质量标准:	项目                         I型        II型        III型     IV型     V型
平均分子量M.W                700000     250000      250000    250000   90000  
外观Appearance               白色至浅灰色结晶粉末   白色至灰色结晶     白色至浅黄色颗粒粉末
含量Assay other ,%           >99.5     >99.5        >99.5     >99.5   >99.5
干燥损失Loss on drying,%     <10       <10           <10      <10     <10
                              (3-5 g, 105°C, 2 小时)
重金属Heavy metals            <20 ppm   <20 ppm      <10 ppm   <10 ppm  <20 ppm
pH(1% 溶液.)                  6.5-8     6.5-8        6.5-8     6.5-8    6.5-8
                              (1% 溶液.)
粘度Viscosity, mPa.s      2500 - 4500  1500-3100   1500-3100 1500-3100  50-100
                             (Brookfield, 1%溶液., 25°C)
砷As measure                  < 3 ppm    < 3 ppm      < 3 ppm  < 3 ppm   < 3 ppm
铅 Pb measure                 < 10 ppm   < 10 ppm     < 3 ppm  < 3 ppm   < 10 ppm
汞Hg measure                  < 1 ppm    -            < 1 ppm  < 1 ppm  < 1 ppm
镉Cd measure                  < 1 ppm    -            < 1 ppm  < 1 ppm  < 1 ppm
乙醇酸钠sodium glycolate,%   < 0.4      -            < 0.4    < 0.4    < 0.4
氯化钠sodium chloride,%      < 0.25     -            < 0.25   < 0.25   < 0.25
取代度degree of substitution: 0.80-0.95 1.15-1.45  0.80-0.95  0.65-0.90 0.65-0.90
USP级                I型        II型       III型
钠含量             6.5-9.5     6.5-9.5    6.5-9.5
粘度mpa . S        300-600     600-1000   1000-1400
PH值               6.0-8.5     6.0-8.5     6.0-8.5
干燥减量%          ≤10        10         10
氯化物(C~)%      ≤1.8       1.8        1.8
重金属(Pb)%      ≤0.004     0.004      0.004
砷(As)%          ≤0.003     0.003      0.003
铁(Fe)%          ≤ 0.03     0.03       0.03