醬油中雙十二烷基硫酸胺明檢驗方法之探討   全文下載

Studies on Analytical Method of Thiamine Dilaurylsulfate in Soy Sauce

雙十二烷基硫酸胺明之檢驗分為十二烷基硫酸鹽及維生素B1兩部份，前者利用azure A比色法測定，醬油於pH3下，加azure A溶液，以氯仿萃取後，於波長640nm測吸光度；後者只採用螢光檢測液相層析法分析，檢體以0.1N鹽酸稀釋後，加含1% 鐵氰化鉀之20% NaOH溶液，反應生成truochrome後，加磷酸中和，再以異丁醇萃取，最後利用高效液相層析儀分析定量。檢體中添加相當於3、5、10、12及15 ppm laurylsulfate之雙十二烷基硫酸胺明時，其回收率以azure A 比色法檢測為98.04～98.89%，以螢光檢測液相層析法分析為91.57～92.53%，變異係數皆小於5%。經探討結果，兩種方法皆以0.7ppm以下視為未檢出。本研究於民國80年10月至81年5月於全省抽驗市售醬油檢體國產27件，日本進口36件，共計63件，經檢測結果，國產檢體全部未檢出雙十二烷基硫酸胺明，日本進口檢體檢出8件，兩種方法所測得之數據幾乎一致，其中4件超過本署公告「食品添加物使用範圍及用量標準」中以laurylsulfate計10ppm以之規定。

The methods for the determination of thiamine dilaurylsulfate (TLS) in soy sauce have been developed. TLS is a complex of thiamine hydrochloride (TCl) and sodium lauryl sulfate (SLS). The LS portion was determined by the azure A colorimetric method (AA method). Azure A solution and IN sulfuric acid were added to the sample, LS was extracted with chloroform, and then detected at 640nm. The TCl portion was determined by the fluorimetric HPLC method. TCl was converted to its fluorescent derivative, thiochrome, by adding 1% potassium ferricyanide in 20% sodium hydroxide to diluted sample, and neutra lizing with phosphoric acid. The thiochrome thus formed was extracted it with isobutanol and then determined by HPLC. Recovery studies of TLS were performed at 3, 5, 10, 12 and 15 ppm (calculated as LS) fortification levels in the samples with both methods. Average recoveries were 98.04～98.89% with the AA method and 91.57～92.53% with the fluorimetric HPLC method. Coefficients of variation were less than 5%. The limits of detection of both methods were 0.7 ppm. Twenty-seven domestic and thirty-six imported soy sauce samples were analyzed. No TLS was detected in domestic samples, while eight imported samples were found positive for TLS. The data obtained with both methods were practically identical.