1.Validation Overview
Item:Method Validation Report for Cr(Ⅵ) in Soil & Sediment
REF: HJ 1082—2019Instrument:AA-1800E Atomic Absorption Spectrometer
2.Instrument Conditions
2.1 Main Parameters
Wavelength: 357.9 nm
Bandwidth: 0.4 nm
Lamp current: 6 mA
Burner height: 8 mm
Burner: 50 mm Ti head
Acetylene: 1.8 L/min
Air: 8.5 L/min
Integration: 3 s
Mode: Peak height
Replicates: 3, averaged
2.2 Instrument Performance
| Item | Spec | Actual | Conclusion |
|---|---|---|---|
| Static Baseline Drift | ≤±0.002A/30min | ±0.0012A/30m | Pass |
| Dynamic Baseline Drif | ≤±0.005A/30min | ±0.0028A/30min | Pass |
| Precision（RSD） | ≤0.5% | 0.32% | Pass |
| Wavelength Accuracy | ≤0.15nm | 0.08nm | Pass |
3.Calibration Curve Validation
3.1 Standard Solution Prep
Certified 1000 mg/L Cr(Ⅵ) stock, serially diluted by 0.1 mol/L NaOH:
| No. | Conc.（mg/L） | Method |
|---|---|---|
| 0 | 0.00 | Blank（0.1 mol/L NaOH） |
| 1 | 0.50 | Serial dilution |
| 2 | 1.00 | Serial dilution |
| 3 | 2.00 | Serial dilution |
| 4 | 4.00 | Serial dilution |
| 5 | 6.00 | Serial dilution |
| 6 | 8.00 | Serial dilution |
3.2 Calibration Curve Data
| Conc.（mg/L） | A1 | A2 | A3 | Average |
|---|---|---|---|---|
| 0.00 | 0.0012 | 0.0010 | 0.0011 | 0.0011 |
| 0.50 | 0.0825 | 0.0831 | 0.0828 | 0.0828 |
| 1.00 | 0.1652 | 0.1648 | 0.1655 | 0.1652 |
| 2.00 | 0.3298 | 0.3305 | 0.3292 | 0.3300 |
| 4.00 | 0.6585 | 0.6592 | 0.6578 | 0.6585 |
| 6.00 | 0.9852 | 0.9845 | 0.9858 | 0.9852 |
| 8.00 | 1.3125 | 1.3118 | 1.3132 | 1.3125 |
3.3 Curve Fitting Result
Regression：y = 0.1641x + 0.0008
Correlation coefficient：（r）0.9998
Intercept：0.0008
Slope：0.1641
Criterion：r ≥ 0.999Conclusion：r = 0.9998，meets requirement
4. MDL & LOQ Verification
4.1 Method Detection Limit (MDL) Test
Per HJ 1082-2019, with 5.0 g soil sample and final volume 100 mL, MDL = 0.5 mg/kg .
Test procedure：
Prepare standard solution near detection limit（0.1 mg/L）
Measure for 7 consecutive runs
Calculate MDL = t × S (t=3.143, df=6, 99% confidence)
| No. | Absorbance | Conc.（mg/L） |
|---|---|---|
| 1 | 0.0165 | 0.100 |
| 2 | 0.0158 | 0.096 |
| 3 | 0.0172 | 0.104 |
| 4 | 0.0161 | 0.098 |
| 5 | 0.0168 | 0.102 |
| 6 | 0.0155 | 0.094 |
| 7 | 0.0163 | 0.099 |
Calculation：
Mean：0.099 mg/L
S：0.0035 mg/L
MDL = 3.143 × 0.0035 = 0.011 mg/L（soln）
Soil MDL：0.011 × 100 / 5.0 = 0.22 mg/kg
4.2 LOQ Verification
| Item | Spec | Result | Conclusion |
|---|---|---|---|
| MDL | 0.5 mg/kg | 0.22 mg/kg | Exceeds spec |
| LOQ | 2.0 mg/kg | 0.88 mg/kg | Exceeds spec |
Rule: LOQ=4×MDL
Verdict: MDL & LOQ comply with HJ1082 2019
5. Precision Verification
5.1 Scheme
HJ1082 2019: low/med/high levels, 6 parallels each
| Level | Spike（mg/kg） | Soln（mg/L） |
|---|---|---|
| Low | 2.0 | 0.10 |
| Med | 10.0 | 0.50 |
| High | 40.0 | 2.00 |
5.2 Precision Test Results
Low level（2.0 mg/kg）
| No. | Result（mg/kg） |
|---|---|
| 1 | 2.08 |
| 2 | 2.12 |
| 3 | 2.05 |
| 4 | 2.10 |
| 5 | 2.07 |
| 6 | 2.09 |
Mean：2.08 mg/kg
Std Dev：0.029 mg/kg
RSD = 1.40%Medium level（10.0 mg/kg）
| No. | Result（mg/kg） |
|---|---|
| 1 | 10.15 |
| 2 | 10.22 |
| 3 | 10.08 |
| 4 | 10.18 |
| 5 | 10.12 |
| 6 | 10.20 |
Mean：10.15 mg/kg
Std Dev：0.057 mg/kg
RSD = 0.56%
High level（40.0 mg/kg）
| No. | Result（mg/kg） |
|---|---|
| 1 | 40.25 |
| 2 | 40.18 |
| 3 | 40.32 |
| 4 | 40.20 |
| 5 | 40.28 |
| 6 | 40.15 |
Mean：40.22 mg/kg
Std Dev.：0.065 mg/kg
RSD = 0.16%
5.3 Precision Conclusion
| Level | Spike（mg/kg） | RSD（%） | Spec | Result |
|---|---|---|---|---|
| Low | 2.0 | 1.40 | ≤10% | Pass |
| Med | 10.0 | 0.56 | ≤5% | Pass |
| High | 40.0 | 0.16 | ≤5% | Pass |
Rule: HJ1082 2019: RSD ≤10%(low), ≤5%(med/high) Verdict: All three levels comply, precision qualified.
6. Accuracy Verification
6.1 Scheme
Accuracy was verified using certified soil reference material via spike recovery test.
Reference material information：
Name: Certified Reference Material for Hexavalent Chromium in Soil
CRM：RMH-A048
Certified Cr(VI)：28.8 mg/kg
Uncertainty：±2.5 mg/kg
6.2 Spike Recovery
Low spike（2.0 mg/kg）
| No. | Background（mg/kg） | Spiked（mg/kg） | Recovery（%） |
|---|---|---|---|
| 1 | 0.12 | 2.18 | 103.0 |
| 2 | 0.15 | 2.22 | 102.7 |
| 3 | 0.10 | 2.15 | 103.5 |
| 4 | 0.13 | 2.20 | 103.1 |
| 5 | 0.11 | 2.17 | 103.3 |
| 6 | 0.14 | 2.21 | 102.9 |
Avg recovery：103.1%
Recovery range：102.7% ~ 103.5%
Medium spike（10.0 mg/kg）
| No. | Background（mg/kg） | Spiked（mg/kg） | Recovery（%） |
|---|---|---|---|
| 1 | 0.15 | 10.28 | 101.3 |
| 2 | 0.12 | 10.22 | 101.0 |
| 3 | 0.18 | 10.35 | 101.7 |
| 4 | 0.14 | 10.25 | 101.1 |
| 5 | 0.16 | 10.30 | 101.4 |
| 6 | 0.13 | 10.23 | 101.0 |
Avg recovery：101.3%
Range：101.0% ~ 101.7%
High spike（40.0 mg/kg）
| No. | Background（mg/kg） | Spiked（mg/kg） | Recovery（%） |
|---|---|---|---|
| 1 | 0.18 | 40.35 | 99.9 |
| 2 | 0.15 | 40.28 | 99.7 |
| 3 | 0.20 | 40.42 | 100.0 |
| 4 | 0.17 | 40.32 | 99.8 |
| 5 | 0.19 | 40.38 | 99.9 |
| 6 | 0.16 | 40.25 | 99.6 |
Avg recovery：99.8%
Range：99.6% ~ 100.0%
6.3 CRM Verification
Soil CRM RMH A048 (certified value 28.8 mg/kg) was tested：
| No. | Measured（mg/kg） |
|---|---|
| 1 | 28.52 |
| 2 | 28.68 |
| 3 | 28.75 |
| 4 | 28.62 |
| 5 | 28.70 |
| 6 | 28.65 |
Mean：28.65 mg/kg
Certified value：28.8 mg/kg
Relative error：(28.65 – 28.8) / 28.8 × 100% = -0.52%
RSD：0.28%
Criterion：CRM measured value shall lie within certified uncertainty interval.Verdict: 28.65 mg/kg falls in 28.8 ± 2.5 mg/kg, compliant
6.4 Accuracy Conclusion
| Level | Spike（mg/kg） | Avg Recovery（%） | Spec | Result |
|---|---|---|---|---|
| Low | 2.0 | 103.1 | 85%~115% | Pass |
| Med | 10.0 | 101.3 | 90%~110% | Pass |
| High | 40.0 | 99.8 | 90%~110% | Pass |
| CRM | 28.8 | RE-0.52% | ≤10% | Pass |
Verdict: Recoveries of three levels and CRM test satisfy criteria, method accuracy qualified.
7. Actual Sample Verification
7.1 Sample Information
| Sample ID | Type | Location | Date |
|---|---|---|---|
| SP-2026-001 | Soil | Industrial park,Shanghai | 2026-06-28 |
| SP-2026-002 | Sediment | River channel, Shanghai | 2026-06-29 |
| SP-2026-003 | Soil | Farmland, Shanghai | 2026-06-30 |
7.2 Test Results
| Sample ID | test 1（mg/kg） | test 2（mg/kg） | test 3（mg/kg） | AVG（mg/kg） | RSD（%） |
|---|---|---|---|---|---|
| SP-2026-001 | 3.25 | 3.32 | 3.28 | 3.28 | 1.08 |
| SP-2026-002 | 1.85 | 1.92 | 1.88 | 1.88 | 1.89 |
| SP-2026-003 | 0.42 | 0.45 | 0.43 | 0.43 | 3.45 |
7.3 Actual Sample Spike Test
| Sample ID | Spike（mg/kg） | Measured（mg/kg） | Recovery（%） |
|---|---|---|---|
| SP-2026-001 | 10.0 | 13.35 | 100.7 |
| SP-2026-002 | 10.0 | 11.92 | 100.5 |
| SP-2026-003 | 10.0 | 10.48 | 100.5 |
Conclusion: Actual sample results are reasonable; spike recoveries 95%–105%. This method is suitable for real sample analysis
8.Whole-process Sample Preparation Verification
8.1 Sample Preparation Process
In accordance with the requirements of HJ 1082-2019, the validation covers the entire process, including sample preparation：
Collection & storage: Stainless steel sampler, 4℃ preservation, test within 24 h
Pretreatment: Air dry, grind, 0.15 mm sieve
Alkaline extraction: 5.0 g sample + 50 mL 0.1 mol/L NaOH, shake 30 min
Centrifuge: 4000 r/min, 10 min
Test: Direct injection of supernatant
8.2 Verification Results
| Item | Content | Result | Conclusion |
|---|---|---|---|
| Sample Representativeness | Homogeneity check | RD<5% | Pass |
| Extraction Efficiency | Spike recovery | 99.8%~103.1% | Pass |
| Operation Compliance | SOP execution | MeetHJ 1082-2019 | Pass |
| Data Integrity | Traceable raw data | Complete | Pass |
9. Verification Conclusion
9.1 Comprehensive Assessment
| Item | Result | Compliance HJ 1082-2019 |
|---|---|---|
| Instrument | Parameters reasonable,performance qualified | Compliant |
| Calibration Curve | r = 0.9998 | Compliant（r≥0.999） |
| MDL | 0.22 mg/kg | Better than（0.5 mg/kg） |
| Quant Limit | 0.88 mg/kg | Better than（2.0 mg/kg） |
| Precision | RSD = 0.16%~1.40% | Compliant（≤5%~10%） |
| Accuracy | Recovery 99.8%~103.1% | Compliant（85%~115%） |
| Real Samples | Valid results,recovery100.5%~100.7% | Compliant |
| Sample Prep | Full process standardized | Compliant |
9.2 Final Conclusion
Validated with AA 1800E AAS per HJ 1082 2019 for Cr(VI) in soil & sediment. All performance indicators satisfy requirements. Sample preparation is standardized, data traceable. Method is qualified for routine analysis.
10. Document Information
Validation Organization: Shanghai Macylab Instrument Inc.
Report No.: MACY-2026-0705
Validation Date: July 05, 2026
This application validation report is applicable to the sample and test conditions described in this document. Reproduction or distribution of this report, in whole or in part, requires prior written authorization from Shanghai Macylab Instrument Inc.
2026 Shanghai Macylab Instrument Inc. All rights reserved.
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