Veterinary drugs and pesticide residues have expired.
Generally, when testing veterinary drug residues in aquatic products, some standard products such as malachite green and sand stars will be used. If the valid period has passed and it has not been used up, how to deal with it? Basically, according to the CNAS certification regulations, there is only one way to destroy it.
The issue of standard product expiration is necessary to discuss, because some standard products have expired, but they may still be valid and can be used for other meaningful research. For example, they can be used for internal quality control, that is, without notifying personnel of the sample content, send them blind samples, let them do inter-personnel comparison tests, and then determine the results of the comparison tests according to relevant testing standards, which will help internal quality control.
But...Standard valid periodThe regulations also have a certain reference. For example, after two or five years, the nature of some standards may change, which may affect quantitative analysis.
For example, yourmalachite greenIt has been used with the crystal violet standard for 2 years, and when the standard solution is reformulated, the dominance may be OK, but the retention time may be advanced, and the recessive ones may also be too different. For example, 2ppb is basically impossible to make, and the recessive malachite green and recessive crystal violet are inseparable...
