Maleic acid and oxalic acid in glyoxylic acid

At present, the process of producing glyoxylic acid is glyoxal HNO3 oxidation method, maleic acid (maleic acid) O3 oxidation method and oxalic acid electrolysis reduction method. The advantage of glyoxal HNO3 oxidation is that the process is mature and the degree of glyoxal reaction is high. As the HNO3 corrosion equipment, combined with nitrogen oxides pollute the environment, affect the health of the operator, the method of application space is small. O3 oxidation of maleic acid is a new glyoxylic acid production process, gradually by the people's attention. O3 has a strong oxidizing property and a higher selectivity of the reaction, and the maleic acid reaction is complete and no by-product is produced. But the large-scale production of O3 is more difficult, and the need for follow-up use of Zn powder reduction, so that the method cost is higher. Oxalic acid electrolysis reduction method is a low cost method, the use of oxalic acid as raw material, cathodic electrolysis reduction of glyoxylic acid, the disadvantage is that oxalic acid can not be fully reacted, affecting the purity of the product glyoxylic acid.
Although the above organic acids are suitable for liquid chromatography separation and UV detection, but the liquid chromatography column on the analyte selectivity is poor, and ion chromatography separation of the organic acid can be a price of glyoxylic acid first wash out , And then the divalent maleic acid and oxalic acid wash out. And can change the retention time and selectivity by changing the composition and concentration of the eluent. Therefore, the use of ion chromatography analysis.
The analysis of maleic acid and oxalic acid in glyoxylic acid involves the determination of trace components in high concentrations of matrix, which must be carried out using high-fold dilution methods as well as high-capacity columns and higher concentrations of eluent. Accurate to take glyoxylic acid solid 1.00g (accurate to 0.1mg), with ultra-pure water into the 100ml volumetric flask to shake the volume. A solution dilution of 200, 500, 1000, 2000, 4000 and 10000 was obtained by stepwise dilution. The diluted samples were filtered through a 0.22 mm needle filter and analyzed in the order of concentration from low to high. The results show that the glyoxylic acid samples are clearly symmetrical in the chromatogram after the glyoxylate is diluted with a certain number of times. When the dilution factor is low, the concentration of glyoxylic acid is significantly beyond the column capacity, in the chromatogram appears "flat peak", affecting the life of the column. If the dilution factor is too high, maleic acid can not be detected. After the analysis, rinse the column for 30 minutes with 10 times the concentration of eluent, pure water and normal eluent.