Hi,

Kindly dilute your sample and run again.

Regards

No, it's not acceptable.

See this link you will understand

http://www.chromatographyonline.com/internal-standard-calibration-problems-0

Risk of reporting a faulty analysis result is large if the concentration lies outside the calibration range.

It means your sample is concentrated.

Over-Curve Samples

Now, what happens if the analyte concentration is greater than the upper end of the calibration curve (we'll refer to these as "over-curve" samples)? It is not a good analytical practice to extrapolate the calibration curve above the upper end or below the lower end of the actual calibrator concentrations. This is because it may not be a valid conclusion that the analyte response is the same outside the test range as inside it. For example, many detectors will show a nonlinear drop-off in response at high concentrations; at low concentrations, nonlinear changes in response may be seen because of absorptive losses or other factors. Unfortunately, such changes in response seldom are predictable, so the risk of reporting a faulty analysis result is large if the concentration lies outside the calibration range.

For external standardization, the solution to over-curve samples is quite simple—just dilute the sample until its concentration is within the calibration range. For example, let's consider a calibration curve that covers 1–1000 ng/mL, as in the example above, and a sample that is estimated to contain ~1500 ng/mL based on an extrapolated curve. We could dilute this sample by a factor of two with injection solvent and reinject the sample. If it now assays as 725 ng/mL, we would correct for the dilution factor and report 1450 ng/mL as the sample concentration. Of course, this could not be done without proper supporting evidence that dilution was an acceptable solution to such problems. You could show this during the validation process by preparing test samples at known over-curve concentrations, then diluting them after sample preparation and showing that you obtained the appropriate results. This information would be included in the validation report and the method would be written so that over-curve samples could be diluted by twofold (or 10-fold, or whatever had been demonstrated) to obtain accurate results.

Source:

http://www.chromatographyonline.com/internal-standard-calibration-problems-0

If you are diluting your sample and it fits in calibration range.

That result is most accurate (Obviously you will apply Dilution factor in calculations)

Yes, Bold one(1450) is most accurate and should be reported.

I have pasted the link above

Kindly read it properly

Your query will be solved.

Yes, I agree.

You can extend your calibration curve to high concentrations so that over curve samples are eliminated

Regards

Dear Assefa:

Even though your calibration range is 0-10ppm, it is still possible to get a number for an over-range measurement by assuming a linear extrapolation. As Ankita pointed out results may not be acceptable for reporting purposes, as we are not sure about the validity of extrapolation, or how far the linearity is valid. However, the value is "useful" as an approximate number to decide an optimum dilution factor. For example, if you dilute the sample by 10X, it will give you a result of around 30-40ppm, which is still over the range. If the dilution is 100X, and it will give you a concentration 4.1ppm, it would be a more accurate valid measurement as it is now within the calibration range. On the other hand, if you arbitrarily dilute by 1000X, your result will be 0.41ppm which is still a valid measurement, but is closer to the limit of detection and may not be as reliable as 100X dilution. Of course, you have to multiply the measured value by the dilution factor.

Best wishes,

I totally agree with Ankita. Ideally, the calibration curve should cover the sample concentration. If the sample concentration is high, then you have to dilute the sample as suggested by Ankita,. You can incorporate the multiplication factor in the calculation.