37 isotopes.

For example, the transition of 35Cl16O4–

(m/z 98.9) into 35Cl16O3–

(m/z 82.8)

was monitored for quantifying the

main analyte; 37Cl16O4–

(m/z 100.9)

into 37Cl16O3–

(m/z 84.9) was moni-

tored for examining a proper isotopic

abundance ratio of 37Cl/35Cl; and

another transition of 35Cl18O4–

(m/z

107.0) into 35Cl18O3–

(m/z 89.0) was

monitored for quantifying the internal

standard. This significantly reduces

the chances of false positives, and

allows better evidence in a court

of law.

Recently, we assisted the EPA in devel-

oping Method 332.0 “Determination

of Perchlorate in Drinking Water by

Ion Chromatography with Suppressed

Conductivity and Electrospray Ionization

Mass Spectrometry.”18 EPA will pub-

lish the method in the near future.

We have applied this analytical approach

to determine the amount of perchlo-

rate in various foodstuff and beverages

and wish to present our findings below.

Experimental ConditionsEquipmentMass Spectrometer: Applied

Biosystems/MDS SCIEX API 2000™

Triple Quadrupole LC/MS/MS System

equipped with a TurboIonSpray® source

with the following operational param-

eters: source temperature: 500 oC;

polarity: negative ion mode; curtain

gas: 30.0 psi; gas supply 1: 50 psi; gas

supply 2: 75 psi; ion spray voltage:

-4500 V; collision gas thickness: 6;

declustering potential: -50 V; focusing

potential: -300 V; entrance potential:

-10 V; collision energy: -35 V; colli-

sion exit potential, -13.5 V; MRM

transitions: 98.9/82.9, 100.9/84.9,

and 107.0/89.0 Daltons; dwell time:

150 msec; run time: 15 min. We

used Analyst® 1.4.1 Software to

acquire and reduce data.

Ion Chromatography: ICS-2500 Ion

Chromatography System consisting of

a Dionex GS 50 pump, EG50 eluent

generator, AS50 auto-sampler, CD25A

conductivity detector, LC30 chro-

matography oven with rear-loading

Rheodyne injection valve (100 µL

loop), Rheodyne 6-port valve for

matrix diversion, shielded conductivity

cell, static mixing “Tee” (Upchurch),

Dionex AXP-MS auxiliary pump,

external water kit, P/N 038018 and

Chromeleon® 6.6 software.

Column: Dionex IonPac®AS16, 250

x 2 mm i.d.; guard column: IonPac®

AG16, 50 x 2 mm i.d.; suppressor:

ASRS® MS, 2 mm, external water,

55 mA; GS50 eluent: 45 mM KOH.

Eluent: 90% acetonitrile + 10% water;

analytical flow rate: 0.3 mL/min; AXP-

MS flow rate: 0.2 mL/min; IC oven

temperature: 28 oC; matrix diversion

time: 2–9 min; injection volume:100 µL.

A schematic diagram is shown on

Figure 1.

This method includes an on-line

diversion valve (MD Valve in the dia-

gram), located inside the LC30, to

divert matrix ions to waste early in

the method. Matrix diversion is a

technique that uses a valve to divert

non-analyte chromatographic peaks to

the waste, thereby avoiding possible

contamination of downstream system

components. In most cases, this tech-

nique eliminates the need to perform

off-line matrix elimination sample

preparation. The diversion is performed

during the normal analytical run (the

first 9 minutes) so that no additional

time is required. An auxiliary pump



supplies post-column solvent to the

MS during the divert time. The AXP-

MS pump (AXP-MS in the diagram)

is used to supply the API 2000™

LC/MS/MS System with 90% ace-

tonitrile + 10% water throughout

the run. The addition of this solvent

through the static mixer improves the

electrospray process and provides a

better sensitivity than 100% water-

based run. The column effluent is

then switched to combine with post-

column solvent about 2 minutes before

ClO4–

elutes so that the aqueous ana-

lytical stream combines with the solvent

stream before entering the MS. This

mixing occurs inside a static mixing

Tee (“static mixer” in the diagram)

with a frit inside to aid mixing. An

eluent generator is used to produce

high purity potassium hydroxide (KOH)

eluent and an electrolytic suppressor

(ASRS® suppressor in the diagram) is

used to replace metallic cations with

hydronium [H3O]+ ions prior to enter-

ing the detector. This new generation

of chemical suppressors is known as

the self-regenerating suppressors. These

suppressors exploit the electrolytic reac-

tions of water to generate hydronium

[H3O]+ and hydroxide [OH]– ions,

thus eliminating the need for a separate

source of regenerant.

Reagents and StandardsDeionized water, Type I reagent-grade,

18 MΩ cm resistance; acetonitrile,

HPLC grade; sodium perchlorate, 99%

ACS reagent-grade (Aldrich cat. no.

41,024-1); 18O-perchlorate internal

standard, 1 mg/L, Dionex P/N 062923.

Sample PreparationThe procedure described in references7,8

was modified. This method is simpler

and less time-consuming than the earlier

extraction procedures.

Fruits and Vegetables: Bulk samples

were first cut into small, 1– 2 cm pieces

and chopped in a food processor.

Individual samples were prepared by

weighing 10 ± 0.10 g of each food

samples into separate 50 mL disposable

polypropylene centrifuge tubes.

Deionized water (20 mL) was added

and 18O-perchlorate internal standard,35Cl18O4

–, was added in some cases.

The centrifuge tubes were capped and

shaken with a Vortex-Genie® for 5 min.

The tubes containing the test portion

were then centrifuged at 2,500 rpm

for 25 minutes at room temperature.

The liquid portions of the samples

were then filtered with a 0.2 µm pore

size nylon-mesh disposable syringe filter.

Milk products: 5 ± 0.05 mL of each

sample was pipetted into separate 50 mL

disposable polypropylene centrifuge

tubes. 1 µg/L of 18O-perchlorate

internal standard, 35Cl18O4–

was added.

After adding 5 mL of deionized water

and 20 mL of acetonitrile, the cen-

trifuge tubes were capped and shaken

by hand for 2 min. The tubes containing

the test portion were then centrifuged

at 2,500 rpm for 25 minutes at room

temperature. The samples were then

filtered with a 0.2 µm pore size nylon-

mesh syringe filter.

Alcoholic and other beverages were

prepared the same way as milk products,

but the amount of added acetonitrile

was replaced with deionized water.

Results and DiscussionMultiple Reaction Monitoring (MRM)

was used to quantify perchlorate anion

in food and beverage products. We

monitored MRM transitions 35Cl16O4–

(m/z 98.9) into 35Cl16O3–

(m/z 82.8),37Cl16O4

–(m/z 100.9) into 37Cl16O3

–

(m/z 84.8) and 35Cl18O4–

(m/z 107.0)

into 35Cl18O3–

(m/z 89.0). The first

transition is used for quantitation and

the second is used for confirmation.

The measured isotopic ratio of 37Cl to35Cl was used to confirm the presence

of ClO4–

and to determine any inter-

ference that may cause a systematic

error in detection.

Figure 2 shows two calibration curves

in deionized water, covering the range

from 0.005 µg/L to 5.0 µg/L of

ClO4–

and using a 1 µg/L of 35Cl18O4

–. The correlation coefficients


Figure 1. Schematic diagram of method.

ICS 2500 API 2000

AS16 ASRSMD valve Static

mixer

AXP-MS90%CH3CN+10%H2O0.2 mL/min

ColumnKOH0.3 mL/min

Suppressor

waste

ECD ESI6

1 2



were 1.000 and 0.999 using a linear

fit and (1/x) weighting factor for the

98.9/82.8 (Figure 2A) and 100.9/84.8

(Figure 2B) transitions respectively.

These data clearly show that quantifi-

cation can be performed with good

linearity and sensitivity.

Figure 3 shows the MRM chromatograms

for analysis of green grapes from

California spiked with 10 µg/L of

internal standard (35Cl18O4–). The

chromatograms B and C show

adequate signals for both transitions

and no significant interferences were

detected. The chromatogram A

observed for 35Cl18O3–

is a response

from a 10 µg/L solution added to the

green grape sample. Based on the area

counts, the 37Cl/35Cl ratio is 0.323 for

analysis of the green grape sample. For

the 149 ratio measurements of the

food and beverage samples analyzed,

the average measured 37Cl/35Cl ratio

was 0.325 and the standard deviation

was ± 0.006. The theoretical ratio of37Cl/35Cl is 0.324.

Tables 1 and 2 summarize perchlorate

levels found in food and beverage

products. The perchlorate values are

averages of duplicate or triplicate

readings with standard deviations of

the readings.

All of the tested food samples con-

tained measurable amounts of

perchlorate, except for a canned tea

sample from Japan and a bottled

water sample from Canada. These two

samples showed the perchlorate level

below our detection limit. From the

level of perchlorate found in the same

type of food products such as red

tomatoes, oranges, and grapes, it is

interesting to see only certain agricul-

tural areas indicated the strong

presence of perchlorate in produces,

that most likely came from the water

or soil they were grown. Perchlorate

Figure 2. Calibration curves for the two MRM transitions: A. m/z 107.0 m/z 89.0 and B. m/z 100.9 m/z 84.8 from 0.005 µg/L to 5.0 µg/L.

Figure 3. IC-MS/MS chromatograms showing perchlorate in green grapes from California and 10 µg/L 18O perchlorate internal standard.

A

B

A

B

C


was likely introduced into produces

when they were irrigated with

perchlorate-containing water, fertiliz-

er, or soil. Perchlorate in water used

for food and beverage processing

might also be a source of contamina-

tion in products.

Our analysis showed that products

from State of California and some

South American countries such as

Chili, Costa Rica, Guatemala, and

Mexico had very high levels of per-

chlorate, especially, cantaloupe from

Guatemala being the highest (463.50

± 6.364 µg/Kg). Foods produced in

Canada and China showed the lowest

level of perchlorate. In addition, food

products from Europe showed relatively

low level of perchlorate; grape leaves

from Turkey (6.195 ± 0.064 µg/Kg) and

mushrooms from Poland (5.670 ±

0.255 µg/Kg) showed the highest and

oranges from Cyprus (0.079 ± 0.007

µg/Kg) had the lowest amount of

perchlorate among the commodities

examined. The amount of perchlorate

(24.345 ± 0.955 µg/Kg) found in

cooked asparagus clearly showed that

perchlorate can survive in food even

after processing at a high temperature.

In the USA, the Colorado River is

known to have a high degree of

perchlorate contamination. It is used to

irrigate 1.4 million acres of cropland in

the States of California and Arizona. A

study by the Environmental Working

Group reported that about 1 in 5 winter

lettuce samples that were irrigated by

the Colorado River system showed

perchlorate levels averaging four times

the EPA’s draft safety standard. The

level of perchorate reported by the

FDA in green lettuces from State of

California ranged from 1.0 µg/L to

21.7 µg/Kg.8 In the present work, the

amount of perchlorate found in green

lettuce from State of California is

6.630 ± 0.042 µg/Kg.


Table 1. Analysis Results

Concentrations of perchlorate found in various fresh produces

Fruit/Vegetable Country/Province of Origin Perchlorate (µg/Kg) (or ppb)

Red Tomato Canada, Ontario 0.329 ± 0.016a

Red Tomato USA, Florida 0.260 ± 0.002a

Red Tomato Mexico 62.800 ± 2.706a

Blueberries Canada, Quebec 0.217 ± 0.003a

Blueberries (Baby Food) Canada, Ontario 0.109 ± 0.005a

Blueberries USA, Florida 0.094 ± 0.005a

Blackberries Mexico 0.289 ± 0.018a

Raspberries Chili 23.110 ± 2.086a

Kiwi Italy 2.221 ± 0.024a

Peach Juice Japan 0.721 ± 0.022a

Pomegranates Spain 2.952 ± 0.293a

Ginger England 0.589 ± 0.002a

Green Grapes Chili 21.980 ± 0.763a

Green Grapes USA, California 19.290± 1.061b

Grape Leaves Turkey 6.195 ± 0.064b

Red Grapefruits Cuba 0.047 ± 0.007a

Clementine oranges Morocco 0.446 ± 0.099a

Clementine oranges China 0.093 ± 0.004b

Oranges Cyprus 0.079 ± 0.007b

Oranges USA, California 9.990 ± 1.350b

Lemon AAA China 0.058 ± 0.002b

Red Apples Canada, Ontario 0.088 ± 0.007b

Red Delicious Apples USA 0.116 ± 0.014b

Fuji Apples China 0.077 ± 0.002b

White Golden Apples China 0.149 ± 0.002b

Fargrand Pears China 0.120 ± 0.002b

Sinco Pears Korea 0.219 ± 0.001b

Abate Pears Italy 0.369 ± 0.000b

Star Fruit Taiwan 0.407 ± 0.002b

Pineapples Costa Rica 1.023 ± 0.026b

Cantaloupe Costa Rica 151.650 ± 1.909b

Cantaloupe Guatemala 463.50 ± 6.364b

Raw Asparagus Mexico 39.900 ± 0.424b

Cooked Asparagus Mexico 24.345 ± 0.955b

Banana Ecuador 0.299 ± 0.019b

Banana Columbia 2.432 ± 0.168b

Papaya Brazil 2.657 ± 0.045b

Mango Jamaica 0.112 ± 0.005b

Mango Peru 0.164 ± 0.016b

Green lettuce USA, California 6.630 ± 0.042b

Lyches South Africa 0.938 ± 0.091b

Plums Italy 2.795 ± 0.070b

Snow Peas Guatemala 0.752 ± 0.023b

Persimmon Israel 0.599 ± 0.011b

Mushrooms Poland 5.670 ± 0.255b

Pickled Onions Holland 0.197 ± 0.004b

Apricot Chili 145.650 ± 4.031b

Chili Peppers Dominican Republic 0.153Note: aAverage of triplicates ± standard deviation.

bAverage of duplicates ± standard deviation.


Milk, alcoholic beverages, tea drinks,

and bottled water showed relatively

low level of perchlorate. A 1% Milk

sample from Canada showed the

highest level of perchlorate (4.795 ±

0.038 µg/L). The level of perchlorate

reported by the FDA in 1% milk from

State of California ranged from 4.69

µg/L to 8.33 µg/L.8 All these values

are higher than the US Environmental

Protection Agency’s most recent

proposed safety standard of 1 µg/L.

ConclusionThe IC-ESI-MS/MS method was

found to be a robust, specific, and

sensitive system for the determination

of perchlorate in food and beverages

samples. The use of 35Cl18O4–

as an

internal standard and the matrix

diversion technique provided accurate

quantitation of perchlorate. In addi-

tion, the use of MS/MS to monitor

the 37Cl/35Cl ratios improved the speci-

ficity of this method and maximized

assurance in perchlorate determination

in food and beverage samples.

This present method clearly improved

the analytical capabilities for the detec-

tion of low level perchlorate in foods,

beverages, and maybe other complex

matrixes where IC with conductivity

detection simply cannot meet desired

detection limits and is too non-specific

for regulatory analysis.

Because our sampling was limited, it

is difficult to say how widespread

perchlorate contamination of food and

beverage products is. More survey is

needed to understand the scope of

perchlorate contamination.

References1“Perchlorate Environmental

Contamination: Toxicological

Review and Risk Characterization

(2002 External Review Draft)”

http://cfpub.epa.gov/ncea/cfm/recordi

splay.cfm?deid=24002

2Urbansky, E. T. Biorem. J., 1998, 2,

81-95

3Urbansky, E. T.; Anchock, M.R.

J. Environ. Manage., 1999, 56, 79 – 81

4Magnuson, M. L.; Urbansky, E. T.;

Kelty, C. A. Anal. Chem., 2000, 72,

25-29.

5U.S. Environmental Protection

Agency: Federal Facilities Restoration

and Reuse: Perchlorate

http://www.epa.gov/fedfac/docu-

ments/perchlorate.htm

6California Department of Health

Services: “Perchlorate in Drinking

Water: Action Level” http://www.dhs.

ca.gov/ps/ddwem/chemicals/perchl/ac

tionlevel.htm

7Krynitsky, A. J.; Niemann, R. A.;

Nortrup, D. A. Anal. Chem., 2004,

76, 5518-5522.

8U.S. Food and Drug Administration,

Center for Food Safety and Applied

Nutrition, “Exploratory Data on

Perchlorate in Food” http://www.cf

san.fda.gov/~dms/clo4data.html

9Valentin-Blasini, L.; Mauldin, J. P.;

Maple, D.; Blount, B. C. Anal.Chem., 2005, 77, 2475-2481

10Clewell, R. A.; Merrill, E. A.; Yu,

K. O.; Mahle, D. A.; Sterner, T. R.;

Mattie, D. R.; Robinson, P. J.;

Fishert, J. W.; Gerahart, J. M.

Toxicol. Sci. 2003, 73, 235-255.


Concentrations of perchlorate found in various liquid products.

Beverage Country/Province of Origin Perchlorate (µg/L) (or ppb)

Sake Japan 0.103 ± 0.007a

Plum wine Japan 0.296 ± 0.018a

Aguadente de Cana Rum Brazil 0.065 ± 0.007a

Aloevera Pokka Malaysia 1.185± 0.020a

Ciacobazzi Italy 1.707 ± 0.002a

Whisky England 0.089 ± 0.008a

Soy Milk Korea 0.174

Milk (1%) Canada, Ontario 4.795 ± 0.038a

Nestle Milk (baby formula) Canada, Ontario 1.245 ± 0.057b

Aloha Iced Tea Hawaii 0.785 ± 0.002a

Itoen Barley Tea Japan NQ ± NQa

Mineral water (Gerolsteiner) Germany 0.198 ± 0.032b

Mineral water (Nestle) Canada, Ontario 0.067 ± 0.002b

Mineral water (Evian) France 0.092 ± 0.002b

Mineral water Canada, Ontario NQ ± NQa

(Fresh water Industries) Note: aAverage of triplicates ± standard deviation.

bAverage of duplicates ± standard deviation.NQ = non-quantifiable

Table 2. Analysis Results


11Dsgupta, P. K.; Kirk, A. B.; Smith,

E. E.; Tian, K.; Anderson, T. A.

Environ. Sci. Technol. 2003, 37,

4979-4981

12National News: “EPA Sets Reference

Dose for Perchlorate” http://yose

mite.epa.gov/opa/admpress.nsf/b1ab

9f485b098972852562e7004dc686/c

1a57d2077c4bfda85256fac005b8b3

2!OpenDocument

13Method 314.0 “Determination ofPerchlorate in Drinking Water UsingIon Chromatography” November

1999. http://www.epa.gov/safewa-

ter/methods/met314.pdf

14Dionex Corporation. “Determinationof Low Concentrations of Perchloratein Drinking and Ground Waters UsingIon Chromatography”; Application

Note 134; Sunnyvale, CA.

15Dionex Corporation. “Determinationof Perchlorate in Drinking Water byIon Chromatography”; Application

Update 145; Sunnyvale, CA.

16Dionex Corporation. “Determinationof Perchlorate in Drinking WaterUsing Reagent-Free IonChromatography”; Application

Update 148; Sunnyvale, CA.

17Roehl, R.; Slingsby, R.; Avdalovic,

N.; Jackson, P. E. J. Chromatogr.A 2002, 956, 245–254.

18U.S. EPA Method 332.0,

“Determination of Perchlorate in Drinking Water by IonChromatography with SuppressedConductivity and ElectrosprayIonization Mass Spectrometry,”http://www.epa.gov/nerlcwww/

m_332_0.pdf.

AuthorsH. El Aribi and T. Sakuma,

Applied Biosystems/MDS SCIEX,

Concord, ON, Canada

AcknowledgementsThe authors wish to thank Mr. Stephen

Antonsen, Dionex Canada Ltd and

Ms. Rosanne W. Slingsby of Dionex

Corporation, Sunnyvale, CA for their

help with the IC system, and colleagues

at MDS SCIEX for the donation and

procurement of various samples

examined the the application note.



API 2000 and accessories—For Research Use Only. Not for use in diagnostic procedures.

©2005 Applera Corporation and MDS Inc. All rights reserved. Applied Biosystems is a registered trademark and AB (Design) and Applera are trademarks of Applera Corporation or itssubsidiaries in the US and/or certain other countries. Q TRAP, LINAC, and TurboIonSpray are registered trademarks and API 2000 and Turbo V are trademarks of Applied Biosystems/MDS SCIEX, a joint venture between Applera Corporation and MDS Inc. MDS and SCIEX are registered trademarks of MDS Inc. All other trademarks are the sole property of theirrespective owners.

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Analysis of Perchlorate in Foods and Beverages by Ion ... · surface water, its contamination may persist for long time. Since April 19976, perchlorate has been found in over 500