<<< Back to Sampling and Analytical Methods Link to Printing Instructions Printing Instructions

For problems with accessibility in using figures, illustrations and PDFs in this method, please contact
the SLTC at (801) 233-4900. These procedures were designed and tested for internal use by OSHA personnel.
Mention of any company name or commercial product does not constitute endorsement by OSHA.

Apron

Related Information: Chemical Sampling - Apron
Method no.: PV2102
    
Control no.: T-PV2102-01-8709-CH
    
Matrix: Air
   
Target Concentration: 5 mg/m3 (arbitrary). There is no OSHA PEL or ACGIH TLV for Apron.
   
Procedure: Samples are collected by drawing 60 L of air through glass fiber filters. Samples are extracted with acetonitrile and analyzed by high performance liquid chromatography (HPLC).
   
Recommended air volume and sampling rate studied: 60 L at 1 L/min
   
Detection limit of the overall procedure based on the recommended air volume: 0.02 mg/m3
   
Status of method: Stopgap method. This method has been only partially evaluated and is presented for information and trial use.
   
Date: September 1987
   
Chemist: Yihlin Chan
   
Carcinogen and Pesticide Branch
OSHA Analytical Laboratory
Sandy, Utah


1.  General discussion
1.1 Background

The OSHA Analytical Laboratory received a set of samples for which an analysis of Apron was requested. The air samples had been collected on glass fiber filters at a flow rate of 1 L/min. This report describes the analytical method developed for Apron and a preliminary validation of glass fiber filter as the sampling medium. 

1.2 Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy.)
 
The oral LD50 of Apron is 669 mg/kg in rats. The acute dermal LD50 is >3100 mg/kg for rats. It is relatively non-toxic to fish and wildlife. (Ref. 5.1

1.3 Potential workplace exposure (Ref. 5.3)
 
Apron is used as a fungicide in agricultural applications. No estimate of worker exposure during its production, formulation and use as a fungicide could be found. 

1.4 Physical properties (Ref. 5.1 and 5.2)

Chemical name: N-(2,6-Dimethylphenyl)-N-(methoxyacetyl) -DL-alanine methyl ester
Synonym: Apron 2E; CG 117; CGA 48988; Metalaxil; Ridomil; Ridomil 2E; Subdue; Subdue 2E; Subdue 5SP; N-(Methoxyacetyl)-N-(2,6-xylyl)-DL-alanine methyl ester
CAS no.: 57837-19-1
Molecular formula: C15H21NO4
Molecular weight: 279.37
Appearance: White crystals
Melting point: 71-72C
Vapor pressure: 2.210-6 mmHg at 20C
 
Structure:     

structure of Apron

    
Solubility: Solubility in water at 20C: 7.1 g/L. Readily soluble in most organic solvents. 
UV scan: For problems with accessibility in using figures please contact the SLTC at (801) 233-4900.
1.5 Detection limit of the analytical procedure

The detection limit of the analytical procedure is 4.3 ng per injection. 
2. Sampling procedure
2.1 Apparatus and reagents
2.1.1 A personal sampling pump that can be calibrated to within 5% of the recommended flow rate.
 
2.1.2 Glass fiber filter, 37-mm diameter, Gelman Type A, or equivalent. 

2.1.3 Filter holder for 37-mm filters, Millipore M000037A0, or equivalent.
2.2 Sampling procedure  

Use standard air sampling technique as specified in OSHA Instruction CPL 2-2.20A, Chapter II: Standard Methods for Sampling Air Contaminants. 

2.3 Recommended air volume and sampling rate

2.3.1 The recommended air volume is 60 L. 

2.3.2 The recommended sampling rate is 1 L/min.
2.4 Extraction efficiency

Three glass fiber filters were each spiked with 16.35 g of Apron. The filters were extracted with 5.0 mL of acetonitrile and analyzed. The average recovery of Apron was 100.4%.

    Sample Apron recovered    Recovery

YC1 16.07 g      98.3%
YC2 16.60 g     101.5%
YC3 16.56 g     101.3%
Average  = 100.4%


2.5 Retention efficiency

Three glass fiber filters were each spiked with 16.35 g of Apron. Humid air (50% RH, 183 L @ 1 L/min) was drawn through the filters. The filters were extracted with 5.0 mL of acetonitrile and analyzed. The average recovery of Apron was 97.9%.

Sample Apron recovered Recovery

    YC7 15.46 g   94.6%
    YC8 16.40 g  100.3%
    YC9 16.13 g   98.7%
Average = 97.9%

2.5 Storage

Three glass fiber filters were each spiked with 16.35 g of Apron. Humid air (50% RH, 183 min @ 1 L/min) was drawn through the filters. The filters were stored at room temperature for 5 days, extracted with acetonitrile, and analyzed. The average recovery of Apron was 104.9%.

Sample Apron recovered Recovery

YC10 17.05 g  104.3%
YC11 17.05 g  104.3%
YC12 17.33 g  106.0%
Average = 104.9% 

2.6 Interferences
 
There are no known interferences to the sampling procedure.
3. Analytical method
3.1 Apparatus
3.1.1 High performance liquid chromatograph. 

3.1.2 Alltech C18 column or equivalent. 

3.1.3 UV detector.
 
3.1.4 Stripchart recorder.
3.2 Reagents
3.2.1 Water, HPLC grade.
 
3.2.2 Acetonitrile, HPLC grade.
 
3.2.3 Apron (Ridomil), EPA standard # F701. 
3.3 Standard preparation

Weigh 2 to 4 mg of Apron in a 10-mL volumetric flask. Add acetonitrile to the mark. Dilute with acetonitrile to a suitable working range. 

3.4 Sample preparation

Samples were extracted with 5.0 mL of acetonitrile, 30 minutes on a mechanical shaker.  

3.5 Analysis

3.5.1 Instrument conditions
Column: Alltech C18
Mobile phase: 60% acetonitrile, 40% water
Detector: 198 nm (primary), 214 nm
Flow rate: 1.0 mL/min
Injection size: 25 L
Retention time: 7.0 min
3.5.2 Chromatogram

For problems with accessibility in using figures please contact the SLTC at (801) 233-4900.  
Figure 1. HPLC Chromatogram of Apron.
3.6 Interferences
3.6.1 Any collected compound that has the same retention time as Apron and absorbs at 198 and 214 nm is an interference.
 
3.6.2 HPLC parameters may be varied to circumvent most interferences.
 
3.6.3 Retention time alone is not proof of a chemical identity. Confirmation by other means should be sought when possible.
3.7 Calculations
3.7.1 A calibration curve is constructed by plotting standard concentrations versus detector response. 

3.7.2 The concentration of a sample is determined from the calibration curve.


For problems with accessibility in using figures please contact the SLTC at (801) 233-4900.  
Figure 2.  Calibration curve of Apron.
 
3.7.3 The air concentration is determined by the formula: 
 
mg/m3 = (g/mL)(5 mL)

(air volume, L)(extraction efficiency)
 
4. Recommendations for further study

The method should be fully validated. 

5. References
5.1 Registry of Toxic Effects of Chemical Substances, 1983-84 Supplement, DHHS (NIOSH) Publication No. 86-103, Cincinnati, Ohio, 1986.
 
5.2 Merck Index, Tenth Edition, Merck & Co., Rahway, N.J., 1983.
 
5.3 Farm Chemicals Handbook, Meister Publishing, Willoughby, Ohio, 1981.