Is there an expiration date for the indicator?
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RT, I would like to ask the experts here: do various indicators have an expiration date? If so, what is that specific deadline? For example, methyl red, bromocresol green, phenolphthalein, etc
There definitely is a deadline! You can look it up for specific details!
It has a usage deadline; cresol orange should not be used for more than two weeks
No relevant documents were found that specify this, but depending on the conditions of use, different indicators have varying shelf lives; bromocresol green and phenolphthalein are relatively stable, and it should be possible to use them for 3 months
Every chemical reagent has a shelf life, and the shelf life of indicators depends on how they are used and the surrounding conditions; however, experienced analysts can usually tell whether an indicator is still effective by observing its usage pattern.
The original poster should refer to the national standards GB/T 601-603; these three standards establish clear guidelines for the preparation, use, and storage of chemical reagents.
Indicators all have a limited shelf life; for example, the usage period for starch is one week in summer, and no more than two weeks in winter
Of course, there is a deadline, just like with medications. Solid indicators can be stored for a longer period of time, but their solutions are not stable for very long and must be used before they lose their effectiveness.
The shelf life of indicators is relatively long, right? Indicators stored in a solid-sealed form can generally be kept for several years, while prepared solutions in brown bottles can also be preserved for about a year. Of course, it depends on the environment in which it is used. Temperature and humidity both affect its shelf life.
Different indicators have different expiration dates. The validity periods of the three indicators mentioned by the original poster are relatively long. Indicators that are prone to deterioration include metal-based indicators such as xylene orange, sodium diphenylamine sulfonate, and starch.
In the analysis lab where I work, the deadline is three months, and the same applies to other reagents as well
Indicators have a limited shelf life; exceeding this limit affects the accuracy of the analysis
There is **no specific regulation** regarding the shelf life of indicators; some are used immediately after preparation and have a shelf life of one day, while other indicators, when stored at 4°C, have a shelf life of one year. It’s a bit chaotic, but generally internal regulations specify that the shelf life of indicators is 3 months.
There is definitely a deadline, and it depends on your usage patterns, sealing conditions, storage conditions, and so on
Support is available; it depends on the specific situation. In general, it is necessary to pay attention