Short Note #65: SO2 Determination in Wine

Distillation Unit K-355

Distillation Unit K-355

Short Note #65 on the distillation of wine describes a novel procedure for the determination of Total SO2 contents in wine. The most important advance stems from a calibration by means of a stabilized SO2 standard containing acetaldehyde simulating a wine matrix. A calibration equation is derived from a linear correlation of a series of SO2 determinations with SO2 standards and the calibration equation is applied in order to adjust measured SO2 results in samples. Total SO2 contents in a series of 11 wines were evaluated and results compared to the OIV SO2 Method.

The OIV SO2 Method is based on the entrainment of SO2 from the wine sample into a titration vessel by means of a nitrogen stream.

Simple steam distillation, as a possible alternative, does not produce results comparable to the OIV SO2 Method without further optimization and adaption.

The most important improvements stem from acidification of the sample with an acid mixture of methanol, water and ortho-phosphoric acid and a calibration by means of a stabilized SO2 standard solution containing acetaldehyde simulating a wine matrix. The calibration reveals an excellent linear relationship between the determined SO2 amounts and the corresponding known amounts of standard solution. The linear equation is applied in the calculations to correct for Total SO2.

The distillation unit should preferably be equipped with an acid resistant pump as available in the BUCHI K-355 (picture above) and the K-360.

The sample is acidified with the acid mixture and steam distilled into the specially designed BUCHI SO2 absorption vessel in which the SO2 reacts with a defined volume of iodine standard solution. Subsequently the distillate is back-titrated with Na-thiosulfate standard solution using a titrator suitable to carry out redox titrations.

>> Download the entire Short Note #65


Free Seminar: Kjeldahl and Extraction Solutions for Quality Control

Kjeldahl & Extraction for Quality Control

Kjeldahl & Extraction for Quality Control

By attending this FREE one day seminar you will learn essential technical information about our Kjeldahl and Extraction systems, as well as participate in open discussions regarding implementation, application, and method development.

This seminar in Montreal is the first in a technical seminar series BUCHI has developed to engage with existing customers and new prospects in their local areas. The seminars will be held in various locations all across North America, after this one we will be in Itasca, Illinois on July 27th and then Irving, Texas on August 4th.

The main focus of the technical seminars are how our Kjeldahl, Extraction and NIR products positively enhance quality control analysis. At all locations, the stages in a production process are subject to regular and demanding checks, from the reception of the raw materials to the formulation of the finished product.

These analyses require not only high performance coupled with accurate and reliable equipment, but also a reliable supplier. BUCHI not only manufactures market leading instruments, but we also provide method development and application support to our customers. For the past 70 years, BUCHI has developed techniques and equipment designed to simplify your workflow and make your lab and facility more productive. From the reception and inspection of raw material to the formulation of the finished product, learn how BUCHI equipment can help streamline your process.

Wednesday, July 6, 2011
9:00 am – 4:00 pm

Holiday Inn Expres Montreal Airport
10888, Cote-de-Liesse
Montreal, Quebec, H8T 1A6

For accommodations call the hotel directly at: 919-549-8885

Click To Register

9:00 Registration and continental breakfast

9:15 Introduction to BUCHI and product overview

9:30 Kjeldahl Solutions – Fundamentals of the Kjeldahl method for the determination of protein in food samples. Presented by William Ickes, BUCHI Corporation

•Method discussion of protein in food by Kjeldahl
•Comparisons of different Kjeldahl method strategies

10:15 Break

10:30 BUCHI automated Kjeldahl solutions – From the very basic to fully automated solutions for fast, reliable quality control determination of proten in food samples. Presented by William Ickes, BUCHI Corporation

•Introducing the New SpeedDigester digestion systems for the fastest digestion on the market
•Unique design of the Scrubber B-414 for neutralization of digestion vapors
•Fast 4 minute steam distillation from basic to autosampler system

11:15 Demonstration and hands-on: Kjeldahl instrumentation K-370
Open discussion and hands-on operation of instrument

12:00 Lunch – provided by BUCHI

1:00 Extraction Solutions – Fundamentals of Extraction techniques for the determination of fat/oil/pesticides in food samples. Presented by William Ickes, BUCHI Corporation

•Comparison of Soxhlet, Hot, and Pressurized Solvent Extraction
•Hydrolysis prior to extraction
•Importance of homogenization to the extraction process

1:45 Break

2:00 Automated Extraction Solutions. Presented by William Ickes, BUCHI Corporation

•Automated Soxhlet, Hot, and Pressurized Solvent Extraction units
•Hydrolysis units
•BUCHI B-400 Mixer

2:30 Demonstration of E-816 Sox
Open discussion and hands-on operation of instruments