| With the expanding application of plant growth regulators（PGR）,the determination of PGR residues has become an important part of food health and environmental safety monitoring.In this paper,ion chromatography（IC）and ion chromatography-mass spectrometry（IC-MS/MS）methods for the determination of nine polar PGRs（maleic hydrazide,abscisic acid,glyphosine,fosamine ammonium,ethephon,2,4-D,NAA,AMPA and bentazone）were established,the recovery and specificity of each method were investigated.Meanwhile,the practical application of these methods was studied.The study found that the methods were highly sensitive,specific,and well applied.The main research contents and achievements are as follows:（1）IC methods for the determination of nine PGRs were established.Using Dionex Ion Pac AS11-HC,AS19 and AS20 column as separation columns,and KOH were used as the mobile phase in gradient elution.The separation and analysis of nine PGRs were accomplished by optimizing gradient programs,flow rates and column temperatures.Maleic hydrazide,abscisic acid and glyphosine were detected by AS11-HC column.Fosamine ammonium,ethephon,2,4-D,NAA and AMPA were detected by AS19 column.Bentazone was detected by AS20 column.The results showed that the three IC methods had good linear relationship（R~2>0.999）within a certain mass concentration range.The limits of detection（LOD）were in the range of 0.01～0.53 mg/kg and the limits of quantification（LOQ）were in the range of 0.04～1.75 mg/kg.The average recoveries of nine PGRs ranged from 76.9%to 116.0%and the relative standard deviations（RSDs,n=6）ranged from 0.8%to 5.3%with the addition of standard concentrations of 5.0,10.0 and 20.0 mg/L.The results showed that the IC methods could complete the separation analysis of nine polar PGRs.There are also shortcomings in the IC methods for some substances,such as the LOQ cannot reach the needs of residue limit standards in GB2763-2021:National Food Safety Standard—Maximum Residue Limits for Pesticide Residues in Food（Regulations）.Further research is needed on this issue.（2）IC-MS/MS methods for the determination of nine PGRs were established.Dionex Ion Pac AS11-HC,AS19 and AS20 columns were used as separation columns.Ion chromatography was used for separation followed by triple quadrupole mass spectrometry detection.Compared with the IC methods,the IC-MS/MS determination methods have the advantages of rapidity,high efficiency,and strong specificity.The study found that it not only reduces the LOD and LOQ of the methods by nearly 1000 times,but also shortens the detection time of the methods by more than 10 minutes.The results showed that three IC-MS/MS methods had good linear relationship（R~2>0.999）within a certain mass concentration range.The LOD and LOQ of nine PGRs were reduced to 0.04～1.28μg/kg and 0.13～4.26μg/kg by IC-MS/MS methods.The average recoveries of the nine PGRs ranged from 75.9%to 112.1%and the RSDs（n=6）ranged from 1.2%to 6.8%with the addition of standard concentrations of 20.0and 50.0μg/L.The results showed that the IC-MS/MS methods for nine PGRs have accurate qualitative and low detection limits,which comprehensively makes up for the deficiencies of IC methods.（3）The extraction effects of three pretreatment methods and the specificity of IC and IC-MS/MS methods were studied.Nine PGRs were extracted from eight kinds of samples（orange,grape,tomato,corn,apple,potato,soybean,onion）by solid phase extraction purification（SPE）,accelerated solvent extraction（ASE）and centrifugal ultrafiltration.The results showed that centrifuge ultrafiltration method had higher extraction recoveries than SPE and ASE method.The extraction recoveries of nine PGRs in different samples ranged from 75.9%to 112.1%,with high extraction efficiency and good purification effect.Nine PGRs standard samples at 5.0,10.0 and 20.0 mg/L were added to the blank solvent and sample matrix to investigate the specificity of the IC methods.Nine PGRs standard samples at 20.0 and 50.0μg/L were added to the blank solvent and sample to investigate the specificity of IC-MS/MS methods.The results showed that the IC methods and IC-MS/MS methods of nine PGRs had strong specificity and good stability,which met the requirements of qualitative and quantitative detection.（4）The application effect of IC-MS/MS methods for the determination of nine PGRs was studied.The optimized IC-MS/MS method was used to detect the PGR residues in commercial food sample.The results showed that the detection rates of nine PGRs were high,and the residues amount were low,which all met the limit standards of Regulations.Meanwhile,using these methods to detect the samples of a poisoning case in Nanjing.The possibility of four kinds of organophosphorus PGRs poisoning were successfully ruled out by IC-MS/MS methods,which provided direction for the investigation of the case.The results showed that the IC-MS/MS determination methods of nine polar PGRs have good application effect,which can provide methods for environmental health supervision and guidance for food safety cases. |
