【原创】方法论证 请大家给点意见

建议楼主把内容直接贴出来,这样看比较方便.下载比较麻烦.

1.    Summary
1.1 Linearity;
1.2 Instrumental Detection Limit (IDL) Determination;
1.3 Sample Homogeneity and Method Detection Limit (MDL) Determination;
1.4 Bias Check;
1.5 Precision Check.
2.    Introduction
2.1 To the nearest mg, weigh 1 g of sample in a 200mL beaker
2.2 For non-polycarbonate material, add 20mL THF (5.2.4) and ultrasonic at 40℃ for 60 minutes.
2.3 Re-precipitated the plastic with 100mL ACN (5.2.1) with drop-wise and constant swirling.
2.4 Stand for 30 minutes to allow precipitate plastic residue
2.5 Filter the solvent mixture through filter paper (4.8) into a flat bottom flask. Rinse filter paper with small amount of ACN (5.2.1) and collect the washings into the flask.
2.6 Concentrate the filtrate to approximately 2mL with vacuum rotary evaporator (4.7) at 57℃, 300 mbar.
2.7 Transfer the filtrate into a 20mL volumetric flask. Rinse the flask twice with small amount of 1:1 ACN /water
2.8 Combine the washings and make up to the mark with 1:1 ACN / water.
2.9 Filter the final solution into an injection vial for HPLC-DAD-FLD analysis.
2.10 For polycarbonate material, Dissolve the PC sample with 20 mL DCM (5.2.2), shake well until the sample totally dissolve, if the sample cannot completely dissolve, ultrasonic at 40oC for 60 minutes.
2.11 Re-precipitated the plastic with 100mL acetone (5.2.3) with drop-wise and constant swirling.
2.12 Follow the steps 2.4-2.9.

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以上是楼主文档中的内容。

3.    Results:
3.1 Test parameters
Fluorescence Detector
Signal:   
Excitation:    225nm
Emission:    310nm

3.2 Linearity
3.2.1 Working linearity Range: 0.05mg/L to 2.50mg/L
3.2.2 Acceptable correlation coefficient (R2): >0.99

3.3 Instrumental Detection Limit (IDL)
3.3.1 7 repeating analysis with concentration 0.005mg/L, and after calculation (S.D x 1.645).
3.3.2 Theoretical IDL calculated by excel = 0.0005 mg/L.
3.3.3 Actual IDL after analysis by HPLC-DAD-FLD = 0.0025 mg/L achieve S/N ratio>3

3.4 Method Detection Limit (MDL)
3.4.1 Sample matrix: Yellow plastic.
3.4.2 Test Condition: 40°C for 1hr in ultrasonic bath.
3.4.3 Prepare 7 sets of sample (1.0g) and spike with 0.10mL 10mg/L Bisphenol A standard solution and follow 2.1~2.9, after calculation (S.D. x 3.14)
3.4.4    Theoretical MDLs calculated by excel are as below: (mg/L in sample solution or mg/kg in sample matrix):

Substance    Average Conc. mg/L    Average Recovery    MDL
            mg/L    mg/kg
Bisphenol A    0.044     87.5%    0.019    0.374

3.4.5    Actual MDL after analysis by HPLC-DAD-FLD =0.05 mg/L (1.0mg/kg in sample matrix).

3.5 Bias Check
3.5.1 Sample matrix: Yellow plastic.
3.5.2 Test Condition: 40°C for 1hr in ultrasonic bath.
3.5.3 Prepare 7 sets of sample (1.0g) and spike with 0.50mL 100mg/L Bisphenol A standard solution and follow 2.1~2.9.

3.5.4 Recovery and RSD are calculated by excel as below:
Substance    Spiked Conc. mg/L    Average Recovery    RSD
Bisphenol A    2.50    92.0%    3.29%
Remark: The fail limit of Bisphenol A is 50mg/kg.

3.6 Precision Check
3.6.1 Sample matrix: Yellow plastic.
3.6.2 Test Condition: 40°C for 1hr in ultrasonic bath.
3.6.3 Prepare 7 sets of sample (1.0g) and spike with 0.20mL 10mg/L Bisphenol A standard solution and follow 2.1~2.9.
For 50mg/L bisphenol A in sample, refer to data of Bias check.
3.6.4 Recovery and RSD are calculated by excel as below:

Substance    Spiked Conc. mg/L    Average Recovery    RSD
Bisphenol A    0.10     84.9%    7.22%
Bisphenol A    2.50    92.0%    3.29%

Remark: Perform a lower concentration (spiked concentration is 0.10 mg/L) and a higher concentration (spiked concentration is 2.50mg/L)
4.    Experimental:
4.1 Sample Homogeneity Check --- Sample Blank (C)
4.1.1 To the nearest mg, weigh 1 g of sample in a 200mL beaker
4.1.2 For non-polycarbonate material, add 20mL THF (5.2.4) and ultrasonic at 40℃ for 60 minutes.
4.1.3 Re-precipitated the plastic with 100mL ACN (5.2.1) with drop-wise and constant swirling.
4.1.4 Stand for 30 minutes to allow precipitate plastic residue
4.1.5 Filter the solvent mixture through filter paper (4.8) into a flat bottom flask.
4.1.6 Concentrate the filtrate to approximately 2mL with vacuum rotary evaporator (4.7) at 57oC, 300 mbar.
4.1.7 Transfer the filtrate into a 20mL volumetric flask. Rinse the flask twice with small amount of 1:1 ACN /water
4.1.8 Combine the washings and make up to the mark with 1:1 ACN / water.
4.1.9 Filter the final solution into an injection vial for HPLC-DAD-FLD analysis.
4.1.10 Repeat the steps 4.1.1 – 4.1.9 to perform 7 times of sample blank. Take an average value if any.

4.2 Spike sample (Cs)
4.2.1 To the nearest mg, weigh 1 g of sample in a 200mL beaker and spike the following amount of Bisphenol A standard solution into the beaker.

MDL    BIAS    PRECISION
0.10mL 10mg/L    0.50mL 100mg/L    0.20mL 10mg/L    0.50mL 100mg/L

4.2.2 Proceed the steps 4.1.2 – 4.1.10.
4.2.3 Repeat the steps 4.2.1 – 4.2.2 and prepare 7 set of spike sample.
4.2.4 Analysis with HPLC-DAD-FLD and calculate the amount of each spike sample.
4.2.5 Calculate the spike recovery in each spike sample as following equation
Spike Recovery (%) = (Cs –C)/CT x100%
Where,
C = Average concentration of the sample blank, mg/L
Cs = Concentration of spike sample, mg/L
CT = Concentration of theoretical spike amount, mg/L

4.2.6 Calculate the amount of spike sample in sample matrix, mg/kg

Bisphenol A, mg/kg = (Cs –C) x V/W
Where,
C = Average concentration of the sample blank, mg/L
Cs = Concentration of spike sample, mg/L
V = Final volume of ACN: H2O=1:1, 20mL
W = Sample weight, approximate 1.0g
4.2.7 Calculate the theoretical method detection limit (MDL) in sample matrix by the following equation
Bisphenol A, mg/kg = S.D. x t (n-1)
Where,
S.D = Standard derivation of n spike sample which calculate by 4.2.6, mg/kg
t (n-1) = The value from table of one-sided t distribution at n-1 degree of freedom and at 99% confident level
5. Conclusion:
5.1 Linearity: Working range between 0.05 mg/L to 2.50 mg/L, R2 > 0.99.
And extract 0.05 mg/L, 0.10mg/L, 0.50mg/L, and 2.50mg/L as calibration points in operation.

5.2 IDL: 0.0025 mg/L in standard solution and achieve S/N ratio>3.

5.3 MDL:
5.3.1 Spike Recovery in MDL (0.05mg/L): 87.5% average between 7 set of spike sample trials.
5.3.2 Actual MDL: After calculated by excel, 0.38mg/kg is our theoretical MDL for Bisphenol A (i.e.0.019mg/L in extract). Take a trial to spike at higher concentration in 0.05mg/L (i.e. 1.0mg/kg Bisphenol A in sample) and the result satisfies our requirement (± 50% Recovery, within 10 times of spike range).

5.4 The Reporting Limit: Since actual MDL is 0.05mg/L, the reporting limit is calculated as below:
The reporting limit, mg/kg = (Actual MDL) x V/W
Where,
V = Final volume of ACN: H2O=1:1, 20mL
W = Sample weight, approximate 1.0g

Therefore, the Reporting Limit is 1.0mg/kg.

5.5 Bias Check: Proceed 7 set of spike sample trials at each concentration. The average recovery is 92.0%. RSD is less than 10%, which satisfy our requirements (Recovery is within 80-120% and RSD<20%).

5.6 Precision Check: Proceed 2* 7 set of spike sample trials at each concentration. The average recovery is 84.9% and 92.0%, respectively. Both RSD is less than 10%, which satisfy our requirements (RSD<20%).

大致看了一下，基本上该做的都做了，线性，检出限（仪器的、方法的），精密度，回收率，其他的就不太了解了，好像方法就包括这几项吧？没发现什么不合适的