EDT directION produce a wide range of stock standards to ensure that ISE calibration is both simple, accurate saving valuable time in a busy laboratory.  

All of our stock standards are 1000ppm and are supplied in 500ml leak proof bottles. It is anticipated that the end user will prepare standard sets by serial dilution of this stock standard as required.

Please ensure that lower concentration standards (typically below 10ppm) are not kept for future work as this gives cause to potential errors as concentration of these may be affected significantly during storage.

As these standards are used for ion analysis it is important that all standards are diluted using distilled or deionised water. Tap water or softened water cannot be used due to their high ionic content. For successful analysis most applications will require an ISAB (Ionic strength Adjustment Buffer).

All glassware should be clean. If glassware has been washed in tap water or in a glassware washing machine  it will need to be rinsed in deionised water prior to use. Residual water causes unwanted dilution so thoroughly dry glassware prior to use.

Be careful to avoid touching the insides of glassware or containers which are used for measurement if possible. The most common contaminants are Sodium and Chloride from sweat and in some applications this may not be desirable. It is advisable to prepare two standards which should have concentrations that span the expected sample concentration. e.g. a typical Nitrate in water analysis may yield a result of 40ppm . The standards should therefore be 100 and 10ppm made from two serial dilutions from the 1000ppm stock.