Why High-Quality Water Matters for Food and Beverage Analysis

With the globalization of our food supply, food safety and quality have become great concerns for both consumers and regulatory bodies. Sugars and organic acids, for example, influence the organoleptic properties of many products. They must be identified and analyzed in raw ingredients and throughout the production process, all the way to final quality control and nutritional labeling.

Water is a crucial reagent in the IC workflow as it is required in many steps, including the preparation of samples, standards, blanks, and eluents. To ensure accurate and reliable IC analysis, the water used should be of the highest quality level and be free of the analytes of interest. Any contaminant present in the water may impact results and should be avoided.

In this app note, you’ll learn about:

Suitability of ultrapure water for the IC analysis of food and beverages
Quantification of sugars in ultrapure water
Quantification of small organic acids in ultrapure water
And more!

Application Note

Ultrapure Water for Food and Beverage

Analysis by Ion Chromatography

Authors

Merina Corpinot PhD

, Estelle Riche PhD

, Beatrice Frocrain

, Stephane Mabic PhD

R&D

and Marketing

, Lab Water Solutions, MilliporeSigma, Guyancourt, France

Ion chromatography in quality

assurance & quality control of food

and beverages

One of the main challenges in food and beverage

testing is detecting trace amounts of analytes in

complex matrices. Ion chromatography (IC) is

increasingly used in food and beverage Quality

Assurance/Quality Control (QA/QC) laboratories since

it is a versatile and sensitive analytical method that

allows the simultaneous analysis of a wide array

of compounds.

Analyzing sugars to monitor food safety

& food authenticity

With the globalization of our food supply, food

safety and quality have become great concerns for

both consumers and regulatory bodies. Sugars and

organic acids, for example, in?uence the organoleptic

properties of many products. They must be identi?ed

and analyzed in raw ingredients and throughout the

production process, all the way to ?nal quality control

and nutritional labeling. In addition, pro?ling the sugar

makeup of foods and identifying additives is a useful

way to assess food authenticity and detect adulteration.

Water is a crucial reagent in the IC work?ow as it is

required in many steps, including the preparation of

samples, standards, blanks and eluents. To ensure

accurate and reliable IC analysis, the water used

should be of the highest quality level and be free of the

analytes of interest. Any contaminant present in the

water may impact results and should be avoided.

Suitability of ultrapure water for the IC

analysis of food and beverages

This study examines the suitability of ultrapure water

obtained from a Milli-Q

IQ 7000 ultrapure water

puri?cation system for the IC analysis of sugars and

small organic acids commonly assessed in food and

beverage testing labs.

Quanti?cation of sugars in ultrapure water

Sugars are important for human nutrition and must

be analyzed for nutritional labeling and to monitor

product quality. Lactose is carefully monitored in many

products, especially those claiming to be lactose-free.

Sugars are also good indicators of the ?avor of drinks,

such as beer or co?ee.

High-performance anion-exchange chromatography

with pulsed amperometric detection (HPAE-PAD)

is an increasingly used IC method that allows the

direct and sensitive quanti?cation of a wide range of

carbohydrates at low nanomolar levels without the

need for derivatization.

1,2

Obtaining reliable, consistent and accurate results

requires water that is free of the analytes of interest.

Using HPAE-PAD, freshly produced ultrapure water

obtained from the Milli-Q

IQ 7000 system was

analyzed for the presence of common monosaccharides

(fructose, glucose) and disaccharides (sucrose,

maltose, lactose). Table 1 shows that the ultrapure

water contained less than the method’s quanti?cation

limit (1 mg/L) of each of the sugars. This water is

therefore suitable to be used in sample and eluent

preparation, as well as standard preparation for

sugar analyses.

MilliporeSigma is the U.S. and Canada

Life Science business of Merck KGaA,

Darmstadt, Germany.

Sugar Ultrapure water LOQ (mg/L)

Glucose < LOQ 1.0

Fructose < LOQ 1.0

Sucrose < LOQ 1.0

Maltose < LOQ 1.0

Lactose < LOQ 1.0

Small organic acid Ultrapure water LOQ (mg/L)

Citric acid < LOQ 1.0

Malic acid < LOQ 1.0

Tartaric acid < LOQ 1.0

Lactic acid < LOQ 0.2

Acetic acid* < LOQ 0.003

Formic acid* < LOQ 0.002

Table 1. Concentrations of various sugars in ultrapure water obtained

from a Milli-Q

IQ 7000 ultrapure water puri?cation system. Samples

were tested by an independent, accredited laboratory. LOQ, Limit of

Quanti?cation.

Table 2. Concentrations of small organic acids in ultrapure water

delivered from a Milli-Q

IQ 7000 ultrapure water puri?cation system.

Samples were tested by an independent, accredited laboratory, except

for acetic and formic acids (*), which were tested in-house after pre-

concentration. LOQ, Limit of Quanti?cation.

Conclusion: Milli-Q

ultrapure water

meets the needs of food and beverage

ion chromatography analyses

When analyzing foods or beverages, high quality

reagents should be used throughout the analytical

work?ow, from the preparation of standards and

samples to analysis, as the presence of contaminants

can a?ect results. In this study, ultrapure water

dispensed from a Milli-Q

IQ 7000 lab water system

was shown to be e?ectively free of commonly analyzed

sugars and organic acids, making this water ideal for

the IC analysis of food and beverage samples.

Ultrapure water is also free of other contaminants,

such as inorganic ions, bacteria and particles, that may

a?ect the performance of the analytical instrument

itself. Instrument manufacturers have observed that

the HPAE-PAD chromatographic technique is more

sensitive to certain water contaminants compared with

other analytical techniques.

For example, if the eluent

is prepared using bacteria-contaminated water, high

background signals may reduce the peak areas of the

analytes of interest. Furthermore, extra peaks may

be observed if such water is used to prepare samples

for this method. For this reason, when dispensing

ultrapure water from a Milli-Q

ultrapure water system,

the Millipak

0.22 μm ?nal ?lter is highly recommended

to remove these critical contaminants.

This study demonstrates that ultrapure water freshly

produced by a Milli-Q

IQ 7000 water puri?cation

system is suitable for IC analysis of sugars and small

organic acids. A Milli-Q

IQ 7000 ultrapure water

puri?cation system can be fed by a Milli-Q

IX pure

water system. Alternatively, it is possible to use

the Milli-Q

IQ 7003/05/10/15 all-in-one pure and

ultrapure system, which also dispenses ultrapure

water suitable for IC analysis using tap water as its

feed source.

The Milli-Q

IQ 7000 system produces ultrapure

water suitable for ion chromatography.

Quanti?cation of small organic acids in

ultrapure water

Small organic acids in?uence the taste and aroma

of foods and drinks. These acids may be present

naturally, or may be added in order to enhance a

product’s tartness and acidity, stabilize the pH, or act

as a preservative. Tartaric, citric and malic acids are

closely monitored in wine, beer and fruit juices. They

have organoleptic properties and are good indicators

of quality. Acetate and lactate, on the other hand, are

often used as indicators of microbiological spoilage,

for example in fruit juices. In soft drinks, citrate and

malate are monitored as they act as acidi?ers or

?avor enhancers.

We analyzed freshly produced ultrapure water

dispensed from a Milli-Q

IQ 7000 water system for

the presence of the above organic acids by IC with

suppressed conductivity detection. Table 2 shows

that the ultrapure water did not contain measurable

ion concentrations of citric, malic, tartaric or lactic

acid, as determined by an independent laboratory.

Acetic and formic acid levels were measured in-house

after pre-concentration. Results showed that their ion

concentrations were also below the method’s limit of

quanti?cation (LOQ). Ultrapure water from a Milli-Q

IQ 7000 system is therefore suitable for use in sample

preparation and organic acid analysis of foods and

beverages by IC.

Experimental section

Samples tested

Ultrapure water dispensed from a Milli-Q

IQ 7000

water puri?cation system (Resistivity: 18.2 MΩ.cm at

25 °C, TOC < 5 ppb) ?tted with a 0.22 µm ?nal ?lter

(Millipak

) and fed by an Elix

electrodeionization

(EDI)-based pretreatment system similar to the Milli-Q

IX pure water system.

Analysis of sugars

• Glucose, fructose, sucrose, maltose and lactose

were analyzed by an independent, accredited

(COFRAC) laboratory.

• Instrument: Thermo Scienti?c Dionex™ ICS-5000+

• Analytical Column: CarboPac™ PA1, 4 x 250 mm

• Eluent: NaOH gradient (A: 50 mM of NaOH and

B: 100 mM NaOH, both prepared with water from a

Milli-Q

ultrapure water system)

• Detection: Pulsed amperometry

Analysis of small organic acids

1. Citric, malic, tartaric, and lactic acids were analyzed

by an independent accredited (COFRAC) laboratory.

• Instrument: Thermo Scienti?c Dionex™ ICS-5000+

• Analytical column: IonPac™ AS 11-HC

• Eluent: NaOH gradient 1 to 60 mM (NaOH

solutions prepared with water from a Milli-Q

ultrapure water system)

• Detection: Suppressed conductivity

2. Acetic and formic acids were analyzed (after pre-

concentration) in our R&D laboratories.

• Instrument: Thermo Scienti?c Dionex™ ICS-3000

• Columns: Anion concentrator: IonPac™ UTAC-

ULP1 5 x 23 mm; Guard column: IonPac™ AG19

2 x 50 mm; Analytical column: IonPac™ AS19 2 x

250 mm

References

1. Corradini C, Cavazza A, Bignardi C. High-Performance

Anion-Exchange Chromatography Coupled with Pulsed

Electrochemical Detection as a Powerful Tool to Evaluate

Carbohydrates of Food Interest: Principles and Applications.

Int J Carbohydr Chem 2012;2012:1-13. https://doi.

org/10.1155/2012/487564

2. Jahnel JB, Ilieva P, Frimmel FH. HPAE-PAD - A sensitive method

for the determination of carbohydrates. Fresenius J of Anal Chem

1998;360:827-9. https://doi.org/10.1007/s002160050819

3. Rohrer J. Eluent Preparation for High-Performance Anion-Exchange

Chromatography with Pulsed Amperometric Detection. Technical

Note 71. Thermo Fisher Scienti?c, Sunnyvale, CA, USA. 2017.

• Sample volumes: 100 mL

• Standards: TraceCERT

standards

• Eluent: KOH gradient: 1 to 35 mM KOH from

0 to 20 min; 35 mM from 20 to 25 min; 35 to

1 mM from 25 to 25.1 min; 1 mM from 25.1 to

30 min. Eluent source: EG40 with KOH cartridge

and ultrapure water by direct-feed from an ICW-

3000™ water puri?cation system; ?ow rate:

0.25 mL/min

• Detection: Suppressed conductivity; eluent

suppressor: ASRS

Ultra II 2 mm

Water puri?cation systems and solutions Cat. No.

Milli-Q

IQ 7000 ultrapure water puri?cation

system

ZIQ7000T0C

Milli-Q

IQ 7003 pure and ultrapure water

puri?cation system

ZIQ7003T0C

Milli-Q

IQ 7005 pure and ultrapure water

puri?cation system

ZIQ7005T0C

Milli-Q

IQ 7010 pure and ultrapure water

puri?cation system

ZIQ7010T0C

Milli-Q

IQ 7015 pure and ultrapure water

puri?cation system

ZIQ7015T0C

Millipak

0.22 μm ?lter MPGP002A1

Reference standards Cat. No.

TraceCERT

Acetate Standard for IC

51791

TraceCERT

Tartrate Standard for IC

43484

Products related to this article

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Detailed information on trademarks is available via publicly accessible resources.

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02/2023

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Why High-Quality Water Matters for Food and Beverage Analysis

Ultrapure water for food and beverage analysis by ion chromatography