Determination of Six Conventional Cations in Wine by Ion Chromatography

Determination of Six Conventional Cations in Wine by Ion Chromatography

In this test, an ion chromatograph is used to test the six cations in wine. The method is simple, with good linearity and stable repeatability, and fully meets the testing requirements.

1. Experiment

1.1 Main Instruments and Reagents

Ion Chromatograph: IC6600 series with conductivity detector, cation suppressor, autosampler AS3110 series.

Chromatography Column: MS-5C-P2, 4.6*250mm, 5μm

Guard Column: MS-5CG, 4*30mm

Li⁺ Standard Solution (1000mg/L)

Na⁺ Standard Solution (1000mg/L)

NH₄⁺ Standard Solution (1000mg/L)

K⁺ Standard Solution (1000mg/L)

Mg²⁺ Standard Solution (1000mg/L)

Ca²⁺ Standard Solution (1000mg/L)

Disposable Syringe (2mL)

Aqueous Microporous Filter Membrane(0.45μm)

Pretreatment Column: RP column

White Wine

Yellow Wine

Wine

1.2 Solution Preparation

1.2.1 Mixed Standard Solution

Pipette 0.1mL of Li⁺ standard solution (1000mg/L) into a 100mL volumetric flask, dilute and fix the volume with water, mix well; prepared to Li⁺ standard solution of 1.0 mg/L. Pipette 10mL of NH₄⁺standard solution (1000mg/L), 10mL of Ca²⁺ standard solution (1000mg/L), 10mL of Mg²⁺ standard solution (1000mg/L) in one 100mL volumetric flask, dilute and fix the volume with water, mix well; prepared a standard solution containing 100mg/L of NH₄⁺, 100mg/L of Mg²⁺, and 100mg/L of Ca²⁺ mixed standard solution.

1.2.2 Standard Working Solution

Pipette 0.1mL, 0.2mL, 0.5mL, 1mL, 2 mL, 5mL, 10mL, 20mL of Li⁺ standard solution (1.0mg/L), 0.05mL, 0.1mL, 0.2mL, 0.5mL, 1mL, 4mL, 10mL of NH₄⁺, Mg²⁺, and Ca²⁺ mixed standard solution (100mg/L) respectively, 0.05mL, 0.1mL, 0.2mL, 0.5mL, 0.8mL, 1mL, 1.5mL, 2.0mL of Na²⁺ standard solution (1000mg/L), K⁺ standard solution (1000mg/L) 0.01mL, 0.05mL, 0.1mL, 0.2mL, 0.5mL, 1mL, 2mL, 5mL. Put in a set of 100mL volumetric flasks, diluted and fix the volume with water, mix well, and prepared into 8 different concentrations of the mixed standard series, the standard series of mass concentration is shown in Table 1.

Table 1 Concentration Gradient Table of Standard Curve

1.3 Instrument Working Condition

Chromatography Column: MS-5C-P2, 4.6*250mm, 5μm

Guard Column: MS-5CG, 4*30mm

Temperature: 40°C

Conductivity Cell Temperature

Eluent: 22mM MSA

Flow Rate: 1.0mL/min

Suppressor Current: 66mA

Injection Volume: 25μL

1.4 Sample Pretreatment

A disposable syringe is used to aspirate the sample and pass it through the pre-treatment cartridge RP column and 0.45μm aqueous filtration membrane for the removal of organic matter in the sample, and 0.45μm aqueous filtration membrane for the removal of particulate matter in the sample.

2. Result and Discussion

2.1 Separation Verification

In 1.3 working conditions of the mixed standard solution, the standard chromatograms of 9 cations are shown in Fig. 1, and the test results are shown in Table 2. After testing, the peak shapes of the nine cations are symmetrical, and the separation of the components is good.

Fig 1 Chromatogram of 9 Ions Mixed Standard

Table 2 Testing Result of 9 Ions Mixed Standard

2.2 Verification of Standard Curve Linearity

The working solution of the standard curve series prepared in 1.2.2 was injected into the system and analyzed according to the working conditions of 1.3, and the linearity of the standard curve was obtained as shown in Table 3 below, with good linearity.

Table 3 Linearity of Standard Curve

2.3 Sample Testing

Samples of white wine, yellow wine and wine are tested according to 1.4 Sample pretreatment method, and the test spectra are shown in Fig. 3, Fig. 4 and Fig. 5, and the data are shown in Table 4 below.

Fig 3 White Wine Chromatogram of 6 Repeated Injections

Fig 4 6 Repeated Injections Chromatogram of Wine Diluted 20 Times

Fig 5 6 Repeated Injections Chromatogram of Yellow Wine Diluted 20 Times

Table 4 Test Data