LIS 45 Study Summary
These tables summarize the measurements reported to the QA-SAC for the 45th Laboratory Intercomparison Study. A total of 78 laboratories reported measurements. Some measurements were missing or below the analytical detection limit (DL). N designates the number of reported values above the DL. Target values were provided by the reference laboratory. At the center of each set of N measurements is the Median or accepted target value of the set. Sigmas were estimated from the interquartile ranges and can be used to calculate Z-values. Half of the N measurements are within the 25th to 75th percentiles, which defines the range of Good measurements. Satisfactory measurements fall within the range defined by the Median ± Sigma. The limits for a measurement that Meets Data Quality Objectives are defined on page 4 of the Manual for the GAW Precipitation Chemistry Programme.
Email any questions you have to manager@qasac-americas.org.
Last update: June 20, 2017, 11:48 am
Sample 1 Results
Measurement | Units | N | Target | Median | Sigmaest. | Good (25th to 75th percentiles) | Satisfactory (Median ± Sigma) | Meets Data Quality Objectives | |||
---|---|---|---|---|---|---|---|---|---|---|---|
pH | pH units | 69 | 4.68 | 4.71 | 0.06 | 4.67 | 4.76 | 4.65 | 4.77 | 4.64 | 4.78 |
Conductivity | μS/cm | 65 | 22.0 | 21.7 | 1.2 | 20.7 | 22.3 | 20.5 | 22.9 | 20.2 | 23.2 |
Acidity (optional) | μeq/L | 8 | N/A | 21.3 | 9.9 | 17.5 | 30.8 | 11.4 | 31.1 | 16.0 | 26.5 |
Sulfate as SO42- | mg/L | 69 | 2.435 | 2.436 | 0.118 | 2.363 | 2.522 | 2.318 | 2.554 | 2.266 | 2.606 |
Nitrate as NO3- | mg/L | 73 | 1.230 | 1.213 | 0.047 | 1.176 | 1.240 | 1.166 | 1.260 | 1.129 | 1.297 |
Ammonium as NH4+ | mg/L | 70 | 0.447 | 0.452 | 0.026 | 0.437 | 0.471 | 0.426 | 0.477 | 0.420 | 0.483 |
Fluoride (optional) | mg/L | 17 | 0.020 | 0.021 | 0.006 | 0.016 | 0.024 | 0.015 | 0.027 | N/A | N/A |
Chloride | mg/L | 68 | 1.620 | 1.600 | 0.048 | 1.566 | 1.632 | 1.552 | 1.648 | 1.440 | 1.760 |
Sodium | mg/L | 68 | 1.035 | 1.019 | 0.048 | 0.991 | 1.056 | 0.971 | 1.067 | 0.918 | 1.120 |
Potassium | mg/L | 64 | 0.183 | 0.180 | 0.013 | 0.170 | 0.187 | 0.167 | 0.193 | 0.144 | 0.216 |
Calcium | mg/L | 67 | 0.240 | 0.239 | 0.026 | 0.220 | 0.256 | 0.213 | 0.265 | 0.204 | 0.274 |
Magnesium | mg/L | 66 | 0.123 | 0.120 | 0.012 | 0.113 | 0.129 | 0.108 | 0.132 | 0.108 | 0.132 |
Sample 2 Results
Measurement | Units | N | Target | Median | Sigmaest. | Good (25th to 75th percentiles) | Satisfactory (Median ± Sigma) | Meets Data Quality Objectives | |||
---|---|---|---|---|---|---|---|---|---|---|---|
pH | pH units | 69 | 4.72 | 4.74 | 0.07 | 4.70 | 4.80 | 4.67 | 4.81 | 4.67 | 4.81 |
Conductivity | μS/cm | 65 | 11.5 | 11.8 | 1.0 | 10.8 | 12.2 | 10.8 | 12.8 | 11.0 | 12.6 |
Acidity (optional) | μeq/L | 8 | N/A | 18.8 | 8.8 | 15.8 | 27.8 | 10.0 | 27.6 | 14.1 | 23.5 |
Sulfate as SO42- | mg/L | 68 | 1.028 | 1.041 | 0.064 | 0.995 | 1.081 | 0.977 | 1.105 | 0.969 | 1.113 |
Nitrate as NO3- | mg/L | 73 | 1.107 | 1.117 | 0.051 | 1.077 | 1.146 | 1.066 | 1.168 | 1.039 | 1.195 |
Ammonium as NH4+ | mg/L | 70 | 0.210 | 0.211 | 0.017 | 0.203 | 0.227 | 0.194 | 0.228 | 0.197 | 0.225 |
Fluoride (optional) | mg/L | 19 | 0.020 | 0.020 | 0.006 | 0.017 | 0.026 | 0.014 | 0.026 | N/A | N/A |
Chloride | mg/L | 67 | 0.120 | 0.120 | 0.021 | 0.112 | 0.141 | 0.099 | 0.141 | 0.108 | 0.132 |
Sodium | mg/L | 60 | 0.084 | 0.081 | 0.010 | 0.074 | 0.086 | 0.071 | 0.091 | 0.073 | 0.089 |
Potassium | mg/L | 56 | 0.031 | 0.031 | 0.008 | 0.025 | 0.036 | 0.023 | 0.039 | 0.025 | 0.037 |
Calcium | mg/L | 64 | 0.110 | 0.112 | 0.014 | 0.103 | 0.122 | 0.098 | 0.126 | 0.096 | 0.128 |
Magnesium | mg/L | 59 | 0.043 | 0.043 | 0.005 | 0.040 | 0.048 | 0.038 | 0.048 | 0.039 | 0.047 |
Sample 3 Results
Measurement | Units | N | Target | Median | Sigmaest. | Good (25th to 75th percentiles) | Satisfactory (Median ± Sigma) | Meets Data Quality Objectives | |||
---|---|---|---|---|---|---|---|---|---|---|---|
pH | pH units | 69 | 4.59 | 4.60 | 0.06 | 4.56 | 4.65 | 4.54 | 4.66 | 4.53 | 4.67 |
Conductivity | μS/cm | 65 | 38.4 | 37.9 | 2.0 | 36.3 | 39.0 | 35.9 | 39.9 | 35.3 | 40.5 |
Acidity (optional) | μeq/L | 8 | N/A | 28.1 | 11.6 | 23.1 | 38.7 | 16.5 | 39.7 | 21.1 | 35.1 |
Sulfate as SO42- | mg/L | 69 | 4.262 | 4.320 | 0.235 | 4.147 | 4.464 | 4.085 | 4.555 | 4.018 | 4.622 |
Nitrate as NO3- | mg/L | 72 | 2.148 | 2.145 | 0.091 | 2.077 | 2.200 | 2.054 | 2.236 | 1.995 | 2.295 |
Ammonium as NH4+ | mg/L | 69 | 0.775 | 0.778 | 0.058 | 0.740 | 0.818 | 0.720 | 0.836 | 0.724 | 0.832 |
Fluoride (optional) | mg/L | 23 | 0.100 | 0.097 | 0.014 | 0.085 | 0.105 | 0.083 | 0.111 | N/A | N/A |
Chloride | mg/L | 67 | 3.591 | 3.593 | 0.118 | 3.530 | 3.690 | 3.475 | 3.711 | 3.234 | 3.952 |
Sodium | mg/L | 67 | 2.301 | 2.312 | 0.095 | 2.236 | 2.365 | 2.217 | 2.407 | 2.081 | 2.543 |
Potassium | mg/L | 67 | 0.390 | 0.390 | 0.025 | 0.368 | 0.403 | 0.365 | 0.415 | 0.312 | 0.468 |
Calcium | mg/L | 68 | 0.623 | 0.612 | 0.037 | 0.583 | 0.633 | 0.575 | 0.649 | 0.521 | 0.703 |
Magnesium | mg/L | 66 | 0.248 | 0.248 | 0.013 | 0.238 | 0.256 | 0.235 | 0.260 | 0.223 | 0.272 |