Access Agilent eNewsletter, April 2013 

Accurate, lower-cost determination of metals in wine with the Agilent 4100 MP-AES

By Neli Drvodelic and John Cauduro
Agilent Application Chemist – Elemental Spectroscopy

Metals can adversely affect the winemaking process, so producers need strict analytical control of the trace element content during the entire process. For example, metals such as potassium, calcium, and iron can produce precipitates, cause cloudiness, or affect taste. A number of traditional analytical techniques produce successful analyses of metals in wine, but the Agilent 4100 Microwave Plasma-Atomic Emission Spectrometer (MP-AES) provides an alternative, safer, and less expensive analytical method.

Winemakers must properly control the production process so they can ensure the quality of the product. It is most critical to monitor trace elements during vintage, so sample turnaround time – and to a lesser extent sample throughput – becomes important. Most wine labs are small to medium in size, so they value ease of use and reduced infrastructure requirements.

The most common technique for determination of metals in wine is flame atomic absorption (FAA), while inductively coupled plasma atomic emission spectroscopy (ICP-OES) is sometimes used in larger central laboratories that require extra sample throughput. The disadvantage with ICP-OES is that wineries generally prefer to have elemental analysis capabilities close to the winery during vintage.

Reduce operating costs

The Agilent 4100 MP-AES is a compact bench-top microwave plasma atomic emission spectrometer. It offers significantly reduced ongoing operating costs compared with both FAA and ICP-OES, because MP-AES runs on nitrogen that you can supply via a nitrogen generator. It eliminates the need for on-going gas resupply. And it avoids flammable gases (required for FAA), which enhances safety and allows unattended, overnight operation. The reduced infrastructure required for MP-AES also makes it well suited for remote sites where supply of expensive specialty gases can be difficult.

The 4100 MP-AES fits between FAA and ICP-OES in detection power, dynamic range, and speed of analysis. For these key performance metrics, the MP-AES offers a unique alternative to both FAA and ICP-OES. The 4100 MP-AES is an attractive technique for many small to medium size laboratories, particularly those at remote locations, and for an increasing number of laboratories that require the lowest possible on-going operating costs.

Get powerful performance

We recently measured a variety of red and white wine samples, along with two certified reference materials, on an Agilent 4100 MP-AES using a dewar nitrogen supply. The 4100 MP-AES generates a robust, magnetically excited nitrogen plasma. Use of the optional Agilent 4100 Nitrogen Generator further reduces the operating costs.

For comparison purposes, we also measured the samples on a radially viewed Agilent 725 ICP-OES and an Agilent 240FS AA spectrometer. Table 1 shows results for two of the wines, while Agilent Application Note 5991-1586EN provides results for the rest. In all cases, the three techniques gave similar results.

Sample

Element

Concentration (mg/L)

 

 

4100 MP-AES

240FS AA

725 ICP-OES

Wine 1

Ca

52

52

54

K

1205

1116

1112

Na

37

37

35

Mg

148

149

150

Fe

1.2

1.1

1.0

Wine 5

Ca

32

31

34

K

689

627

661

Na

48

48

45

Mg

121

125

134

Fe

1.8

1.7

1.7

Table 1. Comparable results for the analysis of wine sample by three techniques.

Method detection limits (MDLs) were also good with MP-AES. We calculated MDLs as three times the standard deviation of 10 replicate measurements of the blank. Table 2 lists analytical wavelengths used and the MDLs.

Element

Wavelength (nm)

MDL (µg/L)

Ca

396.847

8

K

769.897

110

Na

589.592

15

Mg

285.213

11

Fe

371.993

15

Table 2. Method detection limits by MP-AES show excellent results.

We verified the accuracy of MP-AES measurement of metals in wine samples by the analysis of certified red and white wine reference materials. We observed good agreement with certified values, with recoveries between 94 and 110 percent.

Alternative technique with many advantages

The Agilent 4100 MP-AES is an accurate and reliable instrument for this application and is an ideal alternative to FAA and ICP-OES. Results for certified samples were in good agreement with the reference values and results for various wine samples agreed well across all three techniques.

The 4100 MP-AES also offers significant benefits over the commonly used FAA. They include:

  • Enhanced productivity through greatly simplified sample preparation and unattended multi-element analysis
  • Greater performance through improved detection limits and greater linear dynamic range
  • Lower cost of ownership and operating costs, because the instrument runs on nitrogen
  • Elimination of flammable gases such as acetylene and nitrous oxide

If these advantages appeal to you, read the full Application Note 5991-1586EN to learn more about wine analysis with the Agilent 4100 MP-AES.

Welcome To Agilent Technologies

To enhance your online experience and our partnership with you, please select your country from the lists below.This will ensure that you discover the most relevant information and services available, including local product news, events, and more.

Other Countries
Please select