Cation-SR is a poly(styrenedivinylbenzene) copolymer that has been modified with sulfonic acid. Note that Cation-SR is not bonded to silica but is a 100% copolymeric particle that is spherical, porous and cross-linked. The functional group imparts selectivity for cationic analytes, such as primary, secondary and tertiary amines.
应用领域:水分析
吸附物举例:金属离子,胺类
产品形式 | 产品编号 | 产品描述 | 固定相描述 | 包装 |
盘片 | 2251 | 阳离子47 mm | 磺酸盐键合SDB树脂 表面积:350 m2/g 粒径:16 um 孔径:80 Å 吸附容量:1.1 meq/g Cu+2, 0.4 meq/47 mm disk | 60片/盒( 20片/包 x 3包) |
Adjust the sample pH as necessary to ensure that the analytes are ionic. A general guideline is to lower the sample pH at least two units below the pKa of the analytes being extracted. Next dilute the sample with reagent water as needed to reduce the ionic strength to < 0.1M.
Disk conditioning is critical for a successful extraction. Conditioning prepares the sorbent to interact efficiently with the sample matrix.
Failure to condition the Extraction Disk properly will result in erratic and low recoveries.
The disk is now conditioned and ready to extract the sample.
Note: If the disk becomes dry while conditioning, repeat the conditioning steps starting with the methanol step.
Add the sample and apply vacuum (< 20 in Hg, 0.68 bar). Flow rates will vary. Typically 1 Liter of DI water at 25oC at 20 in Hg of vacuum (47 mm disk) will extract in less than 10 minutes.
Flow rate is dependent on vacuum source and the particulate content of the sample. Empore™ Filter Aid 400 and/or other prefiltration may be helpful if the sample contains excessive amounts of particulates.
Remove as much of the residual water as possible from the disk by applying the vacuum to dry the disk for 5-10 minutes.
Optional: An intermediate wash with methanol or another organic solvent will remove neutral organics. Electrostatic forces will not be disturbed by this step.
Eluting twice with 10-15 mL (47 mm disk) is suggested. Elution is often encouraged by the selection of a high selectivity counterion, high ionic strength, and a pH adjusted to 1-2 units above than the pKa of the analytes extracted. An effective elution solvent for metals is 50% (v/v) nitric acid. An effective elution solvent for non-metals is 0.1N sodium hydroxide. Very strong bases such as quaternary amines may be difficult to elute from the cation exchange disks.
If the disk dries prior to elution, pre-wetting with a minimum amount of methanol is necessary to re-establish surface tension. For example, to elute with an aqueous buffer, simply wet the disk with enough methanol to cover the surface, then add the buffer. Another option is to elute with an acidic methanol solution.