建立了一套测定味精中硫化物的离子色谱分析方 法，利用阴离子交换色谱柱IonPac AS7进行分离，脉 冲安培检测器测定了99%味精、加盐味精和增鲜味精样 品中的痕量硫化物。方法的选择性好，灵敏度高，分析 时间短，适用于市场上各品牌味精样品的分析，且方法 可应用到味精生产过程中各级谷氨酸钠溶液的实时监测 中，保障生产效率、产品品质和老百姓的食品安全。

The method presented here overcomes analyte interference by separating the two chromium using a detection method specific for Cr(VI) that is capable of handling the high-ionic-strength sample matrices generated in many leaching, and digestion procedures. Cr(VI) is separated as the divalent anion on the IonPac AS7 column using ammonium sulfate, ammonium hydroxide eluent. After the separation, Cr(VI) reacts with the color reagent diphenylcarbohydrazide (DPC) and detected by UV absorbance at 520 nm. This method is consistent with U.S. EPA Method 218.6. Please refer to AU179 for an updated method.

The work shown here describes modification of the conditions described in EPA Method 218.6, including use of the column in the 2 mm format and a smaller reaction coil to increase method sensitivity. The modified method uses Dionex IonPac AS7 column (2 × 250 mm), a 1000 μL injection volume, and post column reaction (using a 125 μL reaction coil) followed by visible absorbance detection at 530 nm. This method permits an MDL for chromate of 0.001 μg/L. This results in a quantitation limit of 0.003 μg/L, which is more than sufficient for analysis at the proposed California PHG level of 0.02 μg/L.

Inorganic and organic arsenic compounds have very different toxicities, and therefore speciation analysis is needed to assess the potential health risk posed by the food product. Here two inorganic and four organic arsenic species are determined in an apple juice sample using IC coupled to iCAP Q ICP-MS. Arsenic species are first separated by IC using an ammonium carbonate gradient on an IonPac AS7 column. Then the eluting species are detected and quantified by the ICP-MS down to ng/g concentrations. Arsenic speciation is also demonstrated in organic brown rice syrup (OBRS) in AN43126.

Speciation determinations of ionic compounds are important to determine the concentration of the more toxic form in the total elemental composition. Chromium is an industrial waste contaminant that can have serious health effects and therefore requires monitoring in municipal water systems. This method determines Chromium VI and Chromium III species in a municipal drinking water sample. The ions are separated by ion chromatography (IC) on an IonPac AG7 guard column and detected by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) at ng/g. This method is further optimized in AN43175.