Growing wine consumption has led to the implementation of stringent regulations related to acceptable metal content in wines. Table 1 lists the limit of copper, iron and manganese contents in imported wines accepted by China.
Flame atomic absorption (AA) spectrometry is an ideal technology for measuring a limited number of high-level elements due to its price, speed of analysis, and simplicity of operation. This article discusses the application of the PinAAcle™ 500 flame atomic absorption spectrometer to determine the copper, iron and manganese content in wine samples.
Table 1. Chinese limits on copper, iron, and manganese in imported wines
| Element |
Limit (mg/L) |
| Copper (Cu) |
1 |
| Iron (Fe) |
8 |
| Manganese (Mn) |
2 |
Experimental Procedure
A PerkinElmer PinAAcle™ 500 Flame AA spectrometer was used to perform all analyses using an air/acetylene flame, hollow cathode lamps, and the standard nebulizer and spray chamber. Table 2 summarizes the experimental conditions.
All samples and standards were introduced manually using self-aspiration. Table 3 lists the wine samples analyzed in this experiment.
Table 2. PinAAcle 500 AA spectrometer instrumental conditions
| Parameter |
Copper |
Iron |
Manganese |
| Primary Wavelength (nm) |
324.75 |
248.33 |
279.48 |
| Secondary Wavelength (nm) |
327.40 |
302.06 |
279.83 |
| Slit (nm) |
0.7 |
0.2 |
0.2 |
| Air Flow (L/min) |
2.5 |
2.66 |
2.66 |
| Acetylene Flow (L/min) |
10 |
7.36 |
7.36 |
| Calibration Standards (mg/L) |
1 ,2, 3 |
1, 5, 12 |
1, 2, 5 |
| Calibration Curve Type |
Linear Through Zero |
Non-Linear Through Zero |
Non-Linear Through Zero |
Table 3. Wines analyzed
| Type |
Country of Origin |
| Chardonnay |
Australia |
| Cabernet Sauvignon |
France |
| Red |
USA |
| White Zinfandel |
USA |
The analyses were performed by simply transferring the samples into sample tubes. This means no sample preparation was involved. Two different wavelengths were used for sample measurement to determine accuracy.
This was followed by performing spike recoveries at the regulated limits as well as at half the regulated limits. The standards were prepared in deionized water and all analyses were performed against external calibration curves. For each element, the highest calibration standard was beyond the upper regulatory limit.
Experimental Results
The experimental results are summarized in Tables 4 to 6. However, the results obtained from multiple analyses of each wine sample have not been presented here for clarity. The results show all elements in the samples are within the regulatory limits, although the manganese level in the Chardonnay is very close to the regulatory limits.
Matrix interference was not present as spike recoveries were within 15% for all samples, proving the accuracy of the results provided by the PerkinElmer PinAAcle 500 Flame AA spectrometer.
All samples and spikes were repeatedly analyzed to show the consistency of the method. The results generated were comparable with the values listed in Tables 4 to 6. The measurement of all wines and spikes was also performed at a second wavelength, under the conditions listed in Table 2. The results generated were in agreement with the values listed in Tables 4 to 6, further corroborating the accuracy of the results.
Table 4. Copper in wine results (regulated level = 1 mg/L).
| Wine |
Concentration (mg/L) |
+ 0.5 mg/L (mg/L) |
% Recovery |
+ 1 mg/L (mg/L) |
% Recovery |
| Chardonnay |
0.29 |
0.80 |
102 |
1.30 |
101 |
| Red |
0.19 |
0.72 |
107 |
1.24 |
105 |
| White Zinfandel |
0.14 |
0.63 |
98 |
1.13 |
99 |
| Cabernet Sauvignon |
0.13 |
0.61 |
96 |
1.09 |
96 |
Table 5. Iron in wine results (regulated level = 8 mg/L).
| Wine |
Concentration (mg/L) |
+ 4 mg/L (mg/L) |
% Recovery |
+ 8 mg/L (mg/L) |
% Recovery |
| Chardonnay |
0.57 |
4.63 |
102 |
8.72 |
102 |
| Red |
1.56 |
5.99 |
111 |
10.1 |
107 |
| White Zinfandel |
2.02 |
6.03 |
100 |
10.2 |
102 |
| Cabernet Sauvignon |
3.33 |
7.33 |
100 |
11.1 |
97 |
Table 6. Manganese in wine results (regulated level = 2 mg/L).
| Wine |
Concentration (mg/L) |
+ 1 mg/L (mg/L) |
% Recovery |
+ 2 mg/L (mg/L) |
% Recovery |
| Chardonnay |
1.70 |
2.60 |
90 |
3.49 |
90 |
| Red |
1.30 |
2.24 |
94 |
3.17 |
94 |
| White Zinfandel |
1.06 |
1.94 |
88 |
2.89 |
92 |
| Cabernet Sauvignon |
0.97 |
2.04 |
107 |
2.93 |
98 |
Conclusion
From the results, it is evident that the PinAAcle 500 Flame AA spectrometer can provide accurate measurements of copper, iron and manganese contents in different wine samples in order to comply with the Chinese regulatory limits for imported wines. The sample analyses were convenient to perform, thanks to the Syngistix Touch™ software running from the large touchscreen display of the PinAAcle 500.
For more flexibility, it is also possible to use the Syngistix™ for AA software operating from an on-board computer. The use of a FAST Flame sample automation accessory in combination with the PinAAcle 500 enables increased sample throughput to analyze large batches while obtaining equivalent results.
With a variety of sample introduction systems and operating modes available, coupled to superior analytical capabilities, the PinAAcle 500 Flame AA spectrometer is ideally suited to wine analysis.
This information has been sourced, reviewed and adapted from materials provided by PerkinElmer.
For more information on this source, please visit PerkinElmer.