I have a number of calibration standards (solutions that contain binding antibodies in exact quantities). The lowest-concentration standard is 200 ng/mL, the highest is 5000 ng/mL. Between them, there are standards with concentrations of 250, 300, and so forth.
The permitted deviation of concentration for the highest and lowest standards is 25%, while the permitted deviation for the other standards is 20%.
How do I indicate in writing that the range I'm describing in sentence 2 (below) excludes the two "outermost" standards?
The measured concentration of binding antibodies in the calibration standards (concentrations: 200 and 5000 ng/mL) should not deviate by more than 25 % from the nominal concentration.
The measured concentration of binding antibodies in the calibration standards (concentrations: from 200 to 5000 ng/mL) should not deviate by more than 20 % from the nominal concentration.
Should I write "concentrations: above 200 but below 5000 ng/mL"? This looks a bit out of style for technical writing. There must be some elegant way of expressing this.
Could "concentrations: between 200 and 5000 ng/mL" be a suitable choice?