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deepakpangavhane ☆ India, 2018-09-03 10:28 (2052 d 08:46 ago) Posting: # 19205 Views: 5,006 |
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Hi everyone! The % recovery was 107.80%, 112.65% and 105.92% for the low quality control (LQC) and middle quality controls (MQC2 and MQC1), respectively. Whereas % recovery for higher quality control (HQC) was 98.25%. The % recovery was determined by comparing the mean peak area of 6 replicates of extracted quality control samples at High, Middle and Low concentrations against respective mean peak area of 6 replicates of un-extracted quality control samples at High, Middle and Low concentrations. Internal standard used was deuterated. Kindly confirm recoveries markedly higher than 100% for LQC, MQC2 and MQC1 are acceptable as per USFDA guidelines?? Also specify reason for higher recoveries. |
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Ohlbe ★★★ France, 2018-09-03 21:21 (2051 d 21:54 ago) @ deepakpangavhane Posting: # 19231 Views: 4,405 |
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Dear Deepak, ❝ The % recovery was determined by comparing the mean peak area of 6 replicates of extracted quality control samples at High, Middle and Low concentrations against respective mean peak area of 6 replicates of un-extracted quality control samples at High, Middle and Low concentrations. Meaning that what you observe is a mix of extraction recovery and matrix effect. If you want to see the true extraction recovery you have to compare to samples spiked post-extraction. You can combine with matrix effects experiments. ❝ Internal standard used was deuterated. Makes no difference. You are looking at peak areas, not peak area ratios. ❝ Kindly confirm recoveries markedly higher than 100% for LQC, MQC2 and MQC1 are acceptable as per USFDA guidelines?? Did you see any limit for absolute recovery in either direction in the FDA guidance ? ❝ Also specify reason for higher recoveries. Multiple. The most probable: analytical variability (your results are well within the 15 % acceptance limits for precision and accuracy). Other possibilities include ion enhancement, sample preparation, calculation errors... — Regards Ohlbe |
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Ladi ☆ Thailand, 2018-09-04 05:51 (2051 d 13:24 ago) @ deepakpangavhane Posting: # 19232 Views: 4,330 |
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Hello Deepak and Ohlbe, ❝ The % recovery was 107.80%, 112.65% and 105.92% for the low quality control (LQC) and middle quality controls (MQC2 and MQC1), respectively. Whereas % recovery for higher quality control (HQC) was 98.25%. My lab called the 'post-extraction' as 'un-extracted', I am guessing you also mean that? I observed recovery 100-115% mostly with protein precipitation projects in our lab. My explanation to auditors was that the extracted samples are little bit more concentrated than the post-extracted samples because some protein is precipitated out in extracted samples. While in the post-extracted samples, the measured volume of supernatant from precipitated blank is use to make up a required concentration. Ususally for protein precipitation, recovery is almost 100%. So if extracted is more concentrated than it supposed to be (expected conc.), recovery may cross 100%. However, I normally see similar %recovery across all concentrations. Regards, Ladi |
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Kintan Patel ☆ India, 2018-11-29 12:48 (1965 d 05:26 ago) @ Ladi Posting: # 19659 Views: 3,958 |
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Hello Ladi and Deepak, The % recovery across all concentration levels (i.e LOW ,MED add High) should be consistent that means %CV should be within 20% across all levels and also you should mentioned the accepted % recovery range (i.e from 30% to 120%) in your SOP and this high % recovery might be due to ion enhancement , sample preparation error etc. and also it is acceptable as per FDA guideline.(limit for % recovery is not mentioned in FDA Guideline) Thank You, Kintan Patel Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post! [Ohlbe] |
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Ohlbe ★★★ France, 2018-11-30 19:23 (1963 d 22:52 ago) @ Kintan Patel Posting: # 19665 Views: 3,954 |
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Dear Kintan Patel, ❝ The % recovery across all concentration levels (i.e LOW ,MED add High) should be consistent that means %CV should be within 20% across all levels Could you clarify where you took this value of 20 % from ? ❝ and also you should mentioned the accepted % recovery range (i.e from 30% to 120%) in your SOP Why 30% to 120% ? Where do these values come from ? — Regards Ohlbe |
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Kintan Patel ☆ India, 2018-12-05 11:04 (1959 d 07:10 ago) @ Ohlbe Posting: # 19668 Views: 3,922 |
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Dear Ohlbe, ❝ ❝ The % recovery across all concentration levels (i.e LOW ,MED add High) should be consistent that means %CV should be within 20% across all levels %CV for % recoveries across Low, med and high level shall be within 20 %. ❝ Why 30% to 120% ? Where do these values come from ? This is just example. You can keep accepted % recovery as 25 % to 125 % etc. in you SOP,but in guideline % recovery criteria no where mentioned but many industries had included acceptance criteria of % recovery in their SOP. Thanks , Kintan Patel Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post! [Ohlbe] |
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Ohlbe ★★★ France, 2018-12-05 11:30 (1959 d 06:44 ago) @ Kintan Patel Posting: # 19669 Views: 3,842 |
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Dear Kintan Patel, ❝ %CV for % recoveries across Low, med and high level shall be within 20 %. Why 20 % ? Where did you take that value from (apart from your own SOP) ? How do you calculate the CV: take all individual values ? Or the average at L, average at M and average at H level ? ❝ ❝ Why 30% to 120% ? Where do these values come from ? ❝ ❝ This is just example. You can keep accepted % recovery as 25 % to 125 % etc. in you SOP [...] Right. Then e.g., not i.e. — Regards Ohlbe |
Ing. Helmut Schütz