Objective: To establish a high performance liquid chromatography method for the simultaneous determination of dimethyl oxalate (DMO) and diethyl oxalate (DEO) in workplace air. Methods: From January 2022 to January 2023, air samples were collected by silica gel tubes, desorbed by acetonitrile, separated by C18 chromatographic column, detected by photo-array detector, and retention time was used to characterize and peak area was used to quantify at 210 nm wavelength. Results: The linear relationships of DMO and DEO were good, r>0.999. The detection limits of DMO and DEO were 0.39 and 0.52 μg/ml, respectively. The quantitative limit was 1.28 μg/ml for DMO and 1.72 μg/ml for DEO. Average desorption efficiency for DMO was 82.40%-92.72%, and DEO was 94.13%-97.69%. The intra-assay precision of DMO was 1.87%-6.18%, and DEO was 2.25%-3.31%. Inter-assay precision of DMO was 3.29%-5.73%, and DEO was 1.38%-2.94%. Average sampling efficiencies were 100% for both DMO and DEO. Breakthrough capacity of DMO was 37.61 mg (200 mg solid adsorbent), DEO was >28.11 mg (200 mg solid adsorbent). Samples should be stored at 4 ℃ for at least 7 days. Conclusion: This method is easy to operate and has strong practicability. All indicators meet the requirements of the specification, and it is suitable for the simultaneous determination of DMO and DEO in the workplace air.
目的： 建立工作场所空气中草酸二甲酯（DMO）和草酸二乙酯（DEO）同时测定的高效液相色谱检测方法。 方法： 于2022年1月至2023年1月，空气样品采用硅胶管采集，乙腈洗脱解吸，经C18色谱柱分离，二极管阵列检测器检测，在210 nm波长下，以保留时间定性，峰面积定量。 结果： DMO和DEO测定方法的线性关系良好，r>0.999。DMO和DEO的方法检出限分别为0.39 μg/ml、0.52 μg/ml，方法定量下限分别为1.28 μg/ml、1.72 μg/ml。DMO和DEO的平均解吸效率分别为82.40%~92.72%、94.13%~97.69%，批内精密度分别为1.87%~6.18%、2.25%~3.31%，批间精密度分别为3.29%~5.73%、1.38%~2.94%。平均采样效率均为100%。DMO穿透容量为37.61 mg（200 mg固体吸附剂），DEO穿透容量为>28.11 mg（200 mg固体吸附剂）。在4 ℃条件下样品至少可以保存7 d。 结论： 该方法操作简便、实用性强，各项指标均满足规范要求，适用于工作场所空气中DMO和DEO的同时测定。.

Objective: To establish an HPLC method for determining p-Anisidine in workplace air. Methods: An C(18) capillary column was used with the detection wavelength of 240 nm, the methanol solution (v/v=62:38) as mobile phase, the flow rate was 0.9 ml/min, and the injection volume was 20 μl. Results: The linear range (μg/ml) for p-Anisidine was 0~100; correlation coefficient was 0.999 7; the detection limit was 0.15 μg/ml; the average precision of RSD was 4.4%. The sampling efficiency was more than 95% using silicone tube as sampling filter. Sample can be stored at room temperature for more than 7 d. Conclusion: the method appered to be accurate, simple, sensitive and reliable, also have a high sampling efficiency, and can be usd to determine p-anisidine in workplace air simultaneously.
目的： 建立工作场所空气中对氨基苯甲醚的高效液相色谱检测法。 方法： 采用高效液相色谱法,色谱柱为C(18)柱，流动相为甲醇：纯水=62:38（v/v），流速0.9 ml/min，检测波长240 nm，进样体积20 μl。 结果： 该方法测定对氨基苯甲醚线性范围（μg/ml）为0~100；相关系数（r）0.999 7；最低检出限为0.15 μg/ml；平均精密度RSD为4.4 %。以硅胶管为采样滤料，采样效率>95 %。样品室温下可保存7 d以上。 结论： 该方法采样效率高，操作简便，精密度和灵敏度较高，可以满足工作场所空气中对氨基苯甲醚的测定。.

A tandem mass spectrometry method combined with an ion-pair chromatographic separation after weak cation exchange solid phase sample extraction for epinephrine (E), norepinephrine (NE) and dopamine (DA) has been developed. Two surrogate matrixes for plasma and urine as well as stable isotope labeled internal standards were utilized for quantitation. The observed dynamic range of E, NE and DA was 0.025-100ng/ml for plasma, and 0.25-1000ng/ml for urine with a r(2) regression coefficient >0.99. Extraction recoveries were greater than 60% and the lower limit of quantitation was 25pg/ml for all three analytes in plasma. This method provided excellent sensitivity and selectivity for use with small sample volumes (≤25uL), enabling high-throughput pharmacodynamic animal model development and screening of adverse effects.