饮料、白酒、啤酒、酒类中Acetic acid检测方案(毛细管电泳仪)

HIGH PERFORMANCECAPILLARYELECTROPHORESIS SYSTEM DETERMINATION OF ORGANIC ACIDS IN BEVERAGES LUMEX Method M 04-47 (2007) INTRODUCTION The method allows determination of organic acids， in soft drinks (juices， fizz drinks) and alcoholic drinks(wines， beer). MEASUREMENT METHOD The method is based on differential migration and separation of anions of organic acids in electric field dueto their different electrophoretic mobility. Identification and quantitative determination of the analyzed components are performed by detecting theoptical density of a solution at 254 nm wavelength. MEASUREMENT RANGE Acids Measurement range， mg/L Acetic acid 1.0-2000 Citric acid 1.0-10000 Formic acid 1.0-500 Lactic acid 1.0-5000 Malic acid 1.0-10000 Oxalic acid 1.0-500 Succinic acid 1.0-2000 Tartaric acid 1.0-6000 Inorganic anions (chloride， nitrite， sulphate， nitrate， fluoride， phosphate， carbonate)， ascorbic acid， andpreservatives (benzoic and sorbic acids) do not influence the determination of analyzed organic acids. EQUIPMENT AND REAGENTS The"CAPEL” capillary electrophoresis system with high-voltage negative polarity is used in measurements.Data acquisition， collection， processing and output are performed using a personal computer running under"WINDOWS 2000/XP”operating system with installed dedicated software package for acquisition andprocessing of chromatography data. EXAMPLES OF REAL ANALYSES Buffer：benzoic acid， with DEA， CTAB， and disodium EDTACapillary：LEFF/LTOTAL 50/60 cm， ID 75 pmInjection：150 mbar x secVoltage：-20kVDetection：254 nm， indirect Sample： test solution of o3rganic acids.5 mAU and phosphate (10 mg/L of each acid)： 1- oxalic acid 9 2 - formic acid 3- tartaric acid 4 - malic acid 10 5- citric acid 6 - succinic acid 7 - lactic acid 8- phosphate (as hydrophosphate) 9 - acetic acid 10 - propionic acid 2 3 min Sample： dark beer (dilution 1：19) Measurement results： 1 -oxalic acid (9.8 mg/L) 2 - malic acid (82.3 mg/L) 3 - citric acid (148 mg/L) 4 - succinic acid (46.2 mg/L) 5 - lactic acid (67 mg/L) 6 - phosphate (as hydrophosphate) 7 - acetic acid (107 mg/L) Sample： dry white wine (dilution 1：49) Measurement results： 1 - tartaric acid (1415 mg/L 2 - malic acid (1643 mg/L) 3 - citric acid (465 mg/L) 4 -succinic acid (500 mg/L) 5 - lactic acid (1165 mg/L) 6- phosphate (as hydrophosphate) 7 - acetic acid (405 mg/L) Sample： cherry juice (dilution 1：99) Measurement results： 1 - malic acid (2725 mg/L) 2 - citric acid (3054 mg/L) 3 -lactic acid (112 mg/L) 4-phosphate (as hydrophosphate) ADVANTAGES OF CAPILLARY ELECTROPHORESIS Compared with determination of organic acids in beverages samples by HPLC method， capillaryelectrophoresis has several advantages： high separation efficiency； low analysis cost； absence of an expensive chromatographic column； short analysis time. The contents on this paper are subject to change without notice. WWW.LUMEX.BIZ     LUMEX毛细管电泳法可以测定软饮料（果汁，汽水饮料）和酒精饮料（葡萄酒，啤酒）中的有机酸含量。该方法是基于电场中有机酸阴离子的迁移和分离的迁移率不同，通过检测溶液在254 nm波长处的光密度来识别和定量分析所分析的组分。无机阴离子（氯化物、亚硝酸盐、硫酸盐、硝酸盐、氟化物、磷酸盐、碳酸盐）、抗坏血酸和防腐剂（苯甲酸和山梨酸）不影响有机酸的测定。    与HPLC法测定饮料样品中的有机酸相比，毛细管电泳有几个优点：1.分离效率高；2.低分析成本；3.没有昂贵的色谱柱；4.分析时间短。