- 背景資料
1️⃣亞硫酸鉀(Potassium Sulfite)、亞硫酸鈉(Sodium Sulfite)、亞硫酸鈉（無水）Sodium Sulfite (Anhydrous)、亞硫酸氫鈉(Sodium Bisulfite)、低亞硫酸鈉(Sodium Hydrosulfite)、偏亞硫酸氫鉀(Potassium Metabisulfite)、亞硫酸氫鉀(Potassium Bisulfite)、偏亞硫酸氫鈉(Sodium Metabisulfite)被歸類為「亞硫酸鹽類」之食品添加物，其類別為: (四) 漂白劑，亞硫酸鹽類具有殺菌的功效以及極強的還原力，故可將食品的著色物還原漂白，並可抑制氧化作用，防止酵素與非酵素褐變反應，因而具有漂白的作用。此外，亞硫酸鹽之限量標準，以產品中SO2殘留量為判斷依據。
2️⃣依據衛生福利部於 2018 年 8 月 21 日正式發佈「食品過敏原標示規定」（衛授食字第1071302165號），使用亞硫酸鹽類或二氧化硫等，其終產品以二氧化硫殘留量計每公斤十毫克以上之製品，必須要有過敏原醒語標示方式。
3️⃣食品中，總亞硫酸鹽(Total Sulfite)=游離態亞硫酸鹽(Free Sulfite)+結合型亞硫酸鹽(Bond Sulfite)。結合型亞硫酸鹽(Bond Sulfite)又可區分成可逆結合態和不可逆結合態。
游離態亞硫酸鹽(Free Sulfite)➡️未與食品做鍵結，以SO2、HSO3-、SO32-、S2O52- 的形式存在(SO2較為常見)(無機物)，在弱酸的環境下可被釋出
可逆結合態➡️以Hydroxysulphonate、Carbonyl Sulphonate 型式存在
不可逆結合態➡️以C-及S-sulphonates 形式存在
- MANUAL ASSAY PROCEDURES:
A. MANUAL ASSAY PROCEDURE FOR TOTAL SULFITE (TSO2):
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B. MANUAL ASSAY PROCEDURE FOR FREE SULFITE (FSO2):
- AUTO-ANALYSER ASSAY PROCEDURES:
A. AUTO-ANALYSER ASSAY PROCEDURE FOR TOTAL SULFITE (TSO2):
B. AUTO-ANALYSER ASSAY PROCEDURE FOR FREE SULFITE (FSO2):
- MICROPLATE ASSAY PROCEDURES:
A. MICROPLATE ASSAY PROCEDURE FOR TOTAL SULFITE (TSO2):
B. MICROPLATE ASSAY PROCEDURE FOR FREE SULFITE (FSO2):
- SAMPLE PREPARATION:
1. Sample dilution.
The amount of TSO2 or FSO2 present in the cuvette (i.e. in the 0.05 mL of sample being analysed) should range between 0.25 and 20 µg for TSO2 and 0.25 and 7.5 µg for FSO2. The sample solution must therefore be diluted sufficiently to yield a concentration between 5 and 400 mg/L for TSO2 and 5 and 150 mg/L for FSO2
2. Sample clarification.
a. Solutions:
Carrez I solution. Dissolve 3.60 g of potassium hexacyanoferrate (II) {K4[Fe(CN)6].3H2O} (Sigma cat. no. P9387) in 100 mL of distilled water. Store at room temperature.
Carrez II solution. Dissolve 7.20 g of zinc sulphate (ZnSO4.7H2O) (Sigma cat. no. Z4750) in 100 mL of distilled water. Store at room temperature.
Sodium hydroxide (NaOH, 100 mM). Dissolve 4 g of NaOH in 1 L of distilled water. Store at room temperature.
b. Procedure:
Pipette the liquid sample into a 100 mL volumetric flask which contains approx. 60 mL of distilled water, or weigh sufficient quantity of the sample into a 100 mL volumetric flask, and add 60 mL of distilled water. Carefully add 5 mL of Carrez I solution, 5 mL of Carrez II solution and 10 mL of NaOH solution (100 mM). Mix after each addition. Fill the volumetric flask to the mark, mix and filter.
3. General considerations.
(a) Liquid samples: clear, slightly coloured and approximately neutral, liquid samples can be used directly in the assay.
(b) Acidic samples: if > 0.1 mL of an acidic sample is to be used undiluted (such as red wine or coloured fruit juice), the pH of the solution should be increased to approx. 7.4 using 2 M NaOH, and the solution incubated at room temperature for 30 min.
(c) Carbon dioxide: samples containing carbon dioxide should be degassed by increasing the pH to approx. 7.4 with 2 M NaOH and gentle stirring, or by stirring with a glass rod.
(d) Strongly coloured samples: if used undiluted, strongly coloured samples should be treated by the addition of 0.2 g of polyvinylpolypyrrolidone (PVPP)/10 mL of sample. Shake the tube vigorously for 5 min and then filter through Whatman No. 1 filter paper.
(e) Solid samples: homogenise or crush solid samples in distilled water and filter if necessary.
(f) Samples containing fat: extract such samples with hot water at a temperature above the melting point of the fat, e.g. in a 100 mL volumetric flask at 60°C. Adjust to room temperature and fill the volumetric flask to the mark with distilled water. Store on ice or in a refrigerator for 15-30 min and then filter. Discard the first few mL of filtrate and use the clear supernatant (which may be slightly opalescent) for assay.
(g) Samples containing protein: deproteinise samples containing protein with Carrez reagents, alternatively use ice cold perchloric acid. Add an equal volume of ice-cold 1 M perchloric acid with mixing. Filter or centrifuge at 1,500 g for 10 min and adjust the pH of the supernatant to between 7 and 8 with 1 M KOH. Use the supernatant in the assay after appropriate dilution.
商品特色
商品規格
- 商品規格
40 assays of each (manual) / 400 assays of each (microplate) / 400 assays of each (auto-analyser)
Bottle 1:
Total Sulfite Reagent 1 (40 mL)
Contains sodium azide (0.05% w/v) as a preservative. Store at room temperature. See individual label for expiry date.
Bottle 2:
Total Sulfite Reagent 2 (20 mL)
Contains sodium azide (0.05% w/v) as a preservative. Store at room temperature. See individual label for expiry date.
Bottle 3:
Free Sulfite Reagent 1 (40 mL)
Store at room temperature. See individual label for expiry date.
Bottle 4:
Free Sulfite Reagent 2 (20 mL)
Store at room temperature. See individual label for expiry date.
Bottle 5:
Sulfite Standard
Sodium Sulfite (5 g).
Store sealed at room temperature. See individual label for expiry date.
